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Old January 18, 2013, 12:45 PM   #1
Join Date: August 29, 2009
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Confused on reloading 7.62x54R

I am planning to reload some 7.62x54R for the several Mosin-Nagants I have. I do have boxer-primed cases (from WWB stuff I've fired).

The spec says .312" bullets. My Lyman manual lists four bullets (2 by Sierra, 2 by Hornady) which are .311" and .312". However, it notes that many rifles will shoot .308" just fine, and I talked to someone who shot .308 out of a similar Mosin-Nagant with good results.

So what is the best way to proceed? Should I slug each barrel and then load based on that? As I understand it, the process is to ram a lead sinker through the barrel and then measure its width with calipers.

BTW, what is the effect of shooting a .308" bullet out of a barrel that slugs to .311" or .312"? I assume it would work there would be a loss of accuracy because the bullet wouldn't be gripped and get rifled going down the barrel...?
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Old January 18, 2013, 12:52 PM   #2
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Slugging the barrel is never a bad idea. It's better to know than to not know.
I shot a few .308 bullet reloads from mine, and didn't notice any problem with accuracy. I didn't chrono them, so I don't know if there was any loss of velocity. (doubt it)
Mine slugged between .312 and .313. When I'm loading cast bullets, I won't try any that are smaller than .313... .314-.315 is better.
In my experience, jacketed bullets are not that finicky...
So what is the best way to proceed? Should I slug each barrel and then load based on that? As I understand it, the process is to ram a lead sinker through the barrel and then measure its width with calipers.
The process you quoted is pretty accurate. As long as the lead slug is a few thousandths bigger than you expect the bore to be, you'll be golden. I recommend doing it at least twice, to help eliminate errors.
I always felt that if I got to the point where I thought it was time to bury my firearms, it was actually time to pick them up..
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Old January 18, 2013, 04:56 PM   #3
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I've never been able to hit the broad side of a barn with .308 bullets.
Odddly enough, some factory ammo is loaded with .308's, even though the only Mosins with true .308 groove barrels are limited to a few Finns.

Most rifles will not shoot .308 well. Loss of pressure, and instability, as the bullet spins down the barrel.

Ideally, with any rifle, the diameter of the slug should match the groove diameter of the barrel.

Shoot the .311-.312 bullets. For many of us (including me) that handload, the .311, 174 grain SMK is the winnaaaa...I shoot mine (sporter) at 600 yards with that bullet over 43.5 of Varget.
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Old January 19, 2013, 02:09 PM   #4
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I have shot the 174gr SMK in all 3 of my mosin's with very good results as well. Great bullet for the mosin imho.
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Old January 19, 2013, 04:36 PM   #5
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7.62 mm or .300" or 30 Cal. rifle bores are all basically the same when it comes to the land to land dia. They may vary a couple thousands but the main difference is the groove to groove dia. which can run from 309.5 to .313" on average or in some cases even higher.

Using a smaller dia. bullet gives it less grip on the rifling especially if the edges of the lands are worn. It also allow for more gas blowby which can affect both velocity and accuracy.

308 dia. bullets are always going to be the safe bet for reloading but they may or may not shoot as accurately. My Mosins all have .312 groove bores and shoot the 150 gr. .311" J bullets the most accurately.
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