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Left/right alternating poi's = bedding issue?

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11 June 2013, 20:18
Cullbuck
Left/right alternating poi's = bedding issue?
I've got a Mod. 70 (270 WSM) bedded in a Hogue (full lngth. alum. block) stock. The action is bedded including approx. the first 2" of barrel. I recently replaced the trigger on this rifle and had it in/out of the stock several times during the process. This rifle has had the tendency to shoot two distinct groups about 1/2" (or a little less) apart horizontally since the bedding job which I was OK with. Now the two groups are approx. 3/4 to 1" (alteranting left/right with each shot) apart and I would like to find a solution.
Should I start by removing some of the bedding from the barrel portion forward of the recoil lug, or does someone have experience with this type of problem?
As a side note, I have replaced the scope with a new Burris (not thinking the scope was the problem but wanted more magnification)
12 June 2013, 15:51
M Pursell
Has the action been glass bedded too?


Mark Pursell
12 June 2013, 18:55
Cullbuck
M.Purcell,
Yes the entire action is glass bedded. Bedding job appears to be good.
12 June 2013, 19:16
TomP
Is there any sequence to this, left-when-cold, right-when-warm, or is it random which direction it takes?


TomP

Our country, right or wrong. When right, to be kept right, when wrong to be put right.

Carl Schurz (1829 - 1906)
12 June 2013, 22:12
Glen71
Does it have a windage-adjustable rear scope base? I've had those work loose and cause those symptoms.
12 June 2013, 23:33
Cullbuck
Tom/Glen,
The sequence is left cold then right/left/right/ect. (also note I allow barrel to cool completely between shots)

The base is windage adjustable, however I just replaced the rings and applied locktite to the windage screws once I centered the rear ring. I have also since checked these screws to ensure tightness.

Thanks for the replies, as I need the help.
12 June 2013, 23:40
BaxterB
My brother had a similar issue with a 223AI...he rebedded the entire thing (full length) and it seems the left/right went away but it's still not a very consistent shooter...yet...
13 June 2013, 02:57
Gerry
quote:
I recently replaced the trigger on this rifle and had it in/out of the stock several times during the process.

Yo Cullbuck .....

For my $0.02 worth it's usually bedding/mount/optic issue for the 2-group Syndrome.

Could it be your new/replacement trigger requires some additional tweaking? Perhaps something's not Hoyle with the trigger housing, flooplate or trigger guard?

I'm not a real M70 expert on all the model variations but my Model 70 Super Express 375H&H has two action screws and a third wood screw underneath the Trigger guard/magazine floorplate. Does the Hogue stock also have these features? Perhaps one (or more) of the screws is whack-o? Do either of the action screws bottom out? You may think they're tight but in effect, they're not, perhaps there's a measurement off from the factory stock, although I don't actually know if the stock has been replaced or if Wincheter made models with Hogue stocks? Perhaps too much bedding material making the original mesurements Goofy?

Having said that several years ago when the Camo Hogue rubber armoured stocks came out we did a 270 Win build using a Mauser action and the "so-called" full-length aluminium bed was all outa whack when we attempted to seat the action; required lotsa Dremel attention to finally get things right.

Good Luck getting your 2 group issue sorted.

lol


Cheers,

Number 10
13 June 2013, 18:01
Glen71
IMO, two groups indicates movement shot to shot. Something is loose. If not a scope base, then action screw(s).
13 June 2013, 18:16
Toomany Tools
Just a thought, but do you have an absolute consistent cheek weld on the stock? If the scope is mounted a bit too high, making it difficult to anchor your face in the same position every time, you could be introducing a variable. A lace-on cheek rest or maybe a Karsten Kydex adjustable cheek rest might help.


John Farner

If you haven't, please join the NRA!
13 June 2013, 19:26
Cullbuck
Glen..the front and rear action screws are at 45(+) in./lbs. and the middle is just beyond snug tight. Should I tighten more?

Toomany...I suppose that my technique could be to blame as I am far from a professional shooter, but I would think the left/right shot placement would vary and not alternate. Maybe I'll get somone else to shoot it.
13 June 2013, 20:53
TomP
quote:
Originally posted by Cullbuck:
Tom/Glen,
The sequence is left cold then right/left/right/ect. (also note I allow barrel to cool completely between shots)

The base is windage adjustable, however I just replaced the rings and applied locktite to the windage screws once I centered the rear ring. I have also since checked these screws to ensure tightness.

Thanks for the replies, as I need the help.


I have to wonder if the bedding block is fitting right.


TomP

Our country, right or wrong. When right, to be kept right, when wrong to be put right.

Carl Schurz (1829 - 1906)
13 June 2013, 22:40
Glen71
1. Have you taken the barreled action out of the stock and looked for high spots in the bedding, indicated by areas on the metal where the blueing may be worn or missing?
2. Is there a "pressure pad" in the barrel channel near the tip that is contacting the bottom of the barrel? Does the barrel contact the sides of the barrel channel or is there clearance?
13 June 2013, 22:55
Cullbuck
Glen,
1. I have had the action out of the stock numerous times (3 or 4) messin with the trigger adjustment. I did not look for worn or shiny spots as you suggested. Is there any place in particular to start looking for such?

2.The first couple of inches of barrel past the recoil lug is bedded (a pad of bedding exists) the the barrel is free floated with plenty of clearance the remainder of the way. It is this pad of bedding that I was suspicious of to begin with, but I have no basis for this suspicion as I am no gunsmith nor have I encountered this before.
13 June 2013, 23:34
Glen71
If the bedding encircles at least the bottom 1/3 of the barrel's circumference, it is unlikely to be the culprit.
Is the aluminum bedding block visible through the skim coat of glass bedding? No cracks covered up with epoxy?
Is there clearance around the action screws, i.e., are the holes through stock and bedding larger than the screw diameter? Do the screws show any evidence of contact with stock or bedding?
14 June 2013, 04:09
Cullbuck
Glen,
I will need to take it back apart to answer your questions. I dont' remember seeing the alum. block visible through a skim coat of bedding and there are no cracks I am aware of. Clearance around action screws I am usnsure of and I just replaced the action screws as well so there will be no evidence of bedding contact.
I will let you know when I get a chance to check it out. Thanks a bunch for the help.
14 June 2013, 16:55
M Pursell
One thing I like to do when checking out a rifle that just won't shoot. Secure the barrel tightly in a vise. I use lead jaws but wood should work too. Just so it's solid. This allows you to grab the scope, mount, stock and check for movement. Even a little can make for a problem. Sometimes you just feel a little 'snap' as something shifts.

A had a fellow that was helping me out some change out the scope on a customers rifle to see if it would help. He took it to the range and it made no difference. A couple of day later, I put the rifle in the vise as described, after checking several things, I grabbed the scope and felt movement. My helper hadn't tightened the scope in the rings. Now I get to do the whole exercise again. It's easy to overlook the little things.


Mark Pursell
15 June 2013, 09:27
Philip A.
Alternating, i.e. non-random, movement of the POI=something moves, that is quite clear. The only other alternative would be some sort of freak stress in the barrel, with properties worth a doctorate in metallurgy's papers...

A question: the stock is glass-bedded, etc., but was it bedded with that action? Or did the stock come from another similar rifle, wich would mean that actually there could be movement of the action due to dimensional differences between the original action and this one?


Philip


16 June 2013, 23:06
Cullbuck
Same action/barrel. The only thin I have changed (other than the scope), is the action screws.

Is there potential to make the situation worse by sanding/releiving the bedding pad beneath the barrel just forward of the recoil lug?
16 June 2013, 23:17
richj
If you get nowhere try a piece of leather or cardboard or paper under 1/2 way around the barrel near the tip of the stock.

Rich