Brazilian Mauser crazy groupings

[Ganderite]

Crown looks fine from what I can tell.

Used some 1980s Federal Power Shock 140 grain, modern Federal Power Shock 140 grain and Winchester grey box 145 grain. None of which I believe are boat tail.

I know it's not scientific but I figured if indeed the barrel might be 7.62 for a 3006 I took a 7mm mauser and tried to drop the bullet into the muzzle end and it wouldn't drop in freely, for what it's worth.

Well, that rules out 30-06 and 308.

It could be a 270, but you say the brass does not change on firing.

Two things come to my mind:

The barrel is loose. Try wiggling it and see if there is any movement.

The bedding is very, very sloppy.

As a temporary test, put a dab of epoxy in the key bedding areas. If it is a bedding issue, you will see an immediate improvement.

 

[mbogo3]

The one I had you could shoot hen's eggs at 100 yards with anything it would chamber.MOA was easy.

 

[Sniper_485]

7mm would go into a .308 barrel. I'm sure you have a 7mm barrel from what you said. Sometimes the crown is worse than it looks but from the pics of your stock I think it was bubbad. Someone made a carbine looking stock by removing the front barrel band/bayonet lug and sanding the end round. A proper mauser stock only touches at the very end of the stock, right where the bayonet lug is, right where wood was removed. Make some shims out of pop can and put them on the bottom half of the barrel near the end of the stock untill the barrel has a slight gap right up until the shim. $.02

 

[Claven2]

It's a mix master for sure.

I suspect the action is a poor fit in the stock.

 

[200250126]

I plan on taking the rifle apart to inspect with my untrained eye.

If I got to the point where I wanted to re-barrel this, would this work with my action?

https://www.tradeexcanada.com/content/mauser-m98-barrels-zastava-30-06