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Tumbling, accuracy issues- Worn G34 barrel?


lugnut

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I've been struggling with some issues with my trusty G34 lately. I had a connector crack on me last week and I've been see many of my rounds tumble a bunch lately. Recently it's been quite bad and I thought it might have been some crappy bullets- but that doesn't seem to be the case as I've used other know good batches of bullets.

I've used Berrys 147gr with 3.8gr of W231 for years. I shoot this one G34 a LOT... I'd estimate well over 50K rounds. I'll also admit to cleaning the barrel very infrequently... however when I did clean it out it's always looked nice (to my eyes anyway). I did seem to notice that the chrono readings seem to be dropping a bit since I can recall. This gun used to be at about 135PF and now regualrly tests at about 130PF... but I attributed that to lot variation of the powder.

In frustration I went to the range early this AM. I shot some "groups" with the gun and same ammo- the groups sucked and each 3rd or 4th rounds tumbled even at 7 yds! The tumbled round always seemed to be off my POA... but they all weren't good.

I switch to my G34 back up... built identically. Wouldn't you know!! Nice tight groups and NO tumbling! WTF... how long have I been shooting like this! Then a put another NEW G34 barrel in the original gun.... and same thing- TIGHT groups- no tumbling! I must have shot over 100 rounds- equally spread out and the results were the same.

I understand that in some cases the 147gr bullets have a tendency to tumble in other guns... so I wonder if this gun's barrel is just worn out enough to cause the rounds to lose stability??? I didn't check any other loads with 115s or 124s today... I might try that. Barrel crown looked fine too... I'll have to check it better tonight.

Has anyone else had this happen to them??? I'd call Glock but I'm not sure what they'd do, plus they probably will just tell me not to shoot reloads!

Edited by lugnut
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Shoot some factory ammo through it and see how it behaves. If it still struggles with factory then call Glock.

If not, check your dope. i.e. crimp, charge weights, oal, everything real close. Up the charge and see if it does anything. Run an entirely different load (bullet, powder) in the gun and see what happens

50k rounds does not seem like all that much. Could anything have happened like a squib that damaged the barrel?

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50k rounds does not seem like all that much. Could anything have happened like a squib that damaged the barrel?

I had a friend that was having more problems than mine with accuracy issues... he struggled with it for almost a year... till one day I just happened to look down the inside of his barrel- the polygonal rifling looked almost distorted. Upon closet review- he had a VERY slight bulge in the barrel- it was difficult to see but you could feel it.

My barrel does not seem off at all- I gauged it all the way down the barrel and it was fine. I don't recall ever having a squib... but neither did he.

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Have you tried slugging the barrel and comparing it to a new barrel? One thing I have found with 147's is that they like to driven over 900 to work well.

I'm going to 135gr RN after I use up my 147's. I tested some and they were more accurate in my MP

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Have you tried slugging the barrel and comparing it to a new barrel? One thing I have found with 147's is that they like to driven over 900 to work well.

I'm going to 135gr RN after I use up my 147's. I tested some and they were more accurate in my MP

What is slugging? I did try two other barrels and they worked fine... today at least!

I have ton of these Berrys and they worked fine for years so I think a new barrel is in order.

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Have you tried slugging the barrel and comparing it to a new barrel? One thing I have found with 147's is that they like to driven over 900 to work well.

I'm going to 135gr RN after I use up my 147's. I tested some and they were more accurate in my MP

What is slugging? I did try two other barrels and they worked fine... today at least!

I have ton of these Berrys and they worked fine for years so I think a new barrel is in order.

Slugging is forcing a bullet through the barrel and then measuring it. It ususally done to determine the bore size. have you tried bumping the load slightly to see if it goes away?

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Have you tried slugging the barrel and comparing it to a new barrel? One thing I have found with 147's is that they like to driven over 900 to work well.

I'm going to 135gr RN after I use up my 147's. I tested some and they were more accurate in my MP

What is slugging? I did try two other barrels and they worked fine... today at least!

I have ton of these Berrys and they worked fine for years so I think a new barrel is in order.

Slugging is forcing a bullet through the barrel and then measuring it. It ususally done to determine the bore size. have you tried bumping the load slightly to see if it goes away?

As a test- I will try other loads with the original barrel. I would guess that the light bullets will be more stable and not tumble... even with a "worn" barrel.

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Unless you're pouring sand down the barrel before shooting or using a powder that is notoriously abrasive (231 is not one of those), I cannot imagine that barrel "wear" is a problem. The surfaces of those barrels are harder than woodpecker lips and there have been documented accounts of barrels with significantly more than 50k rounds with no ill effects.

The copper-washed bullets (Raniers and Berrys are two of the most popular) have had their issues in all sorts of barrels. They are generally soft, since the copper plating is so thin. They act like lead bullets ballistically; you just don't have to break out the Lewis Lead Remover after a good session.

The polygonal rifling of the Glock and the H-K doesn't particularly care for anything other than gilding copper jacketed ("REAL" jacketed) bullets. The profile of the rifling is subtle as opposed the lands-and-grooves profile of conventional rifling. The bullets will sometimes skip right past the rifling and not twist at the rate that the barrel wants it to. Slow spinning bullets will tumble like that, especially 147s, since they prefer a slightly faster twist rate.

The OP said that he's used these bullets in that barrel before, but "Has ANYTHING changed?", especially in the crimp specification of your loads. The last time I had a copper-washed bullet tumble, it was because I was actually crimping too tightly.

Just thoughts....

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Bruce- all I can say is I have two other G34s. All guns shot the same ammo without issues. The "bad" barrel didn't. Crimp didn't change but before I swapped barrels I loosened the crimp. I had other folks check that the crimp was fine.

It is indeed strange as the barrel looks fine with no obvious defects. On the round count- I'm not good at tracking this at all... but I still think it's over 50K but likely less than 100K.

Yeah I'm puzzled.

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Have you put a micrometer to your current batch of bullets to make sure they are the diameter they are supposed to be? Check several places to make sure they are round too.

I'm thinking something is different with the bullet or your load. If they worked before they should work now if there's no damage to the barrel. I suppose that whatever amount of wear you have on the barrel could be enough to cause issues, but it seems very very unlikely.

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I've measured the bullets, visually checked them as well. Here's the thing. I made a batch of a couple hundred rounds with the same bullets. Tested them with the "old" barrel. I was definitely getting at least 2 good tumblers per 10 with more slight tumbles. Grouping seemed to suck. Using the same batch of ammo I tested another G34 (my back up gun) and everything was good, groups actually seemed tighter too. Then I tried another newer barrel in the G34- it too shot fine.

My reloading process and materials hasn't changed in a long time and I think I've eliminated potential variables.

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Have you had a look at vluc's thread? He shoots 147's too, if I recall correctly

http://www.brianenos...howtopic=130688

I just reread the whole thing! Damn I even posted in that thread.. pre-tumbling era though. ;)

Just change the barrel. That's all it took for me though ymmv.

Still running the same loads, same oal, same crimp, etc. Running fine in the other guns.

Yep, I have one on order. Like you though, I wanted to see what the cause may be or how it happened. Maybe I'm in denial of the round count (don't want to think about how much I've spent!) and it's higher than I thought... but I am still surprised as the barrel "looks" fine to my eyes. Matter of fact- just for kicks I cleaned it with some copper cleaner... not one bit of green the patch after 5 mins. I was very surprised. It is retired.. but I may do some experimentation in the fall....

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Have you had a look at vluc's thread? He shoots 147's too, if I recall correctly

http://www.brianenos...howtopic=130688

I just reread the whole thing! Damn I even posted in that thread.. pre-tumbling era though. ;)

Just change the barrel. That's all it took for me though ymmv.

Still running the same loads, same oal, same crimp, etc. Running fine in the other guns.

Yep, I have one on order. Like you though, I wanted to see what the cause may be or how it happened. Maybe I'm in denial of the round count (don't want to think about how much I've spent!) and it's higher than I thought... but I am still surprised as the barrel "looks" fine to my eyes. Matter of fact- just for kicks I cleaned it with some copper cleaner... not one bit of green the patch after 5 mins. I was very surprised. It is retired.. but I may do some experimentation in the fall....

I was hot to find the cause, may still look, but I spent too much skull sweat and angst over it, so I moved on! I was thinking more about it than the shooting.

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I'm with you Vince! I lose my mind when my guns/ammo aren't working 100% I've seen too many people get stuck for a long time and not advancing because of gun problems. I struggled with a 1911 for a year and realized this as well. No more. That's why I love my Glocks. closedeyes.gif

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