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Allen Humphrey
02-13-2013, 09:24
Finally getting to shoot my CMP Garand some and noticing a pretty big shift in my elevation zero between sitting and offhand. About 2 MOA higher in Offhand. Is that consistent with what other folks get? I do use a pretty tight sling for sitting, but my 1903 only moves about 1 MOA.

As a side note, I get to shoot an RMC 80 this weekend with the Garand for fun. It will be my first time at 300 and 600 with it so I'll be using the basic come-ups from 200. Should be a hoot!

Maury Krupp
02-14-2013, 06:36
Normal.

At least it is for me and most of the folks I see/coach at our club Garand Matches.

Considering the differences between the two positions (head position, eye relief, sling/no sling, how the rifle is held, how it acts, etc) a different zero isn't too surprising.

Personally, I've found trying to compare one position's zero to another's to be pretty much of a tail-chase. My Standing zero is my Standing zero; my Sitting zero is my Sitting zero. That's all I need to know.

Maury

Johnny in Texas
02-14-2013, 09:55
The difference is caused by the offhand position offers less resistance to recoil and barrel time meaning the time it take the bullet to exit the barrel allows the barrel to be slightly high at exit in the offhand position. So the bullet impact is higher. Other things like light conditions will change POI as well.

Allen Humphrey
02-14-2013, 12:13
Thanks guys. I was a little concerned that the magnitude of the change might be a symptom of some other setup and fit issues. Since it seems to be in the realm of "normal" I'll leave it alone and try to do my part!

John Kepler
02-15-2013, 06:39
It's quite normal, so you've nothing to fix, though I disagree to a point with JIT. The zero-shift is generally based on ergonomics and your stock spot-weld based on the physiology of the different positions. BTW, that POI difference tends to disappear when you shift to the AR...but I too had a 2 click POI shift with my .30 cals. The rest Maury covered perfectly, so as always.....listen to him!

emmagee1917
02-15-2013, 11:33
John , a question. If the difference is ergonomics , why would going from .30 to .22 remove it as the positions still differ. Now , JITs make more sense to me as the reduced recoil would tend to remove the difference in gun jump.
Chris

Art
02-15-2013, 11:34
Good advice from Maury Krupp and John Kepler. My zero is slightly different in each position. I personally tend to shoot a bit low standing. One just has to understand that and adjust a bit. John Kepler's observation on the AR I'm sure is one of the many reasons these weapons dominate high power competition now, that and the fact that they just are more accurate.

Allen Humphrey
02-15-2013, 05:34
My NM AR has no zero change from standing to sitting. I've always attributed it (perhaps incorrectly) to the free float handguard and the quicker lock time. (and it weighs more than my Garand with all the lead!)

Maury Krupp
02-16-2013, 07:55
And taller sights, and a shorter sight radius, and a full pistol grip, and a straight stock, and a buffer system, and different recoil characteristics, and bullets of less mass getting pushed down a shorter barrel, and, and, and...

It's a whole different rifle in a whole bunch of aspects, all of which affect how the rifle acts, how the shooter interacts, and what adjustments need to be made to put the bullet in the middle.

Figure out each rifle's dope; write that down in that rifle's databook. Then the next time you shoot that rifle, put on what you wrote down and go shoot Xs. Don't over-think :icon_wink:

Maury

John Sukey
03-03-2013, 01:04
Well , the M1 is not a target rifle though it has been used as such. It was designed to kill people, and 2 moa isn't going to make a difference when you are doing that;)

John Kepler
03-03-2013, 09:06
2 MOA is the difference between a lethal hit and clean miss at 300 yds! Oh, and John, this forum is ALL about target shooting!

Art
03-03-2013, 09:23
2 MOA is the difference between a lethal hit and clean miss at 300 yds! Oh, and John, this forum is ALL about target shooting!

I had a favorite uncle who fought all the way across Europe with the 3rd Army in WWII. He had an interesting observation on this. He said a bullet that will wound a big man, lets say 6'2" and 200 pounds will miss a small man, lets say 5'7" and 145 pounds. A bullet that kills a big man will often only wound a small man.

I think every countries military rifles are capable of about 2 moa at a minimum as far as mechanical accuracy goes. Some are better, in fact a few are a lot better. There are a lot of other factors though, the quality of the sights, trigger, and ammunition come to mind. Of course the biggest variable is the skill of the individual rifleman. If the old boy can't shoot straight it doesn't matter how good his rifle is and shooting at living human beings who are moving and shooting back is a significant variable with this part.

And John Kepler is right. This forum is about target shooting usually with military or military type rifles.

madsenshooter
03-09-2013, 06:34
John , a question. If the difference is ergonomics , why would going from .30 to .22 remove it as the positions still differ. Now , JITs make more sense to me as the reduced recoil would tend to remove the difference in gun jump.
Chris

Ergonomically, the biggest difference is there's little change in side to side and up and down eye position relative to the rear sight, even with the different weld. With a Garand or similarly profiled rifle stock, there's a difference in both due to the taper of the stock from butt to wrist and the angle of the comb.