IMR 7383, A little work..........

[Coastie]

Finally a nice day and a little time to try a couple of loads of IMR 7383. The lot Number is RAD78L 47985. The rifle is a Ruger 77 Mark II 30-06 and the brass is once fired Remington brass and CCI standard large rifle primers. Shooting over a Beta Master Chrony on a 30 yard home range.

IMR 7383 under 150 grain Lee C309-150-F (WW) (NO gas check used)

37 grains: average 2054 fps (some powder in barrel)
40 grains: " 2081 fps ( no powder " " )
43 grains: " 2250 fps (clean barrel )

IMR 7383 under 200 grain Lee C309-200-1R (WW) (No gas check used)

45 grains: average 2258 fps (clean barrel) *(NOT a compressed load)

Out of the Store Bought Remington Box: 150 grain Core-Lokt SP
??? grains of ??? 3000 sps (Just for something different to compare.)

An interesting powder - more smoke than I expected, but I think that it has possiblilties . No real pattern for accuracy - the Store Bought and the 40 grains were where they were supposed to be, but I'm rusty and that makes a difference. This was only a mini-test and not a scientific work up, but I thought maybe someone might be interested. Have a great day.
LK

[singleshotbuff]

Coastie,

Thanks for the info, I am working a lot with 7383 at this time and I'll put your data into my book. I have been working with 7383 in 7.5X55mm, 7.62x54r and 8X57mm, only with jWord bullets so far. I am finding 7383 to be a useful powder, especially for the price.

You may want to check out my thread on temp sensitivity, just as a heads up.

SSB

[Coastie]

Singleshotbuff,

Thanks for the "Heads Up". As the weather inproves I plan to do some more work with the IMR 7383 powder and cast boolits. First with the 30-06 then the following, but not necessarily in any order: .303 British, 7.62X54R, and the 8X57mm ( others too - but later). I would be interested in anything that you are working on.
Thanks again,

Coastie

[Jim]

I've been burning 7383 for about 5 years. If you're willing to think outside the box, you'll find that it's a much more versatile powder than most will tell you. One characteristic about this powder that needs to be kept in mind is that it is pressure sensitive. There seems to be a point where the chamber pressure will spike like crazy. I've found that point to be where you pass 100% case volume, in other words, a compressed charge. On the other hand, if you work up slowly and watchfully, you'll discover some unusual traits about this weird powder.

Explore CAUTIOUSLY!!

[Coastie]

Jim,
I did some experimenting with IMR-7383 earlier (no firing) before I did the "mini-test" above. I loaded the IMR-7383 in Remington brass and seated a jacked bullet to see what would happen with various amounts of compressed charges. I loaded the rounds with various weighed charges, seated the bullet to the proper depth and then pulled the bullet and examined the powder. A general statement of what I found was that: the powder grains of my lot of powder began to break down under the pressure of compressed loads. The greater the pressure in the compressed load the greater the number of brokern grains. Some of the grains in the more compressed loads were broken and some pieces actually "crushed" enough to make "powder dust". I'm sure that these broken grains change the burn rate of the powder which may account for the "spike" in pressure that has been written about. I have only fired this powder in a 30-06, but I will not compress any loads when using it. With the 30-06 case 45 grains was close to the base of the bullets I tested with. Check the first box on these thread for firing information.
I don't think that I would reduce this powder more than about 75% of a "full" case load ( "full": the base of the bullet - not compressed). The 40 grain load under a 150 gr cast gave me POA and a clean barrel in my rifle at 30 yards. So lots of work to do, but that is what makes it interesting.