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45flaco · March 16, 2020, 12:47 PM

Hey guys. Recently bought two mosin barreled actions, both with sewer pipe barrels. I happen to own 2 0.375" barrel blanks, and the equipment to load 375 H&H.
My plan is to put the blanks on the mosins, and chamber to 375 H&H for one, and 375 winchester for the other. The H&H is going to likely be a single shot, as I tried to fit one in the mag, and it didn't even come close to fitting, although a 300 Win mag will.
I plan to usually load around 375 flanged mag pressures, and only use the full power stuff for hunting.

I found that the blanks need to be threaded 1x16 TPI to fit the mosin receiver, by trying to thread random barrels into a spare receiver stub until one fit (ruger M77). This part should be relatively easy.

My other problem is bushing the bolt for the smaller rim diameter of the H&H. I've bushed a bolt before, but it was a much larger difference.
In this conversion, I will need to go from a 0.565" rim to a 0.535" one. That is a very small difference, but nowhere near small enough to ignore. The only time I have ever bushed a bolt was going from a 0.473" to a 0.378", a much bigger difference.

Ideas, suggestions?

March 16, 2020, 12:47 PM	#1
45flaco Senior Member Join Date: November 19, 2017 Posts: 134	375 H&H Mosin Hey guys. Recently bought two mosin barreled actions, both with sewer pipe barrels. I happen to own 2 0.375" barrel blanks, and the equipment to load 375 H&H. My plan is to put the blanks on the mosins, and chamber to 375 H&H for one, and 375 winchester for the other. The H&H is going to likely be a single shot, as I tried to fit one in the mag, and it didn't even come close to fitting, although a 300 Win mag will. I plan to usually load around 375 flanged mag pressures, and only use the full power stuff for hunting. I found that the blanks need to be threaded 1x16 TPI to fit the mosin receiver, by trying to thread random barrels into a spare receiver stub until one fit (ruger M77). This part should be relatively easy. My other problem is bushing the bolt for the smaller rim diameter of the H&H. I've bushed a bolt before, but it was a much larger difference. In this conversion, I will need to go from a 0.565" rim to a 0.535" one. That is a very small difference, but nowhere near small enough to ignore. The only time I have ever bushed a bolt was going from a 0.473" to a 0.378", a much bigger difference. Ideas, suggestions?