Total tune results of Benji Trail NP .22 caliber

[mtsheron70]

Okay...............preliminary results in but are not what I believe will be factual once I get the gun broke back in with about another 500-1000 pellets pumped through it.

But here is what I have so far and some of this was dieseling as well from a few crazy fast fps results over the original!

H&N FTT 14.66 grain pellets-

Original numbers were:
Low- 721.56
High- 735.82
Avg.- 726.85

New numbers after tune were:
Low- 729.96
High- 748.32
Avg.- 740.44


JSB Exact Jumbo Heavy 18.13 grain pellets-

Original numbers were:
Low- 645.90
High- 658.09
Avg.- 652.59

New numbers after tune were:
Low- 662.08
High- 787.98    (dieseling)
Avg.- 693.42

H&N Crow Magnum 18.21 grain pellets-

Original numbers were:
Low- 640.57
High- 662.99
Avg.- 658.66

New numbers after tune were:
Low- 642.27
High- 750.27    (dieseling)
Avg.- 673.29

I really believe once I get the gun free of all the excess moly paste and put another 500 pellets in it to settle it in the numbers will come back close together with a small extreme spread and deviation.  These are the first shots after the tune on the chrony to get an idea of what success I may be having.

Once I do this I will re-chrony and post.  But I do believe it to be a success and taking out the shots that were extreme I still have a way better than 2-3% increase I wanted.

In fact taking out the way high shots on the following resulted in better closer numbers which I expect will be indicative of what I will have:

H&N FTT avg. minus the extreme fps shots yielded an avg. of: There were no extremes on these for some reason.  The extreme spread was 18.36 fps and the std. deviation was 6.32 fps

JSB EJHD as follows:  Taking out two extreme fps shots the avg. was 679.75 which is an increase of roughly 23 fps

H&N Crow Magnum as follows:  Taking out three extreme fps shots the avg. was 659.75 which is an increase of roughly 1.1 fps over the original.  Slightly lower than what I would have expected to the original.

So I believe some plinking is in order to get excess moly out of the way to eliminate extraneous variables of fps extremes and then re-chrony.

[Petey]

This is what I got on my Trail NP ... after a Tin of Pellets.
Trail NP Hardwood 22.CAL  ( No tune No mods,  trigger only)
CPHP 14.3 Grn.
1)730.8
2)729.2
3)727.9
4)729.4
5)730.5

Hi: 730.8
Lo: 727.6
AV: 729.6
ES:2.82
SD:1.0

[mtsheron70]

Great numbers.  I put about another 150 pellets through the gun today in doing some general plinking.  Another 300 or so I will chrony again.  Most of the dieseling I noticed has gone.  The every so often one slips by but almost settled now. 

[microsalmo]

That's pretty amazing. What does it do on a 10 shot count?

I never saw  chrony that only counted to 5.  How did you get it to do that?  I ask becasue I get some amazing 5 shot counts too, but finishing the 10 shot string always mellows out the scores.

Thanks.

[Petey]

That's pretty amazing. What does it do on a 10 shot count?

I never saw  chrony that only counted to 5.  How did you get it to do that?  I ask becasue I get some amazing 5 shot counts too, but finishing the 10 shot string always mellows out the scores.

Thanks.

https://www.pyramydair.com/product/shooting-chrony-alpha-chronograph-red?a=838

[mtsheron70]

Trigger pull on the Trail via a Lyman digital trigger pull gauge is: 1 lb. 10.7 oz. average reading!

[microsalmo]

wow, thats lite!  I would be curious to know what the gun shoots once the dieseling is over with.  Can you post some picture/printouts of some 10 shot strings? I would like to see the whole picture of what is going on with fps.

Thanks.

[mtsheron70]

UPDATE:

After the gun settled in I notice a slight drop in fps.  Then every so often a total dud!  Broke down the gun and re-examined the new piston seal and guess what?  Two nicks in it.  Now this could have happened after re-inserting the piston cylinder and new seal upon reassembly and it took some time for the moly to wear in to exhibit the drop in air pressure.  I have since Dremeled the edges of the compression tube where you can visibly see into the chamber.  I will wipe the gun down and clean once again the compression tube inside once the new seal arrives.  Going to make every so cautious effort to get the piston cylinder back in and reassemble.  Hopefully not to nick the seal.  As I recall the first time I had a little catch when the seal went by the last cut opening of the compression tube.  This may be where the seal was nicked.

Either way............I will post the chrony results again once I reassemble to surgeon like results!

[microsalmo]

Yea, have to be real careful with those seals. I go to great extreems to make sure all the slots and openings are polished smooth. Start inside the slots with a dowl & 400 grit. Then follow up with a rubberized dremel cone. Then finish with a dremel felt pad. The slots & holes will be smooth as glass.  I also have had great results with a dot of super lube grease spead over an entire shot gun bore mop. Fixed to a corless drill & cleaning rod, it shines the inside of the tube, and will protect your seal upon entry. Just keep it out of the compression chamber.

[mtsheron70]

I even went to the extreme to spray brake parts cleaner which contains a super solvent called TCE (Tetrachlorethylene) to get every single molecule of grit out of the chamber!!!  I will probably still do some polishing of the edges to make ever sure no catches this time.  May even soak the seal in hot hot water to make it very darn pliable upon re-insertion!  trying every trick of the trade to make sure it gets in okay.  I did do a cocking test to make sure the seal never comes back on the cutout of the cylinder tube and it does not which is a relief.

I ordered two extra piston seals to be safe!!!

Will post again!  Stay tuned.

[microsalmo]

I use an entire can per gun, lol. Crc brand works great. When i pulled my seal from my npss, i could not distinguish it from new... even after a few hundred shots.

[Wild Onion]

...Broke down the gun and re-examined the new piston seal and guess what?  Two nicks in it.  Now this could have happened after re-inserting the piston cylinder and new seal upon reassembly...

You guys are scaring me. I just got an NP XL in .22 two weeks ago and will add a TUNA trigger. I also plan to clean the bore with J-B cleaner. I don't plan any compression chamber mods. Is the nicked seal because of poor design? If so, how can I tell without a chrony?

[microsalmo]

The design is good. The nicked seal comes from hurried installation on a bured tube. You'll know because your accuracy will stink... at least if the nick is large enough to worry about.

[mtsheron70]

New piston seals came and the gun is back together!  Some pre-chrony shooting already done to get a "in the park" idea.  The dieseling is already over and now to settle in the piston seal with maybe another 100 pellets.  Then to chrony to get new results.  Preliminary or what I think I will find.....................a slight drop in fps per pellet brand but a smoother cycle.  Then again, it may pick back up before I do the official post tune chrony session.

Still shooting H&N FTT 14.6 grains over 700 fps and if memory serves me I may have gotten a 711 fps avg. on a 10 shot string I did today.

Stay tuned.

[microsalmo]

my npss also had a slight drop in fps immediately after the tune. Within a few hundred shots, it was back up.  The other 2 guns were max power right away after the tune.  I would guess you will settle into 720-740 with that pellet after 500 rounds or so.

Funny about the dieseling. I never had any after a tune if I did the lubes right. In the beginning, i would get some after a tune that would go away in 20-30 shots. Now I seem to have figured oit the lube thing to where i dont get dieseling at all any more in the beginning. Keep at it. Good work. Keep us postee.
 

[Bryan Heimann]

you might lose a couple feet per seconmd due to the tighter piston seal, but that will wear in over time.  In my experience, a slightly snug seal will yield a much nicer shot cycle, as well.  Shoot like a thousand pellets, then check the chrony.  I bet she's at, near, or better than stock for power, and still with a nicer shot cycle

[mtsheron70]

my npss also had a slight drop in fps immediately after the tune. Within a few hundred shots, it was back up.  The other 2 guns were max power right away after the tune.  I would guess you will settle into 720-740 with that pellet after 500 rounds or so.

Funny about the dieseling. I never had any after a tune if I did the lubes right. In the beginning, i would get some after a tune that would go away in 20-30 shots. Now I seem to have figured oit the lube thing to where i dont get dieseling at all any more in the beginning. Keep at it. Good work. Keep us postee.

That is what may happen after it settles a bit more.  The dieseling this time was from me putting a little heavy on the moly on the chamber tube where the open areas are for the piston to hopefully slide by without getting nicked!!!!  Gonna shoot about 200 more pellets to really seat this thing then I am going to run three 10 shot strings of each pellet to get an avg. from that.  I know, a little overboard but if I have a large descrepancy I would say maybe another damaged piston seal.  I really hope the fact I cleaned the chamber tube with brake parts cleaner to get all the muck out helped this time.

If I can get this thing very close on the chrony I will say it was a success and then sight it in again.

I really think the gun the first tune had grit in the tube and it nicked the seal.  I really think from the Dremeling I did not get all of the muck out and it wore the piston seal edges off.  I don't think the edges on the compression tube I used the Dremel to round off to a smooth finish was the culprit.

But then again, I am no pro tuner, just an assumption on my part.  I just don't recall my compression tube on my RWS 34 when I did a tune being this picky.............but then again, your talking German quality on those guns!

Will keep you guys posted!

[mtsheron70]

...Broke down the gun and re-examined the new piston seal and guess what?  Two nicks in it.  Now this could have happened after re-inserting the piston cylinder and new seal upon reassembly...

You guys are scaring me. I just got an NP XL in .22 two weeks ago and will add a TUNA trigger. I also plan to clean the bore with J-B cleaner. I don't plan any compression chamber mods. Is the nicked seal because of poor design? If so, how can I tell without a chrony?

WO, no real way of knowing unless you can chrony and have some wild drops then pick back ups.  Even then it could be a multitude of things especially if the drops are rare.  Air temp. comes to mind; wind speeds; and the cleanliness of the barrel.  I do believe these guns are great for the money and a little modding makes them great...........mainly a CDT trigger!   

I would say if your having drastic drops on paper targets within a 10 shot string you may have a piston seal with a nick in it.  I can only assume why the fps picks up and acts normal again is from the paste inside the chamber acts as a seal around any nicks.

Check to see if there is a airgun club in your area with a chrony and do some strings to get a baseline idea.  You have a XL though which is a bit more fps than the regular version like I have.  Good luck!

[mtsheron70]

you might lose a couple feet per seconmd due to the tighter piston seal, but that will wear in over time.  In my experience, a slightly snug seal will yield a much nicer shot cycle, as well.  Shoot like a thousand pellets, then check the chrony.  I bet she's at, near, or better than stock for power, and still with a nicer shot cycle

I hope that may be the case.  It will make me feel better as a amateur tuner!!!!

[Bryan Heimann]

Instead of measuring your success over the chrony, compare some of your previous shot groups with your current shot groups.  If there's not a noticeable improvement, then try shooting like a 50 shot group at the same target with a different hold for each shot.  Pay special attention to follow-through, but completely disregard your hold.  Tight, loose, artillery, benched, held against a tree/fence post/ gate for stability, prone, seating, etc.  at 25-30 yards.  If you can hit a 1.5" target most of the time at 30 yards without regards to what kind of hold you are using, that's pretty darn good for a break-barrel.  Unless I were going after a coyote or a hog or something, I'd rather hunt with a 12 or 13 fpe gun that's easy to shoot than a 25 fpe gun that requires perfect technique to hit the target.  Especially when rabbit, squirrel, or bird hunting when you know you're going to get many shot opportunities