accuracy .308 problem

[lt dan]

i inherited a .308 eusta(austria origin). my father used this rifle on his farm in south-africa since mid 1975 when he bought it. this rifle has brought home a lot of game. accuracy was NEVER a problem. my father never reloaded. he once shot almost 2 tons of game in 2 days. he did this in Namibia a place not favouring 308 rather 300wm or 270 due to the exsesive distances.

recently i have experienced accuracy problems. the first 2/3 shots is spot on then the next couple goes right and up-- a lot. as soon as we adjust the scope and return to the range the rifle now shoots left. here the next chapter starts again with 2/3 shots spot on and the goes right and up.

i have bought a new scope and did the bedding. still the problem remains. allthough the bedding may be suspect.

HELP!

 

[CPTMurdoc30]

Have you tried a different batch of ammo. I would also do some dryfire drills to see if it is you the shooter. Could be the ammo or it could be the rifle. Aproxmently how many rounds has this rifle shot? You might need a new barrel. If a local gunshop has a bore scope have them take a look at it and see if it is fouled with copper or if it is worn out. This sounds like a working rifle that has seen a lot of use.

 

[lt dan]

we shoot this rifle in a rest made out of a car jack. i took a gunsmit with the last time. i tried several loads( i unlike my father reload). i as well as the smity shot with it. same results.this rifle used to shoot very well even with mill surplus ammo. the gunsmit says the barrel and headspace are good.

 

[30Cal]

Sounds like it's wandering as it heats up which is not uncommon for a hunting rifle. If your father never shot more than 2-3 rounds at a time, he may have never seen it. Check for contact between the stock and the barrel at the forend.

 

[Slamfire]

After a web search, I have not found an example of a Eusta rifle. I assume it is a Mauser 98 type action.

First thing to do is to clean out the barrel good. This is something Compass Lake Engineering recommended to me, and that is was to use J. B. Bore paste.

This is an abrasive, to be used sparingly. What CLE told me was that chemical cleaners will not remove impacted crud in the throat. You at some point need to use JB. I also use Sweets as a copper remover.

Now you have a clean barrel.

If you still have group walking issues, check the rings and mount and verify that everything is mechanically tight.

If you still have group walking issues, the next thing to check is the barrel to foreend fit. I do not know how you checked your bedding. First thing I do is put a thin piece of paper under the barrel and attempt to find if the barrel is touching the stock. If the barrel touches the stock, the point of impact will change as the barrel heats up. Some rifles have a contact point at the end of the forend at the bottom of the barrel. Still, I prefer free floating barrels.

If the barrel is touching the fore end, I will increase the clearance, and bed the action.

Still, if the barrel is not touching anywhere, I suspect the receiver fit within the stock has gone bad. I have no idea how anyone "checks" this. Unless the receiver is actually bowing in the middle, as the action screws are tightened up, I can't visually determine bad bedding. So, I just bed the receiver with a 2 part epoxy. It makes an amazing improvement most of the time.

However, I had two rifles that none of these actions improved the accuracy.

In one rifle, a Featherweight pre 64 M70 in 270, the problem turned out to be a barrel ring. Within a half inch of the end of the barrel, there was a shadow. The barrel had been bulged out and was flinging shots. It would groups within 4 to 6 inches at 100 yards. The barrel was counterbored by a gunsmith, and now accuracy is acceptable, about 2 inches at 100 yards.

In a classic M70 featherweight in 243, the barrel was the factory barrel, nothing I did improved the accuracy, so the barrel was removed and replaced. The replacement 308 barrel shoots sub MOA. So the 243 barrel must have been a bad barrel. Looking through the barrel, nice sharp rifling, no shadows, crown is good. Heck if I know what was wrong with it.

Barrels are expensive to replace, so do the cheap things first.

 

[Scorch]

Shot stringing as the barrel heats up is the classical example of a bedding problem. You can either relieve the bedding along the inside of the stock's forearm and bed the action, or take it to a gunsmith for a bedding job. As suggested, your father may have never seen this before if he fired just a few shots at a time, or the stock could be warping slightly as it ages and dries.

 

[bobn]

i second the thorough cleaning routine. most of the knowledge and supplies relating to cleaning were not available to the hunters of yesteryear. however they saw game fields the likes of which we never will. bobn

 

[johnwilliamson062]

I am going to buy a full size M14 and varmint, but all my fun to shoot guns will probably be carbines. I was very tempted to buy a youth .22LR instead of full size, but worried the stock would just be way too short.

 

[lt dan]

Bedding Problem

I took the rifle to the same gunsmith that is custom building my 300H&H. the answer: bedding problem for sure. the rifle has a thin barrel and this is not supposed to be free floating. so the job is as follows: new complete bedding, new trigger, remove sights from barrel, lower scope mounts and redo the finish on the stock. after this the smity will do the sighting on the rifle and if the grouping is not 1 inch on a 100 yards the problem is with the barrel wear.

 

[HiBC]

I will assume your rifle is in good hands with your gunsmith.I am curious,does this rifle have 2 guard screws to tighten,or three?Also,how do you go about tightening the screws? Ask your gunsmith to show you how. Also,it is critical the holes the screws pass through have clearance.
While opinions differ on free floating light barrels,I like featherweight barrels,and I freefloat them .They hold zero very well,and using a sling does not deflect the shot.Forends are quite flexible,unless they are massive.For accuracy,well I'll just say I have been very pleased.I'm not at all surprised by free float featherweight barrels that make 300 meter 3 shot groups the size of a lemon.I expect it.

 

[lt dan]

there are two screws.SLAMFIRE1, the eusta apparently was a product of Voere (austria). i used to tighten the front screw first and did this very tight. the back screw i tighten second and not nearly as tight.

 

[Art Eatman]

Stock-screw tighterning according to the Remingotn folks is 60 inch-pounds or five foot-pounds. That's easily achieved with a screwdriver.

I've always found that any vertical stringing is from forearm pressure. The barrel's steel and the wood behave differently with heating, and the pressure changes as the steel expands. That changes the harmonics. Changes in humidity are a common cause for degradation in a previously tight-group rifle, as the wood warps some infinitismal amount.

Anytime I'm not getting nice tight groups, I free float the barrel and then shim for about a five-pound pressure on the barrel from the stock. The shim, according to what my uncle told me back around 1950 or so, seems to function like the shock absorber of a car, dampening the vibrations of the spring. Lemme just say that this process has never, ever, failed me.

FWIW, I use a 3/4" strip of kitchen wax paper, folding it back and forth until it's just thick enough to need a slight pull to separate the barrel from the forend for insertion. Trim with razor. Shoot a few times, and the wax bonds to itself and the barrel.

 

[lt dan]

like i said got my 308 back from the gunshop. new bedding, new scope new mounts, new trigger . the old sights were removed and it is a plain barrel now.

STILL no group!!!!!!. the barrel was tested no problems.

so i took a boresight with me to the shooting range. the first two shots are in one hole. the next is either to the right or the left. never higher or lower. the bore sight shows that the crosshair of the scope shifts after every 3 or 4 shots. scope problem right? so i took two other scopes. SAME PROBLEM!!!!

the net result is that acording to the bore sight the reciol of the 308 shifts the crosshairs of the scopes.


this barrelis now free floating like art describes with the paper and light presure
there was a gunsmith with me he said he has never ever seen this.

the grouping at this stage on 100m are about 5-6 inch.

at this stage any sugestion will help!!!!!

 

[lt dan]

yes i reload

 

[thallub]

this barrelis now free floating like art describes with the paper and light presure

Remove the shim and totally free float the barrel.

 

[44 AMP]

This is a very unusual problem....

Not the poor grouping, but the fact that all the usual fixes (and you have done them) has not had any effect on the group size. Very curious.

Logic (and I love logic, although sometimes it doesn't love me) says, when trying to figure out a problem with multiple possible causes, you eliminate only one variable at a time. Then see if anything has changed.

right now, you have changed the scope, the mounts, the bases, the bedding, free floated the barrel, then shimmed the barrel for light pressure, and still no change to the way the gun shoots, right?

Usually one or a couple of these things will have some effect on how the rifle groups, and from that effect we can determine what, if anything, else needs to be done. This is truly strange.

Your test with the boresight shows you that the scope reticle is moving after two shots (or 3 or 4). The way to be sure that the problem is in the scope, or the mounts is to shoot the rifle without them. Normally we would say, try a different scope. You have done that, with the same results. Scope fit in the rings (and proper tightness) should not be an issue, but ought to be easy checked. Mount fit on the reciever, again, should not be an issue, but lets look a little deeper.

What kind of mount are you using? One piece? two piece? Is the mount made for your rifle, or is it one that just seems to "fit"? Fit of the rings to the mount is another point. When there is less than correct fit between all these things the mounts may "flex" from the recoil, giving the appearance that the scope is the problem.

You could have the scope & mounts removed, the iron sights replaced and then shoot the rifle. If it does the same thing, then the problem is definately not the scope or mounting system.

You say you shoot from a rest made from a car jack. Make sure nothing is touching the barrel when you shoot, as the change in barrel vibration can cause shots to go "off" opening the group size. You make no mention of how fast you shoot. try shooting over a longer period of time, so the barrel is cool for each shot (if you haven't already) and see what that does.

Your gunsmith has checked the barrel, and says it is ok for headspace, has he checked it for throat erosion and damage to the muzzle crown as well?

You might have him "slug" the barrel, which, if done properly will tell you the actual groove diameter, and can reveal any tight or loose spots in the barrel.

This one is a real puzzler, especially since you have done all the things that ought to fix the problem, short of replacing the barrel, stock (not usually needed, if the bedding is redone, and done right), or the action. The real puzzle is that the rifle used to be accurate, and now is not. If the barrel were worn out, I would not expect the first two shots in one hole, then the rest far away. I would expect a general scatter.

Since you are certain that the ammo is not the problem, I am pretty much out of ideas right now, sorry.

I just had another idea, which may or not be of any use. Put a drop of paint, nail polish, Torq-seal, or anything like that on one of the rings so it covers the edge of the ring and the scope body. Then shoot. If the paint (or whatever) cracks, this tells you that the scope is moving in the rings from recoil. If it is moving, that is a problem, if not, that is one problem you can rule out.

Shoot the rifle two shots, and they go in the same hole, right? What happens if after those two shots you wait a half hour or so, and shoot two more? Do they go in the same hole? Or do they go in a different hole of their own? Or does each one in a different place, right or left?

Have you done shooting from field positions, like standing, kneeling, sitting? Does the rifle group the same way as it does off the rest? or is it different?

I am trying to give you everything I can think of for ideas, in the hope that one of them might lead to being able to identify the cause, but fankly I just don't know. Your rifle does the same thing in the hands of other shooters as well, so it likely isn't you.

Good luck, and let us know if anything else you try works (or doesn't).

 

[lt dan]

44 amp, thanks for all the ideas. i am going to print your reply and take it with me to the gunsmith. i phoned him this morning and he said i must bring back the rifle as soon as possible. this is the gunsmith that did all the work that i mentioned on the rifle. the other gunsmith that went along(to the firing range) is a friend of mine but he doesnt practice as a gunsmith. the other smithy is in the city. so i will tell him about all the sugestions including the sugestion thallub made, and give feedback, thank you.

 

[Scorch]

lt dan-
the point of impact shifting right or left is typically the sign of loose scope mount bases. Does this rifle have integral bases or separate bases mounted on the receiver? If it has integral bases, then you may need to epoxy the rings onto the dovetail bases. If it has bases mounted on the receiver, remove them, clean them, then epoxy or loc-tite them to the reciver when you re-mount them. If the gun has a claw mount (as you often see on European rifles), talk to your smith about removing them and replacing them with a different mount.

 

[Tim R]

What happens when you shoot what your father used to shoot?

 

[lt dan]

scorch, you may have a piont. when sending(today) this rifle to the g/smith i found one srew on the mount base to be stripped/doesnt want to turn any more only turns around and around but doesnt tighten to a piont where it doesnt tighten any more. however the mount seems "unmovable". i am not telling the g/smith about this, i want to confirm his competence when he does fault finding on this rifle.

Tim R, i have not shot with what my father used in some time now. he never reloaded and shot with what he got from the shelf. shows you how trustworthy this rifle used to be. however the g/smith shot his standerd confirmation shots with shelf ammo and got an inch grouping on 100m. this is more or less the same ammo my father used. sir, i am confused!!