consistency of pistol reloads

[jon1985]

Today I was out with the first of my 9mm reloads. I am reloading 147g campro projectiles over titegroup powder. Minimum is 3.2g, max is 3.6g so I started with 3.3g, 3.4g and 3.5g loads.

When I put them over the chrono there was quite a range of velocities, the 3.3g ranged 96fps, the 3.4g ranged 68fps and the 3.5g ranged 63fps. All of these are an average over 20 shots. I ran 10 factory loads and they ranged 115fps.

What is strange is the high end of the 3.3g was 903 fps, the high end of the 3.4g was 901 fps, and the high end of the 3.5g was 929 fps.

What is the generally accepted variance in reloads using a progressive press and a powder throw? I picked up a hornady electronic scale that only has 1 decimal point, but there may be another setting to get 2 decimal points to be more accurate.

On the positive side, all 60 rounds, fed-fired-and ejected without issue.

Tips? Tricks? opinions?

Thanks

 

[tjhaile]

By ranged do you mean extreme spread? If so, standard deviation is actually a more meaningful value. Average velocities are also more meaningful than the highest velocity of a series of shots. Counting only the extremes only tells you about the outliers, not what is typical.

I would say that you are doing well if you can get more uniform velocities than factory ammo with no function issues. I would be happy with +/- 0.1 grain charge accuracy for pistol loads; 0.1 grain is less than a 3% error for a 3.5 grain powder charge. The powder measure on my Dillon 550 throws most charges dead on with Titegroup with the occasional charge being out by a tenth.

You do not need a scale that measures hundredths of a grain.

 

[Ganderite]

How much flare are you giving the case? keep it to just enough to accept the bullet without shaving. This will increase tension and improve ES.

When you use the Chrony, aim at something on the far side, so bullet passes screens on same plane for each shot.

Use Chrony on a cloudy or overcast day. Blue sky results can be erratic.

 

[Lead hammer]

Lots of cardboard on a sunny day works for me usually.

 

[AHiltz]

When doing chrono work use the same kind of brass. Different brass can be slightly different sizes and can throw numbers off a bit

 

[jon1985]

All great tips.

Yes, extreme range. I will work on an average tonight.

It was fairly cloudy yesterday, which is why I went out yesterday.

I have a pretty good mix of brass as I bought 3 or 4 brands of factory ammo and thats the brass Im reloading (AE, Wolf, Blazer Brass) aswell as range pick up. I will sort it out for my load building purposes.

I had an IDPA target set up about 15 yards beyond the target that I was aiming at, but probably not as accurately aiming every round as I could have.

 

[tjhaile]

Sorting brass to satisfy your curiosity as to how it affects results is fine, but I would not bother for production purposes. Almost everybody uses mixed brass to reload for pistols because sorting it would be lots of work for no gain.

One of the most important things in reloading is to know when to say "good enough" and not get caught up in analysis paralysis. If the following criteria are met, you have a good load:

1. Functions in your gun.
2. Acceptable accuracy (with plated or jacketed bullets, any load that works in your gun will probably shoot better than you can hold).
3. All shots chronographed make power factor, if required for games like IPSC or IDPA.

 

[Chrossphyre]

There are a huge number of variables involved that explain your spread of velocities:
Case neck tension - governs where in the pressure curve the projectile releases from the case.
Projectile quality - micro-imperfections or changes in profile can have enormous impact on velocity.
Barrel quality - everyone knows about "cold bore" shots, but differing amounts of debris from previous firings also impart their impact on velocity.
Primer/powder burn - burn rate are an average over a selected batch of powder, which may be several hundred pounds or more. Precise 3.5g samples of the same powder will not always burn exactly the same. Variations in primer ignition and burn rate also have an effect on the subsequent ignition of the powder and the characteristic of the pressure curve.

There are many others as well but you get the idea. Reloading does enable you to control many of the variables involved but not all of them.

Cheers!

 

[jon1985]

I had thought about cleaning my pistol before starting and between each batch test, I will be shooting more then 20 rounds when Im out so I figured it wasn't a valid test.

As for neck tension, I had hoped it would be fairly similar as there were no adjustments between the 60 rounds, but this could change based on each brass case.

Maybe I will try running a few mags of factory through before I do my next batch of testing and see how it changes.

 

[Suputin]

This topic falls squarely in the "who gives a damn" folder. As long as the thing feeds, fires and ejects reliably and the rounds don't produce a shotgun pattern, velocity variance is entirely moot. It's a handgun, velocity spread is meaningless.

 

[jon1985]

This topic falls squarely in the "who gives a damn" folder. As long as the thing feeds, fires and ejects reliably and the rounds don't produce a shotgun pattern, velocity variance is entirely moot. It's a handgun, velocity spread is meaningless.

I ask because I shoot IDPA and plan to get into IPSC which means I need to meet power factor. Part of the attraction to reloading is being able to tune a load to my pistol that produces minimal recoil while still meeting a required power factor.

If what I am getting is to be expected then so be it, but if there is a simple way to bring the numbers closer, then great.

That said I am hoping to load 100 or so tomorrow to see how they shoot.

 

[silverfoxdj]

I ask because I shoot IDPA and plan to get into IPSC which means I need to meet power factor. Part of the attraction to reloading is being able to tune a load to my pistol that produces minimal recoil while still meeting a required power factor.

If what I am getting is to be expected then so be it, but if there is a simple way to bring the numbers closer, then great.

That said I am hoping to load 100 or so tomorrow to see how they shoot.

That makes sense for competition perhaps while your testing you may bench rest the pistol to remove another variable.. good luck

 

[Magellann]

This topic falls squarely in the "who gives a damn" folder. As long as the thing feeds, fires and ejects reliably and the rounds don't produce a shotgun pattern, velocity variance is entirely moot. It's a handgun, velocity spread is meaningless.

I agree, I'd use the load that shoots the most accurate groups, If you find a load you like check that it meets the power requirement and use that, the speed doesn't really matter.

 

[Grawfr]

I ask because I shoot IDPA and plan to get into IPSC which means I need to meet power factor. Part of the attraction to reloading is being able to tune a load to my pistol that produces minimal recoil while still meeting a required power factor.

If what I am getting is to be expected then so be it, but if there is a simple way to bring the numbers closer, then great.

That said I am hoping to load 100 or so tomorrow to see how they shoot.

By all means experiment and fiddle! Me, I'm trying to figure out how accurate I can make a 9mm reload myself, so I use one single brand of brass at a time, with as consistent a powder load and OAL as I can make it. I'm finding that bullet quality (how consistent they are in ogive shape, weight and coincidence between the geometric centre and the centre of mass) might make a seriously larger difference than I had thought (I usually shoot at 40-50m, and the best groups are a tad under 2 MOA with a Cx4 carbine).

Ultimately it's probably an entirely futile exercise, given the low BC of a 9mm bullet. It's still fun as hell to fiddle with all the variables to try to discover that "golden load" that the firearm would love the most.

 

[jon1985]

all of my 9mm shooting is off the bench so crazy accuracy is not needed. Im sure any of the loads that function in the gun will shoot better then I can.

I have 120 rounds loaded tonight (100 to shoot for accuracy and function, 20 to chrono) and will see how they do tomorrow at the range. If all goes well without a hitch, I will start cranking them out at the current setting.