Please explain this to me

[wheelman]

300 BLK

I have a load for the H&R handi that is 150 gr soft point with 15.6 gr H 110 at 1850 fps. Holding zero - balls on every time.

I have a load for the AR that is 245 gr lead with 12.7 gr IMR 4198 at 1280 fps. Holding zero - balls on every time.

If i put the 245 gr in the H&R, it shoots 3 inches to the right at 35 yards - every time. Why?

[Bodo]

Barrel twist rates?

[Dale Gribble]

Never mind, misunderstood the post.

[Rumbler]

Leade differences? I could see how twist rates could also do that but 3" at 35 yards without noticeable keyholing inclines me to think the bullet is getting the crap wacked out of it (knocked out of round/balance) before it even engages the rifling.

[wheelman]

Both barrels 1-8

[Rumbler]

Wheelman, recall that the first step in developing really accurate ammunition for a given rifle is measuring chamber dimensions carefully.

As an example; the six match rifles RAFSU's long range team has. All the .308s are serial numbered sequentially. As are the 6.5x284's. All six of them have different chamber dimensions, specifically the distance from the bolt face to the beginning of the rifling. The ammunition that shoots best in one gun, may not even allow the bolt to be closed on the next "identical" rifle.

[wheelman]

I know but for an AR OAL matters - correct?. I have not really played with fine tuning a load for the handi yet which is scary given how good it shoots with me just crimping on the cannelure.

If I remember, the factory ammo i bought had a short OAL.

[Rumbler]

You are correct. But keep in mind that the OAL for the Ar pattern is based on the same thing all magazine equipped 'modern' rifles are; "the length that will fit and function in the magazine".

The ammo I make for my Remmy 700 bolt gun in .308 is .076 longer than will fit in the magazine for my M1A.

[wheelman]

I get it.

The round I make for my Handi in .357 mag is on the edge cycling in the Dan Wesson. Way out of spec regarding length (FTP bullet to boot if you are familiar with those).

But that chamber is long and I started playing with the distance from the rifling and oh baby.