M1A and NOE 165gr XCB

I did a ladder test a few weeks ago and decided to load 4 5round groups ranging from 35.8gr of IMR4895 to 36.4 gr going up in .4gr increments. I forgot the magazines, so they were single loaded. If I remember the velocity from the load test, it should be somewhere in the 2250fps range.

Springfield Armory M1A, 3x9 scope set at 9x from bags at 100 yards. Wind was gusty up to about 15mph coming straight towards me.

5 shots 35.8gr IMR4895 CCi #34 165gr XCB 3inch group
5 shots 36.0gr IMR4895 CCi #34 165gr XCB 2inch group
5 shots 36.2gr IMR4895 CCi #34 165gr XCB 3inch group, 4 in 3/4inch group
5 shots 36.4gr IMR4895 CCi #34 165gr XCB 3inch group

That is incremental load testing not ladder testing. The differences are explained well here https://castboolits.gunloads.com/sho...57#post5382457

What twist is your barrel?

I should have explained better. I did the ladder test a few weeks ago. I started at 33.2 gr and went up to 37gr in .2 gr increments. I settled on the 36gr range for tonight's test because I got a cluster of impacts and matching velocity.

I am not really sure of the twist rate. I purchased the rifle used. It is a Springfield Armory with serial 265xxx. The barrel is marked NM308 about 4inches south of the front sight. As far as I can tell. The only modification to the rifle is the ferrule has been cut so the front band can't hook over it. I purchased an Archangel stock, but the modified wood stock seems to perform better.

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Most M1As are barreled with a 1 in 11 twist. Some heavy match barrels 1 in 10.

Easy to check yourself. Put a cleaning rod with a tight fitting patch on a jag in bore, mark the rod with an index mark for rotation and a mark for distance. Slide until you get 1 full rotation, and measure the displacement of the distance mark.

Quote:

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Originally Posted by garrisonjoe

Most M1As are barreled with a 1 in 11 twist. Some heavy match barrels 1 in 10.

Easy to check yourself. Put a cleaning rod with a tight fitting patch on a jag in bore, mark the rod with an index mark for rotation and a mark for distance. Slide until you get 1 full rotation, and measure the displacement of the distance mark.

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I had to do that this with my muzzle loaders to find out the twist for when I had problems with the bullets I was usen .

How do those groups compare to jacketed groups?

I get about 1 1/2" groups with Winchester factory ammo. I haven't tried loading jacketed for it.

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Quote:

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Originally Posted by garrisonjoe

Most M1As are barreled with a 1 in 11 twist. Some heavy match barrels 1 in 10.

Easy to check yourself. Put a cleaning rod with a tight fitting patch on a jag in bore, mark the rod with an index mark for rotation and a mark for distance. Slide until you get 1 full rotation, and measure the displacement of the distance mark.

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Many older M1As such as in the OPs rifle serial number range had milsurp barrels with 12" twists. Even those commercial made barrels of standard contour had 12" twists. The "match" grade SA M1As with heavy barrels could be had with 10 or 11" twist barrels.