45-70 / 45-90 Questions

[GrassLakeRon]

Hi all,

     I am looking at a Gibbs Summit rifle in 45-70.  The action is rated a 49,000 psi.  What type of max loads can I get with this?  Can I get 500 gains to 2000 fps?  If I ream it to 45-90? Or 350 grains to 2500 fps?  I see that Buffalo Bore and Garret load to 33-38,000 but nothing over....

Ron

[efremtags]

I you need that much power, get a 458WM.

The rifle is magazine fed, so unless a single shot is what your after, it may not work. Also, the stock design is not built for severe recoil with it's lineage from military design being built for rapid follow up shot.

[Mikey]

Ron - I doubt you can get a 45-70 or 45-90 to throw a 350 gn slug to 2500'/sec or a 500 gn slug to 2000'/sec from those rifles more than once.  Those loads are way beyond the ranges of the 45-70 or 90 in those actions. 

The actions are British SMLE and while proofed to 47-49k psi I believe the heavy loads you mentioned would hurt both you and the rifle.  If you need heavy loads like that, get a Marlin lever action.

The SMLE has been rebarrelled to both 45-70 and 45-90.  I believe one of the original rebarrels was to 45-90 in a No1 Mk3 and since that worked, others then picked up the idea and ran with the 45-70 as being the more common chambering but used the No4 Mk1 action as it is a imrpovement over the earlier actions.  jmtcw. 

[Lone Star]

The action is rated a 49,000 psi...

Statements of this kind show a lack of understanding of pressures.  While the original chambering - the .303 Brit - was a 49,000 psi cartridge, it is too much of a leap to say that the action is rated to 49,000 psi.  The internal case area of the .303 is far smaller than that of the .45-70, so the case head thrust on the action would be much greater - about 50% greater at the same chamber pressure.  The Enfield action is pretty darn springy as it is with the .303 chambering - hot loads in the .45-70 are just asking for trouble.  Too, the barrel under the threads is pretty small - swelling of the barrel is a real possibility with the larger diameter .45-70 case and high pressures. 

Unless you are after elephant and rhino, a 350-grain bullet at 1800 fps is plenty.  And I wouldn't want to touch off a hotter load in an Enfield with its less-than-satisfactory stock.....




.

[GrassLakeRon]

The pressure numbers are from Chuck Hawks website, so is the idea to make that Gibbs a 45-90.  I wanted to know if it is possible, not that I would but it is an interesting idea that the ole 45-70 could "nip on the heels" of a 458!  The idea is for a backup Brown Bear Gun to my 375 H&H.  I see that Garret and Buffalo Bore have "bear loads" but has anyone shot a charging bear with them?

Thanks Again for the Info!

Ron

[Lone Star]

I see that Garret and Buffalo Bore have "bear loads" but has anyone shot a charging bear with them?

No, but I did shoot a nice brownie on Baranof Island with my M98 .45-70 and the Hornady 350 at around 2000 fps.  Complete pass through after breaking the far shoulder.....but it was about 50 yards off and broadside, not charging.  I have been charged several times by brownies but fortunately never had to shoot one of those......

In a Ruger No. 1 chambered to .45-70 you can heat up a 500 RN to 1800 fps.  Pretty close to a .458.


.

[iiranger]

I built my .45/70 on a Siam 98 back when that was a fad. Two points. #1).  IT KICKS!!! You shoot 500 grains at 2000 at a bear and you better hit because you will be "dis oriented." I loaded 500 grain plain lead once, fired them, moderate charges, and that was enough for me.  #2). The case is little improved, yes solid head instead of the original "balloon head," over the vessel for black powder pressures. If I were going to play "bet your life" with bears, I think I would want something a bit more modern and absolutely reliable. Your bucks, your call. Luck. PS: Your case life will be next to "zip"/ -0-/ nada... O.K. ?