New tin of JSB Heavys and ... wow? What in the heck?

[UlteriorModem]

Typically I use JSB Diabolo Exact Heavy's in my Gauntlet. There pretty consistent.

Today I was putzing around with the gauntlet and was running low on the Heavies. I had it zeroed in pretty good, 9's and 10's.

But I was running low so I opened up a new tin of the Heavies and woah! POI shifted a couple of inches (at 30 yards) to the left!

I don't know what the difference is between the two tins but I saved some from the previous tin to compare them to one another. Don't know if it is weight, head or skirt size, or all of those 

[Insanity]

Check the lot numbers on the tins that will also give some good information. Pellet swages ware larger as they are used so everything is subject to change.

[Motorhead]

Either you HAD spiraling ... or do now

Try changing speed and see what happens

[BillK]

Even all Mc'Donalds fries don't taste the same.  Gonna be some difference in production runs.
Grouping is what counts.....

[Airgun.Sniper]

Even all Mc'Donalds fries don't taste the same.  Gonna be some difference in production runs.
Grouping is what counts.....

 X2 makes sense to me

[UlteriorModem]

Well I expected 'some' difference in 'flavor' but wow... 3 inches?

Also the grouping is not as good as it was, indeed it does seem to have some spiraling.

I did note however when putting the Gauntlet up the barrel shroud was loose so that may explain some of the wandering.

[Hayfoot]

I had a similar experience... so I ran about 6 patches through the barrel to 'semi - clean' 'er out... and Voila:  back to center.
Now I just clean the barrel (Mrod) about every 1.5 tins.

[UlteriorModem]

Could be something to that. I suppose the barrel could have leaded up with the previous tin and the new tin however different are affected by that.

I will give it a cleaning soon and check it out.

[Hayfoot]

I found this works great for me with a little balistol:
http://patchworm.com/

[fwbsport]

I've been watching this thinking if I ever had this happen with me while standing to shoot.  It is easy enough to tell since my steel targets are 1.5" in diameter, and no, never had a group suddenly shift as far as yours did.

While I think target shooters at rests can get into the weeds about POI shift and barrel cleaning I discount the idea your rifle needed cleaning and there is another culprit in the mix overlooked.  I'd be wondering about loose screws and bumps you may have inadvertently encountered.

I'll get a flyer on occasion too few to mark as an accident and found out a can of pellets had a few pellets short of a happy meal, but to get a group going sideways hasn't happened, yet.

I can see where the pellets end up if I miss and by calling the shot before it hits I can tell whether it's the pellet or me.

I'm still waiting to see what you find out and wish the best!
 

[Bayman]

Did the groups tighten up after you tightened the barrel shroud? I recently had a loose locking ring on a front globe sight put my groups in the toilet. Tightened up the ring and so did the groups. Harmonics do weird things with pellet guns. How many times have loose stock screws on springers gotten people crazy? Anything loose on the barrel is a hundred times worse.

[nced]

I had a similar experience... so I ran about 6 patches through the barrel to 'semi - clean' 'er out... and Voila:  back to center.
Now I just clean the barrel (Mrod) about every 1.5 tins.

LOL....I've read on the forums, including this one, that some NEVER clean their airgun barrels because they never need cleanin'. 
Glag I'm not the only one that found it necessary to occasionally clean my bores but I only shoot springers and we all know that they "don't shoot good" to begin with! 

[Bicycleman]

Ed, I am in that group that almost never cleans a barrel.  My first PCP was bought in 2013.  I cleaned the barrel at that time.  My brother is shooting it now with proven success (bag limit kills.)  To my knowledge, the barrel has not been cleaned since 2013.  And I advised my brother to clean the barrel ONLY if the accuracy goes away.
"If it ain't broke, don't fix it!"
Side note:  I have been shooting air guns since the 1940s.

[nced]

Ed, I am in that group that almost never cleans a barrel.  My first PCP was bought in 2013.  I cleaned the barrel at that time.  My brother is shooting it now with proven success (bag limit kills.)  To my knowledge, the barrel has not been cleaned since 2013.  And I advised my brother to clean the barrel ONLY if the accuracy goes away.
"If it ain't broke, don't fix it!"
Side note:  I have been shooting air guns since the 1940s.

"If it ain't broke, don't fix it!"
LOL.....evidently my .177 HW95 was "broke" judging by this target so I "fixed it" simply by cleaning the bore........


I did some work on a .177 HW97 for a friend of my brother and it evidently was also "broke" and was "fixed" with a bore clean..........


LOL.......perhaps we have a different definition of "broke". 

[Bicycleman]

No offense intended, Ed. 
Please understand, it was explained to me some years ago that, because the air is clean going down the barrel (as opposed to burning powder), the only thing left behind is a coating of lead from the pellets.  The next pellet wipes away and leaves a new coating.  So unless that coating is contaminated, the barrel stays accurate.  Possible contamination might come from oil attracted dirt and grit.  Then, YES, the barrel will need cleaning.  Maybe we could call the barrel "Sick" instead of "BROKE". 

[nced]

No offense intended, Ed. 
Please understand, it was explained to me some years ago that, because the air is clean going down the barrel (as opposed to burning powder), the only thing left behind is a coating of lead from the pellets.  The next pellet wipes away and leaves a new coating.  So unless that coating is contaminated, the barrel stays accurate.  Possible contamination might come from oil attracted dirt and grit.  Then, YES, the barrel will need cleaning.  Maybe we could call the barrel "Sick" instead of "BROKE". 

LOL...a difference of opinion certainly isn't an offense to me!

" The next pellet wipes away and leaves a new coating."
Not necessarely! Sometimes different pellets (like hard lead Crosman Premiers) can foul the rifling with lead and the following shots only pack the deposit tighter in the rifling while depositing another layer of fouling on top.
Along with the pics I posted showing before and after bore cleaning groups, I also have a story from a couple decades ago when my brother's .177 R9 started shooting patterns instead of groups at 30 yards.

Here are a couple 3 shot "powder burner style groups" my brother shot from a bench using his R9 and 10.5 grain CP heavies........

Since he shot these two 3 shot groups "back to back" I figured that the two groups were at least as valid as a single "airgun 5 shot group". After a while the same R9 stopped grouping and no amount of pulled patches would improve the accuracy. Using his bore scope he saw the rifling at the "choked muzzle" literally disappeared under a layer lead polished by pulled patches. To correct this issue he soaked his R9 bore with Hoppes #9, then after some time he used a .177cal brass brush on his cleaning rod to scrub out the packed in fouling. After the bore "soak & scrub" he once again had one hole groups. It was at that time that we (brother and I) started the search for a pellet lube that would keep the CP lead from "soldering" itself to the rifling lands. We first tried FP10 and while it worked OK it seemed to cause the Crosman pellets to oxidize when stored in a leather pellet pouch made from a Good Will coin purse. Next we tried aerosol Slick50 one lube and have been using it to lube pellets ever since. After starting to lube our Crosman pellets we never had another occurrence "packed in fouling" and bore cleaning when needed was/is a simple matter of pulling through a few patches.

I've read that pure lead pellets like the Air Arms domes don't foul bores as readily as the hard lead alloy Crosman pellets, however I still lube my AA anyway.

[UlteriorModem]

Cleaning barrel 'discussion' aside, I did get a chance to clean the barrel and tighten the shroud. I ran a few patches down the barrel with a bore snake and the first few came out black as coal! Pretty sure it is residue from whatever they put on the pellets after production or maybe mold release. It probably was not hurting anything but it makes me feel better

About 3 or 4 patches later they started coming out clean.

However I have not had a chance to try again.

It is still bleeping 96F with an RH of over 80% so it will have to wait a while.   

[Hoosier Daddy]

I would think because it was a sudden decline in the POI with the new tin, and if nothing else changed between shot #500 of the old tin and shot #1 of the new... it is the pellet.
 I was going to suggest if you have some of the old pellets, to shoot them and see if you are back to zero.
 But now that you have cleaned the barrel you have added another variable.
 Not saying it was wrong to do so, just muddy's the water.
Now if you shoot the old tins remains and everything is back home you can assume the barrel cleaning had no effect.
 Yet if the new pellets shoot closer, you may think it helped.

Short answer, If the new pellets group well, re-zero. You will never get the old ones back.

[UlteriorModem]

Yea I hear you about too many variables. Add tightening the shroud to the mix too 

I shot it a little some yesterday in the hot day. The JSB's were wandering around a bit so I decided to try some AA field heavys. They did pretty good at first but after about 20 rounds they too started wandering.

I think I am having some spiriling issues. Perhaps the regulator has changed some after several hundred rounds. Need to break out he chrony and tune her down just a bit.

[UlteriorModem]

Well here is an update.

Got off work early today and decided to check things with the Chrony in spite of the sweltering heat. The results were surprising. I had expected to have to back off the fps but just the opposite proved to be the case.

First couple of shots I did not change anything. The FPS had fallen off from the last time I tweaked it and was in the 780 fps range with a pretty good spread from 765 to 785 over 5 shots. Shooting JSB Jumbo Heavys in .22 cal or 18.3 grain.

Long story short I 'tightened' up the Hajimoto mod hammer spring adjustment a few times and settled in at right at 830fps and was much more consistent with the chrony displaying like 3 duplicates in a row. Spread of 834 to 836 much better!

Put out a 30 yard target and shot quickly a 197 out of 200 with 8 X's. The gauntlet is back in stride again

What the velocity change has to do with a different tin of pellets, probably nothing aside from they just made the inconsistency stand out enough for me to look into it.

Thanks for your patience and suggestions. I'm a better shooter thanks to you