I have a CMMG banshee 9mm roller delayed blowback with 5 inch barrell. I am getting ready to load rounds with CFE pistol and 147 grain bullets. It being roller delayed do you think pressures will increase over normal published data? I certainly will start on the low side but if anyone had any experience or knowledge.
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Roller delayed blow back and pressures
- Thread starter andyzx6r
- Start date
HK's are roller delayed, I know CMMG has the radial delayed system. I got the system in 45 acp to play with. You will definately get higher velocities with the bolt closed longer, but with the radial delayed system, it shouldn't make the loads less safe so to speak and have higher pressures. Being radial delayed CMMG says their 45 acp version can safely shoot the 450 SMC, it has much higher pressures than a standard 45. Always be careful when reloading though.
No, the pressure that you are speaking about, occurs before the bolt unlocks, regardless of the type action—even a blow back gun bolt will remain in battery until the pressure drops off.
I believe that there are some powder and bullet combinations-light bullet/slow powder-that can cause a blow back bolt to travel aft before enough pressure has bled off, but the peak pressure is long gone. The sides of the case expand outward and grip the chamber as the powder is ignited, when the pressure drops, the case shrinks back a bit, and the bolt begins to move.
I believe that there are some powder and bullet combinations-light bullet/slow powder-that can cause a blow back bolt to travel aft before enough pressure has bled off, but the peak pressure is long gone. The sides of the case expand outward and grip the chamber as the powder is ignited, when the pressure drops, the case shrinks back a bit, and the bolt begins to move.
A locked bolt moves after the peak pressure drops off, the pressure keeps it locked. Once it drops off to a certain level the bolt begins to move. The locks just add to the delay caused by the brass expanding.
Your brass will blow, and generally the gas will vent through a safety port before the gun blows. On a semi auto handgun the mag well is the vent port. At least that is how they are designed to protect the shooter.
All this is not to say a gun can’t be blown up.
Your brass will blow, and generally the gas will vent through a safety port before the gun blows. On a semi auto handgun the mag well is the vent port. At least that is how they are designed to protect the shooter.
All this is not to say a gun can’t be blown up.
