38 Special +P Loads in 'Old' Wheelguns

[Geronimo45]

Looking at a Model 10-5 lately - which, to the best of my knowledge, is only rated for .38 Special of the regular pressure variety. The +P loadings came around at a later time, methinks, than the time when the 10-5 was made.
This Model 10 version seems to be one of the more 'modern' Model 10s - as far as age is concerned. So the metallurgy, one would think, might be better.

My question: is it safe to fire +P loads in such a revolver? Don't want to ruin the gun by any means - it's just that +P loadings seem to be much more common than standard pressure loads.

 

[ArchAngelCD]

**Disclaimer**
This is my opinion, what you do with it is your choice and responsibility!

From everything I have read and heard about current ammo, the current .38 +P ammo is no heavier than top end .38 Sp ammo of years ago. I have some old reloading books and for the most part current handgun ammo reloading charts have dropped their loads 20% to 25% from those of the 50's and 60's. I'm betting the Lawyers have something to do with that.

Current factory .38+P ammo is just top end .38 Sp ammo, and not even the very top. It's all marketing so they can charge you more for the +P stuff.

 

[Jim March]

On the other hand, the new Buffalo Bore standard pressure 38s are as potent as most 38+Ps. Newfangled powder carefully tuned. It's expensive but it eliminates the worries and gives you loads that will hurt.

 

[ArchAngelCD]

How I understand it, it's not the pressure that makes it a +P, it's the velocity and energy. There are powders which will generate more velocity but less pressure than others. If we only had a way to figure out at home what powders to mix to achieve higher velocities with less pressure we would never need to buy factory ammo again!! LOL

Just to add to what I said above, I got the old books out and here's what I found.

Lyman 45th Edition (1970)
.38 Special 146 gr bullet
Unique 4.5 gr low, 5.5 gr high
2400 9.5 gr low, 11.0 gr high

Speer 13th Edition (2006)
.38 Special +P 146 gr bullet
Unique 4.8 gr low, 5.1 gr high
2400 8.3 gr low, 9.0 gr high

You will notice that the current lard data for the high end .38 +P isn't as high as the standard .38 Special from 35 years ago. It is very noticeable with the numbers for 2400 powder. Current maximum load data for the .38 +P is lower than the minimum load for a standard .38 Special from 1970.

 

[Jim March]

>>How I understand it, it's not the pressure that makes it a +P, it's the velocity and energy.<<

Nope. "+P" is a measure of pressure, not bullet energy. It's possible to build up stupid handloads that do a massive peak pressure spike high enough to near blow a gun up but *short* enough in duration that actual bullet energy is crap.

It's peak pressure blows guns. Which is why the conversion from black powder to smokeless was so painful in the early days of smokeless. It took a bit of time for people to realize that the shorter, peakier power stroke from smokeless was able to damage guns despite bullet performance being identical.

This in turn is how people like Tim Sundles at Buffbore are changing the rules. Newer powder.

As to old load data: DO NOT trust it. First, powder formulas change over time. Second, the way we measure pressure is now much more accurate than in the '70s.

 

[ArchAngelCD]

Thank you for the clarification Jim...

 

[RON in PA]

The model 10-5 is rated for +P ammo as is any Smith steel K frame marked with a model number. Check it out in the faq section of the S&W home page.

People keep saying that the 38 special has been downloaded over the years basing their opinions on lower velocities listed in reloading manuals and lower velocities listed by major manufacturers.

While I have no doubt that some of this "suppossed" dumbing down may be due to "lawyeritis" I am of the opinion that there has been less reduction than people think. First of all sometime in the 1960s-1970s the way testing was done was made more honest, solid 6" and longer test barrels were eliminated and replaced by 4" vented barrels. This led to a reduction of approximately 100 fps reportd for the same ammo. Pressure testing has moved from lead and copper units of pressure to lbs/sq in. measured with piezo-electric sensors. As far as loading manuals, many were based on shooting in revolvers without knowledge of actual pressures.

The question that I have asked before and I suspect no one has an answer for is whether currently available standard velocity 158 grain ammo is any different than the original 38 special blackpowder load of 1899 as far as pressure and velocity.

Does anyone doubt that 38 special +P ammo is hotter than standard. Of course we are talking about only a few thousand pounds per square inch. I have no doubt that most concern about +P is unwarrented unless you are shooting a gun made prior to approx. 1930.

What we need is in-house info from the ammo manufacturers and I suspect that such info not going to become available due to corporate security and because the data going back to the early days of 38 production probably has been destroyed. Does anyone know people who work for an ammo company ballistic lab?

 

[bakert]

Ron in PA has it right. If it has a model number, +Ps are okay. My old 10-5 has had a lot +P ammo throught it and although worn on the outside is still good and tight. I would take it easy on older guns myself. Also, some of the reloads quoted to me by certain individuals for .38 Sp who claim factory +P loads are weak, scare me enough to keep way away from them when they're shooting.

 

[SaxonPig]

Any S&W revolver made after about 1930 will shoot all the +P ammo you care to buy for it.

Here's a pic of my 1942 Military & Police with some of the many hundreds of +P and +P+ ammo I have shot through it.

AACD is correct in that when the 10-5 was made (1960s-70s) the standard ammo was about what +P is today. Your gun was designed to shoot a 158 grain bullet at 900 FPS and factory +P is a lighter 125 slug at barely higher velocity (925) so it's actually lower pressure than the older standard load.

I'm not sure why some people say model marked guns are OK with +P since +P wasn't invented until about 25 years after they started the model marking. Obviously S&W didn't intend for the model marking to be a benchmark for ammo that wouldn't be invented for another 25 years! Plus, there is absolutely no one iota of mechanical or metallurgical difference between the last unmarked S&W and first model marked one. All they did was start stamping the model numbers so how does this make the latter suitable for +P and the former not so?

This issue simply will not rest, will it?

 

[gvf]

Not in Colts

Having a model # does not guarantee in a Colt that +p is OK. I have '62 Colt Detective II and +p is not recommended by Colt. (Though it is for post '72 Detectives). Practically though, I read some do carry +p while shooting regular .38 at 158 at range with my version. I've also read - as mentoned in other posts here - that today's +p is not significantly different than yesteryear's high standard. Lastly, I've also seen some docs that maintain that, at least in a snub, the issue is moot, since the extra powder in a +p does not have the opportunity to ignite before the bullet leaves the very short 2" barrell.

One thing I do know: Colt will tell you what their recommendation is for a particular version of a particular gun, so maybe the other manufacturers will also.

I use common sense: my Detctive is THE most accurate snub - ever made. It is easily shootable, easy to place shots, and I'd rather go with those "powers" and not jeapordize the gun by shooting a diet of +P.
I don't feel underpowered. I have 6 shots, as opposed to J frame's 5, so it's fine.

 

[Old Fuff]

Prior to 1919 (or serial number 316,648) .38 Military & Police model cylinders were not heat treated. On March 7, 1942 they discontinued the practice of heat treating/hardening the end of the yoke barrel on which the cylinder revolves. During the late 1960's and 70's the demand for revolvers resulted in some slippage in quality control, in particular what would have been considered excessive cylinder end shake in earlier times.

Cylinder end-shake is a condition that once stated, tends to increase rapidly, especially if high-end loads are used on a regular basis.

Plus-P loads were created for law enforcement agencies that wanted more power in their .38 Special revolvers, but could not go to .357 Magnums – usually because of politically inspired restrictions. It was generally understood that extensive use of some Plus-P loads could cause accelerated wear on some .38 revolvers, but the agencies involved didn't care, as they simply planed to turn in their old guns and buy new ones if the ammunition they were using took an excessive toll.

In steel, K-frame revolvers the steady use of certain brands of Plus-P ammunition may accelerate cylinder end shake, especially if some back and forth cylinder movement was present when the gun left the factory. In pre-1919 revolvers there is a remote chance that one might expand the chamber(s). All K-frame revolvers in sound mechanical condition should be safe to fire with .38 Special ammunition loaded to 16,000 PSI or lower, and in particular the so-called “cowboy” ammunition loaded with 158 grain lead bullets loaded to a muzzle velocity between 700 to 800 FPS out of a 6” barrel should be fine. These of course are not barnburners in any sense of the word.

Pre-World War Two Military & Police revolvers are usually superb and highly accurate shooters that hit precisely to the point of aim when they are used with the ammunition they were intended to use. The Old Fuff is determined that the ones he has will be passed on to future generations in much the same or better condition then they were when he got them. If and when more cartridge power is required it is easy too obtain revolvers that are rated for Plus-P ammunition, or even better, obtain one of the approximate same size chambered in .357 Magnum. Others can make their own choices.