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shaman Offline OP
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So I have this sporterized K98 Mauser in 8X57. It came to me as a deal sweetener. It's had all sorts of problems, but little by little I've worked through them over the past 4 years. Today I had it out for the first time to shoot with a newly reworked scope mount and a new scope. I loaded 175 grain Prvi Partisans over H4895 and gave it a go. My results were strange.

Round 1 and 2 were about 1.5 feet high and a foot to the right, grouping inside 4 inches.

Round 3, 4, and 5 are in a decent pattern starting 2 inches high from the bull at 12 O'clock and working their way down to 1" out at 3 O'Clock. I let the barrel cool a bit and round 6 was 2 feet out at 10 O'Clock. The next round is back in close to the bull.

I've shot some screwy groups before. This rifle was shooting minute of bushel basket when I first got it, and realized the reason why was the threads were stripped on the back end of the mount. However, I sent it off to new gunsmith this spring and it came back with his assurance the mounting problem was fixed. If it was consistently throwing them all over the target board, I'd be able to understand this. A flyer or two I could grasp. However, I'm trying to figure out how a rifle could throw a flyer 2 feet out and then come back close to the bull.

This is the original stepped barrel and the action has been bedded by a previous owner.


I"m interested in y'all's thoughts.


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My guess, it sounds like something is loose in the mounts/rings or scope for it to come back in like that.

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Any pitting in the original barrel? I had a .308 I picked up used that would shift point of impact about 6 inches from a clean to fouled bore, then settle in. Visible pitting in the barrel.

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As to this being scope/mount related, I have recent history with that problem. In fact the way the Mauser from Hell got its name was related to this. Because the previous smiths had boogered the rear screw hole, the POI would jump around. I'd get 2 or three close together, and then I'd get a group over here and then over there. The POI jumped until the scope got knocked loose and then it would point to a new spot for a few shots. Supposedly the scope and mount are straightend out now. Before, the rifle never returned to a previous POI.

Pitting did occur to me. When I first got the rifle it was badly fouled with copper. I removed the copper, scrubbed the heck out of the barrel and then applied Dyna Borecoat. Yes there is probably a pit here and there.




Last edited by shaman; 09/18/17.

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I know it's a pain, put I'd suggest mounting another scope that you know is good. Can't think of anything else offhand that would cause what you describe, assuming the smith fixed the mount. Wouldn't be surprised if the mount wasn't the real issue at all, despite the loose screw, depending on the type of mount. A collimater might reveal that without swapping scopes if you have one, but I've only used one a couple of times for bore-sighting while working in a store.


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shaman Offline OP
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Oh, believe me, the mount WAS a problem. It had a Leupold STD mount when I got it. With the threads stripped, it was flopping all over the place. Furthermore, one of the smiths overtightened the gross windage adjustment and the head came off the screw as I was attempting to loosen it. There have been 3 smiths involved. The first one boogered the internal thread. The second one jammed a larger screw in the hole semi-cockeyed and used some epoxy. The third, a recently retired fellow on this illustrious forum, took the job on of cleaning up the mess, and as far as I can tell his work is holding steady. He mounted a fresh Leupold STD 1-piece mount and rings and tested it before sending it back to me.

Thanks for the idea.

I've got a collimater. I'll give that a shot tonight. It was just freshly bore-sighted before this shooting session, so if it's off I'll know.


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Try another scope. I mounted a 10 yo Burris Fullfield on a rifle last week. It had been stored in a drawer for several years. I thought something wasn't right when sighting it at 25 yards. Moved to 100 and it was all over the target, so I've boxed it up to go back to Burris.

Last edited by Joe; 09/18/17.

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That's what I was thinking, mount or scope issue.

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Hence my caveat about mount type. The 3-screw std would be pretty wiggly with a loose base screw and/or windage srcew. Still, since you're still having trouble, something else is clearly wrong. Can't imagine a mildly pitted bore throwing shots that wildly. Replacing the scope is a quick way to eliminate one possibility.

The collimater should show if the reticle jumps around, I would think. Also, come to think of it, a cracked stock or REALLY bad bedding might cause your issue, but the huge jumps of POI are striking, no pun intended.


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One other thing you might try is epoxying the scope-mount base to the action. I know more than one gunsmith who's used this trick to deal with 98 Mausers where a screw-hole can easily be buggered, or even become slightly loose, because the thin bridge wasn't originally designed for scope-mount screws. In fact, this is the way my .375 H&H Mark X Mauser's rear base is mounted, using Acra-Glas Gel. If you decide to change mounts later, it can easily be removed by heating the base.

You can also have the mounting holes converted to larger 8-40 screws, but that doesn't solve the problem of very few threads inside the hole, which often causes the problem in the first place.


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shaman Offline OP
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Originally Posted by Mule Deer
One other thing you might try is epoxying the scope-mount base to the action. I know more than one gunsmith who's used this trick to deal with 98 Mausers where a screw-hole can easily be buggered, or even become slightly loose, because the thin bridge wasn't originally designed for scope-mount screws. In fact, this is the way my .375 H&H Mark X Mauser's rear base is mounted, using Acra-Glas Gel. If you decide to change mounts later, it can easily be removed by heating the base.

You can also have the mounting holes converted to larger 8-40 screws, but that doesn't solve the problem of very few threads inside the hole, which often causes the problem in the first place.


The last smith to touch this rifle did just that to clean up the messes from the other smiths. It appears to be holding.


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I'm thinking to myself - "Surely he's checked the stock bedding screws ! " smile


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shaman,

Then the rifle is possessed by demons. I've owned a few of those over the years.


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shaman Offline OP
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Originally Posted by mark shubert
I'm thinking to myself - "Surely he's checked the stock bedding screws ! " smile


With a torque wrench.


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Yep, demons. Try an old priest and a young priest, and tumble your bullets in holy water.


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Make sure the rear guard screw has it`s steel spacer in the stock hole!!!or in drawing down the action screw, you`ll warp the action, then wonder why the gun don`t shoot. Seen this more than once.

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shaman Offline OP
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CGPaul: I did not see this response until now. I'll definately put this on the to-do list.

I got up this morning and went down to the bench and started working through the suggestions.

1) The bore sighter showed the scope had not moved. I then rapped the scope in various places and looked again. Again, no change. My guess is the mount is ok. I did not change out the scope. However, it's a new scope. And the fact that the zero had stayed put indicates to me this is not the problem.

2) I checked the screws. 60 lbs on the front and just beyond hand-tight on the rear. I could still slip a bill down the outside of the barrel.

3) While I was putting the bore sighter away, I noticed the bullets out on the bench. I purchased these back in 2013 from Grafs. They're PRVI Partisan 175 grain PSP's. What caught my eye was that they're marked .322" . All other 8mm bullets are .323" I don't know if .001" is significant. However, I have since acquired some Hornady 170 grain IL RN's . I think I may cook up a batch of those and see if there is a difference.

4) I inspected the muzzle crown one more time. There's nothing there that looks obviously out of place.

5) In regards to M. Mule Deer's concerns, I gave the whole rifle a good shake from the rattle and tapped it gently with a used tomato stake, while commanding all demons within to depart. I then put it back in the rack next to the M1 Garand. Normally I keep these two rifles on opposite ends of the rack for obvious reasons. However, under the circumstances, I figure the commanding presence of the Garand will have positive effects.


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I would check alignment with a boresighter, just to establish a reference point. Then fire a half dozen shots fairly quickly and then check with the boresighter again while the barrel is hot, just to see if things shifted. Then check again after barrel has thoroughly cooled to see if it settled back to the original reference point.

Wouldn't be the first military Mauser barrel I saw that walked around as it heated up. I had a 7x57 Mauser that did pretty much what yours is doing. A fresh barrel cured that rifle's ills. (unless I inadvertently corrected some other issue in the process.)

Last edited by gnoahhh; 09/19/17.

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Also, my old man had a set of el-cheapo Herter's dies that loaded the crookedest ammo you ever saw, which performed as egregiously as your range report. A new set of good dies cured that nonsense too.


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Its either overbore for the bullets you are using or the barrel has a lot of stress. If you feel it is the proper bore size, stock/scope screws are in place properly torqued, scope is good, then you could try a set of LEE Pacesetter dies (the cheapest usually yet good dies) if you feel your dies are OK, try some Sierra bullets instead of the Privi. If you don't want to go to the expense of a new barrel, then the next best thing is to send the barreled action off and have it Cryogenically treated. It will take out any bad stress. Usually under $200, but shop around. Midway USA used to sell Mauser Adams & Bennett short chambered barrels for around $90 bucks! You may find a good "take off" barrel on Ebay, etc too. Its just how much you want to mess with this thing. "Myself", it would get traded off or sold cheap, ha. Good luck to you though, sorry you got a Lemon.

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