Why does my M1 make two groups like this?

[MZ5]

In future watch that the gear bag is under the butt stock and not the front hand guard. Rifle may have worked it's way back on the gear bag during the string (recoil) so that the rifle was being supported in front of the sling swivel. That can cause groups to change POI.

That's very useful; thank you. The rifle was definitely supported in part under the handguard. It's a large gear/range bag, so it was all along under the main stock and the handguard.

[mac1911]

is your front gas cylinder tight on the splines?
you need to at least make sure your tracking your shots precisely

are you 100 % sure each 3 shots in the two groups where shot consecutively ?

[MZ5]

No, I thought I already said (maybe I didn't) that I cannot be positive that the hits alternated according to which side of the clip the cartridge fed from. The gas cylinder is tight on the splines, but the plug cannot screw in tight without putting a bend/bind in things.

[mac1911]

No, I thought I already said (maybe I didn't) that I cannot be positive that the hits alternated according to which side of the clip the cartridge fed from. The gas cylinder is tight on the splines, but the plug cannot screw in tight without putting a bend/bind in things.

Bend and bind? That does not sound good.
Try this draw some 4 3" bulls on a large piece of paper.
Take 2 shots at each bull and see how your groups look vs point of aim.
I have a M1 that has a cork screw pattern to its shots. You can compare shot for shot and it's the same patern.
It's the most correct WWII SA I have so I have not messed with it.
The M1s can be frustrating.
Although remember in the accuracy and testing portion of the weapons command over hall manual
They have you fire 3 warming shots before shooting the 5 consecutive shots for group testing at 1000" inches and that group is good to go at 1.77" or less.
All my M1s like to toss the first cold shot especially with HXP. It's not as bad with my reloads. My current M1 i use in the JCG as issued match will always shoot low right on first shot then settle in and drift a bit high as it gets hot. Not much but enough to loose a few into the 9 ring if I don't pay attention or cant see my impacts.

[karl schmidt]

You are probably seeing the outside edges of a really big group, you are stopping too soon put 5 or 10 more shots into it and see what develops.

[mac1911]

The 3 shots on the paper, plus the 3 just off are all from the same string of fire. 100 yds, just testing a load. However, it does this with other ammo as well. In fact, in the last C&R match I shot, I had wider spreads, but the same general pattern. I didn't/haven't watched closely enough to see if it alternates according to which side of the clip the round feeds from, though it wouldn't surprise me if it was that. The question is: Why does it do this, and how do I get it to put them all into 1 group?

https://www.milsurps.com/images/impo...528148ed-1.jpg

Sorry if my image host has rotated this img 90 degrees left. I can't seem to get it to show it straight.

So I'm looking at your group again where's the 8th shot?
Also your groups are what 1" apart. So your looking at a sub 3moa rifle. Not to shabby.
I say try shooting prone with a sling and support your arm on a nice solid sand bag. If possible get into position find your natural point of aim and have someone push and pack the bag under your slung support arm. Shoot 20 rounds like you would in slow fire course. See how things look. If your in the 10 ring or better, shoot more.