500 S&W primer and crimp test

[.284]

I have been messing around with this stubborn TC Encore rifle for about year and a half. The latest, having to triple ring the scope and do the site in all over again. I have a load I used last year that I decided to experiment with. The load is this:

Barnes 325gr XPB
Stagline Nickle 1.615" trim
45grs W296
CCI 200 primer

The experiment was this, I went back to Hornady brass it was short 1.610", same powder as well as charge, and the Barnes bullet on top. I loaded 15 with Federal LRMP and 15 with the CCI's. Then I took 5 of one group and applied a lite crimp, 5 medium, and 5 heavy. I repeated the same with 15 others with the opposing primer. That's right 6 glorious five shot groups to test. In short, I was pitting primer against primer and the effects of crimp on group size and chronograph numbers.

Here are the targets and they are left to right 2 through 7:
Federal lite, med, heavy and CCI lite, med, heavy.

 

[.284]

Oh, I just thought of some additional information to share. I shot in this order: 2,5,3,6,4,7. Bench rest tested at 100 yards. The best chronograph numbers (SD-7) was target number 4....a terrible group. Target 3 had a SD of 22 which was 2nd best on the chronny. The average velocity of #3 was 2099 ft/sec.

 

[griz]

Were there any sight setting changes? Just seems strange the elevation would change so much with one primer but not the other.

 

[.284]

Good observation. I did adjust the scope after I shot targets 2,5,and 3. I normally wouldn't do that but if I hadn't most likely target 4 and 7 wouldn't have hit the card board. So again, to be clear, I shot 2,5, and then 3 before I made one scope adjustment and then shot 6, 4, and then 7.

What I am wondering most is where I go from here? I like target 3 for group, but I wonder if I can tighten it up a bit? I will be using the gun for deer up in the farm lands of Michigan's thumb. I am trying to make a 250 to 300 yard gun.

Do I give Winchester primers a shot? Do I back down the amount of powder by a half to one grain? I am near max now which is 45.3 grains. Did the short cases have an effect?

Please sound off.

 

[Unclenick]

Just eyeballing, I can't say I'm at all sure the differences in group sizes aren't within normal random variation. I suggest a more careful run through steps to look for an accuracy node with the rifle? Dan Newberry's OCW method is usually pretty good, I find. You'd be working in charge increments of about .3 grains to look for such nodes with his method.

 

[.284]

I did think about the OCW method. Wasn't that also known as the Chocolate ice cream load or something? I know the powder isn't compressed or even full in the case for that matter but I'm a long way over 85%. I really don't want to go max so, I have no choice but to back down. However, I really don't want to loose a significant amount of velocity. I did notice the pressure change with the cases .005 shorter. I have a friend who is retired law enforcement and long time competition pistol shooter. He said I could back down the powder a bit and use Winchester primer to pick up 50 to 70 ft/sec.

 

[Unclenick]

Primers that change velocity do so by changing peak pressure. It can be another way to tune to some degree, as higher peak pressure, even when you back the load down to matching velocity, will shorten barrel time a bit. Be aware they don't always change velocity and pressure as predicted, though. Trying is all you can do.