>30 cal magnum, older build on a M98 action, Bohler barrel. Older style scope mounting system. Action is full length bedded with barrel floated.

Started with a 150 gr 10 shot ladder test to try and find an accurate load and check pressure signs. Rifle sprayed bullets everywhere. Found the scope to be walking and play in the rear scope ring and mount on removing the scope.

Shimmed the rear scope ring / mount to remove play, Lapped the scope rings, mounted same scope and went back to the range with a single 150 gr load. Rifle still sprayed bullets.

No visible fretting after lapping the rings so replaced scope with new Bushnell Elite rated for magnum recoil. Shimmed scope rings with aluminium strips as a precaution against further movement. Went back to the range with same 150 gr loading. Shoots a 3 shot, 6" group at 50 yards.

Using this as a learning curve for me. What is the next step in resurrecting accuracy? Trim barrel and re-crown? Turn breach back and re-cut chamber to clean up throat?

Not worth spending too much on Gunsmith labour on this barrel with the Lothar Walther M98 barrels readily available but willing to try a few tweaks before changing it out.

What do you mean you shimmed the scope rings with alum strips?
Are the rings and scope the same diameter?

Start with the basics.
Was this gun ever accurate?
Is your scope securely and stress free mounted?
Muzzle crown undamaged?
Bore dia, condition?
Bedding?
Try different ammo and bullet weights? Especially heavier bullets.

You need to determine what the problem is before you start down the list of cures like shortening the barrel, recrowning and setting back the barrel, which if you have throat erosion it is doubtful with a sporter weight barrel you could set it back enough to eliminate the erosion.

After the initial 20 rounds showed poor accuracy I removed the scope to find the scope had been walking under recoil with fret marks on the scope tube and matching fret marks around the edge of the rings and a couple of random spots inside the rings, so minimal contact. I lapped the rings to 95% + contact and to ensure correct alignment. Rings and tube are both 25mm. After lapping the rings that much I used strips of shim stock a few thou thick and cut to size to line the inside of the bottom half of both rings to ensure there was no possibility of the ring screws bottoming out. I had brass or aluminium shim stock available, I chose aluminium for better grip. These are older rings and mounts and rough, not modern machined rings, but the scope is now securely mounted.

I'm starting with this gun as is. Someone made the effort to have it custom built so I'm assuming it was more accurate than 6" @ 50m at some stage.

The action is full length bedded and the barrel floated.

Without a bore scope the bore looks clean and shiney with no frosting or pitting. I've seen worse bores still shoot clover leaf groups.

The barrel is .750" at the muzzle so not a light weight. Crown is undamaged but the rifling may be little worn which seems the obvious reason for the poor groups to me after sorting the scope mount.

I have 180 gr projectiles and different powder on the way for the next round of testing but with groups that size the issue appears to be in the rifle not the ammo.

pro tip ... or q-tip

take a cotton swap, DRY, and test the crown for burrs

next, take one of your bullets (not a cartridge, just a lose bullet) and insert it into the muzzle, press and rotate, then mic the ring it makes should be about .302 or .300 (i don't exactly recall) - not 304 or so.

are the bullets keyholing? it wasn't mentioned, but I thought I'd ask...

are the bullet .308 not .311?

are the scope bases installed properly?

does the action bind when going into the stock?

After the above has been completed, have the bore checked out by someone with a borescope. If the barrel is old it may have a rusted bore or the throat could be just burned out.

quote:

Originally posted by Rhodes:
I lapped the rings to 95% + contact and to ensure correct alignment. Rings and tube are both 25mm. After lapping the rings that much I used strips of shim stock a few thou thick and cut to size to line the inside of the bottom half of both rings to ensure there was no possibility of the ring screws bottoming out. I had brass or aluminium shim stock available, I chose aluminium for better grip. These are older rings and mounts and rough, not modern machined rings, but the scope is now securely mounted.

I think you still have issues here.
If you lapped the bottom ring with a 25mm lap, and then added an alum shim to the inside diameter of your lower ring + shim is no longer 25mm.
Then you squashed the scope tube in the smaller diameter lower ring/shim with the upper ring.

What you should have done is remove material from the mating flat surfaces of the rings to insure it clamps the scope.

And why did you have to lap the rings anyways?
Were the base or bases not in alignment or not making good contact with the receiver?
As in tightening the base/bases down distorted the base/receiver and threw the ring bores out of alignment.

I would start with a new decent set of mounts and rings, mounted properly. As in full contact with the receiver and stress free.
It makes no sense to replace the barrel and keep crappy rings and mounts.

And as per jeffeosso's comments, I think you have something big going on, like the wrong bore/wrong bullets.

Assume nothing on a gun you have no knowledge of it's past performance.
I wouldn't be surprised if someone chambered the barrel with a 30 mag (whichever flavor of 30 mag) with the wrong bore dia barrel.
Cuz everybody and their bro have hacked on 'custom' mausers. And some are awful proud of it!

I get these kind of questions all the time; on guns and on the WW2 Jeep side of my business; why doesn't my rifle shoot, and why won't my jeep run?
NO one can diagnose any of that on the internet; all we can do is guess. The first impulse for the owner (and the worst thing to do) is to start replacing and adjusting things, BEFORE they do any kind of detailed, systematic, trouble shooting procedure. Guns or jeeps; same thing.
Did it ever shoot?
What is the last thing you changed?
What is the condition of each component?
The trouble shooting procedures are here; and guys will chime in; make sure each step is thoroughly done before moving on to the next. Don't replace anything unless proven to be faulty. Each component in the system has to be checked and isolated before moving on to the next; Guessing and hoping are not Courses of Action.
It should be a systematic, well managed process. For most guys, it is a close your eyes and stab, kind of thing, with predicable results.

I'd start measuring stuff.
barrel diameters.
torque on the action screws.
crown.
loose spots in the bedding, or stuff only half-assedly rubbing [magazine housing?] or lug area.

basically crawl over the whole rifle from front to back.
probably even making a chamber cast.
it wouldn't be unheard of to have a close-nuff barrel thread cocked against the receiver face on one side.
nor having a chamber cut some crooked.
[I got one of those, and it won't do better than 1-1/2"s,,, ever, and will get worse as time goes on]

The first thing I would try is suitable weight bullets, something around 200 grains, and a suitable powder somewhere in the burn rate of Re22 or Re23......

Why shoot a 30 magnum with 150g bullets?????

quote:

Originally posted by JTEX:
The first thing I would try is suitable weight bullets, something around 200 grains, and a suitable powder somewhere in the burn rate of Re22 or Re23......

Why shoot a 30 magnum with 150g bullets?????

Agreed!

My 300 win hates all 150's and 165's and loves about anything in 180 and 200 weights.

Might be as simple as bullet weight but it sounds like you have plenty of other issues to work on too.

Like dpcd said, be methodical and only work on one thing at a time but go ahead and replace everything that isn't working correctly before you resume.

Bear in mind that some rifle just won't shoot well! Been there and done that.

Zeke

Rhodes,

Also, I'm sure you know magnums generally require letting the barrel cool after only 2 or 3 shots when trying to test accuracy. When I'm shooting ladders, I know this, but I still often get impatient and shoot too quickly and start throwing flyers. Then I start looking for other problems.

i had a friend who shot for the us palma team for many years - he shot out many many barrels - when he would put a new on on and it didn't do right he'd just throw it away and screw on another - i learned that lesson long ago - if i know the rifle was right and the load was right before i screw on a new barrel rather than mess around and end up doing it anyway

quote:

Originally posted by butchloc:
i had a friend who shot for the us palma team for many years - he shot out many many barrels - when he would put a new on on and it didn't do right he'd just throw it away and screw on another - i learned that lesson long ago - if i know the rifle was right and the load was right before i screw on a new barrel rather than mess around and end up doing it anyway

Your friend was shooting competition, the OP is shooting 6" groups at 50 yds.
Your friend also knew his scope, mounting, bedding etc,, was up to snuff and the ONLY variable was the new barrel, that is not the case with the OP.

You don't solve problems by coming up with the solution 1st.

But at least you aren't the 6th guy in this thread, dog piling on to suggest heavier bullets. lol

I went back to read the OP post.

What Magnum cartridge? If it is a long case, the bullets may be seated deep to fit the magazine. Thus a big jump into the throat when fired, this ain't good for accuracy.

Question: What is the twist?

Keep looking. The problem is there you just have to find it.

Prussian blue on the bolt lugs may tell a tale.

Grease laden bolt innards could give you a inconsistent lock time.

I have seen bottomed out scope base screws also, allows the mount to move around.

One thing I would do as I have the tools is to pull the barrel and check runout on the receiver ring. May need a true up.

Another handy tool: Barrel vise, at the headstock of the lathe on the left. Comes in handy when tinkering on rifles. No, I do not do work for others, 'ain't good enough to charge money.



Could be a sloppy chambering job, dial indicators are wonderful for troubleshooting.

Impressive, sir! Reminds me of the place I spent the happiest days of my youth. Complete down to the lucky horseshoe.

WoodHunter,

Nice shop !

quote:

Originally posted by Lamar:

torque on the action screws.

I hate to admit it, but my custom Lapau that used to shoot 1/2 MOA at 500 suddenly opened up to 1 MOA. Action screws were loose.

Two weeks ago one of my 28 Noslers opened up to 1 MOA; I thought I had burned the barrel up already (less than 300 rounds), but alas, the action screws took up a turn, the ring nuts took probably a turn, and the ring screws all took up some slack.

Both guns went back to their normal super accurate self afterwards.

Kind of embarrassing to admit it, but sometimes it is easy to overlook the obvious.

quote:

Originally posted by cdsx:
Impressive, sir! Reminds me of the place I spent the happiest days of my youth. Complete down to the lucky horseshoe.

About a third of the shop in the photo, the shop is my retirement "man cave".

Over on the woodworking bench is a custom tackle center I am building for my 22 foot Mako Center Console. Years ago I played with guns but at my age I am slowly liquidating the collection. Fishing is easier on the old body than chasing Elk in the Mountains!!

If that picture represents how you are spending your retirement, then I say this is a man who's living his life properly. Hats off to you!

How's it shoot with iron sights at 50yds?

quote:

But at least you aren't the 6th guy in this thread, dog piling on to suggest heavier bullets. lol

haha, You're right Doug W, I did dog-pile on about bullet weight but it was to try to help since I went through that with my rig.

No more piling on from me!

Zeke

quote:

Originally posted by ZekeShikar:

quote:

But at least you aren't the 6th guy in this thread, dog piling on to suggest heavier bullets. lol

haha, You're right Doug W, I did dog-pile on about bullet weight but it was to try to help since I went through that with my rig.

No more piling on from me!

Zeke

Not directed at you Zeke, but many times I think this forum and many forums the responses are a bit like what you would hear down at the Memory Care Center. LOL

Try heavier bullets.
You should try heavier bullets.
I think you need heavier bullets.
I saw a film with a guy named Bullet.
That was Steve Martin as Bullett.
No it was Quinn Martin.
Did you try heavier bullets.
Have you tried replacing the barrel.
I had to replace a barrel once.
Here are some pics of indicator I use to replace my barrel.
That is a nice trash barrel in your shop.
Nice shop.
You need heavier bullets.

lol............


Meanwhile no word back from the OP.

This is how the "my rifle won't shoot" threads always go because it is not a matter of tweaking from one inch to 3/4 inch; there is something seriously wrong. Only a systematic check of every part of it, and the ammo, will work.
Recoil asked a smart question.

I hate the sound of that mount.

the comment about bullet weight might have a big bearing. Measure barrel twist and see that it's not something ridiculously slow for the cartridge.

I'd:

Check all screws (base screws, ring screws, action screws), inspect crown, inspect the bedding - looking for something "big" - and shoot it;

Get a better fitting mount, install scope properly and shoot it;

Get a different scope (proven), install properly and shoot it;

Load suitable bullet weights and try different seating depths (don't forget to try shorter/away from the lands);

Something is "big time" wrong if it's shooting that poorly. But most things can be remedied..........at least to the point where they will shoot "acceptably".

Good luck. Send us a picture of you proving how much hair you began with before you started on this beastie.

quote:

Originally posted by dpcd:
This is how the "my rifle won't shoot" threads always go because it is not a matter of tweaking from one inch to 3/4 inch; there is something seriously wrong. Only a systematic check of every part of it, and the ammo, will work.
Recoil asked a smart question.

Yes, 6" groups at 50yds indicates something is drastically wrong.

But many of the responses explains why there are so many 'Anybody know who I can send my rifle to?' topics on this gunsmithing forum.

Rifles shoot patterns, id you can send me a picture of your groups and number the shots 1 to 5, I can usually tell you why its shoot that way..Ive done a lot of work on that over many years, and talked to a lot of people and come up with a really accurate possible, by the formation of the group..

Slug the barrel too.

I'd bet it's in the mounts
or scope's shot.

Been down that trail a couple
times too. Usually when they
go to hell, they wander around
and don't shoot the same shot
to shot.
Don't take much to wreck a scope
internally. Like mentioned above.
Pull the scope off and shoot it
with irons, even if no sights at
all you should be able to hit a
big enough target a few times.

George

He did some funny stuff to the rings for sure..I would suggest an adhesive to start with or maybe some electrictions tape, then test..

I abhore lapping scope rings, its a plan for disaster for most..At worst I might rub the edges with fine paper or steel wool but that's not likely...Its an exercise in ruination as a rule, and so easy to over do..

I know, Ive heard all the claims on lapping scope rings, but todate and probably hundreds of scope mounts Ive never encountered the problem after they have been mounted on the gun, am I just lucky? don't think so!

I do recall a couple of European scopes that has a slickish finish that would not hold position, but changed that after a lot of complaints, no recall the maker, its been awhile.

I'm no gunsmith, but I use rubber cement on my rings and so far so good up to 375 Ruger.

quote:

Originally posted by Recoil Rob:
How's it shoot with iron sights at 50yds?

WELL?

and, what powder are you using, how old is it?