Use +P Brass for +P Loads.

[OldLincoln]

I've been reading on other reloading forums of folks wanting recipes for +P loads. Not a lot said about the brass for them, but I do recall that Starline sells both standard and +P brass. The +P has a thicker wall where it matters and should hold up better to high pressure loads, especially in unsupported chambers. I really wonder is any of those KaBooms we've read about used +P specific cases.

[MW surveyor]

Makes sense to me.
Although I have been known to load some +P in regular 38 special cases.
Very hardly ever load anything +P for the semi-autos

[Ikeo74]

I don't think it makes any difference or little difference which case you use for +P loads, however when reloaders will have problems is when they try to load +P+ loads and if you are pushing the pressures that high you better have the best brass you can get, which would definately be the +P brass. IMO. I will never load +P+ loads at my bench. Max powder manufactures loads from their tables, will do everything I need to do.

[Bongo Boy]

I don't know if it makes much difference, either, although I'd expect that if you going to repeatedly handload the same brass to +P pressures then it will help prevent problems, especially with chamber designs that don't quite manage to do what a chamber is supposed to do. :)

As for loading up to higher pressures, the fact is almost no handloader has any idea what pressure he's loading to if he's outside the published range of loads--and even then it's somewhat sketchy. That's because some load manuals publish pressures in CUP, some are in psi, and SAMMI specs are psi.

Now, some manufacturer's load data is super conservative--take Hodgdon's as the best example. They publish maximum loads for 45ACP at around the 16,000 CUP mark; compare to Accurate's load data for the same cartridge, maxing out closer to 20,000-21,000 psi. A couple of things that we don't know that makes 'guessing' a challenge: how close is CUP to psi for the cartridge in question, and how is the pressure changing with charge weight in the upper range of the data?

At least one gun publication I've seen has had handloading articles wherein the author simply fits a straight line to charge weight vs velocity, and in the data looks pretty good. But I think there's good reason to expect the actual behavior is NOT linear, and so that's not the best model.

In going beyond published maximums, I feel you should look at all the data you DO have to get some idea of a) how far is the published max away from +P, and b) how does it appear to be changing with charge weight? If the entire min-to-max published range is just 0.3 gr or 0.5 gr, this should tell you something about being on thin ice. If pressure isn't changing a lot in the published range and the published max is 25% below SAMMI max (not +P), then you might do some chrono work and fit an exponential to the data and guess as to where 0.2 or 0.4gr over max charge would put you in terms of pressure.

I can fill a spreadsheet with my very best models from as many sources as possible and the test fire, chrono and look at spent casings for 'signs of pressure'. I've done this and still do it. But I'm still guessing. The distance between SAMMI max and SAMMI +P is, I believe, the little space god provides the foolish for guessing poorly or for too large an opinion of himself. Intentionally "loading +P" rounds without knowing the pressure (from a no-kidding measurement) is definitely peein' in the wind.

[saltydog452]

I don't know for sure either. If I was real curious, I'd try to vertically section std and +P cases and measure. Failing that, maybe the, supposedly, thicker case would weigh a tad more.

Federal markets std, and +P+ rounds. You'd think that the +P+ stuff would have thicker, thus heavier, cases. I didn't section a case but was curious enough to compare weight. My balance beam scale wasn't able to determine weight difference from one or the other.

A more sophistated scale might tell a different tale.

salty

[5pins]

Starline states that their +P brass is the same as their standard brass, the only difference is the head stamp.

[jocko]

I never even give it any thought of +P brass being any different than standard brass casings.

[Charlie98]

I'm just speculating but I would think +P brass would be the same...

Think about it... outside dimensions can't change so if +P brass is 'heavier' in any other way, the dimensions inside would change. Less space with an equivalent load = higher pressure, less space with a higher/hotter '+P' load = serious overpressure.

[wyntrout]

If the brass cases are thicker, I would suspect reduced case volume which has bearing on the charge. As the volume is decreased the pressure goes up. All of this has to be taken into consideration, as does compressed charges or not. When you're working near maximum charges, decreasing the volume of the case is like compressing a charge and pressures increase dramatically. All of this must be taken into consideration. That's why some loads are specific to case, primer, and powder. Variations from the "recipe" can give disastrous results.

Wynn:)

[muggsy]

I don't think it makes any difference or little difference which case you use for +P loads, however when reloaders will have problems is when they try to load +P+ loads and if you are pushing the pressures that high you better have the best brass you can get, which would definately be the +P brass. IMO. I will never load +P+ loads at my bench. Max powder manufactures loads from their tables, will do everything I need to do.

I never load anywhere near max loads for range fodder and I never use anything but the best factory loads for defensive rounds. I find that to be a very sound program.