Firearm used: FNH FiveseveN 4.75" barrel
Started with factory AE5728A and SS197SR cases and pulled the bullets. All other components stock
Case: FNH brand new
Bullet: Barnes 36 gr. VG
Powder: Accurate Arms AA-7
C.O.A.L. = 1.580 nominal
Lee Factory Crimp applied
All charges WEIGHED
Test loaded 4 rounds each as follows:
6.4 gr. = 1929/1989/2045/ err/ = Avg. 1988/348
6.5 gr. = 2112/2056/2075/2102 = Avg. 2086/348
6.6 gr. = 2031/2000/2010/2054 = Avg. 2023/327
6.7 gr. = 2108/2137/2185/2205 = Avg. 2159/373
6.8 gr. = 2248/2116/2189/2193 =Avg. 2186/382*
6.9 gr. = 2055/2244/2176/ err = Avg. 2158/372
7.0 gr. = 2143/ err x 3
Velocity corrected to the muzzle = 2,196 fps.
Fired on 3/13/17 - 79 deg. F.
Master Chrony chronograph set at 6 feet.
I consider the Lee factory crimp applied firmly to be crucial to obtaining best velocity due to the lightness of the bullets used.
The 36 gr. Varmint Grenade has a much longer bearing surface than the AE and even the 40 gr. V-max.
Using factory new cases, the primers showed no signs at all of excess pressure all the way up to 7.0 grains. Shoulder movement within expected parameters and not excessive. Despite small sample size, the trend is obvious.
At $15/box of AE brand 5.7x28, it's actually cheaper to buy it and pull the bullets to obtain new brass for working up loads rather than buying once-fired brass, primers, and bullets, plus the much greater labor investment.
Running these numbers through Ammo Guide's Velocity Estimator, substitution of barrels gives the following:
EFK FD 5.4" = 2,255 fps / 407 fpe
EFK FD 6.0" = 2,314 fps / 428 fpe
Elite's EFK FD 7.0" = 2,396 fps / 459 fpe
So much for the naysayers when it comes to the power of the 5.7x28 when fired from the Fiveseven pistol.