M1A inconsistent1

M

Megawatt maker

Member
Joined
Nov 12, 2017
Messages
699
I bought an M1A loaded a few years ago. It shot decent enough, 1 MOA with my hand loads

I have about 1000 rounds out of it at this point, and it's starting to get goofy.
20230420_151541.jpg

This is 100 yards, 200 yard zero, at least last time I took her out. This is a sub MOA. Nice right? Ok...

20230420_151721.jpg
This is 200 yards. The only change...I extended the bipod legs a notch, and the front of the rifle raised a bit. Far from sub MOA. This is using 168 g Match Kings over 47.5 grains 2000MR with a CCI 34 20230420_151546.jpg
This is 100 yards...175 grain MK over 41.5 grains IMR 4064 and WLP primer. Not bad right?
20230420_151707.jpg

200 yards results. Obviously, it loves this load at 200...the problem is...this was the only nice group it printed. I didn't get a picture (getting old) of the pattern it left fir the next shot group. It was a 6 inch scatter.
Again..nothing changed but raising the front of the rifle.

The only issue I've found is..it may need to either have a shim behind the gas block..or unitize it. The handguard doesn't touch, the trigger guard it TIGHT. TIGHT TIGHT...takes all I have to get it open and out...and even more to get it back in and closed. While it's not bedded (it's only a loaded) it's very tight still in the stock.
It has a Harris bi pod, mounted on the stock itself, not the gas block. Harris sells a slick adapter to do this. Nothing is touching the barrel forward of the receiver, as nothing should. Only the front band..with only about .005 play give or take..slop in the gas block to band. I've ordered a shim set, but I really doubt that's the cause. I think I'm missing something.

Any ideas outside what I spelled out?
 
Last edited:
frogfurr said:
Something is loose on your sights.
Click to expand...
Most definitely not. It's scoped. Leupold VX3i LRP. At 100 yards...you see the pictures. It does that all day. At 200, since my range goes uphill..is about 20 feet higher...hence I must raise the front of the rifle. That's when it states going goofy. It didn't used to do this.
No scope adjustments made. I can go back to 100 yards...sub MOA groups again.

It's strange
 
I’m going to offer a different suggestion. You said your 200 yard target is uphill which is causing you to put pressure on both the rifle and the bipod in different places, plus, you are extending the bipod a bit and losing some rigidity in the bipod. Try shooting off of bags instead and see if your 200 yard groups don’t tighten up. Bipods can cause some crazy stuff under recoil if you aren’t pushing them forward and getting consistent pressure on them. You are probably not loading up on the bipod when shooting uphill. Take out that variable and see what happens.
 
I think Marksman13 is onto something. Not with an M1A, but I can induce errors by being inconsistent in forward pressure (loading) on the bipods. We strive for consistency in all things in rifle marksmanship. Could adding angular changes and the different force distribution contribute here?
 
marksman13 said:
I’m going to offer a different suggestion. You said your 200 yard target is uphill which is causing you to put pressure on both the rifle and the bipod in different places, plus, you are extending the bipod a bit and losing some rigidity in the bipod. Try shooting off of bags instead and see if your 200 yard groups don’t tighten up. Bipods can cause some crazy stuff under recoil if you aren’t pushing them forward and getting consistent pressure on them. You are probably not loading up on the bipod when shooting uphill. Take out that variable and see what happens.
Click to expand...
Here's the thing. I agree with you in that a bi pod can effect some rifles. I have a bolt action that simply hates having a bi pod on it.

This rifles wasn't one of those. I've had if for 4 years at least...maybe longer, I'd have to dig out the paperwork, but what it's doing now is new. It always did at least MOA at 100 yards...sometimes tighter..like in my photos..but never more than MOA unless I was using crap ammo.

It kept MOA at all yardage. 200...400...600...until now. This is something new..and its not a random once off. It has done it now for two trips to the range. Nothing has been changed..same bi pod...same shooting range..even shooting during its favorite Temp range (75-85 degrees)..

The shims will be here on Monday...that's simply has to be it. There was almost no play in the gas block before..a very tiny bit...but now a .22 MM (I can't find my SAE feeler gages) feeler gage can be slid in between the band and block. That's not much..but it more than ever before.

Obviously, the stock has shrunk a bit. I'll bet it time to do a bedding job soon too. I've never done that on an M1A before..but looking at my Match M1A..it's going to be a chore.
 
Another thing I would suggest is to ditch the Harris bipod in favor of the issue M2 bipod. (I understand that Springfield Armory™ is now reproducing them, and they are available.) The difference is that while the Harris is spring loaded, the M2 is rigid, while the feet are skids. And it mounts on the barrel / gas cylinder instead of the stock. The Army presumably knew what it was doing when it designed this. (Yes, the Army is currently using Harris bipods.)

IMG_0285b.jpg
 
AlexanderA said:
Another thing I would suggest is to ditch the Harris bipod in favor of the issue M2 bipod. (I understand that Springfield Armory™ is now reproducing them, and they are available.) The difference is that while the Harris is spring loaded, the M2 is rigid, while the feet are skids. And it mounts on the barrel / gas cylinder instead of the stock. The Army presumably knew what it was doing when it designed this. (Yes, the Army is currently using Harris bipods.)

View attachment 1147131
Click to expand...
I have one. I've tried in on my match years ago...the results were...well...less than desired.
The army issued it to provide some control in full auto...so pin point accuracy wasn't the prime function. Machine gun accuracy is all you get with it as well, especially as the barrel heats up...

I have not tried it on one in question..it's just a loaded...I may..but I highly doubt I'll see any improvement.
If it didn't work on the Match..no way will it work better than the Harris here.

I currently have it on my Norico Knock off M1A. On that one...it shoots 2-3 MOA with the bi pod...without the bi pod..with match ammo, with my painstaking built handloads, with crap cheap Pakistan surplus 308, with Austrilian surplus, with Portgese surplus...pretty much never changes no matter what I do to it. That's one thing I'll give it...it's Minute of Man accurate...no matter what you do to it.
 
I don't wish to start a big ruckus here, so I will suggest this just in passing. When we pretty much exhaust mechanical issues their is one left. The shooter. As the OP states the rifle must be elevated to a degree to compensate for the elevation of the target. Would it not follow that a cheek weld difference thereby changing the reticle position is the cause?
 
20230421_094934.jpg
This is the loaded..the one in question.
20230421_095027.jpg
The Norinco Knock off...with the GI bi pod.

I have my Match in cold storage or I'll post a photo of it. When I bought the loaded..I was actually wanting a super match..but I couldn't find one, and a few LGS and Sportsmans warehouse also, all told me that Springfield wasn't making them anymore...although still listed on their website at the time...it turns out to be true. They no longer list the Match or Super Match. So..that's why I bought the only loaded I could find on the rack.
 
Risky buisness said:
I don't wish to start a big ruckus here, so I will suggest this just in passing. When we pretty much exhaust mechanical issues their is one left. The shooter. As the OP states the rifle must be elevated to a degree to compensate for the elevation of the target. Would it not follow that a cheek weld difference thereby changing the reticle position is the cause?
Click to expand...
Anything is possible...but I'm not a rookie. Not my first rodeo..so to speak. I've shot at this exact same range, with all my rifles, in all weather and conditions, for about 20 years now.

Changing the reticle position would only change the zero...not scatter the shots, which is what's happening.
 
Megawatt maker said:
Anything is possible...but I'm not a rookie. Not my first rodeo..so to speak. I've shot at this exact same range, with all my rifles, in all weather and conditions, for about 20 years now.

Changing the reticle position would only change the zero...not scatter the shots, which is what's happening.
Click to expand...

Inconsistent sight picture/cheek weld can absolutely play havoc with parallax which will give more inconsistent groupings.
 
It's not bedded..yet anyway. Up till now, it didn't need it, and may possible need it.

I've never done rapid fire with this one. I have the junker Norinco to do that (at which it excells at). The piston is clean as well.

This one get 3 shot groups...and cools down. At least a few minutes between groups.

My Match keeps good groups..but it's semi retired. Since they stopped making them, I moved the scope to another rifle, oiled it up, greased it up...put it in a silicone sock and into cold storage. It will only got shot on special occasions..which will be Russian/China invasion, or Civil War.
 
M1A's are tanks. They are not exactly bench rest rifles but then again they are certainly not inconsistent. Nothing flops around on M1A's.
 
LoonWulf said:
Shooter/position induced id guess. I cant think of a mechanical reason for a gun to go from moa to 2x that unless bullets are suddenly becoming unstable.
Click to expand...
It's not me. I'm 100% certain of this. As I've said in this thread..I'm not a rookie. Been shooting at this range for 20 years. This rifle did not do this before..as I've said. It's not my ammo..because my AR 10 prints the same holes at the same range as its always done too.

It simply must be the need to shim the gas block...there is no other obvious explanation.

I report the results when I get the shims and install them.
 
Megawatt maker said:
It's not me. I'm 100% certain of this. As I've said in this thread..I'm not a rookie. Been shooting at this range for 20 years. This rifle did not do this before..as I've said. It's not my ammo..because my AR 10 prints the same holes at the same range as its always done too.

It simply must be the need to shim the gas block...there is no other obvious explanation.

I report the results when I get the shims and install them.
Click to expand...
If you knew the cause why post the question? I stand by previous assumption that it is going to be related to the angle of the 200 yard target. Either loading the bipod differently, or changing cheek position as others have suggested. I’m going to bet that your shim fixes absolutely nothing. If that was the cause, it would show up at 100 yards as well as 200 yards. You aren’t shooting sub-MOA groups at 100 yards with a mechanically unsound M1A.
 
I've always heard it takes a 1, 000 rounds to brake in a rifle. You may have proved that point. But something has substantially changed. From your photos it appears either you changed the scope or the scope turrets and that can be a big problem. My shooting buddy occasionally has an empty case hit an extended scobe turret knob. It will affect POI. He could not find a suitable base. He made a plastic deflector from a milk bottle, but eventually had a qualified gunsmith change out his base for an official military sniper base to solve the problem.
 
Megawatt maker said:
It's not me. I'm 100% certain of this. As I've said in this thread..I'm not a rookie. Been shooting at this range for 20 years. This rifle did not do this before..as I've said. It's not my ammo..because my AR 10 prints the same holes at the same range as its always done too.

It simply must be the need to shim the gas block...there is no other obvious explanation.

I report the results when I get the shims and install them.
Click to expand...
Not saying your doing anything wrong or even different than what you would at 100.
Just that in any properly functional system its usually flesh and blood that causes a variation.
I cant think of a mechanical reason for groups to open unless something is changing them between the 100 and 200yd line.
The slight incline maybe just enough to flex something or cause a difference in the way the gun moves during the shot cycle.
You could have someone else shoot the gun, even if they arnt as good a shot as you are, and see if the increase in dispersion continues.

I would be interested to hear if shimming your gas system improves your 200yd groups, your 100s are impressive.
 
You must log in or register to reply here.

Similar threads

M
M1a inconsistent/bloody mess/take 2
2
Replies
44
Views
1K
S.Crockett
S.Crockett
A
  • Locked
77 sierra matchkings groups at 100 yards?
Replies
8
Views
870
Nature Boy
Nature Boy
G
  • Locked
M1A Club
2 3 4 5 6 7 8 9
Replies
202
Views
16K
skipbo32
S
MTMilitiaman
  • Locked
Hunting loads for M1A?
Replies
12
Views
4K
Omnivore
O
cowboy77
  • Locked
Ruger 10-22 barrel band
2
Replies
26
Views
6K
Bwana John
Bwana John
Back
Top