One of my post-sunset builds is an M4gery using a Model 1 chrome-lined upper. It has a true M4 profile barrel, 1/9 twist and an A2 flash hider/crush washer. This rifle has been 100% reliable from the first shot, and now has about 250 rounds of XM193 through it. Unfortunately, it doesn't seem to want to shoot a decent group with this XM193 ammo (recently received "loose" from Sportsmans Guide). We're talking about 3" groups at 50yds.

At first I was concerned about the FH being screwed on too tight (I had to crunch it down pretty hard to align the ports properly), so I removed the FH and shot again. However, the groups have not improved... still 3" at 50yds with XM193. This rifle appears to shoot OK (1" at 50yds) with el cheapo WalMart/Winchester 55gr .223 ammo, so I hope this means there is no fundamental problem (such as a damaged crown or bore).

Lastly, as a point of reference, I tested the same ammo in my IPSC match rifle (20" stainless 1/9, also from Model 1) and it seems to shoot both the XM193 and Winchester about equally well (again, about 1" at 50yds).

Can anyone else here relate their experience with XM193 in a Model 1 chrome-lined M4 barrel ? What about other chrome-lined barrels - I know chrome lining is supposed to degrade accuracy a bit, but this seems excessive. Or should I just try other M193-spec ammo until I find something that will group ?

Any comments, suggestions or other support would be gratefully received.

i could be wrong but isn't white box win m193?

the velocity on the box matches up.....

Quoted: i could be wrong but isn't white box win m193? the velocity on the box matches up.....

If you mean the stuff from WalMart, then no it is not. Out of my rifle it chronos significantly slower. I think its loaded to .223 Rem spec rather than 5.56NATO (i.e. lower pressure). This WalMart Winchester ammo just BARELY makes IPSC minor power factor out of my 20" tube... no chance out of a carbine.

Umm, don't shoot with the XM193 ammo that give you horrible groups. That's the simple answer. Some guns like certain ammo. Find a kind that's fairly inexpensive that gives you good reliability and accuracy, and stick with it.
1" @ 50 yards is acceptable for a non free-floated gun. When you hear of these insane, dime-sized groups at over 100 yards, these are generally not performed with "tactical" or defensive guns but rather purpose-built target rifles with $1000 scopes and a good bench rest.
A non free-floated gun that is getting an inch at 50 yards with the cheap stuff is like a Corvette that's running on 87 octane and still getting to 60 in 4.5 seconds. Believe me, it's a good thing.

Maybe the gun like the ammo but just doesn't like you?  Just kidding!  

Quoted: Umm, don't shoot with the XM193 ammo that give you horrible groups.

I would shoot the Wally World stuff all day, except that its not hot enough. I want some true M193 spec ammo, both for SHTF and to make minor at IPSC.

Has anyone here had a similar experience ? What are you all getting, accuracy wise, from your chrome-lined M4gery barrels, and what M193-spec ammo do you find works best ?

I have a Bushy 16" chrome lined m-4 (Patrolmans Carbine bbl) that'll do 1.5" at 100 yds with XM193, but shoots Win Q3131A into 4" groups at the same distance.

It's a crap shoot. You just have to test different ammo till you find one that you and your gun are happy with.

Larry

I re-zeroed my Oly carbine the other day after having the barrel profiled and threaded. Santose IBZ at 50 yards, with Q3131A, my groups were around 1.5" off a sandbag.

Are you limiting your choices to just 55g  ? What about 62g ?  or PMC ???

This is primarily IPSC and SHTF ammo, so I need to make minor power factor and prefer a proven bullet like M193. I guess SS109 would be OK in a pinch. Price would also be a consideration.

I'm serious. There are plenty of choices when it comes to XM193. Go to your local gun store, buy a box of every 5.56 cartridge they have, and see what works and what doesn't. Certain brands will use different slightly different powders, brass, or might have minor differences in the bullet casting, all contributing to poorer accuracy. There isn't a gun in the world that will shoot the same way with every cartridge manufacturer out there. So, use this as an excuse to buy more ammo, go out to the range, and have some fun.

Just throw enough lead at it, it'll go down.



Just kidding.  Try all kinds of ammo.  Find one it likes.  Buy a shitload of that type.