M1S upper range report

[kdiver58]

I went to the range today armed with 50 rounds of 220 gr. SMK over 10.5 grains of H110.
VERY IMPORTANT !!!! My chamber is SHORT. Sierra manual lists the OAL MAX as 2.26. I had my OAL at 2.245 and my bullets wedged into the riflings and the bolt would not close.
A benchrest shooter saved me he pushed the bullets in another .080 and they chambered like that. I will post the true OAL for a M1S bullet once I know it.

[kdiver58]

Today I made a gauge rod to place on top of the bullet tip, pressed a bullet into the bore until in was firm in the lands of the bore, brought the bolt forward slowly on a dowel rod I used to hold the bullet in place, I depth mic'ed to the gauge rod, removed the bullet and brought the bolt all the way forward, placed the gauge rod on the bolt and depth mic'ed it again.

With a 220 gr. SMK the MAX OAL of my cartridges is 2.185
With a 175 gr. SMK the MAX OAL of my cartridges is 2.189

so with a 220 gr. SMK my chamber is .060 of an inch short. (Using 2.245 and a standard MAX OAL) (Sierra lists 2.260 as a MAX OAL)

Has anyone else had a chamber that short ?????????

[interceptor]

My M1S upper was also short. Borrowed a reamer, GTG now.


Well, GTG other than the accuracy part...

[kdiver58]

My M1S upper was great with 150gr bullets last weekend. Interceptor what type of accuracy are you getting? I was 1.5 to 2 MOA super-sonic at 100 yards and was hitting a 12 x 24 plate at 300 yards sub-sonic.

I've loaded 50 rounds with 13.2gr. of H-110 over a 175gr SMK. Should be in the 1350 to 1400 fps range. Tomorrow I head to the range(weather permitting) I'll let you know how it goes.

It may need to wear in a bit. ??? Good luck .. K

[interceptor]

My supersonic stuff ain't too bad, but I'd like better, about 1.5 MOA at 100, haven't shot that load past 100 to date. Will do it later, possible a 200 zero, haven't decided, haven't actually put much thought to the gun in supersonic because the main reason I bought it was to shoot SUBsonic. The load is 16gn H110 under a Sierra 155gn Palma Match. Now, my subsonic loads suck, pure and simple. The load is 9.2gn H110 with a Hornady 208gn A-Max. I used that particular bullet as it was the heaviest .308 that the shop I work at had in stock, so I got it to try out before I ordered something else. As of this afternoon it will roughly do 5" at 200 yards, which to me is unacceptable.

This is through my M1S 16" upper, DPMS lower + JP trigger at 3lbs 2 oz, the aforementioned loads, and a YHM Phantom supressor. Conditions were: 85 degrees, 80% humidity, maybe a 5mph wind quartering from my right rear, mid afternoon sunlight, bagged front and rear.

[Pitt300]

Get one of these & send Lonnie @ Hornady 2 Fired cases & $10 & you're in business. Get the curved one for Semis. You will need to cut off the guide "tit" or else it is too long in the Whisper Case to get a bullet in.

It's been posted that M1S has too short a throat so as not to "step" into JD's patent.
It's very easy.
Seat short or get a gunsmith w/.308 reamer to lengthen throat.
If your main plan is 125 g (short) supersonic loads you are better off w/short throat as they tend to be more accurate w/the decreased "bullet jump" to lands on firing.

http://www.hornady.com/story.php?s=485

my $.02