I finally got my barrel and was able to hit the range for the first time with my new AR chambered in 257 Bobcat!
For those of you who might not be familiar with it, the 257 Bobcat is a wildcat based off the 6.5x47 case that is designed to have optimal performance from the AR-15 platform.
Here's the rifle with the following specs:
24" 1:9 Twist .257 Bobcat barrel
BRT Covert Comp
BTE ADJ Gas Block with rifle length gas tube
17" Parallax-esque Free Float tube
New Frontier Armory Left Side Non- Reciprocating Upper
DPMS Chrome Bolt Carrier with ARP 800 Series Bolt
CMT Billet Lower
Black Rain Ordnance 3.5# FCG
Ergo Sure Grip
Luth-AR MBA Stock
CMMG small lower parts
PRI 6.8 Magazines
Primary Arms 4-14x44 FFP ACSS HUD DMR in American Defense Recon Mount
Testing
The first bullets tested were the 75g V-max over H335. The brass I'm currently using is Hornady 6.5 Creedmoor. Its been noted with the 270AR that this brass is not optimal due to the large primer pockets stretching from warmer loads in fewer firings than the preferred Lapua brass.
I started off with 15 rounds loaded at a mild charge of 37.0g. I got the rifle zeroed and on its way to being broken in. These loads clocked in at 3410fps average.
The following velocities came from the remainder of the ladder:
37.3- Avg: 3419
Hi: 3460
Low: 3401
37.6- Avg: 3457 **Not sure what happened with this spread**
HI: 3536
Low: 3409
37.9- Avg: 3471
HI: 3482
Low: 3453
38.2- Avg: 3470
HI: 3450
Low: 3487
38.5- Avg: 3502
Hi: 3535
Low: 3471
38.8g & 39.1g - Chrony began acting up as a result of low light
Pressure
Pressure signs did not show up until 38.5g where there was slight cratering and occasional swipes. At 38.8g there was one pierced primer, some flattening and more defined swipes. I only shot one round of the 39.1g load which produced a loosened primer pocket, gas leaking, and a jagged swipe. Based on these results I would say that the maximum semi hot load is somewhere around 38.6g. I plan to run a smaller ladder from 37.8-38.6g.
(Left to right: 37.3, 37.6, 37.9, 38.2, 38.5, 38.8, 39.1
For those of you who might not be familiar with it, the 257 Bobcat is a wildcat based off the 6.5x47 case that is designed to have optimal performance from the AR-15 platform.
Here's the rifle with the following specs:
24" 1:9 Twist .257 Bobcat barrel
BRT Covert Comp
BTE ADJ Gas Block with rifle length gas tube
17" Parallax-esque Free Float tube
New Frontier Armory Left Side Non- Reciprocating Upper
DPMS Chrome Bolt Carrier with ARP 800 Series Bolt
CMT Billet Lower
Black Rain Ordnance 3.5# FCG
Ergo Sure Grip
Luth-AR MBA Stock
CMMG small lower parts
PRI 6.8 Magazines
Primary Arms 4-14x44 FFP ACSS HUD DMR in American Defense Recon Mount
Testing
The first bullets tested were the 75g V-max over H335. The brass I'm currently using is Hornady 6.5 Creedmoor. Its been noted with the 270AR that this brass is not optimal due to the large primer pockets stretching from warmer loads in fewer firings than the preferred Lapua brass.
I started off with 15 rounds loaded at a mild charge of 37.0g. I got the rifle zeroed and on its way to being broken in. These loads clocked in at 3410fps average.
The following velocities came from the remainder of the ladder:
37.3- Avg: 3419
Hi: 3460
Low: 3401
37.6- Avg: 3457 **Not sure what happened with this spread**
HI: 3536
Low: 3409
37.9- Avg: 3471
HI: 3482
Low: 3453
38.2- Avg: 3470
HI: 3450
Low: 3487
38.5- Avg: 3502
Hi: 3535
Low: 3471
38.8g & 39.1g - Chrony began acting up as a result of low light
Pressure
Pressure signs did not show up until 38.5g where there was slight cratering and occasional swipes. At 38.8g there was one pierced primer, some flattening and more defined swipes. I only shot one round of the 39.1g load which produced a loosened primer pocket, gas leaking, and a jagged swipe. Based on these results I would say that the maximum semi hot load is somewhere around 38.6g. I plan to run a smaller ladder from 37.8-38.6g.
(Left to right: 37.3, 37.6, 37.9, 38.2, 38.5, 38.8, 39.1
