I've been doing some chrono testing on my new 16-er build, with a Faxon gunner 16" barrel. I'm liking this one, mostly looking at it for a walking-around weight rifle... but some of my chrono data has me a bit puzzled.
I'm ~100 rounds downrange with it so far.
My routine is to speed test 4-round sets of handloads or factory's and look for low std deviations, ideally in the single digits. This method has shown me several good shooting nodes over several different rifles. I use my magnetospeed.
All handloads are Hornady brass, cci450's.
Anyway, 2 or 3 factory loads seem to do well for this one:
1. Federal AE 90 gr TNT - avg 2840 sd= 7, I've done 2 4-round sets of these.
2. Hornady Black, 1 set of 5, avg 2360 sd=9.
3. Hornady 123st avg 2405 sd=9
4. The Fusion 120 is not too bad, showing 2429 and sd of 14.
And a couple of handloads also tested out well:
4. 100 gr Amax, 29.1 xbr, 2584 sd=5
5. 100 gr Amax, 33.1 cfe223, 2668 sd=3
6. 100 gr Nos BT, 29.8 xbr, 2662 sd=4.
Now the puzzling results. My other Grrrrs take 123 sst's usually 30.8-31.4 (this last one is for the howa), the ARs (18" both) use the 30.8, 2508 give or take with low sd (like 6-8 iirc). But for this 16" above 31.0 results start to scatter and definitely drop, and nowhere near what I thought I would get (2470-ish? for 16").
31.0 2433, sd=10.7
31.2 2451, sd 25.5 (!!!)
31.2 (2d set) 2447 sd=24.5 (!!!)
31.3 2437 sd=12.5
31.4 2444 sd 22
I think the gun is telling me to stay below 31.0. So that's what I will try next time. "Happy gun, happy shooter..." lol!
But the velocities do seem to be slow for this bullet. All of this is a bit of a surprise to me, I have to ponder it a bit...
I'm ~100 rounds downrange with it so far.
My routine is to speed test 4-round sets of handloads or factory's and look for low std deviations, ideally in the single digits. This method has shown me several good shooting nodes over several different rifles. I use my magnetospeed.
All handloads are Hornady brass, cci450's.
Anyway, 2 or 3 factory loads seem to do well for this one:
1. Federal AE 90 gr TNT - avg 2840 sd= 7, I've done 2 4-round sets of these.
2. Hornady Black, 1 set of 5, avg 2360 sd=9.
3. Hornady 123st avg 2405 sd=9
4. The Fusion 120 is not too bad, showing 2429 and sd of 14.
And a couple of handloads also tested out well:
4. 100 gr Amax, 29.1 xbr, 2584 sd=5
5. 100 gr Amax, 33.1 cfe223, 2668 sd=3
6. 100 gr Nos BT, 29.8 xbr, 2662 sd=4.
Now the puzzling results. My other Grrrrs take 123 sst's usually 30.8-31.4 (this last one is for the howa), the ARs (18" both) use the 30.8, 2508 give or take with low sd (like 6-8 iirc). But for this 16" above 31.0 results start to scatter and definitely drop, and nowhere near what I thought I would get (2470-ish? for 16").
31.0 2433, sd=10.7
31.2 2451, sd 25.5 (!!!)
31.2 (2d set) 2447 sd=24.5 (!!!)
31.3 2437 sd=12.5
31.4 2444 sd 22
I think the gun is telling me to stay below 31.0. So that's what I will try next time. "Happy gun, happy shooter..." lol!
But the velocities do seem to be slow for this bullet. All of this is a bit of a surprise to me, I have to ponder it a bit...
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