Load work up weirdness....

[MightyMO1911]

So I decided to out some new knowledge to work over the weekend and work up a load for my 1911 in 45acp. I decided I wanted a load that will do 850 fps using a 230 grain Sierra jhp and Unique powder. The Sierra load manual lists max at 900 so this should not be a problem.

I know 5 rounds isn't the greatest test, but my bullet supply for this is relatively limited. So I loaded 5 each, 5.6 gr, 6 grains, 6.4 and 6.8. I picked up some factory seconds at the Sierra plant and I intended to use those for load work up and then load more with factory firsts. I will list the velocities in their respective order.

806, 840, 905 and 945. Of the 4 loads tested, 2 had good extreme spread and standard deviation. The 6 grain charge had a ES of 23 and a SD of 10 and the 6.8 grain charge showed 24 and 9.

I realized that I loaded them all about 7 thousandths shorter than spec so I loaded 5 more each of those 2 charge weights and retested. The 6 grain charge was so bad I didnt even record all 5 shots and the 6.8 grain charge was also worse but not as bad. ES of 38 and SD of 13. Still not bad but not as good. So I decided ok, I will load 5 more at the original length and retest. This time the numbers were slightly better than the first go round, ES of 19 and SD of only 7. Clearly this is where this load likes to operate in my gun.

So for the final phase I loaded 5 more exactly like the previous 5 with the exception of using factory firsts instead of seconds. I shot them through the chrony and y'all, I did not expect this. ES was 36 and the SD was 14. I laughed. I cried. I wanted to pull my hair out.

Basically all I did was use bullets from different lots and it changed things quite a bit. I was simply stunned. And for anyone wondering about that 6 grain charge, I loaded 5 using factory firsts and those numbers were abysmal. ES of 65 and SD of 25. I learned a ton from this little experiment and will dive headfirst into another this weekend only this time using a 230 grain lrn and I'm not sure which powder yet.

Are these findings inline with what y'all see as well or did I just really screw something up? Also, I hope this all makes sense. Inposted this from my phone and I tend to bounce around on this small screen sometimes.

 

[Nick_C_S]

Heh. It happens. When chronographing, you're going to run into a lot of things like this that defy logic. Your sample size is small and I think you're just running into random chance.

All your SD's are pretty good. If you want to get a definitive, you're going to have to increase your sample size. And even then, you may still be pulling your hair out.

It's been my experience that semi-auto's tend to show more shot to shot variance. I would think it the opposite since revolvers have that pesky barrel/cylinder gap. But apparently, that gap bleeds off gas consistently. 38 Special rounds - what I load and test the most - seem to behave very consistently. Especially target wadcutters. I think they have so much contact with the case that the powder ignites and the bullet releases with exceptional consistency, shot after shot. Just a guess.

Getting back to your situation: It's time to increase sample size if you really want to get some good data. First 10 rounds. Evaluate. Then do 30 round samples. My final step for a round I'm going to use for match, is to go with a 30 round sample - loaded using a regular production process (usually, I'll load 100 or 200 and pull 30 out at random). That way, I really know what I have brought to a match. I'll also retest if I open a new lot number of powder - just to make sure.

 

[Nick_C_S]

A little more

I decided I wanted a load that will do 850 fps using a 230 grain Sierra jhp and Unique powder.

Velocity. Bullet. Powder. Pick two.

Picking three rarely works. If I said I want to achieve 850 fps with a 230gn bullet; I would then run tests looking for the powder that would achieve the velocity with the most consistency (and safely, of course). In fact, the first thing I thought when I started reading your post is that Unique won't be running at its best pushing a 230 at 850 fps. I knew it would run better at a little higher velocity. And your tests - preliminary as they are - show that.

Usually my approach is: I want to try x bullet with y powder and z velocity will be whatever it is when I find the loading where it runs the best. I'm not sure if you were part of my post about a month back where I had a 357 Mag, 125g JHP, with Unique. And I did the load workups 9.2gn, through 9.7gn. I settled on 9.2gn. That post was a classic example of how I normally do my workups. The velocity was 1315 fps or something - but was ancillary to me. I picked the round that was the most consistent.

Getting back to yours: I would try 10 each of 6.4 through 6.8 - in 1/10gn increments. Or your could go in 2/10gn increments, for the sake of economy. Somewhere in there is probably a sweet spot where the round usually runs consistent. Basically, all you've learned from your tests so far is that Unique most probably runs best under those 230's somewhere between 6.4 and 6.8gn. Toss all the other minutiae from your mind. Time for more testing.

Also, I'm not sure why you chose 850 fps. But if you don't mind giving up about 40 fps or so, I have found that W231 delivers exceptional SD's with a 230gn jacketed bullet. W231 really shines in my 1911. Generally speaking, I have found that W231 likes to push heavy bullets to modest but very consistent velocities in a number of calibers.

 

[1100 tac]

231 is a great powder in .45 ACP, I just load practice rounds for accuracy, whatever the charge turns out to be.

For defense, accuracy is not as important as power to me, I'm not going to be engaging at 50 yds. , but some of my hi speed loads have turned out to be very accurate.

 

[MightyMO1911]

Thanks Nick_C_S. This process was really just somewhere to start. I looked at the Sierra manual and the powders I have on hand and, I was involved in your 357 post with Unique so I guessed Unique would work better on the higher end so I basically chose the 850 as a starting point.

This entire process was more academic than anything because its the first time I've loaded for the "craft" of it rather than just loading to shoot. I will heed your advice and load 10 each in tenth grain increments and test some more.

I was just really surprised that such seemingly subtle changes had as much effect as they did.

 

[Mike / Tx]

Another thing you will find while shooting your auto through the chronograph is that you will create or add to some of that ES as well. each shot has to be held as tight as the previous one or the little lapse in grip will change your numbers all over the place.. Been there done that, and my wife didn't like me half bald....

I built me a little stand out of some 1x6. Nothing fancy just one board about 10" long with the other screwed into the front of it having a V notch to rest the frame just ahead of the trigger on. When I set the pistol down however I had a piece of rubber about the consistency of a car tire, screwed onto a pice of wood which would be inserted into holes I drilled into the base. Two 3/8" dowels held everything in place where it needed to be. I put a thin piece of leather in front of the rubber to keep anything from getting marred up and went to town. This let the pistol have a solid rest under the rear of the grip which help it in place during firing. I still held it and allowed the muzzle to rise but the weight of my arm kept everything else in place.

Might help you might not be of concern enough to build one but it only took a couple of hours one rainy day to put it together. It really shrunk those numbers and gave much more consistent spreads.