Boys Anti-Tank Rifle .50 BMG Ammo

Don McManus

I posted this in Ask the Experts as well. Any help on getting proper sized ammo is appreciated.

Does anyone have any experience with a Boys Anti-tank rifle converted to .50 BMG? I just took receipt of one, but the magazine is shorter than 50 BMG rounds. I can fit one in the magazine and still chamber it, but two or more do not fit.

Did I purchase a magazine fed single shot rifle? Still worth it, although a little disappointing.

Can I reload .50 BMG and seat the bullet 1/16" deeper so it fits in the magazine? Better yet, are there speciality ammo houses that would do a production run of 400 - 500 rounds for me?

Any info would be appreciated.

Thanks.

Tailgunner1954

OAL for the 12.7x99 (50BMG) is in the 5.43" range
OAL for the 13.9x99B (55 Boys) is in the 5.26" range

The above dimentions are taken from actual rounds.

Back when these conversions were being commonly done, they were being used as single shot rifles.

If you reload, you can set your OAL to whatever fits in your magazine, just be sure to back off the powder charge and work back up.

JMHO, but on a case that big, changing the OAL by 3/16" won't cause any pressure problems.

Don McManus

quote:Originally posted by Tailgunner1954
OAL for the 12.7x99 (50BMG) is in the 5.43" range
OAL for the 13.9x99B (55 Boys) is in the 5.26" range

The above dimentions are taken from actual rounds.

Back when these conversions were being commonly done, they were being used as single shot rifles.

If you reload, you can set your OAL to whatever fits in your magazine, just be sure to back off the powder charge and work back up.

JMHO, but on a case that big, changing the OAL by 3/16" won't cause any pressure problems.
Thank you, tailgunner, makes sense.

Tailgunner1954

Setting the bullet deeper will give it a longer jump to the lands. The bullet till be traveling further in the leade (freebore) portion of the throat, which is no big deal safety wise.
Accuracy wise it might hurt you a little, but you won't know until you try it.

Worst case is that you end up building 2 "types" of rounds, "plinkers" that fit & feed from the mag and "accuracy loads" that have to be fired in a single shot mode.

I don't have your mag in front of me (obviously), but somewhere between what my 55Boys cartridge measures (we know it would feed) and the maximum lengh your mag will handle (I like to keep .030-.040 operating clearance in my bolt gun mags BTW) will be the max OAL that your mag will feed. Finding that # will be something your going to have to play with. Once you have that #, it's time to start playing with powder types and charge weights to find the combo your rifle prefers.

Don McManus

Thanks again, tailgunner. I realized the error in my question and erased it before I saw your response. Your detailed answer is very much appreciated.

Regards,

Don McManus