M1S seat depth = Trouble?

[superhondaz50]

Was working on the load for my new M1S barrel. 150gr FMJ Hornady on 15.7gr of Win 296. Book says 2.20 overall length. NO WAY would this chamber in the gun. I had to seat the bullet all the way down to 2.03 for the bolt to chamber the round! Will this be a problem to shoot?

[interceptor]

I had to bum a reamer to make my M1S upper chamber a standard length round. If you are looking for optimal performance from yours, I suggest the same.

[Pitt300]

This is a trick question.
M1S's 300 Fireball has a short throat/leade area.
If you're planning on shooting a lot of supersonic 125g loads this is probably the way to go as there will be less "jump" w/these bullets & it should be more accurate.
Problem arises if you want to use the longer projectiles & then you either need to know EXACTLY your COAL - .010" or there about to make life nice so that you can simply seat your bullets deeper to cycle fine OR you cut the throat deeper w/a reamer so that your chamber is closer to the original 300 Whisper.
By the way, does anyone know the actual dimensions of:
300 Whisper? Should be easy to find.
300 -.221?
300 Fireball?

[cubflyer75]

Here it is:

http://www.4-dproducts.com/displayit...2&tname=rental

You can rent the chamber reamer, throating reamer and headspace gauges here as well. Mike

[kdiver58]

I spoke with my gunsmith last weekend. I inquired on the cost for a new 300 W barrel . He told me he had 2 reamers one for 125 grain bullets and one for 200 grain bullets. I'm wondering if M1S is reaming for the 125 grain bullet so as to duplicate the ballistics of a AK-47 type of round ??? The difference in the Sierra manual is .200 +/- of an inch OAL
Just a thought ...

[interceptor]

no they aren't. mine wouldn't even close the bolt on empty brass.

[Pitt300]

interceptor,
you're full length resizing your brass & bolt will not lock?
What dies are you using?
Did you get bolt carrier w/upper from M1S or is it from different upper?

[ranger dave]

you seat your bullets so they work in the mag ( for ar shooters ) as for matching the 7.62x39 i depends on your weapon in you have a pistol gas tube watch loading full load 125g bullets Mr. Jones uses a gas system to control the pressure in his uppers . after 20 years with the whisper i have one load for all four of my guns its 8g of 2400 with a 147g win fmj . im out of the army no more free ammo the load is cheap and works great. i killed a cow at 125 yards ( my friend farms ) with the load what eles do you need

[interceptor]

Originally Posted by Pitt300

interceptor,
you're full length resizing your brass & bolt will not lock?
What dies are you using?
Did you get bolt carrier w/upper from M1S or is it from different upper?

Using premade brass from David Davis here on the forum.

By bolt not lock you mean not close fully? If so then yes. By about 0.300" IIRC, but this was over a year ago and my numbers may be a little off. I remember trying to drop the bolt several times on a round with bullet seated but no primer/powder and it still not closing or even being close and having to tap the dummy round out from the bore with a rod.

I'm using a Redding 2 die set. Purchased a complete upper from M1S.

[Pitt300]

Have you resized the brass yourself w/Redding Dies to make sure it is correct?
Be sure resized brass w/no bullet will close & lock.
Then try w/bullet.
If you are having to tap the dummy round out from the bore with a rod try OAL of 2.106 I think.