I was curious how much velocity do you lose in a semi-auto vs a bolt using the same load?
Range Report Velocity - Semi vs bolt
- Thread starter Shaun Miller
- Start date
Re: Velocity - Semi vs bolt
My DPMS 308 24" was about 15-20 fps faster thn my Remington PSS 308, the chamber was tighter + had to get Forester Match dies.
My DPMS 308 24" was about 15-20 fps faster thn my Remington PSS 308, the chamber was tighter + had to get Forester Match dies.
Re: Velocity - Semi vs bolt
Will differ from rifle to rifle so no set amount of difference or rule of thumb. Also powders and bullet weights will make differences.
As an example, with my 20" Broughton barreled GAP .308 Hornady 168 AMAX factory load is at about 2650fps. With my 24" DPMS LR308 is is about 2625fps and with my 20" POF is is about 2580fps. So a little loss in velocity even with a semi that is 4" longer in barrel length.
Will differ from rifle to rifle so no set amount of difference or rule of thumb. Also powders and bullet weights will make differences.
As an example, with my 20" Broughton barreled GAP .308 Hornady 168 AMAX factory load is at about 2650fps. With my 24" DPMS LR308 is is about 2625fps and with my 20" POF is is about 2580fps. So a little loss in velocity even with a semi that is 4" longer in barrel length.
Re: Velocity - Semi vs bolt
Yep; velocities are not a cut and dried example of comparisons between barrel lengths and/or action types. Matters like chamber clearances and small bore diameter variations can have significant influences on velocity.
Greg
Yep; velocities are not a cut and dried example of comparisons between barrel lengths and/or action types. Matters like chamber clearances and small bore diameter variations can have significant influences on velocity.
Greg
Re: Velocity - Semi vs bolt
Wow judging from the velocities listed in these posts there doesn't seem to be a great loss in the semi-autos.
Thanks for the replies.
Wow judging from the velocities listed in these posts there doesn't seem to be a great loss in the semi-autos.
Thanks for the replies.
Re: Velocity - Semi vs bolt
Velocity loss from porting off the gas in a semiauto is not quite a myth.
The best way to tell is to shoot the same load, same barrel, gas port open and closed and tell the difference. With the M14 system, the 15 fps (or less?) average loss was less than the extreme velocity spread of the load(s) tested. The two samples overlapped. It is also not uncommon to have the average between two samples vary by 15 fps or more.
Velocity differences between barrels, as illustrated above, is often/usually far greater than the velocity effects of bleeding off a very small volume of gas 14 or so inches down the barrel, when the bullet has already reached 80-90% of its final muzzle velocity.
Velocity loss from porting off the gas in a semiauto is not quite a myth.
The best way to tell is to shoot the same load, same barrel, gas port open and closed and tell the difference. With the M14 system, the 15 fps (or less?) average loss was less than the extreme velocity spread of the load(s) tested. The two samples overlapped. It is also not uncommon to have the average between two samples vary by 15 fps or more.
Velocity differences between barrels, as illustrated above, is often/usually far greater than the velocity effects of bleeding off a very small volume of gas 14 or so inches down the barrel, when the bullet has already reached 80-90% of its final muzzle velocity.
