Primers flatter out of handgun than rifle. Why?

[happy7]

Here is a picture of fired primers of .357 mag cases. 125gr. jacketed over 19 gr. h110. The interesting thing is that these fired out of a blackhawk flattened primers significantly more than the identical load fired out of a 94 marlin long gun. I can't really think of an explanation. I bet someone on here can explain it to me.

70885

[ku4hx]

Tighter chambers for the Blackhawk maybe. All other things being held constant, the tighter the chamber the higher the pressure. That's one reason they advise against having an oil coating in the chamber since oil is basically non compressible and therefore makes the chamber "tighter". I don't know about your rifle, but the chambers on my lever guns run a mite to the large and loose side for more positive feeding.

[Hogdaddy]

In a rifle the cartridge is held against the bollt face with the extactor,, In the BH there is more space to the recoil sheid.. Just a guess ; )
H/D

[44Vaquero]

How about this: In the Blackhawk the bullet crossing from the cylinder to the barrel and hitting the forcing cone causes a momentary pressure spike. I have noticed the same results between my S&W and my H&R .357.

[bgokk]

All three of the above are possible causes.

In addition in the revolver the head space is probably longer. There is extra space between the base of the case and the recoil shield to allow the cylinder to revolve freely. This space allows the primer to back up on ignition, then the case moves to the rear as the pressure builds, reseating the primer. The result is the appearance of higher pressure.

[44MAG#1]

I wouldn't let it bother me. Could be more headspace in the handgun less in the rifle and the primer backs out the head of the case slaps it harder thus flatting it out more in the handgun.
But since that is almost a non issue I wouldn't think another thing about it and move on to something more worthwhile in the world of ballistics.

[BAGTIC]

It is because with most revolvers the headspace is greater than in a rifle. In the revolver the distance between the standing breech and the base of the case is comparitively generous. When the hammer hits the primer it pushes the case forward maximizing headspace. The pressure created by the primer causes the primer to back out. Chamber pressure then pushes the entire case backwards reseating the primer resulting in the flattened primers.

I believe this is also the reason that bottlenecked cartridge cases often cause problems in revolvers. When the cartridge fires the case is driven back as far as possible and the case is fireformed to the maximum chamber length. The tapered portions of the case become wedged into the chamber. With such a tight fit it becomes more difficult for the cylinder to rotate. In bolt action guns the bolt is retracted axially relieving pressure on the case. This combined with the camming leverage of a turnbolt facilitates extraction.

[fredj338]

You do understand that pressures are based on individual guns right? So what is good in one may be well over pressure in another. Tighter chambers, bores, headspace issues, etc it all matters. You can't just plug one high end load into any gun & expect identical results.

[fcvan]

I think it may be more complicated than that. A boolit leaving a rifle chamber has no cylinder gap to cross and so moves freely. A boolit approaching the cylinder gap gets scared, hesitates a bit, and then takes that leap of faith. The moment of hesitation is pretty tense and the primer reflects the adrenaline spike. I'm sure that's got to be it. I'd like to see how that same boolit acts to the sudden realization that the ride is coming to an abrupt end.