tumbling bullet

[RockyMtnMT]

We see some rifles stabilize the long for caliber bullets well and other rifles with the same twist struggle. Seems each barrel effects the bullets differently. I think the thought of trying a bit shorter bullet is a good idea.

 

[25WSM]

If he had a stability issue it wouldn't likely shoot 1/2 inch groups. I only shoot 8 twist for the 147eldms. 3 barrels all shot the 147s to 1000 yards no problems. Every customers 6.5 creeds I have built have been 8 twist. The fact that it doesn't do it till he has a lot of rounds on a clean barrel says something. I would inspect the barrel with a borescope when clean to see if there is a large imperfection. Then check it when the first bullet fails.
Shep

 

[RockyMtnMT]

We have shot some very good groups with oblong holes. Even at plus 500y.

 

[25WSM]

I would prefer round holes. Ovals are good if all of them are in it.

 

[HARPERC]

As our bullets trend toward the limits of twist, we seem to see more barrels that don't measure up.

Starting place that cost nothing, is measuring and verifying twist yourself.

 

[25WSM]

I know first hand that ABC and Lederer and Bartlein barrels are exact in there twist and I'm sure that most custom barrel makers are dang close or perfect also. Those are my 3 favorite barrels in order. I really like the Proof Research stainless and the carbon fiber barrels also.
Shep

 

[stljc2]

If he had a stability issue it wouldn't likely shoot 1/2 inch groups. I only shoot 8 twist for the 147eldms. 3 barrels all shot the 147s to 1000 yards no problems. Every customers 6.5 creeds I have built have been 8 twist. The fact that it doesn't do it till he has a lot of rounds on a clean barrel says something. I would inspect the barrel with a borescope when clean to see if there is a large imperfection. Then check it when the first bullet fails.
Shep

Yup..you might be right there. It's just whenever bullets start tumbling my train of thought go's straight to stability problems. LEARN something new every day..THANKS.

 

[26Reload]

Maybe there is a different cause here..being it is a 65creedmore....
the bullet went thru the targets holes and bounced back thru the paper....
How dare y'all say there's something wrong with a 65 crd....that is blasphemy.........
Oh Lord save their souls......

 

[milo-2]

A pic of the target would really help. If a bullet is coming apart and keyholing, it would have a leading or trailing edge, a hook so to speak, visible on paper. When it happened it would have been the perfect opportunity to shoot a farther distance, this would eliminate stability vs failure.
This works, if indeed your barrel twist is correct:
https://bergerbullets.com/twist-rate-calculator/
Without seeing the target, I am betting that there is an inclusion in the barrel causing enough buildup to destroy jacket. Get so many decent shots, then goes south.
A good clean, a borescope, some ammo and a trip to the range, fire 5, scope, fire 5 more, scope, repeat, a bad spot generating problems will surface, I think a novice could see it, things get dirty quick after a bullet passes that spot.
If it is this, it can be as easy as marking the spot and working that area over with JB paste, may take a couple trips.
EDIT: In theory, if this is the issue, you may be able to feel this with a cleaning rod.

 

[J E Custom]

Normally, Key holes are caused by worn barrels and poor engraving in the lands. If this occurs occasionally it is marginal. incorrect twist rates can also cause this but the problem is more frequent.

A well fouled barrel can also prevent the rifling from producing a clean engraving of the bullet and cause this.

The last thing I would look for is the wrong bullet for the barrel. (Some barrels just don't like certain bullets).

J E CUSTOM

 

[26Reload]

JE basically laid it out there for you....
But....we need you foot work now....is the gun doing it arlund the 25 shot like you said....if it is close to that number then it's definitely something in the barrel...if it happens mkre often or less often than it could be bullet size....

 

[HARPERC]

.......I know first hand that ABC and Lederer and Bartlein barrels are exact in there twist and I'm sure that most custom barrel makers are dang close or perfect also. Those are my 3 favorite barrels in order. I really like the Proof Research stainless and the carbon fiber barrels also.Shep

I think mostly they're correct, but lots of of places from ordering, to final product for the odd mistake to have been made. Since I started looking, I've gone from no problem to let's get this off the list of why.

 

[dolomite_supafly]

Some Savage barrels are pretty smooth and some are really rough. Doesn't seem to be much middle ground. I borescope barrels I buy used before I shoot them because I can get a pretty good idea of how they shoot.

 

[SergeantD]

A tumbling bullet is caused by too much crimp. A bullet that is forced down the barrel to fast will not turn in flight. Do not crimp bullets unless they have a cannelure.