Yet Another M1S Upper Report

[kurtz]

Originally Posted by Pitt300

I too have a mildot scope w/target turrets.
I've found it easiest when I switch to subsonic loads to simply crank in about 13-14" of UP elevation & then hold dead on the target @ 100 yards.
This is NOT the problem.
The problem comes into estimating 140/150/160 yards as the drop gets severe.
A 200 yard range finder would be ideal!

Don't know if this will help, I use a 4.5x14 Mark 4 .....I do similar as you do except I zero at 100, a crank of 7" puts it pretty close at 140 to 160.....a crank of 14" puts it dead on at 200 with 220gr SMK at 1,050fps....

kurtz

[Flewis]

Well, I loaded up 50 rounds of the following:

Cases formed from new Winchester .223
trimmed to 1.365
11.6 grains of AA1680
220 grain SMK
COAL at 2.170

All 50 cycled perfectly and the spent brass all looks good.

Shooting from a bench with good sand bags.

However, accuracy sucked at 100 yards. I'll post pics of the targets in a little bit. The groups were large and strung diagonally. I'm using a lower with a match trigger that usually has my .223 varmit upper on it (which I can shoot dime size groups with all day long at 100 yards).

Any ideas on what I should look at for the accuracy problem? I have a cheap scope (NRA Brunton 6-24x50). I'm wondering if it isn't holding zero for some reason.

From the targets, it looks like the 220s are stabilizing (no keyholing). The velocities are all within about 30 fps of each other. How much velocity difference does it take to really start throwing shots? I'd like to get this rifle down to inch or inch and a half groups at 100 yards.

[kurtz]

On my AR whispers, supersonic fire-formed brass seems to be more accurate than first formed subsonic brass....you may also try pushing the load a little faster, even if it goes supersonic, just to see if the groups tighten up....my most consistant accurate 220SMK loads are just on the supersonic side, most of the subsonics are right at 1" or a little bigger....my more accurate loads are set right at the lands or slightly engraved....

[Flewis]

Originally Posted by kurtz

On my AR whispers, supersonic fire-formed brass seems to be more accurate than first formed subsonic brass....you may also try pushing the load a little faster, even if it goes supersonic, just to see if the groups tighten up....my most consistant accurate 220SMK loads are just on the supersonic side, most of the subsonics are right at 1" or a little bigger....my more accurate loads are set right at the lands or slightly engraved....

Thanks, I'll try both if those suggestions.

The barrel twist is 1:8 (confirmed). That should work well with the 220s, right?

[kurtz]

Originally Posted by Flewis

Thanks, I'll try both if those suggestions.

The barrel twist is 1:8 (confirmed). That should work well with the 220s, right?

1:8 ~ 220SMK....that is correct....

[Pitt300]

Kurtz,
Going to try some of the 208 AMaxs on Sunday.
I'll give it a +21" of clicks & shoot @ 200yards.
I have no intermediate targets except 25, 50, 100, 200y.

[interceptor]

Hope the A Max's work for you. Mine didn't.

Been thinking... If the accuracy of this M1S upper doesn't improve, I'm either gonna go one of two ways with it. One: rebarrel with (insert reccomended brand) and length. Two: get another tax stamp and cut it back to something like 8 inches or so, redrill the gas port to the pistol location, reinstall my Phantom adapter and YHM can and cover it with a 12" free float tube so the can just sticks out some and have a smith build me up a bolt action whisper on a Rem700 action.

Really leaning toward option 2. This one is pissing me off so far.

[Flewis]

Anyone know of a place selling .300 Fireball barrels now?

Novekse doesn't, AR15Barrels.com seems to be gone, SSK won't sell just the barrel and so on...

[kdiver58]

Just get a (insert barrel maker here) and have a good AR-15 smith ream it and thread it... That's what I'm going to do once I get the rest of the bugs out.
I'm not as unhappy as interceptor .. but it could be a LOT better ...

[Pitt300]

Interceptor,
Did you get free float hand guards from M1S?