Bullet jacket separation.

[seppos]

184084Major problem!
I visited shooting range and shot some of the .338 light bullets that I made from .32 S&W long cases. Luckily I did not use supressor but had the muzzle brake on. When I went to the target, I did not see a nice little group like normally one could expect from my TRG-42.
Instead of that it looked like buckshot blast from a shotgun.
When I inspected the muzzle brake, I saw some brass in it so started to wonder could the wide hollow point act as an brake and open up the thin wall of the jacket..
Could imagine that in .224 the problems might be magnified as the wall in rimfire cased jacket is even thinner.

S

[bullet maker 57]

You could try bonding the core to the jacket.

[Hickory]

3400 fps seem to be the magic number for maximum velocity for bullets made with 22 RF cases, at least for me and my guns.
I have no idea what velocity your driving your bullets or how the jackets were prepped or annealed.
<<<< more testing needed>>>>

[rancher1913]

others have had problems with swagged rounds and suppressors / breaks

[seppos]

Have not had the same problem when the hollow point has been smaller so I suspect that it has something to do with the large hollowpoint.

S

[Valornor]

Could it be due to staking your core into the jacket? I had some issues once with a batch of tubing jacket bullets I made and found that I likely had used too much force to seat the cores and it affected the jacket integrity. Things came apart before they hit the target.

[seppos]

Can not say. Should study more before make any definite conglutions.
Would have been costly if I would have had the supressor on.

S

[supe47]

3400 fps seem to be the magic number for maximum velocity for bullets made with 22 RF cases, at least for me and my guns.
I have no idea what velocity your driving your bullets or how the jackets were prepped or annealed.
<<<< more testing needed>>>>

Hickory, I've had my 22LR jacketed bullets (40 grainer) past 4200 fps, but that was in a 1-12" twist. That's only 252K rpm. Somewhere near 320K rpm seems to be the limit for my 22LR jacketed bullets. I couldn't quite reach my 4000 fps goal with a 22-250 1-9" twist. Re-barreled with a 1-12" twist and easily went over 4000 fps.

[seppos]

The bahavour of the bullet has a definite link to the twist rate.. That has been proven by many.

S

[clodhopper]

Also linked to diameter.
At the same rotational velocity, a larger diameter will have a faster surface speed.
Then more centrifugal force.

I envision bullet blow up starting at the front edge of the jacket. A smaller meplat should help keep bullet together.

But don't bet a muffler on this hypotheses.

[seppos]

Have you encountered any of these kind of problems with factory bullets?

S

[Valornor]

Your TRG-42 is a 1:10 twist correct? How light where the bullets your were shooting? What velocity do you think you were getting?

[seppos]

My TRG dates back to the time when I trained the reserve snipers. In Finland the defence forces has a sertain status as all men up to 60 years are in the army reserve.
In the early model the twist was 1:12. Later on they changed the quicker twist to handle the 300 grainers that did not stabilize after 800 meters.
As the bullets where made from recycled .32 S&W Long brass, they where light. Thats why I had to leave the mouth open as the ogive was 10 in my die.
velocity was not bad as I used the data for the 180 grainers. No overspeeding so to speak.

S

[clodhopper]

Have you encountered any of these kind of problems with factory bullets?

S I had some .224 50 grain hollow points from a small, now defunct, manufacturer. They had a visibly large hollow point, loaded them in .22-250 cartridges for fire forming to .22-250 AI. The barrel has 1 in 8 twist.
When firing, grey streaks were visible in the air down range starting from 25-175 yards. Some that started streaking later in flight were seen impacting on and around the steel target at 250 yards.
Most that streaked earlier in flight were not seen impacting.
Some did not streak, those hit pretty darn close to the point of aim.
On the same day I fired 40 factory loaded 50 grain soft point .22-250s in the same rifle. No streaks were seen. pretty good groups, considering the gusty crosswinds.
Spotters with optics saw, and talked of the results, and I saw through the scope most of the streaks too.

[seppos]

Sounds bad.. will it need more testing?

S

[clodhopper]

No, much better shooting hornady 75 grain match bullets.

[seppos]

That is good to hear.

S

[runfiverun]

if the bullets are coming apart you'll see little specks of the jacket and core on the target.
you could be setting the core back in the jacket and it's doing so unevenly causing the bullet to be out of balance.
this is common when trying to shoot naked lead boolits at high speeds.
we have to combat it through a couple of different methods [mostly design and alloy combinations] and time it properly through powder burn rate.