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Posted: 5/16/2012 1:22:30 AM EST
I slugged my barrel and the low spots were .300 as supposed to be, and the high spots were .310.  So if i choose to have custom ammo made, or start loading my own, and it has to be a tad smaller than .310, what should i be looking for in terms of a bullet size?

but i guess i'm just confused, because on the 7.62x54r.net website slugging tutorial, it says two things, which appear to contradict themselves, so i'm not really sure if the stock ammo is good enough or not....

1) All models of Mosin Nagant rifles have a nominal bore diameter of .300" or 7.62mm

2) The 1/8 size egg sinkers are very close to the approximately .310" size of a Mosin Nagant bore

arent these each stating the bore is a different size?
Link Posted: 5/16/2012 11:40:43 AM EST
[#1]
Not quite.  If you read their little blurb at the beginning, they explain

In this context the term "bore" is referring to the inside of the barrel in general and is not interchangeable with bore diameter. This may sound confusing at first, but it must be understood that the inside of the barrel has two different dimensions measured at the lands and the grooves. The lands are the high parts that impart spin to the bullet and the distance between them is the bore diameter. The grooves are the low parts between the lands and the distance between them is groove diameter. All models of Mosin Nagant rifles have a nominal bore diameter of .300" or 7.62mm. Although bore diameter will vary somewhat, it is usually not a concern unless the bore is extremely worn. What is important in bullet selection is the groove diameter.


What they're saying is that the "bore diameter" is the distance between the lands on opposite sides of the barrel and is the smallest dimension inside the barrel.  The "bore" is the entirety of the inside of the barrel, and slugging the bore gives you the largest dimension inside the barrel, or the distance between the grooves on opposite sides of the barrel.

Given your measurements, you should be looking for bullets that are .309 or .310" in diameter for jacketed or .311" (maybe .312") for unjacketed.  If you're doing your own handloads and are starting low and working your way up, you can probably get away with .311" diameter jacketed bullets without any problems.
Link Posted: 5/16/2012 12:00:49 PM EST
[#2]
You'll be fine shooting a .311 jacketed bullet, you'll probably even be able to get away with .312 if you adjust your powder accordingly.
Link Posted: 5/16/2012 12:09:12 PM EST
[#3]
Quoted:
I slugged my barrel and the low spots were .300 as supposed to be, and the high spots were .310.  So if i choose to have custom ammo made, or start loading my own, and it has to be a tad smaller than .310, what should i be looking for in terms of a bullet size?

but i guess i'm just confused, because on the 7.62x54r.net website slugging tutorial, it says two things, which appear to contradict themselves, so i'm not really sure if the stock ammo is good enough or not....

1) All models of Mosin Nagant rifles have a nominal bore diameter of .300" or 7.62mm

2) The 1/8 size egg sinkers are very close to the approximately .310" size of a Mosin Nagant bore

arent these each stating the bore is a different size?


Almost all manufacturers make .310 diameter bullets.  Event HPBT ones.

Link Posted: 5/16/2012 12:54:52 PM EST
[#4]
Quoted:
Quoted:
I slugged my barrel and the low spots were .300 as supposed to be, and the high spots were .310.  So if i choose to have custom ammo made, or start loading my own, and it has to be a tad smaller than .310, what should i be looking for in terms of a bullet size?

but i guess i'm just confused, because on the 7.62x54r.net website slugging tutorial, it says two things, which appear to contradict themselves, so i'm not really sure if the stock ammo is good enough or not....

1) All models of Mosin Nagant rifles have a nominal bore diameter of .300" or 7.62mm

2) The 1/8 size egg sinkers are very close to the approximately .310" size of a Mosin Nagant bore

arent these each stating the bore is a different size?


Almost all manufacturers make .310 diameter bullets.  Event HPBT ones.



And they're all (as far as I know) 123 or 125 grain.

I GUARANTEE his Mosin will shoot .311 bullets perfectly, especially considering that's what most surplus ammo is.
Link Posted: 5/16/2012 6:20:26 PM EST
[#5]
I've owned more Mosin's than I care to remember and all of them slugged at or around .310", I mainly shot cast bullets, but shot quite a few jacketed. Hands down the most accurate in all of my Mosin's was the Hornady .312" 150 gr. SP. IMR4350 worked quite well with this bullet. Don't worry a bit about a bullet being .001" or .002" or groove diameter, won't hurt a thing.
 As an example, I own and shoot lots of Swiss K-31's and the largest groove diameter I've found in the several I've slugged was .3075". I even own one with a .3062" groove. They all shoot .308" jacketed bullets safely and very accurately.

GG
Link Posted: 5/17/2012 12:13:22 PM EST
[#6]
Quoted:
I've owned more Mosin's than I care to remember and all of them slugged at or around .310", I mainly shot cast bullets, but shot quite a few jacketed. Hands down the most accurate in all of my Mosin's was the Hornady .312" 150 gr. SP. IMR4350 worked quite well with this bullet. Don't worry a bit about a bullet being .001" or .002" or groove diameter, won't hurt a thing.
 As an example, I own and shoot lots of Swiss K-31's and the largest groove diameter I've found in the several I've slugged was .3075". I even own one with a .3062" groove. They all shoot .308" jacketed bullets safely and very accurately.

GG


The Hornady .312 150gr is also the most accurate for me. The .311 Sierra Prohunters were alright, but not as accurate and are more expensive.
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