.308 shooting real high

R

riverdog

New member
Here's the situation: Pre64 Win M70 in .308 Win with featherweight barrel. Factory iron sights. Federal factory ammo, both AE and GM. Cold/luke warm barrel.

With rear sight bottom'd out, the rifle shoots about 18" high at 100 yds. This is a guess as the bullets were hitting the berm above the target and 18" is estimated. What I'll do next time we go to the range (this week) will check the impact at 50yds. Should be about 9 inches high if my guess is right which puts the zero at 600 yards if my calculator is working -- WTFO. Why would anyone want a featherweight zeroed at 600 yds?

Barrel looks okay to the naked eye although someone mentioned it may need to be recrowned. Could a crown problem throw the bullets that far off consistently? When I look at the crown, I don't see a problem. If the crown isn't the problem, I may need to replace the front sight with one half again as high.

Comments? Any other tests to run?
 
I'd try the sight change first, it is a lot cheaper than barrel work. It is not impossible that the barrel was bent somewhere along the line; some of those featherweight barrels are pretty thin. If so, the barrel can be straightened, but that is not a DIY job unless you have some experience.

Jim
 
I have not run into this problem with the 308 and I doubt It is the problem. But on some calibers bullet weight makes a big difference. as an example I have had 2 different 45/70's, a ruger #1 and a Marlin both which I could not get 300grain bullets to shoot low enough with the factory irons. I am sure it was because they were calibrated to shoot 405grain bullets at the factory.
 
riverdog,

Have you tried bore-sighting the thing? I do that at my dining room table. Look through the bore at some distant object (like a stop sign 100 yards away) then without moving the gun, lift your head and look at the sight alignment.

Or, if you can't see through the barrel at all, then it might be bent :(

But don't let the neighbors see you aiming out your window :eek:
 
When you say "pre64 Winchester" do you mean that style in a new gun or an actual rifle made before 1964? On either, I'd pull the barrelled action from the stock and check for more pressure on the barrel than is normal up front. Could be from grunge build up, on an old rifle, or poor inletting on either old or new. It wouldn't take alot with a lightweight barrel. Have it freefloated and see if that solves your problem.

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"Charlton Heston is my President"

Danny45
NRA, NAHC, Buckmasters
 
sleeping dog -- I did bore-sight the rifle and that's what prompted me to bottom out the rear sight. Still seems to shoot higher than it should. Usually when I do this the first shot is at least on paper, with this particular rifle it wasn't close. The gent who had this rifle prior to me had done some tweaking to the front sight and actually peened it so I had it replaced with an identical blade. Whatever is going on may be the reason the rifle was in such otherwise great shape. It wouldn't shoot so they didn't take it out. The only issue when I bought it seemed to be lots of copper in the bore, now clean.

Danny45 -- Yep it's a real pre-64 Win M70, not a remake. I figure it was manuf around '59 by the sn. I hadn't considered pressure from the stock as an issue but then I've never had the action out of the stock. I'd considered refinishing, but the wood is in great shape so I didn't bother. I'll check for gunk and clearance in the channel. That would be too simple. Thanks.
 
And if all else fails, have a taller front sight installed. As a sort of trial, super-glue a piece of wire onto the existing front bead and see how high it shoots.

Maybe the peening of the old front sight was to thin it out and make it taller? Yo no se.

Art
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>a sort of trial, super-glue a piece of wire onto the existing front bead and see how high it shoots.[/quote]

There is a math formula to figure out how much taller a front sight you need to change point of inpact on a given firearm. I know you need the distance btwn the front and rear sights to plug into the formula. You also need to know exactly how much you want to move the bullet impact. If you sight is bottomed out now you may want to take it up some before you start makeing measurements.

Unfortunitly I'm out of State right now but I think I have the formula back home... somewhere. Maybe someone else has it and can post it here.



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Schmit
GySgt, USMC(Ret)
NRA Life, Lodge 1201-UOSSS
"Si vis Pacem Para Bellum"
 
riverdog,

Let us know if you solve the problem. By the way, I also thought of something else. Especially if it's a featherweight barrel.

Please don't take this wrong, I don't know you or your experience. :) I assume you're sighting in from a bench position. If so, are you resting the forearm on the (whatever devise you use) or resting the barrel on it. With such a lightweight barrel, that could make a difference too.

Like I said, no disrespect intended.

:D


------------------
"Charlton Heston is my President"

Danny45
NRA, NAHC, Buckmasters
 
The amount you want to move the sight up should be (I just did this on an old envelope and it is late ... but I'm usually pretty good with this stuff):

(P.O.I. inches high)x(inches between sights)/3600

For 18" drop with a 20 inch sight radius you would raise the front sight .1" ... yeah ... that sounds about right.
Hope this helps,
Bill
 
Years ago, some guys were hunting in Alaska. It was discovered that there was not enough movement of the crosshairs to allow zeroing a hunter's Model 70 in .300 H&H.

The hunter borrowed a rifle and left camp. A guy who'd already filled out was staying in camp. He took the rifle and found two trees growing close together...You guessed it. After bending, he tested--et voila! Right at perfect!

I did the same thing with an air rifle which zeroed an inch low with the rear sight at its highest position.

Be careful!!!

Art
 
Hi, Art,

I have bent (straightened) barrels with somewhat more sophisticated machinery than that. It is actually no big deal and factories do it all the time. It used to be more common when boring machinery was not as good as it is today, but it is still done.

With some handguns, I used to just clamp the receiver in a soft-jawed vise and whack the barrel with a lead hammer. Worked fine.

The only problem is that overdoing it means a new barrel or worse.

Jim
 
Danny45 -- No offense taken, none of us really know one another. I was using sandbags and the stock was on the bags.

Art -- Trying out different sight heights using a temp front sight sounds like a good idea. I just might give that a try.

Guys, I have no intention of bending the barrel. It appears straight to me and replacing the front sight seems a much better course of action. With my skill, I'd bend it into a new Douglas ;)
 
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