6.8 SPC 90 g. bullet 12.5" ARP barrel. What is the fastest MV FPS you've seen?

Posted by: MPFD

6.8 SPC 90 g. bullet 12.5" ARP barrel. What is the fastest MV FPS you've seen? - 09/18/21 09:13 AM

Title says it all. I'm interested. I have one that doesn't want to seem to break 2600 fps without ruining brass.
Posted by: 1badshee

Re: 6.8 SPC 90 g. bullet 12.5" ARP barrel. What is the fastest MV FPS you've seen? - 09/20/21 09:12 PM

XM68gd load I'm pretty sure was doing 2700+ for guys. What powder and brass?
Posted by: Tonester

Re: 6.8 SPC 90 g. bullet 12.5" ARP barrel. What is the fastest MV FPS you've seen? - 09/21/21 11:10 AM

Jump on the 68 forums. There is a LOT of data. I remember seeing data with 85 gr bullets at close to 3000fps.

TC
Posted by: Tonester

Re: 6.8 SPC 90 g. bullet 12.5" ARP barrel. What is the fastest MV FPS you've seen? - 09/21/21 11:11 AM

Make that AR15.com:

-12.5" Cardinal Armory lapped barrel, shooting SSA's Barnes TSX, 85 grain bullet

-2974 FPS
-2972 FPS
-2987 FPS
-2970 FPS

Avg Vel. 2975 FPS

https://www.ar15.com/forums/ar-15/3000__...bbl/121-408438/
Posted by: MPFD

Re: 6.8 SPC 90 g. bullet 12.5" ARP barrel. What is the fastest MV FPS you've seen? - 09/23/21 10:08 AM

Thanks!
Posted by: Baron85

Re: 6.8 SPC 90 g. bullet 12.5" ARP barrel. What is the fastest MV FPS you've seen? - 09/29/21 01:11 PM

My ARP 12.5 with 90tnt is running 2708 at its accuracy node. I know Iím not at pressure and never measured velocity at max pressure because it didnít shoot good there.
Posted by: Willy Brotz

Re: 6.8 SPC 90 g. bullet 12.5" ARP barrel. What is the fastest MV FPS you've seen? - 11/08/21 07:37 PM

Originally Posted By: MPFD
Title says it all. I'm interested. I have one that doesn't want to seem to break 2600 fps without ruining brass.



In my 12.5Ē arp 6.8 barrel I was seeing over 2700 I thought. With the 90 grain federal xm68gd. It was Saudi or Jordanian military contract overrun ammo if I remember right. That barrel setup in an ar15 pistol, with PRI magazines, and xm68gd ammo has become my travel companion. Packs a good punch in a small lighter weight package. It comes along in the side by side, and in the vehicle wherever we travel, close or across the nation.
Posted by: MPFD

Re: 6.8 SPC 90 g. bullet 12.5" ARP barrel. What is the fastest MV FPS you've seen? - 11/19/21 06:41 PM

I couldn't get the speed I wanted with my can on there without trashing brass, I'm going back to 16" if anyone is interested in my 12.5" it's in the classifieds. I got great accuracy ands decent speed till I put my AAC 7.62 SD on it. If you have a flow through can it may be alot better.
Posted by: 1badshee

Re: 6.8 SPC 90 g. bullet 12.5" ARP barrel. What is the fastest MV FPS you've seen? - 11/21/21 07:06 PM

Ever try cutting the back with a adjustable gas block or BCG? My 16" and 12.5" is rough on federal brass no matter what, everything else is better.