Surplus powder loading data?

[Rifleman]

I am looking for load data for 30-378Wby & 338 Lapua using surplus powders; IMR 7383; IMR 5010 & WC 860?

I would think these slow powders would be good in the large capacity cases with heavy bullets.

[Jim]

I have no experience with 5010. However, I have burned many pounds of 860 and 7383.

860 is fairly safe to play with. It doesn't start cooperating until you get the case full with a bit of compression. This is the powder I use for my "recreational loads". It can still be had in 8 lb. jugs cheaper than any other milsurp.

7383, on the other hand, is NOT a powder to mess with before you do a LOT of reading on this. It is very quirky and can spike with little or no notice. The larger the case volume (like the ones you're using!), the more dangerous it is.

Generally, the rule of thumb for 7383 is first, ACCURATELY determine the case volume WITH THE BULLET LOADED. Start with 90% of that and work up SLOWLY, one grain at a time. You will get some notice of pressure signs, but it is critical that you know how to read those signs and watch for them. This stuff will go from burning like saw dust to nitroglycerin in the blink of an eye.

When I decide to start with a new caliber/bullet combination using 7383, I sacrifice one cartridge case for determining case volume. I drill out the primer pocket with a 1/4" bit, seat the bullet of choice to the depth I intend to use and then fill the case from the back with 7383 up to the inside of the web. That is your loaded volume. Pour the powder back out through the drilled out hole, weigh it AND RECORD IT. Calculate 90% of that and that is your starting point.

Coupla' notes:

You're not likely to find the sweet spot until you get close to case volume. You will find unburnt powder laying in the barrel. PROCEED SLOWLY!

This powder is considered a very poor choice for cast boolits as it does not work at all at reduced charges. It works best under jacketed bullets at top speed.

DO NOT, under ANY CIRCUMSTANCES, assume that this powder is like any commercial powder. It is not. If you are prone to experimenting without research or think you can compare it to any powder you find in the manuals, I strongly suggest you stay away from it.

I have been burning this stuff for over ten years and I am still learning about it's characteristics. During my first year of experimenting with 7383, it cost me a rifle. Fortunately and thank God, I suffered no injuries. This powder can be made to work. However, it requires hours of testing to find out how. I cannot stress how important it is to respect this powder.

[sundog]

Be vary wary of IMR 7383. It is a triple base powder and likely different than most everything else out there. It is a very good powder, but heed Jim's admonition. I love the stuff in '06 with a 168 BTHP, but it only get 2395 fps, consistently, with very low ES and SD. Fine by me. The accuracy is phenominal!

I've used a little 860 in the 7 mag with 175 RN, and it seems to do okay, not that really sharp quiver your liver recoil, either.

[sargenv]

Triple base? I know of Nitro-cellulose and Nitro Glycerin... what is the third component?

[Jack Stanley]

Nitroguanodyne if I remember right

Jack

[Shiloh]

Nitroguanodyne if I remember right

Jack

I believe you are correct.

Isn't this stuff artillery powder, and is it worth risking a rifle or death to get it working correctly?? There are a lot more viable, safer alternatives.
Sounds to me like using this powder is akin to the Japanese people eating Fugu
Carefully prepared deadly poisonous pufferfish.

Can't beat the price though

Shiloh

[Jim]

IMR 7383 was designed for the .50 spotter/tracer round. It is classified as a slow burning tubular stick powder and is coated with a flash suppresant.

I have sucessfully used it in calibers from .223 up to .45-70. I have spoken with handloaders that have used it in large capacity calibers such as .338 RUM, .458 Win Mag. and 458 Lott.

Approached carefully, with experience in handloading unknown powders, it can be made to work. The danger comes in when it is loaded without thought toward high pressure spiking. And spike it most certainly will.

[Shiloh]

How big are the grains??

I saw some powder once that looked like lead from a fat carpenters type pencil.
Is that what this stuff looks like??

Shiloh

[Rifleman]

The grains of my 7383 measures 0.0375X.086

There is also WC870 & WC 872, I don't have either on hand, at the moment, but they could also be considered. I was aware that 7383 can be quirky, I recall seeing a few posts about it on this site a couple of years ago, it may have been a post by Jim.
I haven't messed with it much, I put a few rounds together for the 8X56R with some cast and paper patched boolits. The results were low vel. and a lot of powder left in barrel kinda left it alone after that. Just looking for something economical to feed the cases with big appetites for fun shooting and keep things safe.

[Maven]

How big are the grains?? I saw some powder once that looked like lead from a fat carpenters type pencil. Is that what this stuff looks like??

Shiloh

Shiloh, Actually it looks very much like IMR 4350. Keep in mind there are/were several lots of 7383 on the market, each with a slightly different burning rate. I tested it in my .30-06 following Buckshot & Felix's advice (separately) to treat it as IMR 4064 or H 380, and with the added caveat that it was "peaky," I tried it and was pleased with the result. What I discovered, i.e., for my lot no., is that (a) it's not especially CB friendly; (b) it was slower than 4064/380; (c) it performed very well with CB's in SOME cartridges, e.g., the 7.5 x 55mm Swiss and the 8 x 57mm Mau. if ~3/4 of the case was filled. Sundog found the flash deterrent coating was difficult to remove from the bore after firing, but I really had no such problem. I later began using 7383 with 80gr. - 87gr. jacketed bullets in my .243Win. and was thrilled with the results. However, as Buckshot and Jim warned, a [very] small increase in charge wt. can produce very high and dangerous pressure.

Btw, IMR 5010 is a bit chunkier (and slower), so much so that it doesn't flow at all well through many powder measures.

[Jim]

Lindstrum and Wiljen wrote a bit about 7383 and Wiljen published it on CASTPICS.

Wiljen also published some data that he and I worked up.

UNDERSTAND THIS CLEARLY: The data that is published is simple the results of our testing. In now way is it to be construed as hard and fast data.

[wiljen]

7383 can be really useful and when the price was $18 a jug it made a good bit of sense to do so. It does best in near case capacity loads with little air space and little compression. Start with 4064 data and 85% or so case capacity and work up only until you get a clean burn. Once you hit the point where it doesnt leave crapola all the way down the bore, quit. If you pass the point at which it burns clean you are headed toward a pressure excursion in short order.

[Jim]

7383 can be really useful and when the price was $18 a jug it made a good bit of sense to do so. It does best in near case capacity loads with little air space and little compression. Start with 4064 data and 85% or so case capacity and work up only until you get a clean burn. Once you hit the point where it doesnt leave crapola all the way down the bore, quit. If you pass the point at which it burns clean you are headed toward a pressure excursion in short order.

Yes Sir. And to that, I would like to add that one should examine the fired primers AFTER EVERY SHOT. When the primers start to flatten, you are just before going PAST the 'red zone'!

[runfiverun]

i'll add one more thing to this.
you don't want any initial pressure to get things started.
i tried the above and had an oversized cast boolit all but crammed into the throat,it definatly caused some high pressure,excess recoil, and pressure signs on the brass.
the bolt lift was noticeably heavier too.
i wish i would have had the chrono out that day, but one round told me all i needed to know.
the boolit printed about 6"s higher than my normal loads,no leading either.
there was a little poof of grey smoke at the muzzle.

[shadygrady]

imr-7383 is a single base propellant not triple

[Maven]

imr-7383 is a single base propellant not triple

Perhaps you'd care to tell us how you discovered this fact? The IMR 7383 the rest of us unenlightened folk use appears to be a triple base, fairly high energy propellant. When fired, it has a definite ammoniacal smaell unlike any single oreven double base powder I've ever used.

[shadygrady]

imr-7383 mfg# 10534781-3 = single base tubular propellant

[Maven]

I'm going to check the label on my jug of it to see what it says.

[Jim]

Grady, I did a search on that number and got nothin'. Where'd you find that?

[Maven]

sg, I just checked my label and it doesn't say anything but this, "IMR 7383, Military Surplus Gunpowder." No lot number, no description of the powder's composition, burning rate, or shape of the kernals; nothing.