450 Bushmaster question primer pocket conversion?

Has anyone tried to enlarge the primer pockets of the 450 Bushmaster from SR to LR? How did it work out and how did you do it

Never have tried to move from small to large primer, it will be interesting to see if someone chimes in who has done it.

I'm surprised no one else has asked this question with current weirdness in components.

I'm fooling with the best procedure to convert Berdan to 209 shotgun primers. I think that may have some advantages over the typical conversion from Berdan to large rifle with a sleeve or bushing of some kind.

I suspect that 209's are more than strong enough for whisper loads.

For the primer deprived out there I'm curious if converting some boxer primed cases, from either small or large rifle or pistol primers to 209 shotgun primers might also be an option.

Might get someone shooting when they ain't got the right stuff.

That is the reason I asked. I am about to run out of SR primers but still have some LR I could use.

Well, you got me curious, so I went out to the shed, chucked up a 450 Bushmaster in the South Bend with a collet in the headstock.

I've got a Sinclair carbide primer pocket uniformer. That went into the chuck in the tailstock. Basically used it as an endmill of the correct diameter. Cut the primer pocket to large primer dimensions.

Not the most ideal way to do it, not enough chip clearance to do an efficient cutting job but with repeated cleaning did work.

Seated a primer with a little more than normal effort but it did seat, don't have a 450 Bushmaster to try it in.

May try a 204 Ruger tomorrow just for the grins. Only small rifle primer candidate I have. 22 Hornet is a little too small for this kind of experimenting.

221 Fireball has done some squirrelly things to me in the past. And I'm too much of a wimp to try this in the 30 carbine. Like the idea of a fully locked breech doing something like this.

Just did a little digging, there is a 13/64" endmill available from McMaster-Carr.

13/64 is equal to 0.203125, Large rifle primers are .128 inches in height and .212 inches in width.

Start with the 13/64 endmill and finish with the primer pocket uniformer?

Sounds like it could work, not sure I want to invest in an endmill to experiment.

Luckily I'm still well stocked on primers.

If you could only figure a way to cut down those 50BMG primers that are always available into 2 or 3 large or small rifle primers. LOL

Thanks for trying it out and the information.

Best make sure the tailstock and collet centers are perfect and repeatable. End mills in drilling operations are not forgiving. End mills in a tailstock chuck effectively become a boring bar if not precisely centered.

I've done enough 50BMG primer pocket depth truing to regret my inattention to this little detail...... uh huh, yep..

Not having a lath this a method I will not be able to try. Wonder if they could be swaged larger?

Doubt it, that's a whole bunch of brass that has to go "somewhere".

Just swaging out military primer pocket crimps on occasion can take more mechanical effort than you'd think.

I've read threads about converting SP to LP before and it's generally a time consuming process or requires machining equipment that most people don't have. Going from SR to LR will require a wider and deeper pocket. It's kind of one of those questions where if you have to ask, you probably don't have the equipment to do it...

FWIW I first bought a 450 BM Ruger American January of 2021 assuming it took LR primers and I had about 5,000 of those and only shoot a couple hundred per year. I was kind of miffed when I went to buy brass and could only find SR brass...

There was a thread regarding changing .38 Special from small pistol (same depth as rifle) to large pistol primers (same diameter, but shallower pocket) within the last few years. I think it was in the favorite cartridge section.

Robert