Pistol reloading data more variable than rifle data! Why?

[wogpotter]

This actually is a kind of continuation of my earlier thread on powders for .357 mag loads, but is different enough I thought it deserved it's own input.

I've reloaded for rifle in .30 cal(s) for some time & got used to the variation of load data among different manufacturers, usually about 10~15%. I understand the differences in test equipment & the way they affect the published data. But pistol data has thrown me for a total loop Being new to pistol reloading hasn't helped either as everything I thought I knew seems wrong for pistol loads.

Example: One manufacturer's load lists a minimum load that is 12% higher than another manufacturers MAXIMUM load data. My usual technique when starting a new rifle load is to look at several manuals, pick the highest minimum & lowest maximum for the preferred powder for the bullet in use & then do a ladder load using that data. One load min, one load median & one MAXIMUM. Based on the data I get back I work a load within that range for the performance I'm looking for.

This just doesn't seem possible with the huge variation & contradictory information for pistol loads. For example using the load data quoted above I'd never load anything because I'd always be over maximum & under minimum at the same time!

Can someone set me on the right course here?

[Brian Pfleuger]

I do the same thing with handgun loads that I do with rifle loads... Which is actually the opposite of what you do....

I look at several official sources and start at the LOWEST low and work toward where I want to be, rarely exceeding the highest max load published.

Admittedly, nowadays with QuickLoad for reference, published data is little more than a sanity check against Quickload predictions. So I don't necessarily follow this exact pattern anymore.

[wogpotter]

That works as well. I go with the safest procedure even if it means I work with a much narrower range than you do. Unfortunately it seems to not be working for pistol as I'm now working on 2 differing loads for a plinking load using SWC's at about 1,000 feet per & a SD load with 125Gr HP's at about 1600 feet per because that seems to be what the Unique & the H-110 work as middle of the road.

The original goal was a one size for everything load, but that ain't happening.

[Cascade1911]

Example: One manufacturer's load lists a minimum load that is 12% higher than another manufacturers MAXIMUM load data.

What is the publish date of the one vs. the other?

[dunerjeff]

I've done the same thing as the original poster ,but now I also am trying to watch the published pressure readings, if available,plus coal vs bullet weight to get load densities for the available space in the cartridge as kind of a double check to what max should be.That is what I'm assuming some of the variances come from. When bullets are seated deeper, AKA less volume for powder, the charge weight has to go down too. Is my thinking right?

[Unclenick]

Wogpotter,

Dunerjeff beat my post, but I believe he is correct that you are seeing an artifact of case capacity change with bullet seating depth difference. In a short straight wall case, running a bullet design that seats a tenth of an inch deeper than some other of the same weight will reduce the powder space by a much bigger percentage than the same degree of difference in bullet seating depth will do for a rifle case with much higher powder capacity. That large change in space percentage can have a significant effect on peak chamber pressure.

[wogpotter]

What is the publish date of the one vs. the other?

Both are the same date. the 21 Gr min is from the Hodgdon data, the 19.9 maximum from the Hornady data of the same year.

Case volume & seating depth:
Good thought I dug out both manuals to see what those were for the 2 sources.
Hornady says 1.590 (these were fired in a Colt Python, with an 8"Bbl length.) & doesn't give pressure directly, JUST m/v. they list a range of 17.4Gr min for 1250FPS thru 1500FPS with a MAX OF 19.9 gr.

Hodgdon gives the same COAL of 1.590, but they are using a 10" barrel, so maybe the longer time in barrel & different pressure resulting from that is the major player? They list both M/V & Pressure at 1881 FPS for 38,400CUP min with 21.0 Gr to 1966FPS with 41,400CUP max using 22.0 Gr of powder.

[Brian Pfleuger]

Barrel length is not a factor in peak pressure.
Are they using the same exact bullet, brass and primer?
Different brass has different powder capacity. Different bullets, even of the same weight, can be different length which can effect the remaining capacity inside the case.
Besides that, different lots of the same powder can vary by 10%.

[wogpotter]

Probably not these are the factory test loads from the manufacturers.

I'm expecting variability for just the things you list, it's not the variability that has me going Duh! it's the amount of the variability from below min to beyond max.

[Brian Pfleuger]

Yeah, but you're looking at powders with a max of around 22gr, right?

That means a 10% variance in powder lots could result in something like a theoretical 2.2gr variance, ALL ELSE EQUAL. So, if the one company gets the "hottest" batch and comes up with a max of 19.8gr and another company gets the "coldest" batch, they get 22gr.
The 22gr max company would suggest a starting load right around the max load of the other company.

That's with "all else equal", which it isn't. Personally, I'm a little surprised that small capacity handgun data doesn't vary MORE than it does. QuickLoad is a real eye opener. Variances of .005 can effect pressure DRASTICALLY.

[Clark]

SAAMI registered pressures are only loosely related to reality.

Load book recipes are only loosely related to SAAMI registered pressures.

The whole load book system is good enough for beginners.

If you are good at handloading, you can make up all of your own loads.

The 1905 8mm did 2900 fps 150 gr, and that was the limit of the brass.
The cartridge brass alloy has not changed.
So that rifle is up against a reality, and so it cannot change.

The 380 brass is capable of double the original velocity. There is no reality anchor for the handgun.

[Unclenick]

Wogpotter,

Pretty amazing spans for a powder they tell you never to reduce more than 3%.

In this instance, there is something funny about the data all over. Hodgdon lists 21.0-22.0 grains. Lyman #49 also lists 21.0-22.0 grains for a generic 125 grain HP, but #46 lists 18.5-21.5 grains for the same bullet. QuickLOAD shows those higher loads at about 112% and running pressures in the 43,800 psi (in the larger expanded volume of the case I describe measuring a few paragraphs down). That's a lot more than SAAMI's 35,000 psi MAP spec, but not far from the CIP's 43,511 psi MAP for the cartridge. But QuickLOAD isn't great with straight wall pistol cartridges so that's shaky. Also, I've noticed its powder data for H110 has changed over time, becoming a little slower.

The old Winchester load manual data I have uses 18.5 grains of 296/H110 as a one-and-only load for a 125 grain JHP seated to the same 1.590" COL, and show it getting 1800 fps from an 8 3/8" barrel at 32,500 cup. Another disparity.

One thing that bugs me about the Hodgdon data, aside from being heavier than old data, is the compression of the powder. I see no "c" for "compressed" in their listed data, almost as if they'd used a bigger case, though there's is Winchester case, same as mine. Has this powder's bulk density changed over time? Did Winchester change their brass since I bought mine? I don't know, so I did a little measuring on the density issue.

The lengths I have are 0.547" for the FP XTP, and 0.558" for the HP XTP. That's from QuickLOAD, and its bullet lengths are not always precise, so if you know otherwise, that might improve the calculations. I measured some H110 I have and got the same VMD number listed in Lee's VMD table. 0.0656 cc's/grain. It also matches the bulk density in QuickLOAD's database of 0.988 grams/cc, so it's not like there is a lot of disagreement about this in the world. I even tapped the case for awhile to try to increase the density, but got no measurable change. I did not try a proper vibrating table, however.

I resized a Winchester case I have without decapping it. The case is a range foundling of undetermined age. It might be new, but it might also be over 20 years old. I never bothered segregating .357 cases by lot. It started out 1.277" long with 26.7 grains of water capacity, but came out of the sizing die at 1.285" long and with a capacity of 26.1 grains of water. (If someone wants to measure one they know is new, please do, as it might help explain the discrepancies. Just weigh one that still has the fired primer in and fill it level with the mouth with water (no meniscus) and weigh it again and report the weight difference.)

With the HP XTP seated to 1.590 COL (if my XTP length number is right) that Winchester case of mine will be 100% filled at 19.5 grains of H110/296. Any more will be compressed in it, despite what Hodgdon and the more recent Lyman book show (the Lyman #49 reports 22 grains is compressed, but 21 is not, and #46 says even 21.5 is not). That could be a difference in bullet lengths from what I have, but my bottom line is if I had a revolver with an 8" barrel that was getting 1800 fps out of 19.5 grains, I'd stop.

[wogpotter]

Ok, at least I'm not totally nutz then, I was beginning to wonder for a minute there!

I went with gut feel & tried some 18.5 Gr loads & visually they seem to be about 85~95% capacity with the bullet seated to the cannelure to crimp. The load was pretty sooty so I'm guessing low(ish) pressure. I went up to 19.0 Gr & the dirt cleaned up quite a lot so I loaded a small batch to chronograph. Any more volume & I think you're going to HAVE to compress a ball powder, something I'm just not comfortable with.

On the bright side extraction is now slick & smooth, & that was the goal when this project started out, a load that would drive a Hornady 125 Gr XTP HP fast enough & have easy extraction/ejection.

I have some once-fired Federal nickle-plated brass & some Starline that is unfired. Give me a couple of days & I'll do a water volume test & post the results. I'll also do a case full of H-110 & Unique for weight & volume as well.

[brickeyee]

I went with gut feel & tried some 18.5 Gr loads & visually they seem to be about 85~95% capacity with the bullet seated to the cannelure to crimp. The load was pretty sooty so I'm guessing low(ish) pressure. I went up to 19.0 Gr & the dirt cleaned up quite a lot so I loaded a small batch to chronograph. Any more volume & I think you're going to HAVE to compress a ball powder, something I'm just not comfortable with.

How much the powder fills the case is not a good indicator of anything.

There is no special issue with compressing ball powders.

[dunerjeff]

One other thing about published max is that a manufacturer may not have actually tested till failure or even close. They may just go to a certain point then stop. They won't publish any higher because they didn't personaly PROOF it, while another company may have started higher or proofed closer to max so they publish higher.

[Brian Pfleuger]

Originally Posted by dunerjeff

One other thing about published max is that a manufacturer may not have actually tested till failure or even close. They may just go to a certain point then stop. They won't publish any higher because they didn't personaly PROOF it, while another company may have started higher or proofed closer to max so they publish higher.

The manufacturers do not "test till failure". They use pressure testing equipment to test up to SAAMI max pressures. They do sometimes stop short of max pressure, often for no clear reason, but they do not, at least as a matter of routine methods for producing load data, test until failure.

[wogpotter]

Maybe something we forget is that manufacturers are selling a product, so they'll try to present that product in the best light possible. Perhaps because of this manufacturers have something in addition to pressure issues to consider? Things like "clean burning" powder may influence the vendor far more than pressure issues exclusively perhaps.

The point being that as shooters we look at performance exclusively, vendors have other things to think about as well.

[wogpotter]

How much the powder fills the case is not a good indicator of anything.

There is no special issue with compressing ball powders.

These two statements concern me, the second more than the first.

Case volume, & filling it consistently & accurately have been one of the standards of hand-loading for ever. Some manufacturers even list the % of load density as part of the load data.

As for compressing ball powder........ I still have both eyes, most of my face & all 12 fingers currently. I have no desire to change that situation.

[wogpotter]

Good point about case volume, & about stopping when you have the velocity wanted. I wanted a minimum of 1350, loaded for that & found dirty burn, so I ramped up 0.5 Gr to get a cleaner burn @ 19.0 so I stopped there. If it ever quits raining I'll chrono the loads, but by calculation & other loads tested that should be about 1400 so I'm happy right there as the extra 0.5 Gr cleaned up a lot.

Here's the brass results I got, weights are the average of 5 cases. The R-P, FED, & "AP" is once-fired, not resized. The Starline is unfired. "B" is the weight of the empty case, "W" is the water contained at 100% capacity.

BRAND................B.........W
R-P (brass)........80.7.....24.4
FED (nickle).......74.6.....25.3
AP (nickle)........76.7.....25.9
StLn (brass).......70.9.....25.4