WW748 ball in 6MM BR

[Gary C]

I have a few Lbs. of 748 ball I bought for loading my M1A.
I recently saw a few posts about using this powder in 6BR but mostly it
was used in 14 twist barrels with lighter bullets.
I'm wondering if anyone has used it in an 8 twist with 105-108 weight bullets and if so
where to start with charges.
Any results of this testing will also be interesting.
Even if I only use it to fireform it will save the other more difficult to find powders.

Thanks, G

 

[Kurz]

Funny you should ask...

I've been working with some short barrel, short action hunting rifles (20", 1:8" twist rate) but using the Berger 95 gr. Hunting VLDs for the powder testing portion. One session used Win. 748 with very decent results. But I switched to some of my Berger 105 VLD hunter bullets just to see the results using 748.

All testing was done using an OAL of 2.441 based on my SAAMI chambers, 0.020" off the rifling. The fill was lower than I usually consider but seems to be viable once you arrive at the upper velocity range. My notes state that I started at 29 gr. of 748 seated as above achieving 2600+ using a 20" barrel. The final high end accuracy load achieved 2800 fps.

As always, chant the reloader's mantra:

Start low and work up slowly watching for signs of pressure.

Enjoy!

 

[Old Navy]

That is pretty good for a 20" barrel. What kind of accuracy did you you get?

 

[NZ_Fclass]

I see no reason why it won't work - I have some non-canister (bulk 748 ish ,St Mark's) powder coming to try. There's already load data on it for 308 and 222-250 which looks really close and it's available. All I need is a few 6mm pills, otherwise it will be just a loud bang...

 

[Dgd6mm]

I read in your other thread on your 6br that you have IMR4895. That's what I shoot in my 6br and it's a tad under .5 moa at 300 yards. This is a PRS rifle off of a Harris bipod. I have not tried to refine the load too shoot better, it's good enough for steel. H4895 shoots just as good but the IMR4895 yields a little more speed. I've never thought about Winchester 748, maybe I'll run it on Quickload.

 

[Gary C]

I just looked in the Lyman manual and they list 748 in 6mmPPC so
I can get a starting point from that data.

 

[Kurz]

That is pretty good for a 20" barrel. What kind of accuracy did you you get?

Usually I like to work with slightly longer barrels even with hunting rifles. This group of rifles utilized M7 size actions combined with the 20" barrels in order to minimize the weight and length for smaller frame shooters. The shorter barrel can also accommodate a suppressor if the shooter is so inclined. Most were chambered in the 6x47 Lapua cartridge with the last 2 being chambered on request for the 6mmBR cartridge. The experiment using Win. 748 powder was purely a whim on my part since I have some on hand and wanted to demonstrate a broader range powders to offer the owners. Besides, it meters well making it easier to reload.

The beginning loads (2,600+) were not exactly stellar combinations even at the whiffle ball velocity. They were fairly average for general shooting and hunting, 3/4" to 1" approximately. The groups, although not what I was testing for specifically, as I increased the charge, improved, up to and including the final series of 2,750 fps. according to my Labradars. The last groups held 1/2" consistently over 5-5shot groups. These were not 3-shot groups but 5-shot groups from short, slightly lighter contours to save weight. The case fill was not a full case but seemed to react well with a lower case fill.

The goal was achieved and the rifles will harvest deer out to about 300 yards when the shooter gets some experience and finds a load to settle on.

 

[Old Navy]

Good hunting accuracy. My first BR rifle had a 10 twist mainly because I didn't know any better. I shot lot of WC 846 which at the time was suppose to be 748. It shot really well in everything up to 88 Bergers.

 

[Gary C]

Dgd6mm
What bullet weight do you use?

G

 

[Dgd6mm]

105 Hornaday Amax. I usually plan ahead. I have enough bullets powder and primers to burn this barrel out. Currently 907 rounds down the barrel, this is an accurate round count. I believe I'll be getting another 6br barrel, probably one of Urbanrifleman's and use it for messing around. I will be ordering Vapor Trails V-Tac 103. I'm not in no hurry at all with all I have on hand to shoot.