Quandary - using 62 gn RF Bullets in a 1:8 barrel

[Mozz]

I have made some 62 grain RF bullets and loaded them with 24.3 grains of N135 and traveling aroung 2,850 ftps. I use the Serria reloading manual as a refferance which has neaver let me down.

I shot this morning at 200 meters the above load tumbles and has a spread of about 4 foot, i am using a AR15 straight pull, with a 1:8 barrel.

I realise that I need to do some work to get the right load and i don't have any experiance of tumbling bullets - My quandary is do I need to go faster or slower.

Any help would be great,

Mozz

[35whelenshooter]

Can you post a photo of your target? Very possible the length of bullet for a 1/8 twist will not stabilize do to how short it is. Measure your bullet length plug into one of the bullet stability programs and see if it stable. Sounds like it is not more like they would work in a 1/10 twist.
Respectfully


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[Mozz]

Can you post a photo of your target? Very possible the length of bullet for a 1/8 twist will not stabilize do to how short it is. Measure your bullet length plug into one of the bullet stability programs and see if it stable. Sounds like it is not more like they would work in a 1/10 twist.
Respectfully


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Thank you i didn't think of that... I will let you know.

[35whelenshooter]

Sounds good


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[rking22]

Ignore, I wasn’t paying attention. Sorry

[clodhopper]

Those bullets have a rotational velocity in the neighborhood of 4275 revolutions per second.

The centrifugal force would have less affect on a jacket with a smaller point.

Less revs per second could be achieved by slower twist barrel, or less velocity.

A pic of the target would be good, and any information on bullets that did not hit the target is useful too.

[freddyp]

Not all barrels are created equal. Some barrels have better internal finish than other mass-produced barrels. This might be what's causing the problem. I have made and tested a lot of the rimfire bullets. I found that some barrels were too rough inside and would cause flyers about 30% of the time. I had an older Mini-14 that did what you were experiencing. That same batch of bullets had no issue at 22-250 speeds (3600 fps) from two different guns. You are going to experience some flyers that go off course a little, but four feet is probably your barrel. The paper-thin brass jackets of 22lr cases just can't handle a rough bore. Firing them out a lapped custom barrel will allow you to push them faster, because of the smooth internal finish. The Mini-14 I had was rough. You could see the drill rotation cuts on the lands, when I looked down the muzzle at an angle. I would try them in a few other barrels and see what happens.

[skeettx]

1. Mic the bullets and see if they are 224
2. Insure the barrel is smooth
3. Barrel twist rate is 1 in 8 might not be right for the 62 grain

[rockrat]

Thats almost 260,000rpm. May be way too much rpm for your boolits and depending on your alloy, might be distorting them. I had a gun with a 1-9" twist that the boolits would come apart at about 60ish yards downrange once I approached 2200 fps.

I would back the velocity down to about 2200fps and see what happens. If things are OK, then work your way up in velocity till you reach a threshold. 1-8 twist, I suspect, is a bit to much for your boolits, at 2800+fps. 1-10" or 1-11" would work better, even a 1-12" might work

[mac1911]

Im generalizing for commercial bullets My 2 1/8 barrels will shoot 52 grain as tight as i can achieve. One dis likes sierra 69s both will run hornady bulk 55s to close to moa
I have a 1/9 that will shoot everything pretty well to about sub 2 moa no better or worse. i have a 1/7 that shines with 69/77 but falls flat with 80.....and surprising it will shoot 55s very well at lower velocity.

Now toss in home pressed bullets and the home made jackets from shell cases?

I recently came into a set of 308 S dies and thinking of setting up to make some bullets.