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8mm rm to 338 lm conversion

HardtargetFL

Private
Minuteman
Aug 8, 2022
3
0
Florida
I'm thinking of converting a 8mm rm to a 338 lm. There case dimensions are very close. What does everyone think? Is it doable? Safely.
 
I would reconsider converting your Rem700 to 338 Lapua.

I think the Remington action is barely able to properly handle the 338 Lapua or 300 Norma type rounds.

If I recall correctly you have to open up the lower feed ramp for proper feeding because the Lapua rounds are bigger in diameter on the cases. This makes the bottom bolt recoil lug of the receiver thinner which can in my opinion compromise safety.

You will also need to open up the bolt face for the Lapua round and change the extractor over to a M16 type extractor.

Also the thread size on the Remington actions leaves the chamber area of the barrel thinner. This has been proven to cause more barrel stretch/expansion which can cause extraction issues of a fired round. That's why you see more aftermarket receivers that are set up for 338 Lapua have a bigger thread tenon and or bigger bolt body diameters or both in order to handle the larger diameter rounds.

Can and has it been done to Rem700's? Yes. Again my opinion it makes the action weaker.

Buy a action that is set up to handle the Lapua rounds specifically. By the time you invest $$$$ to convert/modify the receiver and bolt you will have X amount of $$$ into it. Might as well buy a new action and save any headaches you might encounter.

Here at Bartlein we will not install/modify a Rem. 700 action to handle the Lapua/Norma type rounds.

Later, Frank
Bartlein Barrels
 
Consider this as well.....

Savage modified the 110 action to handle the 338 Lapua type rounds. I'll say your pretty much on borrowed time with lug set back on the receiver/bolt assy. with that action. It's a known issue. The Remmy action and the Savage size wise etc....isn't that much different. Yes Savage made the thread on the receiver bigger to 1.120" from the old standard of 1.055" but they didn't change the diameter of the receiver at all. Bolt lugs etc...are all similar in size between them. Also they are still using the factory nut system on the Savage. That limits you on the barrel breech diameter to 1.120". You need more meat on the breech diameter of the barrel because of the diameter of the chamber your making the wall thickness smaller on the barrel. Again more stretching/giving is going to occur.

I'm sure some engineer did all the calculations and on paper everything is safe but I feel the margin for error safety wise has been lowered.

So then we run into the problem of guys overloading the rounds and running up pressures and that ends up stressing the actions and bolts even more. Your safety margin is gone/greatly diminished.

Your just asking for problems.

Later, Frank
Bartlein Barrels