Yep...that's what happened alright.

Here's the set-up:
weapon-- Oly PCR-4 20" 1-9 twist
target-- Outer's 100yd bullseye
distance-- 100yd's
shooter position-- Sitting/benchrest.
Sights-- A-2 iron sights

The Q3131A was awesome.
Q3131A = < 2MOA with the majority on the red dot
XM193 = 3+MOA with more than expected "flyers" into 7-6 ring on the target, this was with Lot-11 and Lot- 9.

Note, the XM193 did have more noticable recoil, accuracy suffered though...however it did rattle a few noggin's when I fired it under the shed. Had it been flesh & bones on the receiving end instead of paper, the target would still be dead...It's just that I have become somewhat anal about accuracy (common side-effect of black rifle fever).  Maybe it was the Lot#, I dunno, but I wanted to find out if anyone else had had similar results.

Anyone else see anything like this?... or maybe the Oly just prefers Israeli Winchester rounds.

I had the exact opposite results with my CAR97-M4 (1:9, s/s bbl.), yesterday. Groupings with XM193 were 1" or less at 100-meters while Q3131a was doing about 2"-3".

Yeah I like Q3131/Q3131a ALOT BETTER than XM193 Federal/Lake City!!

Thats what happens when you have a very hot round you loose a bit of accuracy!

Im glad to see Im not the only one who likes Q3131A better!

Dont get me wrong I love my Lake City M855

I was comparing these two types of ammo this weekend.  I was shooting a Rock River Arms M4 16" with a 3X Leupold CQ/T.

I put 40 rounds of each into two targets at 100 yards while shooting from a bench.

I would say that the Winchester Q3131A shot slightly better.  I shot 2 MOA with the Winchester and nearly the same with the Lake City.  However, the Lake City had a few "flyers" that I know weren't my fault, but they didn't get much more than an inch away from the rest of the group

The two made different patterns.  The Q3131A made a fairly even distribution in the 2 MOA area.  The Lake City had a shot-out hole in the center of the group with a diminishing density of holes further from the center.

I should have set up my chronograph and taken some measurements.... maybe another weekend.

The Q3131A brass looks cleaner.  A few of the Lake City cases seem to have splotches of primer sealant or something on them.

You know guys, XM193 is good stuff.  It's the same stuff I shoot out of my M16 in the Army.  Most of the time we shoot M855, but sometimes we burn off some M193.  XM193 shoots and looks the same as the issue ammunition.  Yeah the brass is not as pretty, but it'll still do bad things to targets.  To each his own, but there's not much point to picking Q3131 over XM193 just because the Winchester ammo is prettier.  

BTW, I took a round of Lot 23 XM193 and compared it to LC93 dated issue ammunition and it was identical in appearance.  Functions the same too.

I don't know...

I seem to get the same groups, 1"-2", out of both with irons.

Which ever is the best deal at the time.  Makes no difference.