Extreme Spread - Should I Be Concerned?

[D.B. Cooper]

Ran some 44 Special loads over the chronograph today, and saw some things I didn't like. All loads mentioned here are Clays with a 200 grain RNFP powder coated, cast lead projectile.

4.0 grns. Three strings of five shots each: Averages were 713, 722, and 713 (fps), but what threw me off is the 80, 47, and 61 fps (respectively) difference between highest and lowest velocities. These seem like significantly high deviations. With a 15-shot average of 716 fps, the extreme spread comes out to be 92 fps. I saw 15- shot extreme spreads of 93 fps with 4.2 grns of powder, and of 97 fps with 4.4 grns. Even 5-shot spreads were 50, 62, and 82 in the 4.2 grn. load, and 61, 77, and 51 in the 4.4 grn load.

Should I be concerned about this? It's obvious that this is being caused by one or two shots outside the bell curve, but does this indicate a problem with either my powder measure/thrower (Lee Auto Drum) or my process? Is this, as Paul Harrell would say "enough of a difference t make a difference"?

I've been shooting the 4.0 grn load a for a while now-at least 2500 rounds or more. Accuracy is consistent and acceptable. The 4.2 grn load was comparable in accuracy to the 4.0 grn load. The 4.4 grn load was the worst I've seen from this gun. So, I'm not sure this issue is causing a problem with the results I'm getting, but I'm just wondering if this indicates a problem somewhere.

 

[rsrocket1]

4.0 grns. Three strings of five shots each: Averages were 713, 722, and 713 (fps), but what threw me off is the 80, 47, and 61 fps (respectively) difference between highest and lowest velocities. These seem like significantly high deviations. With a 15-shot average of 716 fps, the extreme spread comes out to be 92 fps. I saw 15- shot extreme spreads of 93 fps with 4.2 grns of powder, and of 97 fps with 4.4 grns. Even 5-shot spreads were 50, 62, and 82 in the 4.2 grn. load, and 61, 77, and 51 in the 4.4 grn load.

. Accuracy is consistent and acceptable. The 4.2 grn load was comparable in accuracy to the 4.0 grn load.

The difference is between a "mouse fart" and "powder puff" load. Your accuracy is what matters and in this case, a big difference in recoil could affect the shooter (not the gun's accuracy). In your case you are doing fine so I wouldn't worry about it. Chronographing the loads is a good idea to prove to yourself that the MV's are close to the published loads which implies the pressures are acceptable. The spread is a little high but if you can't tell the difference when shooting and you're getting good hits on the target you are GTG.

 

[murf]

are you getting "flyers" in your 5-shot groups?

murf

 

[blue32]

I bet your ES would shrink if you expanded your string to 10 shots each. Though I expect more ES variation in slower powders you're giving each shot a 20% chance of skewing the average.

 

[fxvr5]

wide ESs are not unusual in a large case where the powder does not fill it very much.

 

[fxvr5]

I bet your ES would shrink if you expanded your string to 10 shots each.

The ES will only get larger with more shots.

 

[MarshallDodge]

Clays can be position sensitive. Due to the case volume, the charge can move around inside the case which causes the issues you see. You can try things like tilting the gun forward before each shot.

I really like Clays and have shot it quite a bit with low charges in 45 Colt and 38 Special. Inside of 50 feet, the loads were more accurate than I could be shooting offhand. The difference of 50FPS is barely noticeable at that distance.

 

[drband]

Statistically, the larger the sample, the less the result is influenced by a single outlier. I would not think a larger sample would necessarily increase the ES. If you plotted the data, more points would likely be filled in on the bell curve showing the distribution of all shots fired. Highest and lowest velocity plotted would tend to be similar to the smaller sample results.
The larger sample would give more valid results, however.

The ES is not all that important if you perceive your rounds as accurate.

 

[D.B. Cooper]

are you getting "flyers" in your 5-shot groups?

murf

You know...I probably am. Truth be told, I rarely, if ever, shoot this gun from the bench at a bullseye type target. When I do, I'm usually just verifying that the sights are still set, or adjusting between this load and a hot magnum load. I shoot a lot of paper plates out to 15 yrds. and a lot of Dot Torture at 7 yrds, so when I do have fliers, I tend to attribute those to my shooting, not to the ammo. But when I do shoot from the bench, I'll see 4-5 together with 1-2 outside, although usually by not more than an inch.

 

[AJC1]

My first guess would be your es is caused by crimp consistency. Are your cases the same length and do you feel a consistent crimp round to round. I would expect this more in a slower powder, and the powder position also makes a lot of sense. I've not shot that powder so just taking a stab at it.

 

[fxvr5]

You know...I probably am. Truth be told, I rarely, if ever, shoot this gun from the bench at a bullseye type target. When I do, I'm usually just verifying that the sights are still set, or adjusting between this load and a hot magnum load. I shoot a lot of paper plates out to 15 yrds. and a lot of Dot Torture at 7 yrds, so when I do have fliers, I tend to attribute those to my shooting, not to the ammo. But when I do shoot from the bench, I'll see 4-5 together with 1-2 outside, although usually by not more than an inch.

You can't objectively assess accuracy shooting offhand. You have to bench the gun.

 

[D.B. Cooper]

You can't objectively assess accuracy shooting offhand. You have to bench the gun.

I'm certainly aware of that. But I've already gone through the accuracy testing a couple years ago, found the load I thought was best, and have rarely been back to the bench since.

 

[ATLDave]

Big case, small powder charge = positional variability.

look at the very low end numbers you’re getting. Are you close to sticking a bullet in the bore? If not, and you’re happy with the accuracy, none of this may matter.

 

[Eddietruett]

Obvious question are you sure the powder drops are uniform. I'd then check crimps. Could be inconsistency or just not quite enough crimp. Try another powder as well. I really like Universal. It meters great on my Dillon and I get great accuracy with my 44 special loads. 6.5gr of Universal should give you 950-1000fps depending on barrel length.

 

[D.B. Cooper]

Big case, small powder charge = positional variability.

look at the very low end numbers you’re getting. Are you close to sticking a bullet in the bore? If not, and you’re happy with the accuracy, none of this may matter.

Not too worried about a projectile sticking in the bore. I shot a a thousand or so rounds through it loaded to 3.8 grains of Clays with no problem. I didn't have a chronograph then, so no idea the velocity of that load.

Now, what I am close to is the minimum velocity of the league I'm shooting in. They've set 700 fps as the floor. At 4.0 grns, out of 15-shots, my average is barely above that. Not sure if I should bump it up to 4.2 or not. Never had a problem and no one ever asked me about it.

 

[D.B. Cooper]

My first guess would be your es is caused by crimp consistency. Are your cases the same length and do you feel a consistent crimp round to round. I would expect this more in a slower powder, and the powder position also makes a lot of sense. I've not shot that powder so just taking a stab at it.

I do use a pretty heavy crimp. I have never trimmed my cases. (Although, I had, at one time, over 1k cases, so many of them are only once or twice fired. I tend to lose more in the winter than in summer.)

 

[D.B. Cooper]

Obvious question are you sure the powder drops are uniform. I'd then check crimps. Could be inconsistency or just not quite enough crimp. Try another powder as well. I really like Universal. It meters great on my Dillon and I get great accuracy with my 44 special loads. 6.5gr of Universal should give you 950-1000fps depending on barrel length.

Inconsistent powder drops was the first place my mind went with this. When I started out, I was using Unique, and it was a nightmare to measure and throw the same load twice. That's actually why I went to Clays in the first place. I still have 3 lbs of Clays remaining, so it will be a while before I change.

 

[joneb]

For 44 spl 200gr target loads I use around 6.2gr of W-231 these are for 2.5 and 3" barrel.

 

[drband]

You know...I probably am. Truth be told, I rarely, if ever, shoot this gun from the bench at a bullseye type target. When I do, I'm usually just verifying that the sights are still set, or adjusting between this load and a hot magnum load. I shoot a lot of paper plates out to 15 yrds. and a lot of Dot Torture at 7 yrds, so when I do have fliers, I tend to attribute those to my shooting, not to the ammo. But when I do shoot from the bench, I'll see 4-5 together with 1-2 outside, although usually by not more than an inch.

I bet your "fliers" are shooter-induced. I just don't think there is that much of an accuracy issue with loads at 7-15 yards unless your loads are grossly mis-measured and inconsistent.

 

[Targa]

I have ran five shot strings of factory Magtech .44 Special with very similar deviations between high and low velocities that you are getting. Like already mentioned, if your load is accurate, no big deal.

 

[forrest r]

You might consider changing primers. I've shot countless 1000's of 175gr to 220gr wc's/hbwc's in 44spl cases using a 624 for nra bullseye (50yd/25yd). My go-to powder was clays using +/- 4.2grs, the es's were never over 40fps.

I did a lot of testing over the years simply because I do my lead in 150# batches and end up with 100# of alloy. I'll cast all my target bullets for the year out of the same batch of lead. After the bullets are processed and aged I run test loads over a chronograph looking at the velocity of the bullets. Harder alloy/bullets take more powder/pressure to seal the cylinders/bbl. There's times I've used 4.1gr and the next year 4.4gr of clays for the 624/target loads.

I'd be taking a hard look at the primers & make sure they are fully seated. From there I'd bump the charge up to 4.2gr/4.3gr and re-test. I've always used federal match primers for my 38spl/9mm/44spl/45acp target loads.

Consistency ='s accuracy

 

[Rule3]

If your "accuracy" is good then why concern yourself wit ES. ??

Try other powders see if the ES is better or worse. If you cant see the difference on your targets why bother?

Lets say you shrink the ES to half what it is,and accuracy is the same, what then?

Then you can get into outside temp, humidity, altitude time of day, moon phase.

 

[forrest r]

If your "accuracy" is good then why concern yourself wit ES. ??

Try other powders see if the ES is better or worse. If you cant see the difference on your targets why bother?

Lets say you shrink the ES to half what it is,and accuracy is the same, what then?

Then you can get into outside temp, humidity, altitude time of day, moon phase.

Simply because what might be considered good/accurate at 50ft will fall apart @ 50yds when you have high es's/sd's.

Some people might consider this target/ammo/load accurate.


In reality it's nothing more than blammo ammo/plinking ammo/dirt clod killers @ 10 paces. Good old unique and 60fps+ es's. The only reason I use that load is because it doesn't mater what bullet profile I use, anything in the 240gr to 265gr weight range will produce +/- 2" groups with that 11.5gr load of unique. Which means I don't have to put the rear sight up on blocks to get it high enough to hit 6" plates @ 100yds.

@ 50ft that load shoots bugholes in targets, @ 25yds I start to see a flier/1 shot out of the group. @ 50yds the fliers start showing up & @ 100yds I need to be on my game to hit 6" plates. Hense blammo ammo.

 

[murf]

suggest you weigh ten powder drops and make sure the variation is a tenth of a grain or less. you said your groups gotohell @ 4.4 grains, so a two tenths variation in your 4.2 grain load will give you fliers, i bet.

luck,

murf

 

[sequins]

Try magnum primers and confirm your crimp. I had ES of 105 on a batch of 50 10mm that I trickled to 13.5gn of AA#9 exactly but my inconsistent crimp & standard primers resulted in large ES even with perfectly consistent powder drops. I now feel primer & crimp are the more important factors. 100 FPS is a lot of FPS and it's unlikely powder drop variation accounts for all of it.

With such a large case I also recommend barrel tipping as a good test to see if position sensitivity is getting you.