41 Magnum GP100

[Chief]

Well the .357 magnum and the 41 magnum are the same length. The cylinder is surely long enough.

 

[s4s4u]

I have little doubt that it could be done, but have no doubt that Ruger doesn't care to.

They recently added some floor space, so never say never....

 

[Sugar River]

GOOD CATCH! You are essentially correct. I reversed my info. I hate it when that happens.

SAAMI lists the 10mm case at .425" and the .41 mag at .435"

Makes a difference. How much? Dunno. It would certainly make the chamber walls thinner . . . like .005"

The thickness between chambers would be reduced by .005" X 2 or .010.

 

[GYJ44]

I missed it! don't know how but I did.

The GP cylinder is about 1.55. The cylinder on the Smith Model 57 is 1.56. I'd say it would work .

N-frame cylinder is 1.77". Nearly a quarter inch bigger.

The cylinder is a little short for some bullets.

I'd rather see Ruger legitimize the .41 Special. I really don't want to shoot a .41Mag the size/weight of a half lug GP.

 

[Sugar River]

I missed it! don't know how but I did.

The GP cylinder is about 1.55. The cylinder on the Smith Model 57 is 1.56. I'd say it would work .

Not sure where those dimensions come from but with a dial caliper I'm getting 1.712 for a M57 from 1978,
and 1.550 for the GP. Pics are worth...........

 

[Sugar River]

Not sure why this one didn't appear.....

 

[Ale-8(1)]

Great pics. Thanks. Really emphasize the larger cylinder on the M57.

 

[Thel]

A number of people have converted the GP100 10 mm to 10 mm magnum. I wonder what the pressures on this are compared to the .41 mag? Never mind. Found 10 mm mag pressure max to be 35000 psi vs. regular
10 mm auto at 37500 and .41 mag at 36000 psi and 36200 psi for the .41 Special ( https://www.xxlreloading.com/caliber-load-data/.41-special )

 

[PRichardson87]

A number of people have converted the GP100 10 mm to 10 mm magnum. I wonder what the pressures on this are compared to the .41 mag? Never mind. Found 10 mm mag pressure max to be 35000 psi vs. regular
10 mm auto at 37500 and .41 mag at 36000 psi and 36200 psi for the .41 Special ( https://www.xxlreloading.com/caliber-load-data/.41-special )

10mm magnum?

 

[s4s4u]

10mm magnum?

The 10mm Mag. cartridge, as manufactured by DoubleTap ammunition, employs what is essentially a 10mm Auto cartridge case lengthened to 1.290-inches. These rounds are loaded to a maximum operational pressure of 35,000-psi (or 2,500 less than 10mm Auto) and topped with bullets weighing between 135- to 230-grains. The result is a cartridge capable of developing roughly 25- to 30-percent more bullet energy than the 10mm Auto. This moves the 10mm Mag. cartridge's performance potential much closer to that of the .41 Rem. Mag. rimmed revolver round than the 10mm Auto. And it does so while remaining compatible with commonly used 10mm Auto barrel rifling twist rates and well within the pressure tolerances of typical modern revolvers.

 

[GYJ44]

Not sure where the .41 Special pressure ceiling comes from. It's a wildcat and even the 1200fps loads are probably not more than 26,000psi.

 

[Ale-8(1)]

I can't find any documentation for the pressures associated with the "10mm Magnum". John Taffin did a lengthy review of the round, and revealed everything about it except the pressures. There's no SAAMI spec for it. Anybody have a source?

 

[GYJ44]

Accurate data shows it at 37,500psi and they got a 180gr Speer to 1450fps.

If you wanted to get frisky with a bigger gun like the large frame Blackhawk, you could cut .400Legend brass to 1.4" for a little more powder capacity.

 

[Ale-8(1)]

Interesting. Where'd you find that?

 

[GYJ44]

Interesting. Where'd you find that?

That was on LoadData.com but it's Accurate's data and that was all that came up. I would have sworn Hodgdon had data but I don't see any there or on their site.

 

[Ale-8(1)]

Thanks. I checked the LoadData site. They give a whole bunch of loads, including bullet data, powder used, and velocity attained . . . but you have to "subscribe" to get the actual powder charges.

They list pressure limit for this round at 37,500 PSI.

.41 mag is 36,000 PSI.

 

[WanderLust]

Several Facebook groups on the GP and SP sites talk about that 10mm Magnum. Saw a guy today talking about his and how well he liked it.

 

[magnum0710]

"Rugged, Reliable Ruger Revolvers!"

Their motto.

Due to the number of potential idiots who max load, or think loading manuals are just guidelines,, I seriously doubt the lawyers would approve. And the engineers who may consider it,, well, they too know how stupid some people can be.

Lastly,, while many of us enjoy a .41 magnum,, Ruger is into SALES. LOTS of sales. Initially, they would sell some. But if they offered it in stainless, many would say;

I agree with everything but the "LOTS of sales" part, they're losing too much money by not reintroducing the Six line or making an updated version based off the GP/SP design. They really need a mid size revolver in the line up even if it’s not from the Six series. Not only has Colt and S&W brought back some of their classic models but 3 inch 6 shot 357 carry revolvers have been hot for a while now. The SP is only 5 rounds and no one thinks GP100 when looking for a carry piece.

S&W has the Model 66 2.75 Combat Magnum, the Colt King Cobra and Viper, Rossi RP63, I'll even include the 3 inch Kimber K6s. Everyone but Ruger has a 3 inch, 6 round, medium/K frame carry revolver in their line up. Even if they just scaled up the SP or down scaled the GP slightly and give it a half lug people would be happy. I saw a 3 inch GP in person the other day and I could immediately tell it was bigger than my Sixes. Seeing them compared in pictures I didn't see much of a difference but in person it's definitely bigger. For a while I was thinking I might eventually pick up a 3 inch GP and retire my Sixes. Now I think it would take a lot of work to conceal a GP.

Sorry, I know that was off topic but I just think they're leaving money on the table when every one of their competitors has a "combat magnum" and they don't. One of the biggest complaints I hear about the SP101 is that it's D frame size with J frame capacity.

 

[GYJ44]

Ironically enough, I was sifting through an old PC and found a PDF about the 10mm Mag. It has loads up to 43,000CUP. I saved it in 2014 and have absolutely no idea where it came from.

 

[Ale-8(1)]

Great post. Thanks. Very similar to the LoadData one.

I note that while this one does list pressures, it's in CUP rather than PSI. There is no direct conversion between the two, but SAAMI lists both for each load where available so one can make a good guess as to how they shape up in PSI.

SAAMI lists CUP of 40,000 and 36,000 PSI for the .44 Magnum.

 

[Thel]

" They really need a mid size revolver in the line up even if it's not from the Six series. Not only has Colt and S&W brought back some of their classic models but 3 inch 6 shot 357 carry revolvers have been hot for a while now. The SP is only 5 rounds and no one thinks GP100 when looking for a carry piece."

I agree. The SP101 should hold 6 rounds. Cylinder diameter is about the same as the Kimber K6. The only problem would be if the cylinder axis to bore center is not big enough. They would need a different frame, then, to have 6 shots. As I noted before, though, S&W had to do this when they came out with the 8 shot .357s in the N frames. The alternative is to watch sales of the SP to fall. But then again maybe the autoloader market is far more lucrative and Ruger does not care.

As you note the GP is larger than the K frame. It was meant to compete with the Smith L frame and in that regard I think it does well. It will never be the size of a D frame which has a smaller cylinder diameter than the K frame. Also, if Ruger were to come out with the 6 shot SP I wish they would lose the full lug barrels and have a somewhat slimmer profile. Smith does this with their Mountain Guns.

 

[Thel]

GP100 Cylinder Diameter:

I have come across the following as the diameters: 1.545" , 1.55" and 1.58" (.44 Sp). Some claim Ruger increased the cylinder diameter quietly from 1.545" to 1.55" to solve rimlock on the 7.shot GP's.

 

[Ale-8(1)]

GP100 Cylinder Diameter:

I have come across the following as the diameters: 1.545" , 1.55" and 1.58" (.44 Sp). Some claim Ruger increased the cylinder diameter quietly from 1.545" to 1.55" to solve rimlock on the 7.shot GP's.

That has always been good for a discussion. In order to eliminate the rimlock problem on the seven-shooters Ruger would have had to very slightly increase the diameter of the circle upon which the chambers are bored. Whether this would have been deemed cause for a similar increase in the outside diameter of the cylinder would be a secondary consideration. So long as the outer edges of the rims remained within the cylinders OD it wouldn't necessarily have been required. If it was deemed that the outer chamber walls needed to be slightly increased for pressure considerations would have been checked, I'm sure.

It would have been interesting to sit in on the discussion related to the fact that increasing the chamber circle would have meant the chambers would no longer align perfectly with the barrel bore, and whether that amount of misalignment would have been handled by the barrel forcing cone.

And of course doing this would have assuredly meant a different part number for the "new, improved" cylinder and a consideration for repair parts.

And if the "larger" cylinder wouldn't fit in the existing frame window, would a "new" frame have been required? And would this have meant an entirely new model called the GP107 or something? At least this would have allowed for realigning the chambers with the bore.

Apparently, they sorted it out. Whatever, I'd bet there was enough embarrassment over all this to go 'round.

 

[Thel]

"It would have been interesting to sit in on the discussion related to the fact that increasing the chamber circle would have meant the chambers would no longer align perfectly with the barrel bore, and whether that amount of misalignment would have been handled by the barrel throat taper." Ale-8(1)

I wonder if some of the variations in cylinder diameter are due to measurement error? I see variations not only on the GP but also N frames. I tend to go with this theory.

At another site a gunsmith noted:

"So, more Band-Aid engineering .... if the chambers were tapered just 4 thousands larger at the head, (.002 per side) you could multiply .002x6 and get .012", just enough space where max case rim diameter cartridges would fit without binding. As noted above, this can create more issues than it fixes because cartridges are not in perfect alignment with the bore. The cylinder's throats will straighten out most of the alignment issues and a larger forcing cone diameter will also help. Bottom line .... it's a Band-Aid fix, not a real solution."

https://www.rugerforum.net/threads/gp-100-7-shot-01771.400249/page-2

 

[Ale-8(1)]

That link featured IOWEGAN's commentary on the seven-shooter, mirroring an almost identical thread here. He does it justice.

I note that Ruger lists several seven-shot GP-100's. I'd still like to know what the "fix" was.

 

[Ale-8(1)]

"It would have been interesting to sit in on the discussion related to the fact that increasing the chamber circle would have meant the chambers would no longer align perfectly with the barrel bore, and whether that amount of misalignment would have been handled by the barrel throat taper." Ale-8(1)

I edited that to substitute "forcing cone" for "throat taper". Oops.

 

[foxtrapper]

Have a 6” unfluted slab sided gp-100 in 41 special! Has enough power for my needs.

 

[wildwest77]

No, that would ruin headspace.

 

[wildwest77]

sugar river please sell me that gp100 41 i have several pieces from david but not this one before he retired

 

[wildwest77]

No, that would ruin headspace.

if you want to sell this i will take it. just tell me. daves work was super wildwest