Experts help

[Beekeeper]

Lets see if I can state this right.

Some time ago I bought 2 Isralli 7.62 Rifles that were originally M48 Mausers.
Stocks on both were toast so I made new stocks (Manlicher sporter)
One has a good or better barrel and the other has a good but dark barrel with rounded lands.
I shoot Lee 312-150-2R boolits out of the good bore and it seems to get it done.
The dark bore reads 300 land, 310 groove.
It will not shoot the 312 boolit worth a darn.

Had some 314299 mosin boolits so loaded a dozen with 30 grains 3031 and tried them.
Get the sonic crack and it gets where its going real quick .
with a little tweeking might work great.

Now the Question for the experts.

Am I shooting a too large boolit?
diameter wise that is?
It chambers well , there is no blow by and there doesn't seem to be any signs of over pressure (ie: backed out primers swelled cases and such)

Let me know pro or con as I would love to make them both shoot POA.


beekeeper

[Larry Gibson]

No the 314299 is not too large for the .310 bore nor the other for that matter. If they chamber they will swage to the barrels dimension in the 1st bearing length of travel. From there on they are like any other .308 or .310 bullet would be. The 1st bearing surface of travel happens early in the time/pressure cycle and really doesn't affect psi that much. I make that stayement having measured the ressures of such.

Best accuracy with both rifles will probably be in the 1800 - 1900 fos range.

With the 314299s I suggest backing down to 27 gr 3031 and adding a 1/2 - 3/4 gr dacron filler. Work back up to 32 gr. Best accuracy will be found in that range with 3031 under that bullet.

If you want both rifles to shoot POA, assuming they are shooting low with the rear sight on the lowest range setting, the front sight will need to be file down to bring the POI up to the POA. Windage can be made by drifting the front sight right ir left in the opposite direction you want the group to move.

If your cast loads hit high at 100 yards with the rear sight at the lowest setting you will need to get/make a taller front sight. They can be got from Brownell's and you can or you can weld up the issue front sight to make it taller. File to shape and then file down so POI is the same as POA.

However, the sight settings for longer ranges using your cast loads will not match the ranges on the rear sight. The ballistics of the cast bullet loads will not match the ballistics of service 8x57 ammuntion for which the rear sight is probably made/calibrated for.

Larry Gibson

[MtGun44]

Also - backed out primers are a sign of LOW pressure, not high pressure.

Should be no issue with your diameters.

Bill