Questions about 38 special and +P

[baz]

I'm starting to reload some 38 special, and have some questions about published loads I'm seeing. Besides a wealth of information I've gleaned from manufacturers' materials on the 'net, I have a little booklet dedicated to .38 special. I've been shooting commercial +P, and all my brass is +P. I'll be using, to start, Accurate No. 2 and 125 gr HP.

Combining sources, I'm coming up with the following:

normal: 4.8 gr (start), velocity 871; 5.3 gr (max), velocity 990

+P: 5.2 gr (start), velocity 907; 5.4 gr (max), velocity 1033

+P: 5.0 gr (start), velocity 899; 5.5 gr (max), velocity 1022

Now suppose I load 5.2 gr. From the first line of data, I would interpolate a velocity of ~965. From the third, I would interpolate a velocity of ~949. And from the middle one, it lists 907 for 5.2 gr.

Why would the "normal" load produce a greater velocity than either of the +P loads?

Or is this just indicative of normal "measurement error" in data like this? I would expect 5.2 gr to produce the same result regardless of whether it is characterized as normal or +P, if all other things are equal.

In comparing the "normal" load to factory loads from Winchester and Remington, it looks like a pretty hot load, approaching +P on the max end.

I'm planning to start at 5.0 gr, and then move to 5.2 gr. I doubt that I'll go any higher than that. I'm not looking to live on the edge. I'm just wanting a functional, practical reload that approximates the factory +P that I shoot (usually Remington UMC +P 125 gr).

 

[Jim Watson]

Charge weight - velocity is not a straight line relationship. Linear interpolation is very approximate. (Linear extrapolation can be dangerous.)

Combining sources is extremely approximate, components and equipment vary considerably from source to source.

 

[cdrt]

You have a lot of variables, that will affect velocity; i.e. OAL, bullet type and manufacturer, primers, firearm you're using vs. what the manual used as a benchmark, etc.
My recommendation is, if you're looking at maxing out a load, use the components exactly from whatever manual you're referencing and work up to it slowly. You can't "guesstimate" what velocity you might get by averaging loads as the previous post explains, especially if you change one of the variables listed above.

 

[Sistema1927]

Why do you want to load to +P velocities?

If you need this for self-defense, recognize that folks like Buffalo Bore, Cor-Bon, Double Tap, etc. can produce a better round using powders that you can only dream of. (Low flash, controlled burn, etc.)

Start at the bottom of the chart. You will discover the best accuracy long before you approach +P velocities or pressures.

 

[ilbob]

Start from a known safe load for a specific set of components (case, bullet, primer, powder).

Don't exceed the maximum powder charge in the book for the combination of components your have.

Look for signs of high pressure.

I am not 100% sure but I do not think there is any difference in the case itself between 38 special and 38 special+p. its just a marking so people who pick up a cartridge will know it is an above normal pressure load.

 

[CZ57]

baz: I haven't used #2 for .38 Special +P loads, so I don't know what flash will look like. Try to get some range time at night and do some testing. I suspect that flash with #2 will be fairly low. AA#5 is one of the lowest flash powders you'll come across, as is #7, but data is harder to find for #7 in .38 Sp. +P loads. If these loads are for self defense, the biggest question is how comfortable are you using them in the state you live in? The only opinion I can offer is that it isn't an issue in Texas. That's a whole different issue, but should it come up I can tell you that there is not 1 single case recorded in the US where someone involved in a self defense shooting has been prosecuted because they used a handload. If someone suggests that there is, ask them to provide the evidence.

In the data you posted, lines one and three are from Accurate and I find their data pretty reliable. The velocities came from a S&W K38 with an 8 3/8" barrel, so if you're using a shorter barrel, your velocities are going to run a bit lower. The disagreement you're getting is only 16 FPS and I think you can dismiss it. As Jim Watson pointed out, interpolation is only a linear approximation and no velocity was given by Accurate for the 5.2 grain charge. In the case of the second line of data, I would suspect that it came from a shorter test barrel. If it's from Lyman, it was probably a vented 4" test barrel.


As for the smaller manufacturers, they aren't using anything you can't buy yourself and in the case of one of them, I have never seen anything to suggest that they pressure test their ammo and in the case of 10mm ammo they sell, they should be testing. Especially if the owner is using 800-X in his factory loads like the data he's given to handloaders that is overpressure.

Here's a link you might want to look at for loading .38 and .38 Sp. +P: http://www.gunsandammomag.com/reloads/0605/

You'll notice that Bob Forker went to slower burning powders for pretty high velocity with 125 gr. JHPs in the lower data for +P. Ramshot Enforcer and AA#9. I haven't had a chance to try Enforcer yet, but #9 has surprisingly low flash in the high pressure loads I've used it in, but I can't say what it will look like in a cartridge that's 18,500 PSI or lower. I suspect it will be low enough but I haven't used it in .38 Sp. +P. He used WAP/Ramshot Silhouette for the 135 gr. NOSLER and I wish he had used it for 125s. It has very low flash. Winchester and Ramshot have never published revolover load data and I don't know anyone else that has. I've worked up a defense load, but it was in a .357 Magnum case for .357 snubs. Another powder that will get you higher velocity with minimum flash is V-V 3N37. Ramshot True Blue is another: http://www.ramshot.com/powders/ but they do not currently show +P data, but reproducing the UMC +P ballistics can be done with True Blue without a need for +P pressure.

 

[baz]

Thanks for the replies...

Okay, Jim Watson, on interpolation vs. extrapolation. It strikes me as immenently sensible that interpolation would be approximate, and extrapolation dangerous.

cdrt, I'm not trying to max out a load. I am trying to reasonably approximate what I shoot for practice and carry.

On which, Sistema1927, why I want to load +P... I shoot Remington UMC 125 gr +P JHP for practice, and carry 125 gr +P Speer Gold dots. I shoot the Speer Gold dots for practice occasionally, but mostly use the UMC for pratice because of the lower cost. I'm trying to reload something comparable to the UMC for practice. I can imagine using these rounds for self defense only in a SHFT situation where I've already used up all my Speer Gold Dots. I'm not trying to handload a super duper hot self defense load. I'm trying to load a practice round that would be close to the performance, recoil, etc of my carry load.

CZ57, I'm in a state bordering yours to the east (AR), and while we're not quite as enlighted (yet) as TX on some matters relating to self defense and concealed carry, like I told Sistema1927, I'm not working up an extra hot SD load here. I'm primarily trying to come up with something reasonably comparable to the UMC and Speer GDHP. I'm comfortable carrying the Speer, and don't think it would cause me any problems if I had to use it. Thanks for pointing out the difference in barrel length. The middle line of loads in the OP does indeed indicate the test weapon (S&W M10) had a 4" barrel. I've made a note to look into True Blue.

Again, thanks, all.

 

[CZ57]

baz: Having lived and worked there several years, as well as Mom and my late Dad being born and raised there. I know a little about "Noah looked from the Ark and saw!" Very common sense on gun issues.

It doesn't matter if you'll carry the loads or not! Your decision to practice with something that will have very close performance to your factory carry load is definitely logical and gets overlooked a whole bunch!