GTA
All Springer/NP/PCP Air Gun Discussion General => European/Asian Air Gun Gates => German AirGun Gate => Topic started by: jusanothajoe on May 10, 2017, 08:32:17 PM
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Recently acquired an HW85 in .22
Got a new Hawke Vantage 4-12X40 mounted this weekend and have been shooting the gun every afternoon this week.
Have heard others talk about first or second cold bore shots might hit low.
I have the opposite problem, my first few shots will be on target, then as I shoot more the POI starts dropping. :o
Today with the gun cold I shot 5 shots over chrony, avg was 706 fps.
Then I shot 30 more shots. POI dropped 1.5 in at 15 yards.
The shots will group for 3-4 shots then migrate down a little, then repeat.
Immediately after the 30 shots with a 1.5 in drop in POI, I shot 5 more over chrony and avg was 708 fps.
The next day when gun is cold POI will be back on POA.
What say yee ?
I suspect a scope problem BUT, the POI shift is in a straight vertical line ? No horizontal shift at all.
But would a bad scope right itself overnight ?
Did the tissue test on breach seal and could see no movement in tissue.
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It sounds like a piston seal to me. Try your chronograph when it's cold and shooting well. Check again after it starts dropping. I suspect your velocity will be down by then.
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It sounds like a piston seal to me. Try your chronograph when it's cold and shooting well. Check again after it starts dropping. I suspect your velocity will be down by then.
If you look in my post, I did try that.
Avg FPS was up a little after the drop ?
But I only did a 5 shot string on both.
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That's a good one there... Got me! :o
Sounds like an overly tight piston seal, or dieseling, but your velocity doesn't back that theory up.
A breech seal breaking in or taking a set can cause stringing, but usually upwards.
Double check and make sure the scope isnt sliding back. Can't hurt to check.
HWs in .22 tend to have really tight chokes often times. May try scrubbing it out real good and lubing your pellets. Usually this will cause some pretty lame accuracy, but what the heck, worth a try.
*Are you shooting off of soft bags? If so you could just be changing your hold (unknowingly) as the bag settles and flattens out. I've caught myself doing it on occasion, and it will shift the POI on some guns.
Try shooting 30 shots from a seated position field target style and see if the problem clears up. Even if the groups arent as tight (I know mine arent!) you should still be able to see if that's the issue.
If all else fails, let somebody else shoot it and see what happens! ;)
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Try checking your barrell pivot screws. Had a HW30s doing the exact same thing last week. The FPS was within 1 to 2 deviation. But it kept shooting lower. Checked the screws. Tighted them up and POI back to normal. Worth a try. Screws just barely moved but made a big difference.
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That's a good one there... Got me! :o
Sounds like an overly tight piston seal, or dieseling, but your velocity doesn't back that theory up.
A breech seal breaking in or taking a set can cause stringing, but usually upwards.
Double check and make sure the scope isnt sliding back. Can't hurt to check.
HWs in .22 tend to have really tight chokes often times. May try scrubbing it out real good and lubing your pellets. Usually this will cause some pretty lame accuracy, but what the heck, worth a try.
*Are you shooting off of soft bags? If so you could just be changing your hold (unknowingly) as the bag settles and flattens out. I've caught myself doing it on occasion, and it will shift the POI on some guns.
Try shooting 30 shots from a seated position field target style and see if the problem clears up. Even if the groups arent as tight (I know mine arent!) you should still be able to see if that's the issue.
If all else fails, let somebody else shoot it and see what happens! ;)
I am shooting off a folded towel on my deck rail.
This gun is a little hold sensitive, but I have repeated this scenario three days in a row.
Always set the stock on the towel in the same place, and have tried "fluffing" up the towel and it didn't make any difference.
One reason I was leaning towards the scope is because once this starts happening, if I try to adjust the scope up it seems like
it takes to many clicks to start correcting it up. But I may be imagining that lol.
Yesterday after POI dropped I adjusted the scope up. Today first 7 shots were 1.5 in high. After 35 shots, back on bulls eye ?
I will try shooting off hand, don't shoot like that much. Thanks
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Try checking your barrell pivot screws. Had a HW30s doing the exact same thing last week. The FPS was within 1 to 2 deviation. But it kept shooting lower. Checked the screws. Tighted them up and POI back to normal. Worth a try. Screws just barely moved but made a big difference.
Will give this a try. Thanks !
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Checked every other screw first including the scope mount screws. Thought my scope was messed up also. Have shot a 100 or so pellets since. POI has stayed the exact same. Hope that fixes your problem.
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blue thread lock the screws
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It sounds like a scope / base problem to me as a start. I don't do break-barrels so can't comment on the barrel hinge suggestions but it seems sensible. They can be torqued too!
My suggestion it to tear the whole scope base/mounts setup down to the screws, wash all in rubbing alcohol to degrease them. Get a decent torque wrench - the Wheeler FAT wrench sold at most shooting shops is a good choice. Reassemble and torque all the screws to recommended levels. If your rings and bases didn't come with any such information (not uncommon) read the tome below to find what you need.
Do all that first. Then, since it is an new scope, I would crank all the knobs end-to-end of their operating range, counting the turns. Ultimately, recenter the scope and re-zero. It is possible that the springs and other internals are not quite properly seated after shipping, bouncing around, and possibly sloppy assembly.
I spent quite a bit of time a couple years ago delving into torques and rifles the Book below is a summary of what I found. Sorry to do this but I am a bit anal about answering important questions. This is clearly more than you probably need but I repeat it from an earlier post
I typically use the Wheeler recommendations but here is some more information that you might find useful.
I use a criss-cross pattern to even out the compression on scopes. If there is a line of screws, I start at the middle and zig-zag back and forth to each end of the base. Make sure the rings are well aligned to avoid crimping the scope if you are doing it with the bottom-half of the base installed. Wheeler actually sells a scope alignment kit with lapping compound to help you get them really straight. I am not quite that particular so haven't gone there (yet!)
Steel Rings (clamping the scope into rings) 30in-lb,
I try to avoid aluminum ones but if that's what's there I use lower torques to avoid stripping the threads in the aluminum:
Aluminum Rings: 25in-lb
Bases - attached to steel action: 40-45in-lb as a maximum.
I sometimes go 5in-lb lower if the screws are slotted rather than Allen or Torx. (to avoid damage when I slip!) Steel screws through an aluminum block into steel - use steel recommendations.
Windage (clamping rings to separate bases like Weaver or Picatinny) 45in-lb.
Action Screws - action to stock: 45in-lb.
Below is what I found when I went looking for additional input.
Recommendations from Wheeler FAT wrench manufacturers. They say they have queried scope makers for the following consensus.
Steel rings: 35in-lb on steel rings
Bases: 45in-lb
Windage (clamping to dovetails or Weaver/Picatinny type bases): 45in-lb.
Action screws: 45 in-lb.
Stock / action attachment screws:
wood or synthetic stocks without bedding pillars: 40in-lb
wood or synthetic stocks with bedding pillars: 65 in-lb
Hard service stocks with bedding pillars and military rifles: 65 in-lb.
It also agrees with the straightforward recommendations to use the torque ranges that the screws are designed for. There are two sets of recommendations in the reference books for dry threads and for lubricated threads. Since most gun screws have oil on them, we should use the lubricated thread torque settings. Wheeler specifies the use of lubricated thread torques on the packaging of their current wrench production.
#6 screw size: 18-20 in-lb - most scope rings
#8 screw size: 28-30 in-lb - most scope mount bases
#10 screw size: 40-45 in lb - most scope cross-bolts
over #10 screw size: 65 or higher in-lb
A manual for the Gelmann torque wrench recommended by Anschutz quotes:
Feinwerkbau: 6-8 Nm or 53-70 in-lb
Steyr: 5-6 Nm or 44-53 in-lb
Walther: 7Nm or 62 in-lb
Anschutz: 5 Nm or 44 in-lb.
It is not clear what bolts are being tightened here. Given the numbers, I would think that they are for action/stock screws. These values are probably too high for scopes and rings...
Found this in a Nightforce Scope Owners' Manual
Nightforce Torque Specifications
• Base attachment screws - 25 inch pounds
• Ring top screws - 25 inch pounds
• Ring crossbolt nut - 68 inch pounds
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On re-reading my note, it occurred that I was suggesting a whole lot of work before doing the easy one first. DUH!
Run the turrets on your scope end-to-end as I suggest first. Since it was straight vertical, elevation might be the culprit Easy enough to do except for re-zeroing.
By the way, if you do the torques, I don't find it necessary to use Locktite. I have an RWS 54 that hasn't moved its scope in years after doing the torque routine.
You mentioned cold versus hot? Do you mean storage is cold versus outdoors hot or just the number of shots limbering things up?
Good luck
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I had something very similar in my Walther Terrus when I first got it.
I would get about 10 shots+- then the poi would move. You could repeat it day after day.
I finally pulled the scope off and starting shooting with the open sights.
No issue since then. That's been almost two years ago.
the scope was a utg 4-12x44 compact. I still have the scope but don't use it.
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+1 Dave hit the nail on the head. :D
When in doubt blame the scope! :-*
Try if the POI shifts with just open sights. That way you will know if it is the gun or your scope.
When in doubt blame the scope. ;)
-Y
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That's a good one there... Got me! :o
Sounds like an overly tight piston seal, or dieseling, but your velocity doesn't back that theory up.
A breech seal breaking in or taking a set can cause stringing, but usually upwards.
Double check and make sure the scope isnt sliding back. Can't hurt to check.
HWs in .22 tend to have really tight chokes often times. May try scrubbing it out real good and lubing your pellets. Usually this will cause some pretty lame accuracy, but what the heck, worth a try.
*Are you shooting off of soft bags? If so you could just be changing your hold (unknowingly) as the bag settles and flattens out. I've caught myself doing it on occasion, and it will shift the POI on some guns.
Try shooting 30 shots from a seated position field target style and see if the problem clears up. Even if the groups arent as tight (I know mine arent!) you should still be able to see if that's the issue.
If all else fails, let somebody else shoot it and see what happens! ;)
I am shooting off a folded towel on my deck rail.
This gun is a little hold sensitive, but I have repeated this scenario three days in a row.
Always set the stock on the towel in the same place, and have tried "fluffing" up the towel and it didn't make any difference.
One reason I was leaning towards the scope is because once this starts happening, if I try to adjust the scope up it seems like
it takes to many clicks to start correcting it up. But I may be imagining that lol.
Yesterday after POI dropped I adjusted the scope up. Today first 7 shots were 1.5 in high. After 35 shots, back on bulls eye ?
I will try shooting off hand, don't shoot like that much. Thanks
A few "just guessing" comments..........
"Always set the stock on the towel in the same place,"
Consistency is a good thing, however I've never been able to get good groups on a "solid rest" with my .177 R9s or HW95 without first putting the open palm of my hand between the stock forearm and the rest.
Try that ans see if it makes a difference.
"if I try to adjust the scope up it seems like it takes to many clicks to start correcting it up."
If your scope erector is too far off optical center after zeroing then the spring tension can be loose allowing the erector to "float around".
Some comments were made concerning stock screw torque, here are the specs from HW..........
Front stock screws = 2.5 Nm is equal approximately to 22.1 in/lbs
Large trigger guard screw = 5 Nm is equal to 44.3 in/lbs
Rear trigger guard screw = 2.5 Nm is equal approximately to 22.1 in/lbs
Notice that these torque specs are INCH pounds, not FOOT pounds
Perhaps your barrel pivot bolt tension is too tight which prevents a consistent latchup every time. Every new HW break barrel springer I've bought had the pivot tension set much too tight.
I set my R9 & HW95 barrel pivot tension so the cocked barrel just Barely FALLS when held horizontal after unlatching the lockup detent.
As a side note........here are the torque specs for the screws of a UTG scope mount (15in/lbs for "vertical screws", 35 in/lbs for "horizontal screws"..........
(http://www.snapagogo.com/uploads/source/232015/1422140468_8313716_UTG30mmMedRingsTorqueSpec.jpg) (http://www.snapagogo.com/photo.php?id=65322)Uploaded at Snapagogo.com (http://"http://www.snapagogo.com")
I've read some torque specs that IMHO (personal opinion) are much too high judging by scope tubes I've damaged using much less torque! Even the BKL mounts I have recommends a max base screw torque of 35 in/lbs but BKL gives no spec for the top strap screws.
Off the wall suggestions..........
1. Excess lube in the receiver that gets pushed in front of the piston seal to combust for the first few shots, however you've debunked that theory with your chrony numbers.
2. Optical center the scope and then see if the poi still wanders up or down.
3. Check the barrel pivot tension and adjust to the cocked barrel "barrel just falls" setting.
4. This is really a perplexing problem for sure!
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“Then I shot 30 more shots. POI dropped 1.5 in at 15 yards.
The shots will group for 3-4 shots then migrate down a little, then repeat.”
I would like to better understand the problem description ..
I didn’t get what the “..repeat” means. Repeat what?
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First, thanks so much for all the comments.
Going to try to answer most of them.
dtdtdt: I own a very good inch pound torque screw driver. I clean and torque every screw.
Scope mount screws torqued to Hawke specs, stock screws torqued to HW specs.
By cold I meant first shots from AC house to outside warming up gun by shooting.
I will try turning the turrents.
Ed: I have been very lucky I guess, all of my guns so far will shoot excellent groups off the towel across my deck rail.
I get much better groups off my towel than off my hand.
I didn't check the scope when I mounted it to see if it was optically centered. But the vertical was only a few clicks off. Horizontal was off by about 6 inches at 15 yards.
Yogi and pcp_Dave: sadly with even 4 eyes I can't shoot open sights anymore, even at 15 yards I can't see the sights AND the target Lol, just too inconsistent. I can change scopes though.
mpbby: Cold the gun will shoot a 3-4 shot touching group, then next shot may drop down 1/4 inch, then 3-4 shot touching group. then next shot drop down 1/4 inch or so, then 2 or 3 or 4 shots touching then repeat the same scenario til POI drops about 1 1/2 inches then it seems to stop dropping.
Again thanks for all the help.
Just checked the turrets.
Turned both turrets all the way one way then counted the "rounds" til they were all the way the other way.
Both had 7.5 rounds of adjustment. both turrets were within a half round of optical center.
I did run them back and fourth the full range a few times.
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Thanks for the explanation.
If this "perplexing problem" (+1) persists..
Although sceptic, the closest I could get to a logical explanation for the - round trip!? - would be relevant temperature changes.
What if you let the equipment outside, literally warming up by itself for some time (half an hour?) – before - start shooting?
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Thanks for the explanation.
If this "perplexing problem" (+1) persists..
Although sceptic, the closest I could get to a logical explanation for the - round trip!? - would be relevant temperature changes.
What if you let the equipment outside, literally warming up by itself for some time (half an hour?) – before - start shooting?
Good idea. will try that also
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I suspect something with the lockup or the breach seal. I'm only guessing but it seems logical with the vertical stringing.
Keep us tuned in.
Good luck,
Higgs
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You've tried everything except changing the scope for another known "good" one. If things settle down you have a warranty issue.
I have a RWS scope that my RWS54 finally killed (6+years) that still holds zero and shoots the point of aim but goes in and out of focus on virtually every shot. A thump on the bell changes it. I haven't torn into it but suspect a loose lens. Perhaps the reticle disc is loose in yours? Maybe a couple light taps around the turret housing might induce the problem??
You mentioned cool versus hot. Even Alabama probably isn't hot enough, particularly at this time of the year, to shift things much unless you store the rifles in a meat locker.
Another possibility is the viscous properties of the lubricants used. If they are thixotropic (shear-thinning - the classic example is Ketchup) a few shots could reduce the viscosity and change the piston speed and hence the power. That doesn't really fly though as you said the velocities remain constant throughout.
I keep coming back to something in the scope.
Good Luck!
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For Shi&ts and Giggles, try removing Scope and re mounting it.
Good luck, hope you get it sorted.
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This really is a doozy. :-[
The only other thing that I can think of is the guns action properly bedded to the stock. I assume, even with the stock screws snug, an ill fitting inletting could let your action move around a bit. Maybe a thin piece of foam might help? ::)
Just grasping at straws here....
-Y
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"Then, since it is an new scope, I would crank all the knobs end-to-end of their operating range, counting the turns. Ultimately, recenter the scope and re-zero. It is possible that the springs and other internals are not quite properly seated after shipping, bouncing around, and possibly sloppy assembly."
Think the bold above ^^^^^ was my problem. Since the scope was new this was the first thing I tried.
Ran the turret adjustments end to end 4-5 times, then reset to optical center.
Today I shot 5 shots to sight in then shot the 30 shot group below at 15 yards.
The one low flyer was on shot 28 and was my fault. (not really a flyer, it's touching the group)
Shot 50-60 more times after this group POI stayed at POA.
Thanks dtdtdt ! And thanks for all the responses.
I would recommend doing this on ANY new scope.
(http://i1282.photobucket.com/albums/a525/jusanothajoe/IMG_0689_zpsfu4smspr.jpg) (http://s1282.photobucket.com/user/jusanothajoe/media/IMG_0689_zpsfu4smspr.jpg.html)
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Good info guys!!! thanks for the post JOE :o :P
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That's the importance of breaking in... air rifle and shooter getting to know each other as one.
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Congrats for being able to face and get rid of the nightmare!
Just to let you know..
As a Brazilian, unable to associate coins with American personalities' names, I was free to thought the profile could even be yours; looking to the 30 shots group, a kind of being proud and relieved. 8)
Btw, dealing with inconsistent springers, some times we need some help from God :o ::)
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Congrats for being able to face and get rid of the nightmare!
Just to let you know..
As a Brazilian, unable to associate coins with American personalities' names, I was free to thought the profile could even be yours; looking to the 30 shots group, a kind of being proud and relieved. 8)
Btw, dealing with inconsistent springers, some times we need some help from God :o ::)
Amen ;D
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:'(Sorry not even God can help my groups. :'(
-Y
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Your hold/grip, your cheek rest, the rifle's rest? Are they the same shot after shot after shot?
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Hooray! Glad it seems to be working. Remember that NCED suggested the same thing. I think I learned that trick from him a few years ago...
For the Brazilians it is an American dime ($0.10) 17.9 mm in diameter or, or us Gringos, 0.705 inches. The President is Franklin Delano Roosevelt who led the USA from 1933 to 1945 through and out of the Great Depression and World War II - a Democrat by the way.
In any case that's darn good for a new rifle not broken in.
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Well my problem has returned >:(
So today I swapped scopes and it didn't help the problem.
Today was hottest day so far in Alabama, and I am starting to think it is temperature related.
Bringing gun out of AC house into 90 degree weather.
Seems as gun starts to warm up POI drops. More experiments to come.
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Well my problem has returned >:(
So today I swapped scopes and it didn't help the problem.
Today was hottest day so far in Alabama, and I am starting to think it is temperature related.
Bringing gun out of AC house into 90 degree weather.
Seems as gun starts to warm up POI drops. More experiments to come.
I agree!! I have noticed the same for the 1st and second magazines. If I resist in adjusting the scope, the POI will return right where I had it set the day before.
It doesn't appear to happen with my Discos though. Maybe its because of the metal the breach is made out of.
Glad to see that it is happening to someone else... for a while I thought I was loosing it!
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Well my problem has returned >:(
So today I swapped scopes and it didn't help the problem.
Today was hottest day so far in Alabama, and I am starting to think it is temperature related.
Bringing gun out of AC house into 90 degree weather.
Seems as gun starts to warm up POI drops. More experiments to come.
Are you running a factory white HW breech seal? Or an aftermarket one?
Has the gun been opened up and parts swapped replaced?
Sorry if I missed this, I did look, lol
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1st day of Alabama scientific experiments.
Did what one poster suggested, set the gun outside and let it come to ambient temperature.
shot around 75 pellets, NO drop in POI !
Will try to replicate this again tomorrow.
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Day 2 of Alabama science.
When I quit yesterday POI was 1/8 inch high at 15 yards.
Brought the 85 out of the AC house, 72 degrees, and shot a 6 shot group.
Gun cold 72 degrees. Center of group is 3/4 inch high.
(http://i1282.photobucket.com/albums/a525/jusanothajoe/IMG_0709_zpsax9wypdx.jpg) (http://s1282.photobucket.com/user/jusanothajoe/media/IMG_0709_zpsax9wypdx.jpg.html)
Set the gun outside in the shade, 82 degrees, for 30 minutes. 6 shot group. Center of group 3/8 high. Same POA
(http://i1282.photobucket.com/albums/a525/jusanothajoe/IMG_0710_zpstkvynzjl.jpg) (http://s1282.photobucket.com/user/jusanothajoe/media/IMG_0710_zpstkvynzjl.jpg.html)
Then set the gun in the sun, 82 degrees for 30 minutes. 6 shot group. Center of group is 1/8 high. Same POA
(http://i1282.photobucket.com/albums/a525/jusanothajoe/IMG_0711_zpscb4zzsij.jpg) (http://s1282.photobucket.com/user/jusanothajoe/media/IMG_0711_zpscb4zzsij.jpg.html)
I really think temperature is affecting this gun ?
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i believe i have a new NP air rifle along with a SP rifle doing the same thing.
being down on the coast in Bama, i'm fighting humidity and temps also.
i setup 2 rifles last weekend in the full sun.. 89degree and 97% humidity..
both rifles were inside 1/2" @ 20yrds.
today, cloudy/no sun.. 78degree and 94% there both not even close.
no scope or stocks movement, its gotta be the temps & humidity
all shots were 20yrds in my back yard and no wind on either days. :o
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Well it sure seems to be temp related. And that's no surprise because spring rifles are known to be temp sensitive to a degree.
But IMO it should be a very small degree unless something is a little out of whack. The most temp sensitive guns I've had happened to have a couple things in common out of these factors:
Tight piston seal
Too much lube on the Piston
Too much spring tar on the spring
Very tight spring guides
Very dirty barrel
Tight choke
I live in North AL, where the temp swings wide and the humidity is always nuts. My most temp stable rifle is my 25mm HW77K with a oring piston cap and krytox lube. The spring runs on a barely snug delrin guide with the tiniest bit of plain wheel bearing grease on the OD of the spring. The piston has a liner made from Teflon sheet and this keeps the lubes from moving and mixing. If this gun moves the POI at all from temperature, I haven't been able to tell. It's always very consistent. I actually grab it to take care of a pest in the yard over my PCPs. It hits where I aim the first shot. But it took a lot of work to get it there!
I also have an old R10 that I shoot fairly often. It runs a new style HW factory seal which fits just right and is lubed with moly paste. Spring runs on a fairly loose guide and has a very thin coat of spring tar. Shoots 14fpe with a hint of buzz after the shot. It may hit 1/2 inch low at 25 yards for the first 3 shots or so, then it's right on the money for the rest of the shooting session. From a 50 degree day to the next 75 degree day, it may move the poi 1/2 inch.
What you are experiencing seems rather extreme to me. It still seems like it would show a huge drop in velocity but as you noted it doesn't. If it were my gun id tear it down and see how everything was fitting and how it was lubed.
Scopes can also experience temp shift like the rifle does. I've seen guys at a FT shoot make extra efforts to keep their guns in the shade and even put a towel over the scope to keep it cool. Maybe try swapping brand/make/model scopes and leave it on there for a while and see if it's any better. Since exercising the turrets earlier seemed to help, you may be on to something there.
Hope you get it sorted out. Shifty guns are a pain in the butt
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Well it sure seems to be temp related. And that's no surprise because spring rifles are known to be temp sensitive to a degree.
But IMO it should be a very small degree unless something is a little out of whack. The most temp sensitive guns I've had happened to have a couple things in common out of these factors:
Tight piston seal
Too much lube on the Piston
Too much spring tar on the spring
Very tight spring guides
Very dirty barrel
Tight choke
I live in North AL, where the temp swings wide and the humidity is always nuts. My most temp stable rifle is my 25mm HW77K with a oring piston cap and krytox lube. The spring runs on a barely snug delrin guide with the tiniest bit of plain wheel bearing grease on the OD of the spring. The piston has a liner made from Teflon sheet and this keeps the lubes from moving and mixing. If this gun moves the POI at all from temperature, I haven't been able to tell. It's always very consistent. I actually grab it to take care of a pest in the yard over my PCPs. It hits where I aim the first shot. But it took a lot of work to get it there!
I also have an old R10 that I shoot fairly often. It runs a new style HW factory seal which fits just right and is lubed with moly paste. Spring runs on a fairly loose guide and has a very thin coat of spring tar. Shoots 14fpe with a hint of buzz after the shot. It may hit 1/2 inch low at 25 yards for the first 3 shots or so, then it's right on the money for the rest of the shooting session. From a 50 degree day to the next 75 degree day, it may move the poi 1/2 inch.
What you are experiencing seems rather extreme to me. It still seems like it would show a huge drop in velocity but as you noted it doesn't. If it were my gun id tear it down and see how everything was fitting and how it was lubed.
Scopes can also experience temp shift like the rifle does. I've seen guys at a FT shoot make extra efforts to keep their guns in the shade and even put a towel over the scope to keep it cool. Maybe try swapping brand/make/model scopes and leave it on there for a while and see if it's any better. Since exercising the turrets earlier seemed to help, you may be on to something there.
Hope you get it sorted out. Shifty guns are a pain in the butt
I have been thinking.
The day I shot the gun after rotating the turrets it was around 70 degrees that day, so it was around the same temp inside as outside.
I think that may have made the difference not the turrets ?
My most consistent gun that is neither hold or temp sensitive is my 34, Vortek kit with moly seal and Kytox lube. (Motorhead)
Thinking about several options for this gun, Chop the long barrel down some, Maybe buy a 98 barrel with sleeve for this gun, install Vortek kit.
I ain't giving up on it ! really like the gun. Really thumps squirrels and chipmunks.
Thanks for all the help
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Maybe you could add some data to the Alabama science, just trying to have some food for thought..
By now, what is occurring to me would be:
- at each of the temperature extremes (when the difference is relevant), you could go to the chrony and see what happens with fps;
- and, directly from the AC to the sun, you could do two experiments, treating the rifle and the scope separately.. before shooting; rifle protected and scope/mount exposed; scope/mount protected and rifle exposed;
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Maybe you could add some data to the Alabama science, just trying to have some food for thought..
By now, what is occurring to me would be:
- at each of the temperature extremes (when the difference is relevant), you could go to the chrony and see what happens with fps;
- and, directly from the AC to the sun, you could do two experiments, treating the rifle and the scope separately.. before shooting; rifle protected and scope/mount exposed; scope/mount protected and rifle exposed;
Years ago during an early spring field target match in Virginia my brother and I attended we were both shooting .177 R9s and 7.9 grain CPLs. When we were doing the pre-match sight in the temps were below freezing and there were snow flurries. During the match the temps rose to the upper 50s and both my brother and I experienced poi shifts. Funny thing was that my shift was 1" at only 20 yards and my brother's was the same but in the opposite direction. Thinking that perhaps the poi shift was due to lube viscisity and piston seal durometer changes with the factory HW parachute seal, the molly paste used for lubing the seal, and tar used to lube the spring/spring guide. For the next match I used no "tar" on the spring/guide and only used molly paste for all internal lubing and this did help reduce the poi shifting with a 25 degree temp shift. As one final test of my theory I removed the thin edged HW parachute seal and replaced it with a home turned aluminum piston cap that housed a 1/16" cross section oring bought at an ACE hardware store. LOL....that silly mod actually worked to reduce the temperature induced POI shifting and even helped more by reducing the shots needed to stabilize the poi from about a dozen to a couple. This was great for the late fall squirrel season because I only needed to take a couple shots when I arrived at the "squirrel woods", cock and load the R9 then be good for the first shot of the day on a squirrel. Well....that's been decades ago and while my oring sealed piston cap design has evolved a bit, I still run oring sealed piston caps in my R9 and HW95 even though the new design HW piston seals with the thick parachute edge performs almost on par with the oring seal.
Anywhoo......I know that when my R9 was factory sealed, as long as the temp during the shooting session was rather consistent the poi was rather consistent even when "molly'd and tar'd" , however the changes in "rubber and goop" density due to temperature affected the acceleration of the piston, hense the poi when the temp during a shooting session varied enough. Another consideration is the atmosphere itself that will change the poi simply due to changes in humidity, temperature, barometric pressure (and I'm sure other variables) that changes the resistance to those light lead badminton birdies passing through the air. This is why every field target match starts with a zero session to adjust the scope to the "conditions of the day".
IMHO....the biggest detriment to springer consistency (other than the shooter) is the design of the springer itself, excess internal lube, dieseling (smoke seen in the bore), piston seal tightness, and if a break barrel.....excess barrel pivot bolt tension.
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I had some POI / temp related issues with low end scopes , I am sure the rifle may have added to the POI shift with temps also.
If I use a rifle for a quick grab to shoot gun I sight it in with a cold bore , so to speak and shoot no more than 5 shots and let the rifle rest for a hour or more then check POI again to confirm, that way I can grab it to shoot a starling etc quick and know its DRT.
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I had some POI / temp related issues with low end scopes , I am sure the rifle may have added to the POI shift with temps also.
If I use a rifle for a quick grab to shoot gun I sight it in with a cold bore , so to speak and shoot no more than 5 shots and let the rifle rest for a hour or more then check POI again to confirm, that way I can grab it to shoot a starling etc quick and know its DRT.
Does anyone here know is the $1000+ 35x Leupold Competition scope will shift the poi with temperature changes as I've heard some claim. I've also heard some field target shooters mention that their high end optics "act weird" when heated up with sun light on a hot day and some shooters carry around a "reflective tent" to cover the scope between lanes and when waiting for their turn to shoot.
Anywhoo.......the expansion of aluminum is about twice that of steel (coefficient of expansion, 21-24 for alum, vs 11-12.5 for steel) so perhaps there is enough deflection in the scope tube to change the poi if the mounts are hard clamped. I know one fellow that torqued the rear scope ring to "normal torque", lines the front scope ring with Teflon tape, then uses "low torque" with that ring. His reason was that any "thermal scope expansion" will be accommodated by the front scope ring preventing scope tube deflection. I don't know if the above are simply "scope folk lore" or legitimate, but one of the reasons I like a one piece aluminum mount is that the mount will roughly expand at the same rate as the scope tube and any differential expansion will occur between the base of the mount and the receiver tube.
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As I recall from reading about big game hunters and their trials at high altitudes and cold versus hot temperatures they seem to experience poi shifts too. However, they usually blamed the effects to changes in ammunition and ballistics rather than gear. HMMM! They also mentioned scopes coming loose in shipping. Competition shooters always have the advantage of a sighter on their record target to fine tune zero for wind and other effects. Early target scopes like the Fecker, Unertl, and Lyman external adjustment scopes have recoil springs that would also take care of the expansion problem.
Reading about FT shooters, particularly Hector Medina's blog, who re-establish zero each day and probably between stages? NCED would probably confirm that practice.
NCED comments on steel base, aluminum tube versus aluminum base and aluminum tube makes sense. Worst case would be something like this: 20deg temp shift, aluminum coefficient of linear expansion 0.000022 in/1in. 4" scope ring spacing: 4 x 0.000022 x 20 = 0.0018" expansion - quite a bit. Real case not so much as al bases are fixed to a steel rifle with half the expansion. Such things make a good argument for steel bases, steel rings, steel scope tube, on a steel rifle. At least it would all move together. This could also contribute to scope moving around in their bases with time???
The second factor of lubricant viscosity change with temperature could also be a major contributor.
Suggestion:
Buy a cheap IR temp gauge at Harbor Freight.
Put the rifle in a plastic bag, cover with ice.
Cool to freezing.
Shoot 5 rounds at 32F Allow to warm to about 50, 60, 70, ....
Lay it in full sun, let it warm up to ??
See if POI changes.
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Wow this got edumacitional ??? Now I have ideas of testing from the 40 degree cooler at work to the walk-in freezer at -10 , and the 80 or what ever it is outside.
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Back_Roads
Actually that would be a very good experiment and might solve a LOT of people's chasing their tails on POI shifts!
Cooler & Freezer big enough to shoot in?? ;D You could also wait until winter in Wisconsin (next week or so??) :P
Go for it!
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10 yards in the cooler , 4 in the walk-in freezer, but could chill the gun to -10 , run to the cooler and test quick.
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Seriously, I'll bet you will see if there is anything to the thought by cooling to 40. Shoot 5, let warm up a bit shoot 5, warm again shoot 5 until it gets to room temperature. Shifting around under those conditions would be like my suggestion of putting it in an ice bath. and measure temp with a cheap IR temp device. Don't need supreme accuracy on temperature effects. All that is needed are results that show or don't show POI shift as it warms up.
Original differences were 70 to 90F. So colder to that hot should readily show a problem if it exists.
Any results will be clouded by the lubricant being stiff, hence the need to chronograph all the shots.
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Back_Roads
Actually that would be a very good experiment and might solve a LOT of people's chasing their tails on POI shifts!
Cooler & Freezer big enough to shoot in?? ;D You could also wait until winter in Wisconsin (next week or so??) :P
Go for it!
A while back when testing the Dupont Krytox lube I did some chrony testing by leaving the oring sealed .177 R9 in my unheated sunroom over night in Jan 2014, then rechronying at room temp. Here are the results,,,,,,,,
65 degree CPL velocity.....910fps give or take a few.
16 degree CPL velocity.....915fps give or take a few.
I was rather surprised that the colder temp velocities were a bit higher than the warmer temp velocity however such a variation is negligible.