bullet diameter selection question

[MechanicWithAGlock]

sorry if this is already here somewhere but i can't find the info on the sight online or in the few reloading books i have
.
so i want to get into reloading 7.62x54r and i slugged my bore to confirm diameter but when chose a bullet do i use the landings diameter or the groove diameter? if someone could tell me id be greatly appreciated would also be helpful if you listed your source of information. ive shot factory 7.62x54r ammo from this rifle before but id just like to try to get a more precise load going.

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[Swedish K]

IIRC the correct bullets for reloading 7.62x54r (or other com block 7.62 such as x39 and x25) are the same as 303 brit. (.311 diameter) The reason being that com block ammo used the land for measurement and the U.S. uses the groove so 30-06 and 308, etc. use .308 pills.

 

[coop44]

I was pulling 7.62x39 bullets to load my .303 brit a few years back, worked very nicely.

 

[Mark W.]

unless your barrel slugs out of spec you should use the diameter bullet called for in reloading manuals. If you not using a printed reloading manual. Your well off the reservation.

 

[MechanicWithAGlock]

landing measures at .303 and grooves measure at .312 and there you have my conundrum and i read the reloading manuals i have 2 unless i missed it completely i didn't find the bit that tells me whether i select a diameter based on the landing measurement or the grove measurement which is what im trying to find out.

 

[civilian75]

Always choose bullets by the grooves diameter, in this case, .312". Bullet diameter should be equal or .001, With .002 or more, accuracy may suffer.

I have done some 7.62x54R reloading, with the following .311" bullets:
175gr SMK # 2275
174gr HOR # 3131

I've also used 174gr HOR #3130 for subsonic loads.

My rifle slugged .311. Yours slugs .312, but the above should work just fine.

Also, when slugging an old barrel, I try to slug the first 1-2 in from the muzzle first, then, I slug the rest. With jacketed bullets, accuracy will be mostly dependent on the muzzle grooves/lands. I don't know at what point it should be done but, counter-boring might be needed.

Good luck

 

[AMProducts]

There were only a few makes of mosins that used a .308 groove diameter, IIRC none of them were russian.

In general, you should be just fine using any .303 "caliber" (.311) bullet out there. In general I find bullets that are between the bore and groove diameter shoot best, bullets that are over groove diameter shoot much worse than bullets that are slightly under diameter.

 

[10 Spot Terminator]

There were only a few makes of mosins that used a .308 groove diameter, IIRC none of them were russian.

In general, you should be just fine using any .303 "caliber" (.311) bullet out there. In general I find bullets that are between the bore and groove diameter shoot best, bullets that are over groove diameter shoot much worse than bullets that are slightly under diameter.

+1

If you slug your bore on that Mosin and find it as some have ( including me ) to run abit tight ( around .309 ) you may want to try what others including myself have done . Have a custom .310 bullet sizer made by Lee and run your favorite .311 diameter bullets through them . This works very well and I have used this proceedure for other old or odd firearms as well . Use a good case lube on the bullets for smoothest sizing . You can downsize the bullets comfortably .002 but is best done in .001 incriments to reduce stress between the jacket and the core of the bullet . I have heard of others downsizing more than .002 but have not seen where the bulllets fired were recovered to see if the bullets still retained a decent percentage of their total weight . This would for the most part only matter if you were to hunt with the bullet as I am pretty sure targets dont require terminal performance . Of note I found the Sierra .303 Brittish Pro Hunters to be very user friendly for this proceedure and to be very accurate as well when loading for my Mosin Magant 91/30 with a bore of .3092 .

10 Spot