6mm Br.

[Doc Highwall]

I have both a Remington 40X rifle and a Encore pistol in 6mm Br. that I would like to get some input for cast bullet loads. The moulds I have are the SAECO#243 85 grain TCGC., N.O.E. 245-75gr. FN, and the NOE 245-80gr. MX3-245-EX which are about the heaviest bullets that will work in a 1-14" twist.

The newest Lyman book list loads for the 6mm PPC but nothing for the 6mm Br.
I was wondering about using powders like Unique, 2400, 4749, 5744.

Not trying to get high velocity just great accuracy.

[quilbilly]

I have a 6mm Rem that likes 16 gr of 4759 with a Lyman/Ideal 85 gr boolit. You could start with 14 gr and work up.

[madsenshooter]

Use the MX3-245-EX. Someone needs to report on it, and it's taking me longer to get back on track after my move than I thought it would. I do have some cast and sized, but I don't even know where my 6x45 brass is at the moment. I modified the nose on mine a bit, didn't like that big flatpoint. Two after pics, one before.

[GabbyM]

I have a 6mm Rem that likes 16 gr of 4759 with a Lyman/Ideal 85 gr boolit. You could start with 14 gr and work up.

Would that be the Lyman #245496 Loverine style?

Have that mold and have wondered if it would shoot in a 1:14 twist barrel.
Mine shoots pretty good from my 243 Ackley Imp. 26 inch heavy sporter barrel on a Ruger M77 VT. ER Shaw 1:10" twist replacement. Original barrel was a 1:12 twist but I’d burned it out before starting to cast for 6mm.

My best load so far in my 1:10 twist 243 AI is a simple 11.0 grains of unique. Lyman 84 gain #245496 Loverine style BHN #15 lead of air cooled 2:6 foundry alloy. Gave .875” average at 100 yards ten shot groups. Five groups to empty a fifty round box. Takes about eighteen shots to get the barrel hot. Book says that’s an 1,855 fps load but I’ve not tested with my chronograph. My Saeco 87 grain #243 gives similar results to the Lyman Loverin.
I need harder alloy and softer lube to get those groups down closer to half inch.

The big 243 AI case is flakey with the slower rifle powders. I can get single digit E.S over a Chrony but they still vertical string. 1.0 to .90 inch at 100 yards but that opens way up out at 200. Suppose it’s a variable pressure curve thing. But it’s a dark mystery in fact. Unique is cheep and the ten twist barrel will not run fast anyways. Not tried 2400 yet but that my just be the ticket.

[felix]

"I can get single digit E.S over a Chrony but they still vertical string. 1.0 to .90 inch at 100 yards but that opens way up out at 200. Suppose it’s a variable pressure curve thing. But it’s a dark mystery in fact." ...GabbyM

No, it's no mystery, Gabby! The muzzle is vibrating up and down and the boolit is leaving the barrel at the fastest up or down speed. Change the ignition speed by changing the powder speed (example: same powder, different lot) and/or primer. ... felix

[Doc Highwall]

I have some of the SAECO #243 cast with a Hardball alloy and lubed with Lar's 2700 lube, I think I will give them a try first.

I will have to cast some up with the NOE 245-80gr. MX3-245-EX next to try that.

[GabbyM]

Felix that’s about right for this gun. Barrel vibration and whip. Barrel is 26” long and only .625” at the muzzle. Plus it’s only screwed into a Ruger M77 action.

Regardless though with the 1:10” twist RL7 powder has to narrow of a window for me to mess with. Half grain less powder and not enough pressure to burn good. Half grain more and it’s over speed for the twist rate. 18.0 grains RL7 in the 243 Ackley Improved with Saeco 87gr #243 gives me 2,040 fps. With the 84gr Lyman #245496 Loverin velocity average is 2033 fps. The Unique load at under 1,900 fps shoots better. 2400 powder may be the ticket but I’ve not tried it yet.

Was digging around today lookng for some 30 caliber boolits for my new M70 in 30-06. Found a pint cottage cheese container full of Saeco #243 cast from 2:6 alloy. I think they are already oven heat treated. Seams I can cast them up faster than I can shoot them up.

[Doc Highwall]

Bump.

[Bullshop]

I have no experiance with a 6mm BR but was enjoying a 22 BR for a time. My rifle had a 1/9"twist and shot boolits very well. I no longer have the rifle but might still have load data for it.
Often times it works out that a case will use well the same powders and nearly the same charges when necked up or down a caliber. I often extrapolate loads for one by using the other. I try to use data with bullets in the same weight range for each. The bullets of the same weight but weight range.
For instance a 100gn 6mm bullet is on the heavy end for caliber so if loading for a 22 cal on the same case I would look at bullets on the heavy end like 60 to 70gn to use similer powder types and charges. This systam often prooves true for calibers that are close.
For some cases like the 30/06 with so many caliber variations as caliber increases the burn rate must also get progresively faster so that if you compair a 6mm/06 to a 375/06 the 375 will use quite a bit faster powder but the charge weight will be very close to if not exactly the same.