Advice on 7.62 Israeli Mauser.

[Andrew Leigh]

Long story short, having identified and remedied a couple of problems on my friends full stock rifle that has the action and the barrel fully bedded. I believe that I am at the last hurdle but need advice on the next step.

When the barrel warms up the rifle immediately throws consistent 4" vertically strung 3 shot groups. Shot one +4", shot two +1.5" shot three in the bull, like clockwork, group after group.

I believe it is the bedding so on removing the barrelled action I notice three things.

1.There are three mounting points, the two obvious primary action screws along with a further screw that fastens into a barrel band to secure the forearm to the barrel.

2. I then noticed that the "gunsmith" had used narrow masking tape to wrap around the barrel and then he simply slipped the barrel band over this! So there is no mechanical rigidity or integrity there whatsoever.

3. Finally I notice that there has been no relief provided on the sides and bottom of the recoil lug and the barrel band.

I have not yet dealt with fully bedded barrels so a little in the dark. I was going to;

a) Fix the barrel band to the barrel by means of a "liquid steel" product which is essentially is a steel filing filled epoxy.

b) I was then going to provide the necessary relief at the lugs.

c) Then I was unsure if I should remove the bedding between the recoil lug and the barrel band and then after the barrel band to the tip of the muzzle?

Regards

 

[LAGS]

It sounds like you need your action to be properly bedded, and your barrel to be Free Floated.
I bed Mausers for full contact on the action, and cleararance around the barrel so as the barrel heats up, it causes no side or up pressure on the barrel.
You need at least two solid points of contact on the action to the stock, that remain true when the action screws are fully tightened.
There should be .010 " clearance between the wood stock or Bedding material around the barrel both top sides and bottom.
The barrel bands when installed should not cause the wood to be held against the barrel, or any warping from heat to the wood will effect Point of impact.
The Handguard is only a cover for the barrel and is held in place by the Barrel bands, and not the barrel.

You can Fully bed your barrel and action, and have the barrel being touching the bedding in the barrel channel, As Long as it as well as the action are bedded in such a way to not cause any pressure against the barrel once the action screws are fully tightened.

But I prefer the full bedded action or Point bedding of the action, and a Full Glass Bedded barrel channel with the .010 clearance to the barrel built into the bedding when the rifle is bedded.

 

[Andrew Leigh]

It sounds like you need your action to be properly bedded, and your barrel to be Free Floated.

This is where I was headed, the problem I may have is that the stock is a full stock which is rather elegant and very narrow toward the muzzle. due to this the barrel channel may have to be excessive to cater for any flex in the forearm. I had this with a .375 and had to open the channel significantly to 0.060" before she settled down.

I bed Mausers for full contact on the action, and cleararance around the barrel so as the barrel heats up, it causes no side or up pressure on the barrel.
You need at least two solid points of contact on the action to the stock, that remain true when the action screws are fully tightened.

The bedding job looks real good and if I were to free float the barrel I would doubt if I would need to re-bed.

There should be .010 " clearance between the wood stock or Bedding material around the barrel both top sides and bottom.

.010 would appear to be rather small, would I not get barrel slap with the very thin full length stock?

The barrel bands when installed should not cause the wood to be held against the barrel, or any warping from heat to the wood will effect Point of impact.The Handguard is only a cover for the barrel and is held in place by the Barrel bands, and not the barrel.

OK so if I understand correctly, the barrel band can be used as an additional contact point to keep the barrel from the handguard, providing of course that the barrel remains free from the handguard?

You can Fully bed your barrel and action, and have the barrel being touching the bedding in the barrel channel, As Long as it as well as the action are bedded in such a way to not cause any pressure against the barrel once the action screws are fully tightened.

I think this is what they tried to achieve but it is very difficult to bed along that distance.

I think I can achieve a solution without re-bedding. I plan to have three locating points. The two action screws and the barrel band. I will open the barrel channel from 2" in front of the recoil lug until 3/4" before the mounting point of the barrel band and then reopen until the end of the muzzle from 3/4" past the barrel band. This effectively will give me a free floated barrel save for one barrel fixing point / pad of 1.5" long. At the barrel band I will remove bedding from the sides but not from the bottom.

PS: This barrel band is not like the classic where the sling goes through but rather a band with a tapped portion beneath specifically to mount to the stock.

Any further thoughts from your side?

Thanks
Andrew

 

[LAGS]

I would love to see pictures of the rifle and the barrel band set up that you described.
When Bedding an action, I make it have full contact at the points of the action screws, Front Recoil Lug and first 1.5" of the barrel on the chamber end, then that part is left alone, and the barrel channel is shaped so there is no contact of the wood to the barrel.
There should be enough clearance where you can slide a dollar bill down between the barrel and the forestock to within 1.5 inches of the front of the receiver, With the Action Screws Fully tightened.
The Forend of the rifle is basicly a support for your hand, Not a support for the barrel.
But some rifles shoot better if there is some Point contact at the very tip of the end of the stock.
Some even shoot better with a little UP pressure at the end of the stock.
But if your rifle barrel is Free Floated, you can always add shims made out of cardboard at the tip of your stock to see if point contact or up pressure improved your rifles shooting.

Now, Remember.
Glass bedding, or Free Floating, does not make a rifle more accurate.
It only eliminated the conditions like a loose fitting stock, or a stock that is too tight and putting Pressure on your action or barrel, that is Robbing the "Accuracy Potential" that your rifle already has.

 

[Andrew Leigh]

I would love to see pictures of the rifle and the barrel band set up that you described.

Going to the range this a.m. to try out the new mods. When I had a closer look the bedding which looked good was indeed very poor. The barrel band is not a true barrel band it was an afterthought. Will take pictures on my return.

When Bedding an action, I make it have full contact at the points of the action screws, Front Recoil Lug and first 1.5" of the barrel on the chamber end, then that part is left alone, and the barrel channel is shaped so there is no contact of the wood to the barrel.
There should be enough clearance where you can slide a dollar bill down between the barrel and the forestock to within 1.5 inches of the front of the receiver, With the Action Screws Fully tightened.

Snap, exactly as I do with great success. The full stock just presented circumstances unfamiliar to me. As stated the front end of the forestock is so thin that it bends with minimal pressure.

So here's what I did. I floated from the barrel band to the muzzle, a section of 10". I then reassembled and on tightening up the barrel band screw I noticed it bent the forestock into the barrel. The bedding job although looked great was in fact extremely poor. So I then glass bedded a 2" portion at the barrel band and floated the barrel such that I have 1.5" on the barrel at the receiver and then an inch either side of the barrel band.

The plan is to shoot it that way, if she is still not good then I will insert a business card at the muzzle. If still not good will remove the business card and I will remove the bedding at the barrel band (Dremmel is packed).

The Forend of the rifle is basicly a support for your hand, Not a support for the barrel.

Agreed.

But some rifles shoot better if there is some Point contact at the very tip of the end of the stock.
Some even shoot better with a little UP pressure at the end of the stock.
But if your rifle barrel is Free Floated, you can always add shims made out of cardboard at the tip of your stock to see if point contact or up pressure improved your rifles shooting.

Agreed, but we get massive swings in humidity summer to winter, we develop loads in summer and shoot in winter so I am hoping to remove all influence from a swelling stock.

Now, Remember.
Glass bedding, or Free Floating, does not make a rifle more accurate.
It only eliminated the conditions like a loose fitting stock, or a stock that is too tight and putting Pressure on your action or barrel, that is Robbing the "Accuracy Potential" that your rifle already has.

Agreed, the whole point of developing loads, bedding, blueprinting and practice to wring the most from the rifle.

Chat later

 

[LAGS]

I still don't follow how you can have the barrel free floated an the installation of the barrel band moves the stock up towards the barrel.
That would mean the hangguard is against the top of the barrel, and is pulling the stock upwards.
That could cause a upward curve in your barrel when the band is installed.
If the action is bedded solidly, and then you bed the barrel channel, you do not Clamp the barrel and stock together when bedding.
And if you want it to be free floated after glass bedding the barrel channel, You just put a layer of 10 Mill Pipe Wrap Tape on the bottom of your barrel.
Then after bedding, and you take the tape off the barrel, you will be left with a gap between the barrel and forestock, that is the same thickness as the tape was.
But you have to shave the barrel channel and fit the stock before bedding in the barrel channel with the tape on the barrel.
Otherwise, you are building in pressure points, or excessive gaps.
To bed a gun, you are doing nothing more than "Molding" the two peices together in their Natural Positions.
If you have to clamp things together, then you are exerting some type of unnatural Pressure and forcing the parts tofether.
Once the clamps are removed, the parts might move back to their Naturaal position , thus changing your bedding job.
You clamp an action when doing a bedding job, because you want it to sit down in a certain position and let the bedding compound squesse out to mold perfectly.
But the barrel can be temporarly put in an un- natural curve , as can the stock by clamping.
The barrel channel is Molded with no forces on the barrel or the forestock, and the action secured in it's premenant position, either when you Contact Bed, or Free Float bed your barrel.

 

[Andrew Leigh]

OK, I am being unfair, pictures are required.

I still don't follow how you can have the barrel free floated an the installation of the barrel band moves the stock up towards the barrel.

Here you can see the screw that attaches to the "barrel band"

Now in the next picture you can see what I have done. You can see where I have removed the bedding. The reason for keeping the bedding around the "barrel band is that one would need a lot of gap due to the thin and highly flexible stock.



As stated the if she does not shoot in the configuration then I will remove the bedding at the "barrel ban which will leave the barrel completely freefloated.

She is a pretty sporter is she not?

 

[LAGS]

OK.
Now I have a picture of what you have.
You have a collar that acts as the Sling Swivel stud mount, and the collar is like the old Winchester M70's
Since it will be pulling down on the barrel when you tighten the sling stud, This point at the Band needs to be " Point Bedded "
But it needs to be Point Bedded in such a way that it is NOT pulling down on the barrel.
If the action is bedded, and the barrel channel is Free Floated, you should Bed around the barrel collar with out using the Sling Stud Screw.
Then when the bedding compound is hard, then you install the screw, and it will tighten down Without moving the stock closer to the barrel or pulling the barrel down in a curve.
To get it right, is a little tricky, but can be done easily
The action has to be screwed down tight, and the very Tip of the stock has to have a Neutral Pressure shim installed just to keep the barrel in a Natural No pressure alignment.
The tricky part is when you are bedding at the collar, you should have some kind of "Dam " to keep the bedding compound from running down the rest of the barrel channel and being able to bed up along the sides of the collar.
You also have to plug off the stud hole in the bottom of the stock, and fill the collar stud hole with clay.
You can also use a straight blank guide stud for locating the sling swivel stud hole, and do not clamp the stock to the barrel, when point bedding.
But the Dam can not be disrupting your barrel alignment or putting any kind of UP pressure on the barrel. It has to be a Neutral pressure contact to the barrel. It is only in the barrel channel to Stop or Dam up the bedding compound from running everywhere down the barrel channel.

 

[LAGS]

I don't know exactly how envolved you want to get with your re-bedding, or how you like your rifles set up.
But If I was building a stock like this again, there are some things I would do differently, just from a presonnal preferance standpoint.
What you have is just fine, and very workable.

The first thing I would want is the screw in the front barrel collar to be just that, A Screw, and not a Sling Swivel stud also.
I would install a Screw, and install the sling stud to the Stock only, with a stud and back nut.
That way the screw on the collar can be tightened, and the pressure can be regulated to maintain a Neutral pressure without having to worry about clocking the stud to square up the sling swivel or the sling stud coming loose.
Also, if you use a BiPod, you are not putting pressure on the barrel thru the stud.
Also , when you carry the rifle, you are not tugging on the barrel with the sling, or if you use a sling to shoot, you are not tugging on the barrel.

The only thing I would do differently, would be to Full Bed the Barrel Channel with the Free Floating Clearance Built into the bedding using the Tape Clearance Method.
That will waterproof the barrel channel, on such a thin forestock, and could add some rigidity to it.
I would have the action Full bedded, and only Neutral Point Contact at the Barrel Collar and at the Last 1.5" at the tip of the stock.
The rest of the barrel from the chamber to the collar, and the collar to the last bit at the tip would have at lease .010" clearance.

 

[Andrew Leigh]

Since it will be pulling down on the barrel when you tighten the sling stud, This point at the Band needs to be " Point Bedded "
But it needs to be Point Bedded in such a way that it is NOT pulling down on the barrel.

It is not apparent on the last picture but this is what I have done. I did not add colouring to the bedding material so it is not apparent as the bedding agent is clear.

 

[Andrew Leigh]

The first thing I would want is the screw in the front barrel collar to be just that, A Screw, and not a Sling Swivel stud also.
I would install a Screw, and install the sling stud to the Stock only, with a stud and back nut.

This is not my rifle and I am helping a friend set it up. It will be fitting a sling mounting point just behind the existing one towards the action side. I cannot believe that a "gunsmith" actually did that.

The only thing I would do differently, would be to Full Bed the Barrel Channel with the Free Floating Clearance Built into the bedding using the Tape Clearance Method.
That will waterproof the barrel channel, on such a thin forestock, and could add some rigidity to it.
I would have the action Full bedded, and only Neutral Point Contact at the Barrel Collar and at the Last 1.5" at the tip of the stock.
The rest of the barrel from the chamber to the collar, and the collar to the last bit at the tip would have at lease .010" clearance.

I may still do this if the my next shoot is not successful. I did not make it out on Friday as I needed to take my two youngest grandbuddies to the Doctor.

Do you put release agent on the tape? With all the steps in the barrel the taping could be a challenge.

 

[LAGS]

Yes, You have to put the release agent on the tape, the same as you would the barrel or anything else you do not want the epoxy to stick to.
The Tape is just making the barrel wider for the molding, after it is removed from the barrel and the rifle is re assembled, it leaves a space between the barrel and the bedding that is equil to the thickness of the tape.
So if you wanted more Air space, you just Double up the thickness of the tape.
My Target barrels are free floated with .020" clearance if not more for better Air Flow and cooling.

You are only placing the tape on the sections of the barrel from in front of the chamber to almost the barrel collar.
and then a strip the length from just forward of the barrel collar to just before the nose cap.
The Tape is run the length of the barrel, and folded up the sides of the barrel.
You do not Spiral wrap the barrel.

 

[Andrew Leigh]

I understood it that way, thanks.

 

[Andrew Leigh]

OK range day.

I went out with 2 different bullets, the Hornady 150gr. SST and my go to bullet in times of trouble a SGK 165gr. The reason for this is that I was concerned that the bullet and or weight that I chose may well not be suited for the rifle.

Just some summaries first.

150gr. Hornady
1.00mm off the lands
QuickLoad 2 718fps actual average recorded 2 747fps, std dev 20fps.
The additional actual speed actually took me off the accuracy node.

165gr. SGK
2.00mm off the lands
Quickload 2 691fps actual average recorded 2 692fps std dev 17.5fps.
These loads were smack on an OBT Accuracy Node.

I can only assume that the age of the rifle and condition of the chamber and barrel is causing large deviations in spread and std deviation. I consider these std deviations to be particularly poor but I have not deviated from my normal loading process.

Group 1, 150gr. - Fouling rounds and to collect more speed data.
So I started off with 6 fouling rounds which were nearly evenly distributed about the point of aim. They were pretty much anticlockwise about the point of aim. The group measured 2.9MOA.

Group 2, 150gr. - Remove the front "barrel band" screw, it stayed out from here on in.
Three rounds were fired and immediately the group pattern went vertical. Shot one at the bottom, shot two at the top and shot three in the middle. The group measured 1.80MOA.

Clearly I was getting nowhere so I shifted to the 165gr.

Group 3, 165gr.
Three rounds were fired and they too were vertical. Shot 1 on point of aim, shot 2 low and shot three high. The group size measured 1.80MOA.

Group 4, 165gr.
Three rounds were fired and again they too were vertical. Shot 1 was high, shot two was on point of aim and shot three was between the two. The group size measured 1.90MOA.

Group 5, 150gr - Bedding about the "barrel band" was removed with a Dremel tool.
Three round were fired and the pattern reverted to the more familiar triangular shape. The group measured 1.70MOA.

Still apparently making little progress I decided to introduce the joker and I folded a business card over and inserted under the muzzle. I had also adjusted the scope to come on target as the 165gr. were printing at a different point.

Group 6, 165gr. - I had 6 rounds left of this load so I decided to fire one round to settle the scope that had just been adjusted as experience had shown me that the scope need one dose of recoil to settle the crosshairs.

I then shot 5 shots which measured 0.84MOA. Shiite now we are making progress. Especially considering that the duplicate exercise last week with the 150gr. resulted in a 4.3MOA group.



I then decide to duplicate this exercise with the 150gr. Hornady's

Group 7, 150gr. - I had 6 rounds left of this load as well so again I adjusted the scope and fired one round to settle the scope.

So with the business cards still in under the muzzle I shoot a 5 shot group which disappointingly measures 3.05MOA.

I also had blackened the bases of three of the 165gr. loads to check the bolt contact. Well there was no marks on the cases but the primers were marked and cleaner. This would indicate to me that I have a headspace problem and that the primers are backing out. I can tune the headspace out by setting up my sizing die differently and then fire forming the cases.

Well that was a mouthful. Given the report and the effect of the business card it looks like a fully free floated barrel with pressure point at the muzzle.

Your thoughts.

 

[LAGS]

It seems that your rifle does like a little Posotive Pressure at the muzzle.
You can bed it accordingly.
I would suggest that you bed the tip of the stock with Neutral pressure, and install adjustable bedding pillars near the tip of the stock.
That way you can adjust the Up Pressure as much as you want.
You can make your own pillars out of Brass and a set screw threaded into the center of them.
Then they are Epoxied into the tip of the stock at a 45 degree angle.
They will make a cradle that can put Up pressure or even a little left or right pressure on the bottom of your barrel.

 

[Andrew Leigh]

LAGS,

Do you concur with me on the head spacing? There is a write-up on GS Custom bullets website on how to set up your dies to achieve this. But you probably knew this already.

http://www.gsgroup.co.za/faqsizerdie.html

Can you point me to any picture showing the arrangement up front. I can make the threaded lugs etc. but a picture paints a thousand words.

Oddly I had to get rid of my pressure points on the Sako for that one to shoot properly.

Just a question, we have large humidity swings this side of the pond. This will introduce variable pressure unless the stock is fully sealed? While looking the clearance, barrel to stock it, although the clearance is there some places it looks real close, at the neck down points on the barrel. Could it be that the front end pressure relieved the stock even further from the barrel aiding the accuracy or is it purely a fore end pressure thing, funny I always pooh poohed the business card thing. Should I take a little more away fro the stock first and try it?

I plan on fully bedding as you suggested using the tape for relief along the barrel channel where required.

 

[LAGS]

On a 6mm remington that I had,
I took two peiced of 3/8 Diameter Brass rod about 1/2" long.
I drilled a hole thru the length of them and Tapped them for a 10/32 allen head set screw.
I drilled two 3/8 diameter holes in the forestock about 2" from the end of the stock, on a 45 degree angle from the barrel channel out.
Then I epoxied the brass pillars into the stock so the brass pilar was almost flush with the inside of the barrel channel.
Then when you installed the barrel in the barrel channel, you would thread the set screws into the pillars, untill the JUST Touched the bottom of the barrel.
Then if you screwed them in a little deeper, they put Up Pressure on the bottom of the barrel.
But you also had the option of screwing one in a little tighter than the other to add a little side pressure along with the Up pressure.
I do not have any rifles with this set up, but have done many for friends that want it set up for Bench Rest Shooting.

 

[Andrew Leigh]

Thanks, will check with the rifle owner if het wants this done.

Thanks for all the help.

 

[LAGS]

With this forend nose being so thin, you might have to just do two counterbores inside the barrel channel with a hole for the set screw to pass thru to the outside of the stock tip.
Then you epoxy a fine threaded hex nut in the recess for the pillar.
The finer the thread, the finer the adjustment that is possible.
I take it you will be using a metric thread ?
You will be doing something similar to a Blind nut inside the barrel channel , similar to a sling swivel stud nut set up, except for two on an angle.

 

[Andrew Leigh]

Will be metric.

Do the two have to be directly opposite each other?

 

[LAGS]

It is best if they are opposed to each other, but I guess it also would depend on where you wanted to direct the up or side pressure.
If UP pressure is all that you require, I guess you could install only One Pillar directly under the barrel , Centered in the barrel channel.
But the two studs set on an angle gived you a small cradle that the bottom radius of your barrel sits in so it stays centered in the barrel channel.

 

[Andrew Leigh]

I like the two studs idea and will go with that.

Think I will machine a round collar such that its I.D. matches the barrel channel, the OD will be 3mm larger. I will then tap two M3 holes at an appropriate angle bit not fully tap. I will leave the threaded holes such that there is some friction screwing the grub screws in (create a Nylok effect). I will then cut the tapped portion from the collar. I will then recess the inside of the forearm, using the tapped holes as a guide to drill the holes through the stock, epoxy in place and I should be good to go.

 

[LAGS]

Now , That is a darn good idea for getting the set screws at the proper angle that you want, And it solves part of the problem with the Thin forend.
I Just may have to use that same method sometime. Thanks.

I had used a steel rod the same size as the barrel diameter with a guide hole drilled thru it for drilling my holes for the pillars into the stock to get a consistant angle.