Frustrated with extreme spread

[chris in va]

I have been using a Lee Perfect Powder Measure with my 9mm and 45 lead reloads. Using a Redding beam scale to check drops every couple dozen fills, it appears to be pretty accurate.

Verifying the velocity with my ProChrono reveals I have a hell of an extreme spread, sometimes 150fps! I'm trying to nail down a good plinker load with the stubby 160gr 45's and quite a few were going from 1000 to 1125. Even my 228's had about an 80fps spread. Most were about 30-40 but every now and then I'd get a much snappier load that was considerably higher than my goal.

I tap the measure twice before and after when dropping powder.

Maybe I'll try ten rounds using scale only and see what happens.

What's going on?

 

[Jim Watson]

What powder? Those stubby (low sectional density) bullets call for a very fast powder for any sort of uniformity. I was working with very lightly loaded 200 gr .45s and ended up with good old Bullseye.

 

[Nick_C_S]

^^ What Jim said. ^^

 

[Slamfire]

I have just examined my 45 ACP data and depending on the load, I found a number of loads, loads that I have shot thousands of rounds, which the extreme spreads are in the 80’s, found one test load that the ES was 100.

Handguns have higher ES and standard deviations than rifle rounds. One reason I like Bullseye in the 45 ACP is that it gives unusually tight extreme spreads.

Kimber Custom Classic 45 ACP


200 LSWC 4.0 grs Bullseye Mixed cases CCI300

11-Sep-05 T = 88 °F

Ave Vel = 738.9
Std Dev = 10.34
ES = 37.98
High = = 755.8
Low = 717.8
N = 32


200 LSWC 4.0 grs Bullseye Mixed cases WLP

21-Jun-06 T = 97 °F

Ave Vel = 748.2
Std Dev = 10.86
ES = 41.52
High = = 763.2
Low = 721.7
N = 22

 

[chris in va]

Local powder selection is iffy at best so I've been using PB for a while. It seems to happen with 700x and Green Dot as well. My favorite was Universal but haven't seen it in a year.

I'd love to get some Bullseye again but no dice.

 

[ColColt]

I have found the 200 gr SWC with 6 gr of Universal is about as good as it gets. I'm no great marksman but this shows how just standard loading with a Lee turret press, Winchester brass, CCI LP primers and Universal does together. I don't buy bullets, I make my own in good moulds.

 

[Jimro]

Chris in VA (really in Louisville), how far is the ProChrono? Could it be picking out some unburnt powder or propellent gasses?

Are there any other symptoms such as unexplained flyers?

If your bullets are uniform, and the powder charges are uniform, then either you are getting something like ignition issues or bullet setback causing two different peak chamber pressures or the chrono is picking up something other than your bullets.

Until otherwise ruled out, I suspect a chrono.

Jimro

 

[chris in va]

I'd say about 10' away, certainly no closer.

I guess that's what I'm trying to nail down, how uniform my powder charge is. I know a $24 powder measure can't be expected to meter precisely but 150fps max spread seems extreme. I could live with 40. I lightly taper crimp so no bullet setback.

I trickle and scale measured 10 rounds tonight and will report back in a few days with the results. I also tried not tapping the measure when the powder drops into the tube, which showed that an additional .3 grains was dropping. I guess that step isn't needed.



And yes...Louisville. Moved from VA five years ago but kept the name.

 

[Jimro]

Try moving the chrono to 15 feet and seeing if the velocity spread issue sticks around.

Out of curiosity, what powder are you running through the PPM?

Jimro

 

[Sevens]

Consider a theory that the powder charge may actually be as repeatable and consistent as you wish & hope that it would/could be, and that your wide ES is not actually a result of a randomly varying powder charge weight?

I've seen anecdotal evidence in my chrono playing that suggests bullet pull has a whole lot to do with reigning in the ES on some loads. I've found that a solid, consistent crimp has appeared to go a long way in helping to tighten up an ES for me in the past.

Of course, that was running jacketed slugs in .357 Mag, so running a firm roll crimp in a revolver round... not specifically helpful in your current load.

But even still, my suggestion is that you seem to think that your powder charge isn't consistent and that's where your wide ES simply must be happening, and I'm saying you should consider that maybe the powder charge weight just isn't the reason for your frustration.

I wish I could give better advice, but this is just some of what I've witnessed in my own loads.

 

[totaldla]

Don't use WLP primers - too hot and will increase you ES. Use an uber-fast powder (clays, bullseye, etc.). Just some ideas. And always use a consistent motion with any dispenser.

 

[myfriendis410]

Also; replace the battery in your Chronograph, had to do that last week.

 

[zeke]

1st problem-just using es to determine how good your load is. How accurate is the load and do you get the velocity you want?

2nd problem-expecting a tight es from a 160 lrnfp bullet with absolute minimal interference fit, in a cartridge (45 acp?)not designed for roll crimp.

3rd problem- related to first. What is your bullet setback when releasing the slide from lock back using the slide release?

200 grain lrnfp's are hard to get minimal setback, let alone a 160 lrnfp. At the very least you might want to try seating that bullet to where you can crimp it, and use a lee undersize die, or other means, to increase the interference fit (case neck tension)

 

[WESHOOT2]

when chasing ES

I suggest:

-new sized cases of one lot
-CCI primers of one lot
-bullets of one lot
-weigh each charge
-chrono twenty minimum; 50 is better.

 

[Sharkbite]

I would agree on moving the chrono back a bit. I was working up loads in a 18" 308 and was ready to bash my head into a wall. HUGE ES....

Turns out mzl blast was effecting the readings. Moved it back another 10' and everything went back to normal

I know 45acp is not like 308, but i'll never shoot over a close chrono again

 

[chiefr]

Extreme spread. Had the same problems many times not just on a chrono but on the paper. Yes I have no problem admitting it.

Extreme spread is an indicator something needs to change. Powder, bullet, seating depth, etc or a combination of the above.

Make notes and changes as necessary and enjoy the challenges. If you stick with it, you will find the solution.

After all reloading is fun.

 

[chris in va]

I only use CCI primers.

I'll try moving the chrono out to 15'. I wasn't really sure just how far away it was, definitely at least 10.

When this stupid arctic blast passes, I'll try those trickle charged 160's. Really these are just plinkers but still a little weird.