The Firing Line Forums - View Single Post - Ar15 with shielen barrel loosing velocity

ffffg · March 6, 2012, 12:31 AM

dnprk,

It will do it after several groups have been shot..

example, with 69 grain sierras hpbt the 456 rounds of the day shot a 9/16 inch group at 100 yards, with number 4 high and 5 and 6 9/16 inch below that.

I then set up the chrono and chronoed the next two rounds with a cool gun, number 7 and
8. .. they were at 2754 and 2688 fps respectivly...

This is most likely a simple semi auto gas gun situation, and i just need to run into someone who knows what it is and why its happening, and how i can fix it..

Hopefully its not a barrel problem, some guys at accurate loading.com said the barrel could need to be cryoed, but would need multiple 10 shot strings to show if that is the case.

dave

March 6, 2012, 12:31 AM	#7
ffffg Member Join Date: October 4, 2008 Posts: 59	dnprk, It will do it after several groups have been shot.. example, with 69 grain sierras hpbt the 456 rounds of the day shot a 9/16 inch group at 100 yards, with number 4 high and 5 and 6 9/16 inch below that. I then set up the chrono and chronoed the next two rounds with a cool gun, number 7 and 8. .. they were at 2754 and 2688 fps respectivly... This is most likely a simple semi auto gas gun situation, and i just need to run into someone who knows what it is and why its happening, and how i can fix it.. Hopefully its not a barrel problem, some guys at accurate loading.com said the barrel could need to be cryoed, but would need multiple 10 shot strings to show if that is the case. dave