Mosin Targets... Vertical Stringing... Help?

[Josh Smith]

Hi All,

I'm stumped here.

This is today's shooting. It's just surplus light ball bullets, pulled, over 45 grains of Varget and a Federal primer. This is from a clean bore, and this rifle shoots low with a clean bore.

10 shots. Square is 1"; circle is 2". 60 yards, prone, front support, fire five, stripper clip, five more, as fast as I can BRASS, about every two seconds:



Prior to that, a 174 grain Hornady o.312" Match over 51.2 grains H4350, same distance:



But 174 grain jacketed round nose o.312" bullet, under increasing amounts of Varget, this is the best I could get, and the vertical stringing is really bad though it's an improvement over the lighter loads. If I recall correctly, these are 44 and 44.5 grains, pretty much overlapping each other. 10 shots:



Do I just keep increasing until I max out or find a load that doesn't string? Where do I go from here?

Thanks,

Josh

[GeoffLinder]

If you are using front support and the hand guard is fixed to the barrel, your vertical stringing could easily be caused by barrel bending from the support pressure. Try just very lightly resting the fore end on a sandbag without any pressure to see if this is the cause.

60 yards is too close for ammo charge variances to cause vertical stringing, there has to be a mechanical issue to cause stringing like this at such a short distance.

It is also possible that the barrel is vibrating vertically a whole lot and that when the bullet exits the muzzle when it's is moving up or down the rounds are flung whichever way the barrel is vibrating.

Again though, 60 yards is not usually enuff distance to see this type of result, also, shooting as fast as you can does NOT help you get precise groups that you can use as data points for load development.

[tobkis]

Barrel heating up?

[GeoffLinder]

Barrel heating up?

This is a possible issue too, shooting thin rifle barrels till they are really hot can cause large POI variances as the barrel goes from cold to hot, especially if the barrel to stock bedding is inconsistent.

[Munk]

Perhaps your sights/scope are drifting?

If your "front support" is clamped on or otherwise allowing the weight of the rifle to bear down on the barrel, you may be getting flex, it seems odd to me that it would though.

[mycrstuff]

The bottom straight up and down one looks like a breathing issue not a powder issue.