Hi
I own an old savage 340 which I like very much,but it begins too shoot mad difference between shots are as much as 150 -200 fps in 5shot series and the velocity is as much lower compared to my m24 savage in same caliber(30-30). what shall i do shall I retire it or change the barrel which is not easy du to import regulation for gunparts, or is it some way to cure the old barrel (rifling seems nice). would cast bullet at .311 or 309 without seizing help it's accuracy?
best regards
Danny

What do the fired primers look like in terms of the firing pin indent? Are they uniform? How deep do they look compared to cases fired in other guns?

This can be a lot of things like the ammo, headspace, wrong cartridge, firing pin length or hanging up somehow and a lot of other things.

Dry fire it a few times and listen to see if the sound of the falling firing pin is uniform.

If you suspect the headspace we can get you the dimensions of the chamber and cartridge tolerances and how to make your own gage.

I don't think cast bullets are going to help although that's a excellent cartridge for them

hi s99
I do suspect headspace failure.in that case what shall i do ?
BR
Danny

As one poster said, check the primers for consistant deep enough denting. If that is the problem first clean the firing pin spring ect. It could be excess headspace that prevents the firing pin from striking hard (a lot of headspace). If you reload fire factory ammo with the case lightly oiled from the shoulder back. The case will now stretch out to fill the chamber. When you reload take care to avoid pushing the shoulder back. The 30/30 does not have enough chamber pressure to overcome the friction of the base of the case, and oil is needed to fire form.
Good luck!

Hi guys
I checked the cases indeed the shells fired in old 340 had deeper marks than the new m24. it could not be a firing pin problem. I don,t know why older barrel produce less velocity,but being so erratic is stil a mystery to me.
danny

If the primers aren't bulging out then headspace probably isn't the problem.
It may be that muzzle blast is effecting your chronograph. Move back another 6-8 ft
(2 to 3 meters). and see if the readings change. If you did all the measuring at the same time, try it again and play around with the sky screens to avoid reflections.
Finally if the accuracy is adequate for your needs enjoy!.
Good luck!

Check your firing pin protrusion with the firing pin in the fired condition. Not sure the exact specs on this gun, but a common rule of thumb is usually about or slightly less than the diameter of the tip.

On this gun the firing pin is adjustable & held in position with a "C" clip that slips over a square rear secion of the firing pin.

If this dimension is short, you could be getting erratic ignition.