What experiences have you with 475 JDJ/GNR in lever actions?

[Naphtali]

Those of you who have experience with 475 JDJ or 475 GNR in rifles/carbines -- 45-70 brass blown out to .475-caliber -- what are your experiences? Cartridges of the World comments that the cartridge is significantly more effective on game than comparably loaded 45-70s. Apparently, this cartridge class was first intended for T/C Contenders rather than lever action rifles. A conversion from 45-70 would appear to be simply a barrel rebore/replacement. The cartridge should be equivalent to a 475 Linebaugh on steroids. But this isn't a particularly useful sentence.

[O.S.O.K.]

Well, 50 Alaskan is done, so I see no reason that this couldn't be. What's the operating pressure of this round?

[1886]

A .475 on the necked up .45-110 case would make a nifty thumper on the Ruger #1 platform. Safe operating pressure would be more a function of avoiding bodily harm than action strength. 1886.

[Naphtali]

Well, 50 Alaskan is done, so I see no reason that this couldn't be. What's the operating pressure of this round?

The information I have on this class of cartridge is CUPs are intended to be comparable with modern lever action 45-70s, such as Marlin M1895 and 1886s -- under 42K CUP. Were IMR powders to be selected, Powley's Computer would function acceptably to identify what loads to use.

[JimT]

It was originally developed for use in TC Contenders. Pressures are in line with use in the Marlin leverguns.

From Reeder's site: The 475 GNR. (compared to a .475 Llinebaugh below) This one we developed back in 1987 for the Contender. It is a 45-70 blown out straight and with a 475 caliber bullet seated in it. It puts a 430 gr. LBT bullet out at 2000 fps and has been used extremely well on Cape Buffalo, Bison, and Australian Buffalo. Best in the Encore or in a Marlin 1895 rifle rebarreled. Brass is available.



Recoil in the TC is vicious. I remember JD publishing a photo of some guy who had him build a TC in that caliber. At the shooting bench this guy had to wear a bicycle helmet since the barrel kept whacking him in the head no matter what he did.

[O.S.O.K.]

430 grain bullet at 2000 fps. I don't see much improvement over a .458" 400 grain bullet at 2000 fps.

Perhaps the real gain is with heavier bullets?

To each his own.

I'm rechambering a 30-30 to 30-30 Ackley Improved just to get 200 fps. So, I'm not one to talk.

[JimT]

430 grain bullet at 2000 fps. I don't see much improvement over a .458" 400 grain bullet at 2000 fps.

Perhaps the real gain is with heavier bullets?

To each his own.

I'm rechambering a 30-30 to 30-30 Ackley Improved just to get 200 fps. So, I'm not one to talk.

Well .. you do have to take into account the "2000 fps" is from a Contender handgun, not a rifle.

[Naphtali]

I anticipate a substantial part of its improvement over comparably loaded 45-70s accrues from the bullet's larger meplat. Wound channel would be commensurately larger.

[O.S.O.K.]

Jim - that would mean another 100-150 fps for the rifle you think? That, along with the larger diameter do step it up a bit.

But, for my money, why not just do one in 50 Alaskan? Even better no?

[JimT]

O.S.O.K. -- if it holds true with other large bore cartridge I would expect velocity increases in the 300 to 400 fps range ... I don't have any real-time comparisons except for the .475 Linebaugh in sixgun and 20" rifle .... the top loads with it gave 400 tp 500 fps increase.

The .50 Alaskan is a stomper, but what can it do that a hot-loaded 45-70 cannot do? Why convert a gun at all?

Because it's there!!

It all boils down to personal choices. To say one is demonstratably "better" is impossible.

Now this I do know and can demonstrate ... some guns are better suited to the big-bore conversions than others. But that is a different subject.

[Naphtali]

Would not cost of conversion be significantly less, maintaining a 45-70 basis case in a [converted] 45-70 rifle versus converting to a 50 AK basis case? Conversion to the 475 may be as simple as reboring or rebarrelling.