308 Palma failure to fire

[lloydx2]

Lapua brass is usually short of min sammi use fed primer and seat long on first firing

 

[Webster]

My 6.5x308 Palma brass gave me fits..primers looked just like your FTF'S..told my gunsmith what was going on and he asked me how far I was seating the primers, told him .002, then I hear ''NOOO'' they must be seat at least .006-.008 below flush, 625 rounds later..No FTF's Thank You Ryan Miller!!
BTW..BR-4's

Seating 0.002" below the case head is a made up number. It works 99.9% of the time if the primer cup is held tight. Primer pockets are not all the same depth. The bottom corner of the pockets are rounded. Every manufacturer or SAAMI sets a +/- tolerance for pocket depth. A pocket cleanup tool squares the corner making it 1 or 2 thou deeper. The pockets are swagged in, not machined. All the primer manufactures have spent huge amounts of money studying primers. They all say seat so the anvils touch the bottom of the pocket. Obviously this cannot always result in 0.002" or any other specific depth below the case head. Firing pin protrusion is in the area of 0.055 - .065" this seems to take care of most problems?

 

[StevenDzupin]

Seating 0.002" below the case head is a made up number. It works 99.9% of the time if the primer cup is held tight. Primer pockets are not all the same depth. The bottom corner of the pockets are rounded. Every manufacturer or SAAMI sets a +/- tolerance for pocket depth. A pocket cleanup tool squares the corner making it 1 or 2 thou deeper. The pockets are swagged in, not machined. All the primer manufactures have spent huge amounts of money studying primers. They all say seat so the anvils touch the bottom of the pocket. Obviously this cannot always result in 0.002" or any other specific depth below the case head. Firing pin protrusion is in the area of 0.055 - .065" this seems to take care of most problems?

 

[DRNewcomb]

Hard to tell from photo but does not look like strike depth is as deep as others.

When the powder ignites, the primer will be pushed back against the bolt face and firing pin and appear to have received a harder strike.

 

[243winxb]

Measure the depth of the primer pockets.

Primers look seated to deep.

 

[KevinBaker]

Lapua brass is usually short of min sammi use fed primer and seat long on first firing

I finally got back out to the range yesterday. I took all the shorter cases that I had, and seated the bullets .010" longer (jammed) and used Federal 205 primers. All of them fired this time with no issue, so I'll use this as a learning experience for the next time I buy Palma brass. Thanks again to all that chimed in.

Kevin

 

[BoydAllen]

On the seating to depth thing. I think that it is just plain wrong. IMO you want to feel the primer bottom, and then put a little more on it for preload. If the primer is seated to shallow, some of the force of the strike is used taking it down to its proper position. The strike will look OK but the energy delivered to the pellet will be significantly less.

The only primer seating problem that I have ever had was years ago, in the late 90s when some Lapua .220 Russian brass had too large of a radius at the bottom corners of the pockets. My Sinclair pocket cutter was not made to cut on the sides of the pocked, and was of such a diameter that it would jam up in use. At the time, Russ Haydon sold a carbide cutter that was specially designed for the problem. It had a fixed depth and did not deepen the pocket. It just took care of the problem where the side of the pocket met the floor, removing very little material, and after that, primers seated perfectly.