**Very Preliminary Findings - Limited Data Set**
Saturday I was both doing some training with my second son who wants to shoot pistol better and doing some chronograph testing of some handloads. The test docket included velocity verification for a 45 ACP load. The load is 5.4 grains of W231 under an NOE 453-197 SWC. That bullet weighs 210 grains with powder coat in my alloy. I have used this load for some time, but recently changed from CCI to Ginex primers so I wanted to re-validate. Loads were produced on a Dillon 550C.
The first 5 shots averaged 927 fps, dev 15.8 fps, spread 38 fps. There was no velocity "cluster". Gave about a 4" group at 25 yards two hands off a folding table, no bag. Generally I will measure the "best three" but there really wasn't a best three.
To be honest I was a little disappointed in the accuracy...I am sure the pistol can shoot better than this, and I felt good about the shots, so I didn't think I was the problem.
My son shot a 5 shot string, with similar accuracy results*. These were not chronographed.
On a whim, I loaded up 5 more shots all with Winchester headstamp. Turned the labradar back on and gave it another go. This time the average was 953 fps, deviation was 10 fps and the spread was 20. And this time I had three shots within 4 fps of each other (958, 961, 962) and two that were 942. Group size dropped to 2.5", with three shots in about 1.25".
Two 5-shot tests do not make a statistically significant trend. But the results were enough to inspire me to at least re-sort the brass into headstamp groups. And I am planning some more targeted testing by headstamp.
Generally I have considered minute of soda can "good enough" for pistol ammo, so I have not really sorted brass as the juice wasn't worth the squeeze. But a new game has emerged at the cabin - The Roma Challenge. When a tomato goes over the edge, it is placed on a stump on the side of the mountain. The stump is 25 yards from the deck. The challenge is to hit the tomato standing unsupported from the deck. A roma tomato at 25 yards standing with a pistol is a small target, so "minute of soda can" isn't going to cut it.
I will report back once I have generated a larger data set.
*After a bit of coaching my son was shooting pretty much on par with me. He needed some coaching on his trigger control and his group size dropped from about 6-8" at 25 yards to 3-4" with 9mm Armscor 115 FMJ.
I'm not sure about head stamp, but I just did a test 30 minutes ago with mixed head stamp and 2 different primers.
Fiocchi standard and cci magnum the magnum primers were 67 feet per second faster. And we're much more accurate, with 12.2 of #9, under a 180 grain round Nose 10 mm.
But I do have a case sizer, and some cases that measure long The sizer won't touch to cut, the inside depth is different. That volume difference could matter.
There are probably some differences between makers. PLUS P 45 is said to have a slightly thicker side web as per Starline. Not so for 9mm, but be aware of the 9mm that has that shoulder down inside the case...
Also there are many small pistol primer 45ACP out there to watch for. Here are some pics I had on hand.
(https://i.postimg.cc/N0pzsDV7/45Brass.png) (https://postimages.org/)
(https://i.postimg.cc/Tw1Hpmv8/0025.jpg) (https://postimg.cc/S20GPnKV)
Now I will say that I do a pass-through sizing of my 45ACP with the LEE FCD (guts removed) using the carbide ring to pass through size all of mine!
You sure it wasn't the primers?
That's what I was suggesting primers and different headstamp cases.
All my testing this go was the Ginex primers. Sorry if that wasn't clear. The high SD/ES group was with mixed brass Ginex, the low SD was with all Winchester. I picked winchester as the headstamps were easy for my tired eyes to see in a box of 100.
Last night I sorted out four boxes of 100 - Winchester, Federal, S&B and TZZ. Next week I will load up all these and then get some statistically significant samples of data.
I mean on the one hand I know the answer. Top shooters don't mix headstamps for a reason. But the data nerd in me can't help but independently verify.
I just ran an experiment yesterday. Changing the seating depth of the bullet. I was shooting high left, I seated that same batch of bullets, a little deeper by 15 thousands. And then they hit low center.
Double post
It is amazing the impact that small change can have. .015" is two average human hairs.
My mistake, it was 25 thousands not 15.