Promag scope mount zeroing problem

[rsd86 0]

I got a Promag side mount for my 7.62. It sets a bit high, but guess that'll let you use the irons if ya wanted. I had to shim it a bit to get it centered with the barrel but, after that seemed pretty solid. I threw on an old scope from my 30-06, and went to find out what it'll do.

 

Started off just like I did with the iron sights at 25 yrds. After a few rounds It would group just a little over a quarter sized hole. So I moved to 50 yrds. Not even on the paper, and so far off I couldn't tell if I was high or low. I tried 100 yrds with the same results. With just the irons I can keep a grapefruit sized patern at 100. Moved back up to 25 yrds and grouped great again. So the mount didn't move.

 

The scope was painted when I got it, not sure what it is, but it holds the kick of the 06 just fine. I was using Hornady zmax ammo. Shooting from my varmint sticks.

 

I don't know what's throwing the kink in my setup. Any pointers?

[theorangeplanet 968]

Just what size paper are you shooting at 100? A 25 yard zero is going to be closer to a 200 or 300 yard elevation zero down range. At 100 you're likely shooting 5 or 6 inches high. Either use some bigger paper to see where you're hitting or adjust the scope several clicks down. Also, I'd remove any shimming used to try and center the mount to the bore... that will only add to inconsistency. Original Russian side mount scopes are specifically offset, and that doesn't make them any less accurate or harder to zero.

[rsd86 0]

Ok, I'll remove the shims, and start over. I was shooting at four pieces of 8x11 paper. So the whole thing was around 22x16. I thought that at a 25 yrd zero should be about 3.5" high at 100 yrds. That's about how it worked out with my iron sights.

[rsd86 0]

I think I figured it out. I was playing with Winchesters ballistic calculator. Guess I underestimated the difference in a scope mounted 1.5" above the barrel and one almost 3". Now I think I'll toss this tall mount, and look for a shorter one.

[rsd86 0]

I hate to revive an old thread, but I can't seem to figure out my problem yet. I got a new scope mount, thats lower to the bore, and a new scope. I put the rifle in a vise and made sure the barrel, mount, and scope were all level with each other.

 

Started off at 25 yards to get on paper, and within a few shots got it where I wanted it. So then to 50, where I wanted my zero to be. Few more shots then I was right on, and thought everything was great. Then out to 100 yards where acording to Siera Infinity should be a little under an inch high. Three rounds later, and I'm 11inches high. Reset, scratched my head, and cussed for a sec then tried again. Same thing, about 11 inches high.

 

So then I called a friend of mine who shoots and asked to see what It would do for him. He brought with him a Nikon scope, and a shooting rest. He tried it with my scope and his rest. About 11 inches high. So then we put on his Nikon, leveled it, and after 50 yard zero set, it still shot about 11 inches at 100 yards.

 

I bought this gun brand new, but we still checked the barrel and crown. They looked fine. Take the scopes off and with Irons it shoots pretty good. But I got this gun to shoot pigs off my deer lease and they've gone nocturnal, and I can't see good enough at night to use the irons. I'm all out of ideas. Can't think of anything to check that we haven't checked already. And I've waited too long since I bought it to take it back.

 

So 2 scope mounts, 2 different sets of rings, 3 scopes, about 5 different kinds of ammo, and 2 shooters with no possitive results.

[rsd86 0]

_{I finally got it where I want it. I lapped the rings. Then I put an aluminum shim under the base of the rear ring. That way the scope isn't parallel with the barrel but pointing down forward a degree or two. Sighted it in then shot groups in 25 yrd increments from 25 to 150. They all grouped right where they are supposed to. I don't know for sure which thing I did helped the most, but its fixed. I love this rifle again!}