While out shooting with RS39 for 5 hours yesterday I noticed something I have never seen in an Ak before.

Every time the rifle warms up, I begins to string vertcaly.  Each shot goes about a 1/2 to 1 full inch abouve the other.

I know how to fix this in Mausers and what causes it, but the Ak is not a Mauser.

The lower handguard (bulgy style) is a bit on the loose side, and the gas tube is tight.

Would the hand guard being a little wobbly have anything to do with this?  I know it can be a natural process as the barrel heats, but I want to remove any external "problems".

Quoted: I know how to fix this in Mausers and what causes it

you could share you know...(just bought a mauser)

What kind of Mauser do you have?  How is it shooting?

The fix is usually pretty easy with Mausers.

 There's a Yoda post on AW that hits on foearms and gas tubes and accuracy and as I remember it is: buttstock tight, forearm slightly loose, gas tube with a little bit of for and aft play.

Quoted: What kind of Mauser do you have?  How is it shooting? The fix is usually pretty easy with Mausers.

Sorry about the delay.

I have a Yugo M-48; only took it to the range once so far, and there did seem to be some vertical shot movement.

Of course it was most likely operator error, but I would still like to know how to fix it just in case it wasn't.

Thanks Arndog

Thanks guys.  The gas tube is very tight in this rifle.  I will work on that first.

ARndog, I will send you an IM on Thursday when I have the chance to go into it in detail.  It is really pretty simple, I'll walk you through it no problem.

Arndog, Mausers do have a tendency to string in the vertical when in good shape.  If they string from side to side you have a stock problem.

The problem is caused by the heating barrel putting preasure on the stock at the barrel bands.

You can avoid it all together by keeping your shooting down to a slow pace. ie. 1 shot every 5 - 10 minutes. BUT, since that is no fun, here is how you fix it.

The rifle will have two bands on the barrel. The first one will be a simple loop with a "ring" for the sling to pass though.  The second band comes in different shapes, but it is the "H" shaped, or long solid band before the bayonet lug.  Take these off.

The upper handguard at the front where the first ring is should tapper a bit. Take a dowl rod with some sand paper and relieve the inside of the wood. (you can also do a little bit more of this part if it looks like it is touching the barrel) Don't sand away too much as you don't want this tappered piece to become brittle or too thin.  You can also sand the main stock in this area as well but it is less important.

Now, go back to the main stock at the larger band.  Do the same thing here.  You can take a little more wood off here as it is a stronger thicker area.

Some Mausers will have a screw that tightens the first ring. If your does (it shouldn't but it might) make sure to tighten the screw, but not to over tighten it.

The main cause is the barrel putting uneven presure on the stock at the barrel bands.  Taking away some of the wood will help this, but it may not go away all together as the stocks are military and not made to civilian standards.  This should help greatly.

Should you need to refinnish the stock inside or out, use Boiled Linseed oil only.  Do not use True oil.  To seal the gap in the stock between the barrel and the wood, use bees wax.  That is how it was done for the service life of the rifle and it works well.  (The bees wax is really not that important as you won't be living in the field with the rifle)

I hope this helps. It is a simple fix, just don't over do it.  Some Mausers will still string no matter what, but this will reduce it.

Thanks obershutze.