regulating a 500 Linebaugh double rifle

[greenchile]

My custom 500 Linebaugh double rifle by Aaron Little is in process and I need to think about loads for regulation.  I thought about doing a double rifle 500 Max to go with my 500 Max Ruger but 1.4" brass is easier to source. I will have some 1.6" brass for the Max revolver but not a large quantity plus the maker of the double rifle does not have a Max reamer. Of course, brass can be sourced from 50 AK so that's less of an issue than in the past.

So, my bullet in the 500 Max is the 525 gr WFN from Cast Performance. I would like to run the same bullet in the 1.4" chamber for the double rifle. Lee Martin (and I think Tim Sundles) had recommendations of 25-26.0 grains of H110 (26.0 is max). Lee Martin tested in his 5" Redhawk and got 1080fps with the 525 Cast Performance. I was thinking about 25.0 grains of H110 to get the double rifle regulated. Barrel length isn't finalized yet but I was thinking somewhere between 20-24".

Any thoughts on this load for regulation? I'm not looking for data on 440's or lighter weight bullets. I've got about 2k of the 525's on hand. I remember Jeff Quinn also tested this 525 bullet in the 500 WE.

[bigbrowndog]

H4227, 26-28gr is what I used from my Max with 5.5” barrel and it got 1050-1100fps, when I used 26gr in my 1.4” case I got right at 1000fps.

Personally I’d go with 20-22 inch barrels and make it a nice short and handy walking gun, maybe even consider 18”. I know a 22” Ruger #1 45-70 made for a sweet walking around gun.

Trapr

[greenchile]

I've got a 480 Ruger double rifle that was built (also by Aaron Little) at 16" for the original owner who commissioned it. I've posted about it in this forum. It's really too short for a double rifle since there's no action length to speak of. It's like one of those short coach guns...little too short and whippy. I think that 20-22" sounds about right.

I should have mentioned that H110 or Unique will be the powders to work with. I've got lots of that along with a lot of AA1680 for the 500 Max.

[flyingzebra]

An ideal revolver load strives for optimal (maximum) transformation of the powder before the bullet base passes the gap

A rifle load has a greater potential window for that internal ballistics event

Although you are looking for parallel regulation of the exterior flight paths of the left and right barrels, you are also looking for the best accuracy

Double rifles can be surprisingly accurate

Ask Aaron if you can have the rifle for a bit of load development before he finishes the regulation and subsequent metal finishing

That'll give you a chance to see if there's a load that will shine above the others in terms of accuracy

This is not an uncommon or unreasonable request

Also, typically your double rifle regulation load is built around powders that are (ideally) as insensitive to temperature and load density as possible, to give you a broader range of working temperature and charge sensitivity
Also the swing-open breech of a double rifle might not handle top revolver loads the same as a revolver will
Furthermore the longer barrels will get you more velocity, to some extent

500L is not a common double rifle cartridge - not a terribly common cartridge for any rifle for that matter

Dig around for examples of rifles and carbines (Thompson Center Encore loads would be an ideal search parameter) for what you might find to be best for your project

[messybear]

John Linebaugh has built 500’s on the Ruger number 1.
So I recommend you talk to him about it. I know he said it was surprising the performance they got out of the cartridge in that application. The difference being the strength of the platforms. But he still would have first hand experience many of us don’t.

[messybear]

Also 110 is likely to give you the highest velocity in the rifle also. If that’s a goal, I would stay with it.
4227 is great when you want a little less than 110 performance and is a bit more flexible.
But it never reaches 110 velocity at the same pressures

[potatojudge]

Are you looking for a common load between a pistol and rifle?

If not, has anyone tried lil gun in a 500 rifle?

Are you looking to use top end loads?

I agree with the above barrel length thoughts. You don't really need length for performance, but how it points and swings will be effected. I think most drillings are around 20-22 inches (which are probably similar- two thin shotgun plus one thin rifle barrel=two slightly thicker rifle barrels, or near enough including the extra solder).

[flyingzebra]

Dec 26, 2022 9:24:01 GMT -5 messybear said:

The difference being the strength of the platforms.

Break action double rifles are not known for their great strength

A Ruger No.1 is in a completely different category of action strength than a swing-open double rifle

The double rifle is not the place to exercise extreme load performance

There have been, and there are modern examples of falling (and rising) breech double rifles

With those guns the pressure limits are in kind with the Ruger No.1

[bigbrowndog]

If you look at the big nitro express rounds and their historical performance parameters, regardless of caliber. The magic formula seems to be 2100-2150fps, more velocity wasn’t needed when shoving 450-600gr bullets down barrels and into dangerous game. It wasn’t until the late fifties and the sixties that more velocity was considered. On the 4227 and 110 issue, H110 has considerably more muzzle blast than 4227 for seemingly equal velocity and pressures. Doing a quick look at the Hodgdon data for 500L, a 468gr bullet is the only one where both are used and the difference in velocity is 57fps, not enough to really say one is better than the other. The difference in pressure is 100 more for H110 and 4227 uses one grain less powder, so pretty equal.

Trapr

[pete]

Kool project, what is the donor action? And, please write it up when done!

[jfo4]

Consider a long throat reamer to allow for max length cartridges. Also keeps the hot rounds from being mixed up with my revolver loads.

I intend on using AA1680 with 525 grain cast next in my #1.

~J.O.