Range Report Chrono Results - 175 SMK

[Killer Spade 13]

Got some interesting chrono results with my rig and some 175's.

Published MV is 2600 fps.

I'm shooting a 26" bbl and an AAC Cyclone suppressor.

My average was 2577 fps.

Should I be concerned? Don't have access to another chrono for comparison to establish any potential calibration problems.

 

[midmoguy]

There are so hasn't variables in velocity I wouldn't worry to much about the published number. You're very close to it anyway. what ammo are you using?

 

[Pusher591]

Aftermarket barrel or factory? What chrono? What powder and charge?

2577 is pretty common for factory barrels and FGMM.

When I went to sniper school we chrono'd every gun. My 17.5" aftermarket Brux barrel had the same velocities as a lot of the factory guns that were running 20"-24" factory barrels.

 

[Killer Spade 13]

Factory Rem. 700V (Heavy) RCBS chrono Federal GMMK

 

[tomcatfan]

One thing to consider, is most chrono's you have to place at least 15 ft from the muzzle due to burning powders and such. As a result, the measurement isn't really MV, its bullet velocity at a short distance away from the muzzle. The second the bullet leaves the barrel, it starts slowing down. If your only 30 ft/sec or so off, you may be getting the right MV. Just something to think about.

 

[Killer Spade 13]

Chrono set up at 10'. I understand the physics of diminishing velocity, but I thought it's be a bit higher than that with a 26" barrel and suppressor.

Just curious, not really obsessing upon it.

 

[R6Hybridd]

I have a 22" GAP-10 and averaged 2613fps with 20 rounds of FGMM 175gr. That was measured with a Magneto Speed chrono.

 

[midmoguy]

Probably just from the typical roughness of factory Remington barrels. A tubbs final finish would definitely let you get some extra fps out of it.

 

[M40_A1]

The correction for 175SMK at around 2600 fps with the chronograph at 15 feet is only about 10 fps. At 10 feet, it would obviously be less. So, that would not account for the 25 fps or so.

That said, I was getting about 2585 fps through my 24" 1-12 H-S Precision stainless barrel at 65 F through a Shooting Chrony at 15 feet.

 

[FN in MT]

GMM 175's, 26.5" Rem 40X, 1 in 13" twist, 60 degrees and 3400' elev= 2640 fps on avg. Oehler 32 w/ screens 15' from muzzle.