7383 reduced load techniques?

[BeeMan]

Surplus 7383 has already given impressive accuracy in full case 243 loads with the Sierra 70 HPBT. My challenge now is to find a cast load for 30-06 with this powder. Boolit is the RCBS 180 FP in air cooled wheel weights, sized to the throat at .310, with Felix lube. Seating to the crimp groove just sets the nose into the lands.

First attempts were 30 to 34 grains in 1 gr increments, 5 shots each. Average velocity ranged from 1720 to 1946 fps, about what I was looking for. No leading and no unburned powder in the bore. Lube star at the muzzle seems about right. Groups were about 1 to 1.5 inches horizontally at 100 yards, scoped and from the bench. Unfortunately, vertical dispersion stretched out to 3 to 3.5 inches. I took this as a sign of ignition issues, since ES was as much as 63 fps for 5 shots.

Next step was to take up airspace and reduce potential light off variation. The series was repeated using ground wheat bran filler. Just enough was added to fill the powder to bullet base space without compression, since others have mentioned 7383 spikes quickly on overloading. About 1.2 to 1.4 cc of filler was required. Groups were more rounded but significantly larger at 2.5 to 4 inches. Surprisingly, velocity dropped and ES increased, compared to the same loads without filler. There was also a trace of residue in the bore after each shot, presumably residual filler.

Am I chasing the right idea that something needs to help ignition? The Bf definitely absorbs energy and hurts uniformity. Maybe it is too much on top of the powder column, filling the nearly 1/2 inch space above 30 to 34 grains of 7383. Regardless of why, it doesn't work. I've successfully used dacron with 820 surplus, but am not sure about using it to fill the smaller space above a rifle powder. I'm using Winchester LR primers, and have Remington 9 1/2 available.

The small horizontal spread on the unfilled loads seem to indicate this wants to work. I'm stubborn enough to pursue making 7383 work instead of buying one of the slow surplus ball numbers. The 7383 won't allow double charges like 820 and is inexpensive. Besides, I've got more 7383 than I will burn in the 243, given the cost of jacketed. I'm scratching my head where to go next.

Thanks for listening, ideas anyone?

BeeMan

[felix]

Try 39 grains, no filler. Assuming 4064 speed in this situation, 39 grains makes 2400 fps in the 308 case with the Sierra target 168 grainer. Shoot one shot and see if recoil is acceptable before loading up 5. Do you have a 2 foot long (oak/hickory) log in the basement? Shoot into it lengthwise. ... felix

[Maven]

BeeMan, It would help to know the CB or its weight, but be forewarned: 7383 isn't the ideal reduced load powder. Be that as it may, there are several things you can try and one which you should cease doing immediately. Cereal and/or poly fillers, e.g., Grex, aren't to be used unless loading density is at least 80% else pressures rise dramatically. This is especially likely given the already "peaky" character of 7383. Since dacron fillers have a devoted following, e.g., Bruce B. et al, research his name for posts on this subject. I'd try a small tuft of it a la Bruce B. over 30-34gr. 7383 (standard primers) and also 39gr. as per Felix's suggestion. Btw, I've found 7383 to have almost the same burning rate as IMR 4350 in my .243Win. with 85-87gr. SP's (If anything, it was a bit slower than 4350) and a trifle faster than 4350 in my .30-06 with 125gr. SP's. Btw, with slower milsurp powders such as IMR 5010, I've obtained more uniform results using Grex (.3cc - 1.0cc) than Bf, even though the latter is less expensive.

[BeeMan]

Felix, Maven,

Thanks for the responses. Recoil and pressure signs are both quite low at 34. The large percentage of cereal filler was a concern, so thanks for pointing out the 80% guideline. I'll try beyond 34 without filler, watching velocity per grain increase. The goal is a moderate load for young shooters moving up from 22 rimfire, so 2400 fps isn't needed. Will also try dacron to see if it reduces deviation at lesser speeds. My RCBS .30 180 FP mold works out 194 grains lubed and checked.

BeeMan

[felix]

BeeMan, fill a 30-30 case up to just touch the seated boolit without compression. Velocity should be the same, but with a substantially lower ES. That's the prediction, anyway. However, it is still possible to have a wild ES because of inconsistant pressure to burn that stuff. The pressure produced by this powder starts to come into its own at around 40 grains in the 30-32 bores. ... felix

[ammohead]

BeeMan,

Only use enough dacron to keep the powder put. Tuft is a good description. Just enough that if you shook the round the powder would not compress the dacron to the point of creating space, but not so much as to compress the dacron while seating. Real scientific huh?

It should be able to do its job no more compressed than a wad of dacron sitting on your bench, but the act of getting it into the case will compress it some. Just don't pack it in more than you need to keep the powder put.

Now that should be clear as mud!

ammohead

[sundog]

FWIW. On a whim I tried 40 gr in a .308 with a 168 BTHP. It left unburned powder in the barrel. Stuff needs some pressure to burn. sundog

[swheeler]

Beeman: 200 gr Lee, 37.0 7383 + poly, OEM Std LR primer=1812 fps. It shoots 3/4 in @ 50 yds. Extreme spreads still hibgh at 40 fps for 10.

[Jeffreytooker]

Beeman: 200 gr Lee, 37.0 7383 + poly, OEM Std LR primer=1812 fps. It shoots 3/4 in @ 50 yds. Extreme spreads still hibgh at 40 fps for 10.

What is the cartridge for the load in the above quote?

Jeffrey (newbie) (CB20YR)

[swheeler]

"My challenge now is to find a cast load for 30-06 with this powder."
30-06!

[45 2.1]

I've been useing it in the 7.5 Swiss. It will give ball duplication with a full case and 168 gr. Sierra match bullet. I've found to get low extreme spreads, i've had to drop tube the charge into the case. When I started doing this, the accuracy was excellent and the extremme spread was very low.