Chrono Standard Deviation Cutoff

[redwingshooter]

So, I was curious as to what variability people deem acceptable for their handloads? I chrono'ed some competition loads this weekend that I made off my Dillon SDB and I had mostly favorable results. My 9mm load (using Titegroup) came in with a StDev of 7 fps (10 shots) and 7.9 fps (5 shots). My 45 loads were a little more variable (using W-231) with StDev's of 14 fps (7 shots) and 18 fps (9 shots). Is this normal/acceptable or do you think something is going on with my 45's? I'm very happy with the 9mm loading and StDev's. Just curious as to what other loaders consider acceptable variability. Thanks in advance!

PS. Both loads exceeded power factor and I am not riding the limit by any stretch of the imagination so I may be scaling these loads down a little. Current loads are running about 180 PF for the 45's (165 needed for major) and about 135 PF for the 9mm (125 needed for minor). I am planning on dropping both loads 0.1 gr of each perspective powder and re-testing. I don't want to ride the limit and potentially miss PF so I'm hoping to get them to around 170 and 130 PF eventually.

 

[BehindBlueI's]

That's, IMO, well within acceptable levels. The gun is going to add some variability as well. As long as they group well that's what really matters.

 

[Leo]

SIngle digit standard deviations are a goal for long range or bench rest rifle, where velocity variance make big elevation changes. At pistol distances, you will never see the difference on a target. I would consider your loads absolutely great. You have no problem.

I wanted to check my findings years ago and did chrono and mechanical testing on Federal Gold Medal Match ammo. No one would feel under equiped with that premium ammo. The deviation figures were about 5 x as loose as my reloads. The bullet concenticity on rifle rounds was seldom less than .010" out of perfect, while mine were within .002" of perfect. The powder charge weight were +/- .3 grains, where mine were all tricked to perfect. Since championships can be won with Federal Gold Medal Match (or other premium ammo) I went to the match KNOWING that my ammo was plenty good enough to win, the rest was up to me.

Take your rounds to the match and shoot like a winner, your ammo will get you there.

 

[redwingshooter]

Awesome, thank you both for your replies. Good to hear that from other reloaders. I thought they were good enough but I just wanted to check!

 

[17 squirrel]

SIngle digit standard deviations are a goal for long range or bench rest rifle, where velocity variance make big elevation changes. At pistol distances, you will never see the difference on a target. I would consider your loads absolutely great. You have no problem.

Take your rounds to the match and shoot like a winner, your ammo will get you there.

Absolutely be happy with those loads. I agree.