m1 carbine conversion

[bkjeffrey]

Ive got an Iver Johnson M1 carbine that I love to shoot...when I can find and afford to buy ammo. Ive been in the market for a PPSh type 7.62x25 for a plinker because ammo is still abundant and cheap.....

Then I had the thought of converting my M1 carbine from 30 carbine to 7.62x25. Both .30 cal bullets. Both rounds were designed to be used in carbine rifles. The 762 pressures would be plenty to cycle the action Im sure. Almost makes me think that I could just get my current barrel rechambered for the 7.62 cartridge because the barrel is in good shape.

I wonder if the mags will for 30 carbine would work for the 7.62...Ill have to research that one.

The Iver M1 is a cheap reproduction so its not like it would be a waste of a good carbine either.

What do yall think???? Thoughs???

 

[rcmodel]

7.62x25 Bore size = .310".
.30 Carbine bore size = .308".

7.62x25 case length = .990".
.30 Carbine case length = 1.290".
Or 3/10" inch too long for the 7.65 chamber reamer to clean out the .30 Carbine chamber.

7.62x25 case head = .393".
.30 Carbine case head = .360".
Or, the bolt face,extractor, and magazine feed lips would have to be opened up .033".

7.62x25 cartridge OAL = 1.381".
.30 Carbine cartridge OAL = 1.680".

Typical powder charge:
7.62x25 = 6.0 - 7.0 grains of fast pistol powder.
.30 Carbine = 13.0 - 15.0 grains of slow magnum pistol type powder.
Completely different gas port pressure.

So, gas port location and gas pressure would probably present problems to get reliable cycling in a Carbine.

It would take a lot of gunsmithing to convert one, and even more to get it to work reliably.

Any savings on cheap surplus ammo would quickly be eaten up on the conversion costs.
And then it will run out and cost more then .30 Carbine ammo at some point in the future.

rc

 

[bkjeffrey]

Good foor for thought. Thanks for the effort you put into that post RC.

7.62x25 case length = .990".
.30 Carbine case length = 1.290".
Or 3/10" inch too long for the 7.65 chamber reamer to clean out the .30 Carbine chamber.

While the barrel was removed from the reciever for rechambering couldnt it be shortened 3/10 on the breech end?

7.62x25 Bore size = .310".
.30 Carbine bore size = .308".

Does this mean it wouldnt work? I read a website dedicated to reloading 7.62x25 and 110gr .30 carbine bullets were a popular slug to shove in the cases.

Typical powder charge:
7.62x25 = 6.0 - 7.0 grains of fast pistol powder.
.30 Carbine = 13.0 - 15.0 grains of slow magnum pistol type powder.
Completely different gas port pressure.

Mmmmm.................Do you think the 762 would drop too much pressure too quickly to supply enough pressure to operate the gas piston effectively?

 

[rcmodel]

While the barrel was removed from the reciever for rechambering couldnt it be shortened 3/10 on the breech end?

Setting the barrel back would require shortening the op rod an equal amount, as the distance to the gas piston would be decreased too..

Do you think the 762 would drop too much pressure too quickly to supply enough pressure to operate the gas piston effectively?

That's what I tried to say.

I read a website dedicated to reloading 7.62x25 and 110gr .30 carbine bullets were a popular slug to shove in the cases.

Shooting .308" bullets in a .310" bore is not the same as shooting .310" bullets in a .308" bore.

I wouldn't say it wouldn't work, but a bullet .002" too big for the bore would likely raise pressure on an already high-pressure 7.62x25 round.

rc

 

[bkjeffrey]

Setting the barrel back would require shortening the op rod an equal amount, as the distance to the gas piston would be decreased too..

Good point, nice catch there rc. Thanks. I never would have thought of that.

Do you think that this:

a bullet .002" too big for the bore would likely raise pressure on an already high-pressure 7.62x25 round.

Would fix this:

the 762 would drop too much pressure too quickly to supply enough pressure to operate the gas piston effectively

????

Not trying to get into a pissin match with ya rc, just picking your brain. Thanks again.

 

[bkjeffrey]

Also, I dont know much about the PPSh rifles, but theyre 7.62x39, and function with the fast powder found in the 7.62 cartridge. I guess the gas port is in a different location?? Probably closer to the chamber to take advantage of the fast burning powder? Theres another one Ill have to look into.

 

[BruM]

should be a reloader near you

 

[rcmodel]

Also, I dont know much about the PPSh rifles, but theyre 7.62x39

The PPSh is not 7.62x39.
They are all 7.62x25 straight blow-back operated Sub-Machineguns.
They are not gas-operated.

The 7.62x39 is used in the SKS and AK-47 rifles, which are both gas-operated.
But it is a larger rifle round, and uses slower powder & much more of it then either the 7.62x25, or the M1 Carbine.

rc

 

[bkjeffrey]

The PPSh is not 7.62x39.

Duh.....I knew that. Thats why I used the PPSh for an example because it is 7.62x25. Fingers are used to typing x39 I guess.

However I did not know the PPSh was blowback operated.

 

[bkjeffrey]

should be a reloader near you

Huh? I reload myself. I just dont really enjoy doing it, more of a chore for me. I have however been collecting 30 carbine brass for sometime in hopes of reloading it all someday.. But, for right over a hundred bucks you can still get 1260 rounds of 7.62x25. If I stockpile say 10k rounds Ill be ready for the zombies for many years.