We'd like to shoot this beast tonight or tomarrow, and I'm hoping you'll all pile on here and advise us what to do for starting loads. My brother just finished his 500 Jeffery throated for the 750 A-Max and has some H50BMG, H870 and a few others, so where do we start.

I figured anyone with a 50 Peacekeeper, 510 JAB, the Jeffery, Quickload might help us get an idea for a starting load. The bullet is seated roughly 8/10ths of the way into the neck, bearing surface wise.

Barrel length is 36", somewhere around 39" w/ brake, and is on a Ruger #1. I'll post a pic when I get one today or tomarrow.

THANKS FOR ANY HELP!!!

Brent

Brent,
what OAL are you using for this?

those powders may be a tad slow...
If you are running 3.6 ", you have about 1/3 of the case left...

if 4.5"... well...

email and ask for an EXAMPLE of quickload, with the powder(s), barrel, OAL, and bullets...

for 3.6" oal, 100% loading with h870 is 64 grains, for an anemic ~1100 fps...

for 4.6" oal, it's 114, for a better, but "golf ball" speed of 1780

3031 would be a better choice for a 3.6"
rl22 for a 4.6"

this is because the bullet is SOOOOOOOOOOOOOO LOOOOOOONNNNNGGGGGG

jeffe

IIRC, I load the 510JAB/500A2 with IMR-4350 charges of 100 to 115 grains using the 700 to 750 grain bullets, either milsurp blacktip or A-Max. I am happy with velocities of 2150 to 2250 fps between two rifles of 23" and 27" barrels. My 27 incher is a Ruger No.1 also. My 23 incher is a BRNO ZKK 602.

My most accurate load is the 705 grain AAA Harlow target bullet, a semi-borerider, with 110 grains of IMR-4350.

Your Jeffery ought to have a bit bigger capacity than my 510JAB.

I load the 750 grain A-Max to about 4.750" max COL.

FWIW, but no specific recommendations for you. Cheers!

Hey guys, I appreciate the replies.



It's throated for an OAL of 4.640" using the 750 A-Max.



Here's the rundown-



4.640" OAL



.661" of bullet in case



.360" of bearing surface in case



2.566" 750 A-Max OAL



2.748" case length





479.3 gr case and water /w primer

325.1 gr empty case wt w/primer



154.2 gr water capacity to the top, with no bubble.



Brass is Horneber stuff.



Jeffe,



I'll email you this too.



Thanks for suggestions and help here.

Horneber brass is excellent stuff. My 510JAB has 147 grains water capacity at 2.880" brass length, made from 460Wby Norma brass. You ought to be able to use my accuracy load just fine, but do so at your own risk, you know, etc.

With your longer barrel and 7 grains greater case capacity, you have greater velocity potential.

Right on Ron!!

Just sent you mail too.

Kind of curious what powder burns up completely in the 36" tube and best fills the case, but that can all be tested once we get it up and running on the Oehler M43 with a starting load.

Thanks again guys, I'll report what we find.

Using the numbers you supplied, my QL suggest MRP, Re-25, Re-22 and WXR for that long tube. Velocities are in the range of 2140-2180 fps, and loads are around 110-120 grains. These loads all keep the pressure to a low 40,600 psi so plenty of room to go ....

Thanks guys, very much!!

Looks like tomarrow's the big day.

Just got back from shooting the rifle for the first time a bit ago.
After 2 rounds my brother mentioned he had a headache all morning, and this was killing him every shot. Well, after 5 rounds, he told me to shoot the rest of 'em his headache was just too bad.

For some perspective -
The recoil as much, or a bit more than I expected, although when he was shooting it, it looked fine. It was more than both 50 BMG's I've shot, the Grizzly and the AR50 both. Twice what the AR50 was becuase of it's very efficient brake design, but very bulky too. Recoil got worse with the hotter loads, and should be pretty noticable when the get to 2400 fps or so. It recoils about like a light 338 Ultra with hot loaded 250's and no brake! Not quite like a 375 Ultra or 378 Wby, more of a big push though. It's not like a 300 WM or Ultra...

Ruger #1 (early 80's model w/ adjustable trigger)
36" Pac-Nor barrel
Custom design brake (extended Holland Quick Discharge variant)
NF NXS 5.5-22
Farrel base (20 MOA + 6 MOA barrel taper)
Leupold QRW's
Custom made stock (shaped from 4"x12" blank)(not quite done shaping and finishing it)
Harris bipod


500 Jeffery 750gr A-Max at 4.65" OAL -

IMR4350 106-111gr 36-42k psi 1980-2180 fps

H4831SC 108-112gr 31-34k psi 1897-1989 fps

RL22 108-112gr 30-37k psi 1900-2065 fps

We shot these in 1.0gr increments, 16 rounds in all. Pressures are still way low, should end up with 2350-2450 when they get up there some more.

Here's pix of the rifle, and one of the current brake design. I say current because he's going to go build another one now that's a bit bigger and more efficient for this big boy. The extra set of slots in it over the Holland isn't quite as good as it could be. The new one will have more slots and might even be a lot longer with slots angled rearward too. Shouldn't be too hard to improve it quite a bit to at least 300 WM recoil levels.







The hosting site seemed to be having a problem, pix should show up sometime.

Brent,
How close were these to the QL data i gave you... you might find the constant, per load, for the longer barrel...

I imagine that this brake is proportionally far too small to do much, if any, good for this length barrel. The gases could be greatly expanded, with QL projecting "only" 4400 psi at the muzzle, as nearly 166% of that with a 22incher.

I think it would be a good test to load up the hottest of this bunch, and try it 3 shots with the brake on, 3 shots off, and see how much difference it realy feels like

for gun acclimitization, I recommend www.customcastbullets.com and wayne's 600 gr GC hard cast bullets

jeffe

So Jeffe, you're saying muzzle pressure is too low to make it work efficient as it could?
With higher muzzle pressure it might work better, even though it's hotter?
Not quite sure I follow you?

I'll take the with or without brake test under consideration, although I don't relish the thought one bit!

Couldn't be worse than my 416 Wby Ruger Magnum with no brake tho..... Or could it?

I'll have to look at the data, I haven't compared that QL data and what we found out just yet.

Thanks for the bullet link.

Hi Brent,

Since you are going "tactical" with your long barrel and beefy stock, the more muzzle brake the better, eh?



I am glad to see that you got such reasonable pressures as 42K psi with 111 grains of IMR-4350.



My 510 JAB and 500 A2 have about 5% less case capacity, so maybe my 110 grain IMR-4350 load with the 750 grain A-Max is less than 45K psi after all. I was guessing it was less than 50K psi anyway.



It would seem to me that you will run out of case capacity with the slower powders before your extra-long barrel can be of benefit.



J. D. Jones, designer of the SSK 50 Peacekeeper, ended up with a 23" barrel of 10" twist, with a tanker-style or clamshell brake that directs gasses rearward. It weighed about 14 pounds with scope, for his commercial version, but he had an 18 pounder that he was trying to sell to the military, of what barrel length I do not know.



He said that his cartridge was best with some powders faster than IMR-4350, using 110-115 grains of powders in the burning rate range of:

IMR- and H- 4895

RL-15

AA2250

WW748

H-380

I think he probably meant the above powders for the 650 grain ball to get 2400 fps in the 23" barrel.



Most 50 BMG's with a 30" barrel only do 2700 fps with the 650 ball, and use twice as much slow powder to do it.



What is the twist rate of your barrel? Mine is 10", and that is another variable for me to consider in comparing your pressure readings to my 510 JAB/500 A2 rifles.



I would love to see how much IMR-4350 it takes for you to get up to 50K psi with the 750 grain A-Max.



BTW, what was the temperature at the range when you got the pressure readings?



Thanks

I'm working on some graphs right now to see where well hit 2400 fps at, PSI/charge wt and PSI/MV graphs.

Looks like 54k psi with IMR4350 at 115.5gr, I'm still plotting the other two out. We'll see how well it predicts tho...

I know a guy here that gets 50 BMG MV using a 600 Nitro case pretty easy, and I know he isn't pushing 65k psi to do it, so...

H4831 was slower burning than RL22, and real consistant, not sure if MV will get there with the case capacity, although it has quite a bit of room left, just not so sure theres enough room to get the pressure to do it.

So Jeffe, you're saying muzzle pressure is too low to make it work efficient as it could? With higher muzzle pressure it might work better, even though it's hotter? Not quite sure I follow you? I'll take the with or without brake test under consideration, although I don't relish the thought one bit!

Yeah, Brent... I think the brake is too small for the available energy that is to be scavanaged from the muzzle (exhaust) gases... so it there's not enough, it's not really doing anything... and should reduce MORE recoil as it goes faster, to a limit.

I'll shoot it for ya.. brake, no brake, 2600... surething!!

jeffe