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50 BMG - RL50 and 750 Amax?

M

Mattrmvpd

Gunny Sergeant
Full Member
Minuteman
Sep 30, 2004
1,334
434
South Georgia
#1
I am looking for anyone that has loaded using the following:

RL50
Hornady 750 Amax

Curious as to your load data and what you were seeing.

I am looking to”mimic” the factory Hornady 750 Amax load/speed etc..
 
#2
the factory load is ~234 grains RL50 last time I checked

It used to be 240-something of US869

I load 236 grains RL 50 but I load them about 1/4" longer than factory. This is the "known" load for 750 AMAX in 50 BMG. It shoots very good in most guns, like my profile picture.

Alliant lists 239 as a max load but I never ventured there.
 
#5
I haven't shot my 50BMG for awhile. Here is Hornady data for the 50BMG.
I used RL 50 239 grs with Barnes 750 solid 5 .730" COAL 2603 fps.
260 grs US 869 powder for 650 FMJ was the fastest 2942 fps from a 30" barrel.
I've been playing with the 510 Whisper and wasting? ... my 750 Atips on that. Machined 700 cases for the 510 Whisper.
Still have a bunch of 750 Atips that I haven't shot through the 50BMG.
It's been awhile since I shot the 750 Atips in 50BMG, I believe I used H50BMG and US869 in my 50BMG and used the Hornady data, below. Did a bunch of 50BMG subsonic loads also.
All I have to do is load em up and chronograph them...have several hundred cases ready, and primed.
 

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#6
Here's my notes on RL-50 for the 750gr AMAX out of my Barrett M82A1:

"Hit lands at 5.809, test at -30 thousands or 5.779. John's reloading book say 5.730 max length & 235gr max powder charge. Not sure for what specific gun. Need to test 230.0gr RL 50 with 750 Amax. Alliant says 239 gr out of 24 " barrel gets you 2835 fps seated at 5.730"

Did launch a few at 225gr but my semi auto Barrett is not ideal for this projo. By all accounts 235-239gr would be a max charge,
 
#7
Those Hornady speeds and barrel length are totally jacked. NO WAY you’re going to get 2850 from a 24” barrel. They mean 44” barrel - which is the length John Browning designed the cartridge for.

With a 30” ARMALITE AR50 barrel you can expect 2550-2650 with factory loaded AMAX which has about 235 grains of RL50 in it and figure about 15 fps per inch more or less. Do the math and you’re talking 2850 — maybe up to 2950 – from a 44” barrel. I get 2840 from a 41” barrel with 236 gr RL50 loaded .250” longer than book. I can go to 140 w/o pressure so I could get about 2900 fps w 41” barrel but decided not to push it.

Summary: don’t expect more than 2650-2750 fps from a 29-30” barrel with AMAX and RL50 or you’re asking for pressure
 
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#8
Totally agree. Who the fuck would want a 50 BMG rifle with that barrel length? The only chrono testing I did with my M82A1was with hand loaded, 650gr M33 Ball. With 250gr of RL-50, I got 2956 fps average over 3 shots. Did not want to do any further measurement and destroy my magnetospeed. With a safe charge of 225gr of RL-50 and the AMAX, I should at or slightly over 2600 fps.
 
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#10
Anybody have a pet load of H50BMG for the 750 AMAX?

I think I'm going to abandon my RL50 load - too much velocity variation.

At least I will do that if I can come within 50 FPS with a H50BMG load with acceptable accuracy and single digit SD. (Yesterday my RL50 load had SD 14 over 23 shots - completely unacceptable, and the effects were visible 1850 and 2361 yards down range. High! Low! And the Garmin predicted all of them.

Also, something curious: the old books and even the current Hornady published max is 213 grains, which seems very very anemic. Even teh Hodgdon jug says 233 grains. Is one of them a Typo? Quickload would suggest it's the hornady that has the typo.

And WTF with all the ridiculous barrel lengths and velocities that don't correspond? Alliant RL50 recipes show 239 max (I agree, but QL says you can get to 245) and 2835 fps with a *24" barrel*! Which is complete BS, I get that same velocity with a 40" barrel.
 
#11
I have questions about loading for my AR-50. I've shot 150 rounds of surplus ammo thru my rifle, then reconditioned the cases. The primer pockets were the most time consuming. Then I loaded up about 50 rounds using pulled 660gr projectiles. I seated the bullet to the middle of the canalour and put a very mild crimp on it. They work fine but not very accurate.

I bought a ogive gage and after taking measurements see that the propper seating depth is about .180 less than the middle of the canalour in the bullet and that there isn't much of the bullet actually in the case. My assumption is that I should not try this with the bullet pulls and that I should get some Hornaday 750gn projectiles.

Would the expensive Hornaday bullets seat deep enough in the case for .020 gap before engaging rifling on my AR-50?

What gap are you guys finding to be the best?
 
#12
Pulled 50BMG 650 gr. FMJj 's should be resized in .5095" die. Cause some pull marks are fairly deep, interfearing with loading and bulging necks, and the bullets are out of round.

A 50BMG can be decently accurate with military components.
First I skim neck turn every case about about 1000 pcs, in the lathe and machine out the primer crimp.

I don't chase the rifling, just load all military bullets to the crimping groove... one can drive the steel core through heavy steel by shooting the back of the bullet that didn't make it through at 100 yds...or just use the armor piercing bullets.

Pic of seating, in neck turned cases, & machined primer pockets.

The APITs are accurate in my rifle, 5 shots into .629" at 100 yds.
These are not pull downs, resized pull downs are okay for accuracy.

The last pick is cleaning up a bunch of leftovers, with wildly different powder charges and velocities over 550 fps... but the bulk of the shots actually made a fairly nice group.
 

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