IMR 7383, what's it compare to?

[georgeld]

I just got some new surplus 7383 I've never heard of these numbers and can't find it listed in any books.

The Data sheet with it says a full 223 case only makes about 2600fps.
That's too darned slow for this cartridge.

It looks like 4831 to me. But, does anyone have a comparison between these two, or else loading charts for other than .223 and 50BMG with this powder??

Thank you,

[Linstrum]

Hi, georgeld, here is a copy of a post I made back in 2006, although when others post something here take a good look at what they have to say, too, a lot of folks have good useable data. Your best bet is to use the search function for this particular forum because there has already been a lot of threads and space devoted to 7383. To answer your question, it really doesn't resemble any powsder except itself but some generalizations can be made that range from IMR4064 to IMR4350. It is my favorite powder BUT I ALSO RESPECT IT!

~:/+\:~:/+\:~:/+\:~:/+\:~:/+\:~:/+\:~:/+\:~:/+\:~:/+\:

July 4, 2006. The main thing to remember about IMR7383 is that it is a HIGH ENERGY TRIPLE BASE PROPELLANT that goes by different rules of loading density than the normal single and double base propellants that we are normally used to. The third ingredient is nitroguanidine, which supplies both the increased energy content and confers its flashless characteristics. It also makes it very "peaky" when approaching its upper load limits, giving absolutely no warning like the single and double base propellants do that a high pressure excursion is about to happen. This cranky nature is a very unfortunate characteristic of this otherwise quite useful powder. The reason why it is flashless is because it was designed specifically as the propellant for the .50 cal spotter rifle used to aim the 106 mm recoilless rifle. For the purpose of aiming a cannon by "spotting" it is a good idea for the spotting rifle to be flashless to keep the enemy from seeing the muzzle flash and returning fire before the main 106mm cannon has a chance to be fired, which is not flashless. As soon as the 106mm cannon is fired, the crew leaves immediately. I have fired my .30-06 700 ADL at night and instead of getting blinded with a large bright muzzle flash like IMR4895 makes, all I saw was a faint dull red streak emanating from the muzzle. There are at least three lots of IMR7383 that I know of and their characteristic are all different, so what goes for one lot will not work for another and it is a good idea to start off conservatively using IMR4064 loading data at first, then once you get the feel of it you can creep the load up using IMR4350 data BUT STOP AS SOON AS THE POWDER BURNS CLEAN because you are already into the danger zone even though you are not getting any signs that you are there. This lack of approaching high pressure is what makes the stuff so cranky. I use IMR4064 data myself and have had good results. Also, it is not the best cast boolit powder around, although I get reasonable results in my French 36 MAS with the 180-grain .309 cal Lee. Since the French cartridge is practically identical to the 7.65 Argentine/Belgian Mauser, it should work just as well in that rifle/cartridge combination.

I am not trying to discourage using IMR7383 by any means, just be careful. I like the stuff so much that it is my main powder now, I have bought over 100 pounds of it since it became available.

Maven has what I think is really good info for the stuff and I also go by his recommendations since the caliber cartridge it is used in also has a lot to do with its behavior.

[Buckshot]

............I've used it in cases from the 35 Rem to the 6.5 Swede. It did well in the Swede. Was decently accurate in the 35 Rem but posted large ES's. For the price a person can afford to fool around with it if they have a few different cartidges they reload for. Chances are, in at least one t will shine. As Linstrum said, do your workup with a chronograph and pay close attention to pressure signs and indications.

.............Buckshot

[georgeld]

Great, thank you much, appreciate it.

I'm out of 4831 now and still need to load some 7mmags and 300Win's.

Would one of you fellows be kind enough to give me a starting load for these in
175 gr, and 200gr in the 300win?

Would save me a bundle of work since I have only two lbs of it. By the time I work up a load, will be low on powder again.

Who has it and for what price have you found? In Dec or Jan it looks like I can spend $3-500 on supplies again.

Thanks much, IF you don't want to post the loads here, send 'em to my e/mail.

[Ricochet]

Don't have any loads for you in 7mm Rem Mag or .300 Winchester Mag, but if I were doing it I'd follow Linstrum's advice to work up the load as if the stuff was in the range of 4064 or 4320.

I found it in 150 grain .30-06 and 55 or 60 grain .22-250 loads to behave as a slow burning powder much like 4350, in that a full capacity charge weighed about the same and gave about the same velocity as a minimum charge of 4350. I thought it couldn't be overloaded in such medium sized cartridges and got complacent. Works out that way for me in 8mm Mauser with the bullets I've loaded, even with the big old 8mm Maximum bullet that weighs something like 253 grains as I've cast it. (And will only allow a 2.8cc charge in the case.) But I learned since that where larger charges can be accommodated in the case, where the sectional density of the bullet goes up significantly, the powder is crushed by compression, or other factors that raise pressure such as the bullet seated well into the lands come into play, that the pressure rises very suddenly and it definitely CAN be overloaded. I can also attest that 3.7cc of it in a 7.5x55 Swiss under a 200 grain cast bullet crimped and seated against the lands is TOO HOT! The powder was only used in one application, the .50 caliber spotter rifle for the 106mm recoilless rifle, the cartridge for which is a shortened case based on the old .50 BMG. It looks like a 7.62x39 next to a .308 in comparison. 7383 replaced 4831 in that cartridge, giving the same velocity and pressure with charge weights about like you'd expect if the powder burned like 4350 there, but the maximum working pressure of that cartridge was only 38000 PSI. The powder's optimized for this medium pressure range, and its burning rate apparently goes up steeply as the pressure rises above it. You're on your own developing magnum loads for it. I've used it for mild loads with a 200 grain cast bullet at 2200 FPS in the .300 Weatherby; that's 4.3cc of it with a magnum primer. I can't recall exactly how many grains that equates to, I measure volumetrically generally.

7383 is not a normal IMR powder. There is a substance in it that generates ammonia gas on firing, and that substance is in the powder's coating as the ammonia is in the exhaust gas blown out the muzzle and not present in the residual gas in the bore or case normally. Only time I've smelled it left in the gun is when I tried it in the .45-70 and it barely burned the coating off the grains. The substance most likely to be used in a propellant that burns with an ammonia smell is nitroguanidine. It was most likely used in the coating on this stuff to suppress muzzle flash in the spotter rifle. It also makes lots of sooty carbon when it burns, and is made with carbon black all the way through the powder grains unlike other IMR powders which are translucent inside, likely to facilitate steady burning at lower pressures by enhancing absorption of radiant heat. But I've never been able to find any official data on the powder's composition. It's a mystery powder.

It's not "the best powder" in terms of maximum velocity for anything I have. It doesn't directly compare to any other powder, and its burning rate seems to be variable. But it is a very useful powder if its quirks are taken into account and it's loaded carefully. It can give very good accuracy in the right loads, and it is very inexpensive.

There is an old series of messages on the Accurate Reloading board from a fellow who blew up a rifle in, I believe, a 6.5mmx.300 Weatherby Magnum wildcat chambering using 7383. Be careful and reasonable. You're a ballistic experimenter when you use ANY surplus powder. You have to work the same way as the load developers in the books do, with the handicap that you probably don't have pressure measuring equipment. Don't take anyone's word on the Internet, including mine, as gospel for what you can shoot safely. It's up to you.

[Ricochet]

That curious ammonia smell from IMR 7383, BTW, gets me inquiries about what kind of powder I'm burning nearly every time I shoot at the range with others present. "It's old military surplus powder" is sufficient explanation. They all look at me like I'm a little batty, and if anyone's shooting at a bench near me they usually move away.

[Jim]

I usually identify it as a "milsurp" powder and let it go at that.

[georgeld]

Thank you, I've printed that info from the link out and will study it once I get back from hunting and have time with no demands to meet.

[wiljen]

I'm out of 4831 now and still need to load some 7mmags and 300Win's.

Would one of you fellows be kind enough to give me a starting load for these in
175 gr, and 200gr in the 300win?

If you are getting ready to stock up on surplus powders, I'd buy some 860 or 872 if available. Both are slower than 7383 and probably a bit better suited to the large magnum cases.

80gr of 860 behind a 175gr in the 7mm Rem gives about 2950 fps.
100gr of 860 behind a 200gr bullet in the 300 Weatherby yields right at 3000 fps

Although both of these can be bested by other powders, I haven't found any of those powders at <$7 a lbs.

I like 7383 in midsized bottleneck cases. I like 860/872 in the large magnum cases. And I hope for the day wc852 returns.

[Ricochet]

I'd think we've pretty much seen the last of WC852.

I got some real complaints from the black rifle shooters down the line last week about the stench of my 7383 muzzle exhaust. Funny thing, though, when I got to shoot one of the black rifles with a suppressor on it, the breech blowback the suppressor induced stung my eyes and smelled of ammonia just like the 7383 I was burning in my Persian Mauser. They were shooting some military surplus .223 ammo.

[Jim]

Makes ya' wonder, don't it, Ric?

[Ricochet]

Yep.

But I can't just say "Yep." and click "Submit Reply." Board says that's too short to post.

[Ricochet]

80gr of 860 behind a 175gr in the 7mm Rem gives about 2950 fps.
100gr of 860 behind a 200gr bullet in the 300 Weatherby yields right at 3000 fps

I've found that 80 gr. of WC860 under a 175 gr. Hornady spire point gives 2960 FPS average in near freezing weather in my 26" M70, and gives stubborn bolt opening in hot summer weather. A little on the hot side. After discovering the hot weather pressure signs, I've backed down a bit.

100 grains of WC860 in the .300 Weatherby under the 200 grain Speer at just under 3000 FPS in my 24" Vanguard shows no pressure signs, but the powder has to be shaken to fit in my fired, neck sized Remington cases, compresses hard, and has bulged some of my cases just below the shoulder enough to keep the bolt from closing without a little post-loading squeeze in a full length sizing die with the expander ball removed. (Not running the die all the way down, just until the cartridge will chamber easily.) 97 grains is about the max that fits comfortably. That's about what I get with two 3.3cc Lee dippers struck off level with a knife, too, but this Ball powder works well with my RCBS Uniflow measure. The loading manuals usually stop with H870 and AA8700 at 93-95 grains, due to the compression and probably because they use new, full length sized cases with a little less capacity. I don't think enough can be crammed in to cause an overpressure situation with any bullet up to the 220 grainers, at least with the standard Weatherby freebore. YMMV, though.

That missing list of WC Ball powders I had said that the relative burning rates of WC860, WC870 and WC872 are 82, 81 and 80, respectively. Close enough to be basically interchangeable; likely the lot-to-lot variations exceed the differences in the specified burning rates. They're also the coolest burning of the Ball powders, with flame temperatures of 2700-2750K. (From memory.) WC870 was spherical, and the other two are flattened spheroids rolled between calendars to a particular maximum thickness to make the burning rate more uniform, and use a bit more deterrent because of the higher surface to volume ratio of flattened spheroids vs. spheres. I think the WC870 had 5% deterrent, WC860 7%, and WC872 7.5% by weight. (Deterrent is dibutyl phthalate.) 10% nitroglycerin for all of them, as for nearly all of the Ball rifle powders.

[georgeld]

Wow, what a can of worms I opened up asking that simple, short question! love it, thanks guys.

Soon as I get my head out of it and get the inletting, finishing done. Am building a .358 U/M on a 1917 Enfield action that had been filed on, barrel shortened etc. So it wasn't in collecting condition. Just what I like to start some project with. This will make my third '17 sporter. Nice '06, 300 Win and this .358 U/m.

Building it mostly to test my theories about reducing recoil. 26" Douglas, .870" at muzzle. Should be around 11# when finished. Just about right for a kicker imo. Do believe some mercury will be in this one.

After going thru shoulder surgery a few yrs ago am not as tough as I used to be. After going to 200gr in the .300win, and burning 30 two weeks ago from the bench am thinking about putting some mercury in this one too.

Anyone have experience with them? They work as well as claimed? I've never tried one yet, do have one on hand for the 358 though.

Would one of these 800# you mentioned work better all around for the big guns than 4350, 4831, or 870??

Thanks again. Skunked on antelope, truck troubles again opening day. They were run out by the time I got back and roundup time had started too.

[Ricochet]

Would one of these 800# you mentioned work better all around for the big guns than 4350, 4831, or 870??

They're equivalent to H870, which is relabeled surplus WC870.

I've seen no sign of the hard calcium carbonate fouling that H870's known for with the WC860 I've been using, though. I think it was made after the lime fouling problems were noted in M16s in 1964-5 and they reduced the chalk content of the Ball powders. WC870 is older.

I've had my right shoulder reconstructed, but I batter it with the big Magnums.

[james snodgrass]

I,ve been shooting 7383 in a 30/30 contender 14" with 32 grs and a 155 lee gc and get 1600fps. It is a compressed load , It does seem to leave some unburned kernels but not bad. I,ve also shot it in 308 with a 200gr lee gc 36grs for 1600 fps from a 14"barrel. WC 860 I,ve shot in a 458 Lott a case full with any 500 gr cast bullet gets about 1750 fps from a 24" barrel, I,ve also shot it in a 270wsm with a 140 win failsfe I trickled through a very long drop tube and managed to get in 83 grs for 3340 fps without pressure signs that is about a120 fps faster than factory loads.

[felix]

That 7383 powder compares to none that we typically use. It is a triple base powder, and therefore very rare amongst handloaders. ... felix

[Jim]

George,
It's becoming my experience that nobody's on the fence with regard to 7383. Dedicated users swear by it and the non-informed masses swear at it. A few years back, one guy started a campaign to "educate" everyone to the "dangers" of this "unpredictable" propellant.
I've used it, with varying success, in .223, .243, .270, .308, .30-06, .303, 8MM and .45-70. I've been told it can't/couldn't be done, but I even worked up a load with it for my .45 Colt Vaquero and my .45 Colt Henry repro!
I've got a few7 # jugs of it and use it extensively and will continue to do so until I run out and/or can't get anymore.

That's my story an' I'm stickin' to it.

[Ricochet]

That guy who was "educating" us about the "dangers" of "unpredictable" 7383 is the one who blew up a custom 6.5x300 Weatherby wildcat. No info posted as to what sort of load he tried with it. I wouldn't have thought it a promising powder for such an overbore cartridge anyway, other than for reduced loads as I use it for in the .300 Weatherby.

[nelsonted1]

I've used it extensively in all my military calibers. Works very well with jacketed bullets, not so good with cast. The world beater is a max load in my NEF 38-55 and the lee 375 plain base bullet. I'd used 8 grains of Red Dot and Unique at about 950 fps and was very happy until I tried 7383. 7383 ran it up to 1500 or so. I was just amazed at how well it shot!

TED