What's new

Using up some powder for fire forming.

Roc Doc

2A SNBI
Joined
May 20, 2020
Member Number
580
Messages
2,775
Loc
Way out West.
I built an AR in 6mm ARC, and while I have a good amount of Hornady brass and a load for it, the brass is getting really hard to find and it doesn't seem to last very long anyway, so I picked up 1k Lapua 6.5 Grendel brass which I've converted most of it to ARC, but I want to fire form it as the last step before working up a load. I have 1lb of CFE223 which I can find load data for, but I also have most of a lb of Norma URP that I'd like to use up, and a full lb of RL17 that I have no use for. These will be using the 105g Hornady (Mfg PN #2458), which I think Hornady is closing out, so they were super cheap and good enough for this use, (I'll be using Berger 105 Hybrids for the final load).

RL17 has recipes for .243, but of course the ARC case is much smaller.

I found a load for URP for the Norma 6xC, (Min 38.6 - Max 40.7), but same deal it's a much bigger case. I'd prefer to use the URP as it's open and have no use for it, where I could probably sell the RL17 pretty easily.

 
This from Hornady's load data for 105g ARC. I'm using LeverRevolution for the final loads.


POWDER 2200 2300 2400 2450 2500 2550
H4895 22.7 gr. 23.9 gr. 25.1 gr. TAC 23.6 gr. 24.8 gr. 26.1 gr.
VARGET 24.2 gr. 25.3 gr. 26.4 gr. 27.0 gr.
Power Pro Varmint 24.3 gr. 25.3 gr. 26.4 gr. 26.9 gr. 27.4 gr.
Accurate 2520 24.8 gr. 25.8 gr. 26.9 gr. 27.3 gr. 27.9 gr. 28.4 gr.
Alliant RL-15 24.8 gr. 25.9 gr. 27.0 gr. 27.6 gr.
LEVERevolution 25.0 gr. 26.3 gr. 27.6 gr. 28.2 gr. 28.9 gr. 29.5 gr.
CFE 223 25.5 gr. 26.6 gr. 27.6 gr. 28.1 gr. 28.6 gr.
Power Pro 2000 MR 26.0 gr. 27.1 gr. 28.1 gr. 28.6 gr. 29.1 gr.
 
I've had good results transferring over from other load data, you make up a conversion factor from the other caliber to yours, on a common powder. Like if both have load data for both calibers in H335 or whatever, you figure out the ratio between them, then apply that to the 'popular caliber' load data of the odd powder you've got to get 'odd caliber odd powder' data

then drop a few-ten grains for your starting load
you're just looking to fireform the shoulder out, right? No need to get hasty in working up the pressure, especially if you're just dumping bullets into a bullet trap in your garage.

bucket of sand or whatever
 
I've had good results transferring over from other load data, you make up a conversion factor from the other caliber to yours, on a common powder. Like if both have load data for both calibers in H335 or whatever, you figure out the ratio between them, then apply that to the 'popular caliber' load data of the odd powder you've got to get 'odd caliber odd powder' data

then drop a few-ten grains for your starting load
you're just looking to fireform the shoulder out, right? No need to get hasty in working up the pressure, especially if you're just dumping bullets into a bullet trap in your garage.

bucket of sand or whatever
Yeah, they'll be well under max psi. This is in an ARC that already has a bolt that's marginal for the job. I'll just load up my Hornady brass with my load I developed for matches, and I'll use these low power loads for practice. Dudes on the hide are just saying run it, don't need to worry about making a seperate fire forming load, which I may do since I'm using SAC bushings and a 21st Century mandrel they should be damn close to what my chamber wants.
 
I sat down and started looking at all the necked down grendals. The 6 AR, 6 Rat, and 6 ARC are basically all the same with tiny variations. The ARC is the smallest of the three. Hornady was making dies for the 6 Rat at the time they developed the ARC. My guess is they shortened it a little to protect themselves from someone firing their wildcat ammo in the new SAMMI spec chamber.

There is also the 6AR Improved and the 6 Fat Rat which are Ackley shouldered if the above.

For fire forming information there is a ton of information on those rounds above. Its interesting because most are claiming close to fire formed accuracy from new rounds. My non gas ackley is that way but worked up a load for forming and the ackley round.

I wanted to mention too that Hornady seems to be very conservative on their load data. I have found the sweet spot above their max on most of my round with no signs of pressure. Using Hogdon data Im usually a little under their max. Also Hogden seems to be trying hard not to allow cross referencing between Accurate/Ramshot and their other powders. Not sure why so I'm hoarding old data.

I know a few guys that have developed loads on powder like 486 mentioned but there is more leeway on a bolt gun. If you have an idea on how the powders pressure spike it's safer.

Here are some pages I found. There was some info on CFE as well.



 
Top Back Refresh