Charge weight vs. Barrel Length


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JSmith
March 8, 2013, 10:27 AM
My wife's carry gun is an S&W 36-10 with a 1.8" barrel. That short of a barrel does not allow very much room (or time) for complete powder combustion and gas expansion before the bullet leaves it. Does it makes sense to reduce powder charges somewhat from full-power .38SPL? I'm using W231 with 125gr plated bullets; Hodgdon specifies a range of 4.3 - 4.9 gr for that powder/bullet combination. I wonder if it really makes sense to load near the top of that range for such a short barrel. Does anyone else reduce loads for very short-barreled pistols?

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rcmodel
March 8, 2013, 10:33 AM
No.

For a SD load, you want all the velocity you can get out of any barrel length.
So you want to load near or at the top of the charge range.
If she can handle the recoil?

On the other hand, if you are loading plated bullets for your wifes SD load?

You need to re-access your bullet choice.
The one you are using is a poor one, unless it is a plated Speer Gold-Dot hollow point bullet.

rc

JSmith
March 8, 2013, 10:38 AM
If she can handle the recoil?

Oh, she's fine with it. And the plated bullets are purely for practice rounds. For SD, a different bullet is definitely required.

Thanks, RC. Great advice, as always.

Sam1911
March 8, 2013, 10:42 AM
No. Max velocity is achieved through a max load of a slow powder, regardless of what barrel you're shooting it through.

Now, if there's a level of recoil energy that's her personal comfort maximum, you may find that several powders will reach that energy level and you might choose to pick a load that gives the least flash or some perceived milder recoil signature at the target velocity. So in a sense you can tune a load specifically for HER with that gun, but it won't be the most top-end effective load you could put through the gun.

JSmith
March 8, 2013, 10:53 AM
Max velocity is achieved through a max load of a slow powder, regardless of what barrel you're shooting it through.

That is interesting. Looking at a burn-rate chart, 231 appears to be a medium-fast powder ("fast" and "slow" being relative terms, of course all of it burns in milliseconds.) When we shoot factory .38SPL of any brand in that revolver, we get a lot of soot and flakes of unburned powder on our hands and wrists. That leads me to think that quite a bit of energy is being wasted and we need a more efficient load, perhaps acheivable with a faster-burning powder.

Sam1911
March 8, 2013, 11:00 AM
There very well may be a lot of energy "wasted," (that would be true of any load) but complete burning of powder (or debris you see left over from that) are affected by things like density of the charge in the case.

A light load of certain powders will produce a lot more of a sooty mess (and sometimes erratic velocities) than a full, more densely-packed, charge of the same powder.

And a lot of factory .38Spc. is so lightly loaded these days that IDPA had to change their standards for allowable power factor as factory ammo couldn't cut it any more!

All in all, though, a full case of slow powder (not to exceed published maximums, of course) will deliver the most velocity.

rcmodel
March 8, 2013, 11:06 AM
we get a lot of soot and flakes of unburned powder on our hands and wristsThat is due to:
1. The incredibly low pressure factory .30 Spl is loaded too today.
Powder won't burn clean at low pressure.

2. The manufactures using the cheapest powder they can buy with 'clean burning' being low on the totem pole.

I load 4.5 Unique with a 158 grain LSWC for my 2" S&W's.
And get no unburned powder all over me.

Unique is slower then W231.

With fast to medium burn speed powders, all of it burns inside the cylinder chamber.

With certain types of powder, the stuff you see on your hands is powder 'skeletons' or ash from the burned powder.

rc

JSmith
March 8, 2013, 11:59 AM
The manufactures using the cheapest powder they can buy with 'clean burning' being low on the totem pole.

So Mr. Remington isn't selling me the best ammo, but the most cost-effective ammo? I'm shocked. Shocked, I tell you!

Thanks much for the informative discussion, Sam and RC. I learn something new every time I visit this forum.

Sam1911
March 8, 2013, 12:02 PM
It is shocking, isn't it? :D

gamestalker
March 8, 2013, 03:09 PM
I really like the Speer Gold Dots for short barrels. I've done some testing with those and they perform very well, even at nominal velocities.

GS

Hondo 60
March 8, 2013, 03:18 PM
And the plated bullets are purely for practice rounds. For SD, a different bullet is definitely required.

Maybe it's just me, but I want to practice with the same stuff I use for SD.
If it acts this way for practice & another way for SD,
isn't that defeating the purpose of practice?

JSmith
March 8, 2013, 03:19 PM
It is shocking, isn't it?

It tests my faith in my fellow man, it does.

Sam1911
March 8, 2013, 04:02 PM
Maybe it's just me, but I want to practice with the same stuff I use for SD.
If it acts this way for practice & another way for SD,
isn't that defeating the purpose of practice?
Meh. That's the old saw they used to say about .357s for carry and .38s for practice. But really, if it prints pretty close to the same place and recoils pretty much the same way, that's plenty good enough. That you practice is the key. Whether the ammo (and certainly the bullet itself!) is exactly identical to your carry load machs nict.

(And really...if you can afford to practice with your carry ammo? You aren't practicing NEARLY enough!)

JSmith
March 8, 2013, 07:24 PM
I want to practice with the same stuff I use for SD.

Too expensive. Berry's plated flatpoints are (or were) pretty cheap. I'm basicallly making target rounds that feel like the real thing when you shoot 'em.

Steve C
March 9, 2013, 03:46 AM
Hodgdon specifies a range of 4.3 - 4.9 gr for that powder/bullet combination.

When you reduce powder charge you reduce the velocity regardless of barrel length. Hodgdon's load data for W231 with 125gr is standard pressure only and the real velocity is rather mild with those loads, more in line with light "cowboy" loads even at 4.9grs. While it may make for a fine practice ammo at a modest velocity, probably around 700 to 750 fps, note their velocity data is taken form a 7.7" test barrel so you can deduct about 300 fps for a 2" barrel. These are not a duplicate of factory defensive ammo or a hand load equivalent to practice self defense shooting.

Usually when you load light bullets with light loads and shoot from
fixed sighted gun you find you POI gets skewed. If you are shooting at very close range, 7 to 10 yds it probably will not make a lot of difference since you are talking only inches and fractions of inches at those ranges.

With 125gr JHP's you need around 5.5grs to 5.9grs of W231 to get a decent +P velocity velocity of 950 to 1,000 fps from a 4" barrel. Subtract 100 to 150 fps for a snub.

A load needs enough powder to develop proper pressure and a full power load with a well crimped bullet providing enough bullet pull to allow it to develop will go a long way to making for a more efficient use of that powder in producing velocity at the muzzle.

http://i1171.photobucket.com/albums/r552/s_o_cikkubs/Hodgdon38spl.jpg

JSmith
March 9, 2013, 11:11 AM
If you are shooting at very close range, 7 to 10 yds it probably will not make a lot of difference ...

We do shoot that revolver at close ranges (5-10 yds.) 10 yards is pretty much the maximum range for reliable accuracy with a less-than-2" barrel.

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