Neck turning and Blown primers

[Kennibear]

Whenever there is a sudden change in a load you investigate the first variable that changed. Same gun, same bullets, same cases, same weather, different powder. Check the powder. I do my load development in midsummer so the temps drive the pressure to max. I check that load in the dead of winter for velocity loss.

Bought surplus H322 from Hodgdon's first release of that powder. Used it to feed my M16's. When I replaced it with their next batch which was new manufacture, the new stuff wasSLOWER!

Check the powder.

KB

 

[jsthntn247]

Your problem is the brass was new when you fired it the first time and saw no pressure, now your case walls are blown out to match your chamber and you fire the case the second time and there is no give and you get over pressure issues. Also, if you can't slide a bullet in a case mouth after firing it, it sound's like you don't have enough neck clearance. I would check the reamer dimensions and turn the necks for at least .004 clearance if this rifle sees heavy field use. If you can't get the reamer specs, have a chamber cast done. Sound like you might have gotten a slightly hotter can of powder also, but I would check the neck dimensions b/c not enough clearance will cause issues all the time.

 

[Mikecr]

Your problem is the brass was new when you fired it the first time and saw no pressure, now your case walls are blown out to match your chamber and you fire the case the second time and there is no give and you get over pressure issues.

No, it doesn't work this way.. You should read up on case capacity and pressure.

 

[bill123]

Your problem is the brass was new when you fired it the first time and saw no pressure, now your case walls are blown out to match your chamber and you fire the case the second time and there is no give and you get over pressure issues. Also, if you can't slide a bullet in a case mouth after firing it, it sound's like you don't have enough neck clearance. I would check the reamer dimensions and turn the necks for at least .004 clearance if this rifle sees heavy field use. If you can't get the reamer specs, have a chamber cast done. Sound like you might have gotten a slightly hotter can of powder also, but I would check the neck dimensions b/c not enough clearance will cause issues all the time.

Isn't the case bigger after the first firing, so larger case capacity means less pressure? Also to measure chamber neck diameter, I've always just measured the neck of a fired case and added .001" for spring back.

 

[rooster721]

Isn't the case bigger after the first firing, so larger case capacity means less pressure? Also to measure chamber neck diameter, I've always just measured the neck of a fired case and added .001" for spring back.

This is what I have generally understood and gone by. Recently did some development on one of my rifles with once-fired brass, then loaded "new" brass the same (even measured weight of brass, neck dia. etc) to be as close to the load-developement brass as possible, but still-- got extra pressure!

I will soon see if it was in-fact because that was the new-brass (I'm going to clean & re-load to re-test..) but am **** sure this above post has merit far as capacity/pressure goes toward new-brass. In my experience, new brass does have less capacity and show greater pressures