Barrel lug peening! :(

[olp73]

I have recently started shooting Open with a small frameTanfoglio 9x19. The gun is custom built and has a Braily barrel.

The thing is that I am experiencing some barrel peening on the front edge of all the upper lugs. I do not think it is a lot but still like to hear with you guys. According to my gun smith it is a general problem with the design and that I should expect some peening. I am unsure of how much is acceptable and wonder if you have similar experiences?

Maybe there are some things I could do to prevent it from aggravating? How about a heavier recoil or hammer spring? Maybe rounding off the "corner" of the "kidney" to make it unlock earlier? This is at least what I heard might help, I think it was Henning that told me so.

I am also curious about what causes it, the gun seems to lock and un lock smoothly.

Edited August 17, 2010 by olp73

[CHA-LEE]

I have experienced barrel lug peening on all of the Tanfo gun's I have owned. On one gun I would stone the barrel lugs to level them back out but the peening would just come back after a few thousand rounds. On another gun I would just let the peening happen and it reaches a maximum point of peening and does not get any worse. Both function perfectly when both manually racked or fired.

Its hard to know exactly what the root cause is to the peening because there is a big difference in how the barrel locks/unlock manually when you rack it verses it being shot. When you shoot there are a lot more torsional and front to back forces being exposed on the barrel and it does change the timing of when the barrel lugs disengage from the slide lugs. Open guns are affected by this fired barrel movement situation even more because they have a comp that is artificially manipulating the movement of the barrel by porting the vented gas in whatever direction in an effort to stabilize the gun during recoil.

Then lastly you have the friction of the spent brass against the chamber and extractor against the rim of the spent case as the barrel unlocks and drops down as the slide cycles back. All brass expands to some extent or another after being fired, at least when using major PF loads, and the brass will expand to the maximum size of the chamber its self. If the brass expands to the size of the chamber then the extractor has to literally pull the brass out of the chamber with the force from the slide coming back. This holds the barrel up and pulls it backwards compared to where the kidney is directing it to go (Down and Back)and how its interlocked to the slide lugs. Personally, I think this is where the majority of the barrel lug peening comes from, at least on a non compensated pistol. For an open gun I think a lot of it would come from the comp in how it artificially affects the movement of the barrel in an effort to keep the gun level.

I don't have any numbers to back my opinions up with, but this is my best guess as to why the peening happens.

The way I see it, if it works and does not look like the peening is getting increasingly worse to a point where the gun isn't functioning, don't worry about it.

[shooterbenedetto]

Its definitely a timing issue. I hope Rich from Canyon Creek chimes in.

Slide metal is harder than the barrel.

[Jody Waring]

I have a barrel that has an unbelieveable amount of rounds through it, it was fit by a fantastic gunsmith, fit was tight new, and still is. It peened a bit, I began to worry but it just seemed to only go so far and stop. The slide metal is hard, and it could be at the last stage of the lockup that wears the barrel. Originally I thought it might have been from the comp "pulling the barrel forward- from having improper gap etc.... but I don't think so. I have had 4 barrels do this so far, 3 of them factory, the one I just discussed is a Storm Lake.

[shooterbenedetto]

Old original small frame Eaa slide has a deeper pocket for the lugs compared

to the Goldteam and Limited! never seen a peened barrel on it. The barrel lock

up on the old Eaa is Tightshut and no Light shines thru! compared to new ones that has a bit of play?

[olp73]

I have a barrel that has an unbelieveable amount of rounds through it, it was fit by a fantastic gunsmith, fit was tight new, and still is. It peened a bit, I began to worry but it just seemed to only go so far and stop. The slide metal is hard, and it could be at the last stage of the lockup that wears the barrel. Originally I thought it might have been from the comp "pulling the barrel forward- from having improper gap etc.... but I don't think so. I have had 4 barrels do this so far, 3 of them factory, the one I just discussed is a Storm Lake.

When do you think it should stop? 1000 rounds or 10 000 rounds? And how much is to much??

[Jody Waring]

This was an ongoing topic that was on the forums a while ago, but don't hear much talk of it anymore. I can't say where it stops,lets just say that mine has looked the same way for a few years now. The gun still performs perfectly, and I am considering pulling it out of the vault and shooting it some next season. Do you have a pic of your barrel?

[shooterbenedetto]

my take is to send it to Rich at canyon creek to time the gun.

[Vlad]

I can tell you my production CZ developed the same issue. I noticed it somewhere around 4-5000 rounds and it got worse after that. I replaced the barrel around 10000 for a different reason and by that time it seemed to have stopped advancing. It didn't seem to hurt anything else. Of course, in a open gun I would assume the whole process would be faster and I'm not sure if it would become a problem in the long run.

[olp73]

This was an ongoing topic that was on the forums a while ago, but don't hear much talk of it anymore. I can't say where it stops,lets just say that mine has looked the same way for a few years now. The gun still performs perfectly, and I am considering pulling it out of the vault and shooting it some next season. Do you have a pic of your barrel?

Just an observation. I have two other original Tanfoglio barrels for this gun, one in 9mm and one in 40sw. Both barrels, and particularly the 40 barrel, has much lower lugs than the Briley. The lock up with the Briley is rock solid, but I think the original barrels would peen less but maybe not give the “one piece feeling”.

Last time I came from the range I did not have to remove any peening, the lugs almost looks as if they has been mild now. Things are looking better!

Edited November 1, 2010 by olp73

[Jody Waring]

Mine don't look any worse than that, and they have been that way for a long time.

[Mo Hepworth]

I have a bit of peening,..but like Jody said, it has not got any worse. Does not effect function or accuracy.