RedDust
03-27-2017, 09:17 AM
I've been lurking for far too long - time for a post!
I've recently had my marlin 336 re-barreled.
It's a dedicated cast-only rifle used for target competition and hunting - It had about 2000 rounds through it last year.
The original 20inch, 1 in 10" twist microgroove in 30-30 was replaced with a 26", 1 in 14" twist hand-lapped chrome-moly barrel in 30-30, with a Marlin 30-30 profile.
Velocities seem to have increased a lot more than I expected. Just wondering if the pressures might be up a bit in the new barrel, as 300fps increase in velocity from a 6 inch longer barrel seems rather a lot of difference. Anything to be concerned about when working up conservative cast loads from minimums in the loading data?
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Background:
The Cast Bullet Engineering 313-112GC (124gr lubed and gas-checked, sized to.311) over 20.5 of H4198 came out of the old barrel at 1700fps, the same load shoots more accurately out of the new barrel and comes out the muzzle at 2025fps, a 325fps increase.
I can't shoot Lees TL314-90-SWC, sized .311, slow enough using TrailBoss - 5.5gr gives 1275fps and 6.5gr gives 1415fps - big groups at these velocities - I'll need a heavier projectile for plinking.
I haven't tried any heavier cast yet as my NOE 311-165 RDs are too fat in the nose for the new bore. Just got an NOE 311-180 FN mold (311041 copy) so aiming to have some projectiles to test next week. I want to work up to the 28gr H4895 load with the #311041 clone.
I know that the chamber in the new barrel is a little tighter than the original. About 50% of the old neck-sized cases had some resistance chambering, so about 30 remaining hand-loads were pulled, and all cases full length sized. The bore is smaller, but on the other hand there is much more groove area and it's shiny-shiny, not dull like the old barrel.
I've recently had my marlin 336 re-barreled.
It's a dedicated cast-only rifle used for target competition and hunting - It had about 2000 rounds through it last year.
The original 20inch, 1 in 10" twist microgroove in 30-30 was replaced with a 26", 1 in 14" twist hand-lapped chrome-moly barrel in 30-30, with a Marlin 30-30 profile.
Velocities seem to have increased a lot more than I expected. Just wondering if the pressures might be up a bit in the new barrel, as 300fps increase in velocity from a 6 inch longer barrel seems rather a lot of difference. Anything to be concerned about when working up conservative cast loads from minimums in the loading data?
------------------------------------------------------------------------------------
Background:
The Cast Bullet Engineering 313-112GC (124gr lubed and gas-checked, sized to.311) over 20.5 of H4198 came out of the old barrel at 1700fps, the same load shoots more accurately out of the new barrel and comes out the muzzle at 2025fps, a 325fps increase.
I can't shoot Lees TL314-90-SWC, sized .311, slow enough using TrailBoss - 5.5gr gives 1275fps and 6.5gr gives 1415fps - big groups at these velocities - I'll need a heavier projectile for plinking.
I haven't tried any heavier cast yet as my NOE 311-165 RDs are too fat in the nose for the new bore. Just got an NOE 311-180 FN mold (311041 copy) so aiming to have some projectiles to test next week. I want to work up to the 28gr H4895 load with the #311041 clone.
I know that the chamber in the new barrel is a little tighter than the original. About 50% of the old neck-sized cases had some resistance chambering, so about 30 remaining hand-loads were pulled, and all cases full length sized. The bore is smaller, but on the other hand there is much more groove area and it's shiny-shiny, not dull like the old barrel.