Tuning What can make a barrel a "good" or a "bad" barrel ?

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bigHUN

bigHUN

Member
Jan 16, 2020
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Canada/L4G7X4
Looks like I got some barrels not grouping at all, I can call this disastrous...how can I fix it?

I got a Leshiy2 in .22 with a 350mm barrel just in front of the winter. Not much time to learn all the in-and-outs, but overall not bad at all for the games what it is meant for.

Over the winter I got two 500mm barrels from Russia, with a very last train. One is .22 and the second is .25 (this one I didn't try it yet).

My gun range shooting just started recently.

I swap out the original L2 350mm barrel with 500mm, cal .22.

First pellets I shot the AA Field 15gr, 915 fps. For couple days at 50 meters the tightest groups I got about 2".

I was not happy with that, could be the wind is tossing the pellets too much, so today I grab the heavier JSB RDM's 25gr and retuned the L2 for about 930 fps.

Shot them at the range, absolute disaster. I could see the pellets spiralling in the air, there is no group at all about 3-4" radius.

I left home and tinkering what else I can test? Swap out the barrels from 500mm back to original 350mm and tomorrow if the weather permits me back to the range.

What can be wrong with barrels? When I received them, I washed thoroughly with Balistol and polished all with Carnauba Vax.

Just now inspected the Russian barrels with a high power levellers lupe lens, also with a long rod I pushed through all the barrels their pellets.

The original Alpha barrel (or I think it is Alpha) is 12 rectangular shaped rifling, feels like choked at the end, the pellet head and skirt has a full contact.

The Russian 500mm barrel is 6 round shaped rifling and feels no choke, the pellet head and skirt has a full contact as well. The crown is maybe questionable but I need to visit HomeDepot to pick some ballhead brass screws and have a closer look again if I can improve.

What else?

{btw, to add in last second before posting, I didn't washed/lubed any pallets, not the AA not the JSB, just straight out of tins. OK, that may effect with scoring but shall not brake the groups}
 
Sometimes it can become a very deep rabbit hole. If you haven't checked it out already, here's a troubleshooting guide for detecting and fixing some of the most common barrel shortcomings that I drafted a while back:

https://www.gatewaytoairguns.org/GTA/index.php?topic=130555.0

The good news is spiraling is usually caused by a flaw so severe that it is relatively easy to detect. Something mangling the pellet...burr at the barrel port, sharp edge leading into the rifling, burr at the crown, or an excessively tight choke. Should be able to feel it by pushing a few pellets through. If you're new to it, compare to a known good barrel to get a feel for how much force is needed at the various inflection points of the barrel.

Spiraling can also be caused by very subtle clipping the baffles in a moderator or shroud.
 
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This is interesting because I’ve seen some visually poor barrels shoot pellets well. It’s very common for guys to focus on the muzzle end of the barrel but the chamber end can cause grief too. I’m not sure how a L2 is built but you could have a mag alignment or gap issue with the new barrel. Something is happening to the pellets as they jump from the mag to the barrel.
 
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Here it comes. I typed this post last night, but completely disappeared. This will be fun....because I re-type it 3x and all disappeared. Must be some filtering/analyzing content for specific words...like Russian
Click to expand...

Umm, maybe Russia or some constellation of terms. Might have gotten flagged as political, once they get the filters tuned it should be interesting.
 
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Read nervoustrig link. I don't believe I can add anything to it..... However when I polished my first barrel I forgot to put it up against the wall so the rod and mop left the end of the barrel and scraped the crown. I actually decreased my accuracy by doing that. Also just a tip. Recrowning with those brass screws can really help but sometimes it doesn't. I did one that looked great. I mean I thought it was perfect but it also decreased accuracy. The other 3 I did helped alot. I think it just comes down to the fact that the human hand just can't compete with a good lathe. Impossible to detect microscopic variations and all that. You sound like you know what your doing tho. Just offering the warning. I'd try to find out if there's anything else wrong before you start busting out a drill. That's my philosophy anyway. 
 
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I had problems getting the 600 mm barrel on my Maverick to play ball, somehow it seemed to only work well ( at least with one pellet ) if i went to really slow speeds under 600 FPS

The new 700 MM barrel i got, while i have not tried pellets in it much, just shooting the 2 weights of JSB KO slugs + 15 GR NSA leave me much more confident in the future,,,,,, which is good cuz i am only going to shoot slugs in that gun.

But as for the 600 mm liner, i have tried at least very hard with 4-5 different relevant pellets and shooting 2-3 tins of pellets of each in various setups / speeds, and i only got one of them to fly well at speeds, the rest at best will make 3 sweet groups with 1/4 inch in between the groups,,,,,, which i find literally,,,,, STRANGE CUZ a 21 shot magazine will give me 3 almost perfect groups with just a few "hickups"

BUT ! i would prefer to instead have 1 coherent but still bad group,,,,, that i would sort of be able to sell to myself as shooter error, or at least something i can work with.



It is / was so bad i have made myself unhappy about the vector optics scope i got for the Maverick, even if i dont think there is something wrong with it, so it will probably get replaced. So my FX Maverick, well it have not been a cheap or easy rifle to get rolling with as it is.
 
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Assuming you have checked for moderator clipping and obvious visible signs of barrel defects, those results are not anywhere close to good.

Judging from stated results at 50 yards with AA 15g(2") and MRDs(3 to 4" and spiraling), your barrel doesn't "like" either of them(at least at the speeds you are shooting). You might want to try different ammo(or at least different head sizes). The "usual" advice is to find ammo that YOUR barrel likes.

That being said, the 2 pellets you mentioned are two different "animals" which perform best under different conditions.

AA 15g is a narrow waisted(more traditional shaped diabolo pellet) which typically performs best when shot through a choked barrel with a relatively slower twist rate between 850 and 900 fps.

The MRDs perform better when they are shot more like slugs(from a less choked barrel with a relatively faster twist rate at relatively higher speeds like 925 to 980 fps). MRDs tend to spiral if they are shot too slow and/or don't have fast enough twist rate to stabilize them.
 
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I don't use bipods but a solid tripod and I can clamp the gun solid, so aiming or any possible scope error would be noticeable - I can exclude that.

No moderators-supressors-silencers in Canada, so I can exclude any clipping after the pellet left the crown.

I have 3 air strippers, tried them all and without...a bad grouping is way to extreme the airstripper to fix it.

Now, since somebody mentioned above this turned on the red light ... For my FX Impact I have a nice cleaning kit in .25 (and the FX liners are by design different) but doesn't fit the .22 Leshiy2.

I was using a way older brass solid rod that fits to clean and polish the .22 barrels, and I let the rod exit the crown end...

I checked again with jewellery lupe lens, I can see - visible concentric marks about 0.5-1 mm away from crown edge. This could be mine error.

I don't have a lathe. I just have machinist friends but they are generic. Fixing a barrel may be a best to take it to a gunsmith. I googled two gunsmiths in reasonable driving radius. The question is which one would take a job, I have seen "professionals" in recent years just don't want to bother with small jobs.


 
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I checked again with jewellery lupe lens, I can see – visible concentric marks about 0.5-1 mm away from crown edge. This could be mine error.
Click to expand...

That perfectly describes rifling damage from someone having used a piloted bit to form the crown. See it pretty regularly on lesser barrels. Really a shame to see it on something higher end.

Crosman was one of the repeat offenders for a long time. http://www.gatewaytoairguns.org/GTA/index.php?topic=110179

SPA likes to do it. https://www.gatewaytoairguns.org/GTA/index.php?topic=166821

The fix involves removing the damaged portion and recrowning. Need to evaluate the length of the damaged portion relative to the choke. Usually it is short enough that plenty of choke will remain.
 
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I checked again with jewellery lupe lens, I can see – visible concentric marks about 0.5-1 mm away from crown edge. This could be mine error.
Click to expand...

That perfectly describes rifling damage from someone having used a piloted bit to form the crown...........The fix involves removing the damaged portion and recrowning.......
Click to expand...

The barrel crown is not defined (no visible machined marks) up to a level of thinking no tool was used to do that, but again I don't see any other thing would leave the concentric marks, only my brass polishing rod?

............................................

I am just reading your GTA post, got to about half only, clear so far just tinkering what tools I have in my drawers.

I will have to go back to this barrel downstairs, I want to inspect again if I could see deeper into the bore transition = lead in.

The Leshiy2 is a shoot through mag...the barrel start has a slight pocket about half pellet length before the transition=lead in starts.

I want to push couple more pellets through the lead-in to see if I could pinpoint any malfunctioning. With mag and without a mag.

I remember last night I just pushed through only two pellets (w/o a mag) but directly from the bore lead...one came out with a cracked skirt, my initial thought was possibly from "cold cast" so I put that one aside.........but now I have a trigger in front of my nose.


 
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Uhm....I pushed several pellets through the barrel and feels lighter closer to exit (where some other barrels have a choke). Also noticeable concentric rings about 5-10 mm deep, but interestingly not only the rifling smaller ID but in OD as well.

I have a borecam somewhere deep in my locker, tinkering to put some effort to bring it out, but not sure if the cam can fit the .22.

So far this barrel is ready to re-cut. Tomorrow I will check the other Russian .25 barrel as well.
 
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