Isopher wrote: ↑Wed Dec 18, 2019 7:06 pm
fancygunz wrote: ↑Tue Dec 17, 2019 8:24 pm
jammitchell84 wrote: ↑Mon Dec 16, 2019 8:03 pm
All three stabilized and no keyholes.
All three cycled and bolt held back.
All three subsonic
I wished I had time to check accuracy but was getting dark. No chrony so didn't get velocity.
How can you conclude they were subsonic if you didn't measure velocity?
Not to step on OP but,
Having shot both supers and subs, you can tell by the sound of the bullet going down range if it is super or sub. Subs will lack the distinct crack sound of a super. Also, with that bullet and powder load it should be subsonic anyway just judging by other similar loads you can find on the site.
If we go by the text book of hard knock, there are a number of errors in the way the OP went about this and conclusions drawn. In his defense there is not enough information, but most people with experience would have done it different.
The biggest issue is to use an unknown bullet and check stability with a can on. You don’t want to find out it’s not stable with a baffle strike. That bullet has a good history, but it’s not worth the risk.
Next is it appears he started with a low charge and worked up. This can have a couple issues. Too low and a bullet sticks in the barrel. With marginal twist rate and low velocity, that can be the cause of stability issues.
Starting low can also lead to a lot of wasted time and materials, that is compounded without a chronograph. If you start high, say 12 grains, fire twice and the velocity is 1300 fps and the thing won’t cycle, the project is about finished. If you start at 9 grains and it cycles at 650 fps, then work up until it cracks, you’ll be awhile.
More than one person with a fair amount of experience, have worked up loads that were functional and accurate only to finally check and find out that it was below the minimum velocity they wanted or the bullet needed to function,
Checking sub/not sub by hearing the crack is completely conditions of the day and distance shot reliant. I function check suppressed supers all the time and never get a sonic crack. If the bullet never out runs the gasses coming out of the muzzle, it won’t crack. I shoot into a bullet trap at 3-4’ and never get a sound.
Subs without a suppressor are difficult to hear the silence past the muzzle blast, if they are only traveling 25 yards.
Personally my shooting temps vary well over 100 degrees, so without a chronograph all my sub loads would need to be developed in the winter at say -30, instead of when convenient and warm.
It’s not that it can’t be done the described in the OP, there are just more convenient ways with less cost and risk. As a disclaimer, I would be lying if I said I have not done the exact same thing trying a new powder/bullet combo. If you can load and shoot at home or the range, assembling a few rounds and shooting them takes less time than to set up the chronograph and a lot of valuable information can be gained.