50 BMG - RL50 and 750 Amax?

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.

Anyone using H50 with 750 Amax?

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.

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,

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

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.

I am in the process of a 750 AMAX load development around 222gr to 226gr of H50. I have a 34" barrel in a McBros action. I will report back 226gr looked promising in the run up.