what kind of pressures willl a 4570 contendor live with

[Lloyd Smale]

Im thinking on a carbine barrel and have a pile of ammo loaded thats stout even in my marlin. I dont figure it would be useable in the tc but am not up on them much. will they handle what a marlin will if not whats a good max velocity for a 405 or 500 grain bullet in one. Dont want to sound like an ass here but im looking for answers from people who really know not repeated loading data from someone who read it somewhere. I can work up my own loads i just want to know what the limit is on one without hurting it.

[Graybeard]

Lloyd, when you say they would be "stout" even in a Marlin that tells me you'd be wise to limit them to use in an Encore NOT a Contender. For sure the newer G2 is a stronger frame than the older Contenders and perhaps can take more pressures but frame stretching in the Contender is a very real concern when you push it too hard.

The larger case head of the .45-70 means pressures need to be held lower for it than for rounds with smaller case heads. As you perhaps know it's not just the pressure but case head thrust that is the concern in an action such as the TCs. With a small head like a .223 you can run pressures way up there to the mid 50,000 range with no concern but with larger case heads you need to be more conservative.

I don't know what kinda pressures you might be running so it's really hard to say if they would or wouldn't be OK. Some limited use of them might be OK but continued use might not be. Are they running higher pressures than would say a .44 Magnum using max book data? If so I'd not use them as the case head is a bit larger on the .45-70 and max loads from a .44 mag while OK in a TC is at the upper limit of it's ability to take it long term.

Many loading manuals list data separately for TCs in the .45-70 and that data from a major loading manual should be entirely safe. But data listed as Ruger level should not be used. It is my understanding that in general it's more or less OK to use data listed for the Marlin in the Contenders but some of the small company stuff like Buffalo Bore really pushes the envelope for the Contender and personally I'd limit it to an occasional use only not regular repeated use. I'd also be less concerned if it was a G2 than an older Contender.

[throttleman]

Lloyd,

I have a Contender Carbine in .45-70 and upon inquiring with T/C about maximum pressure, the reply was, "Trapdoor pressure."  When I further inquired what Trapdoor pressure was the fellow replied, "28,000."  If you prefer to get the answer straight from the horse, T/C's number is (603)332-2333.  I would also like to say that this carbine is a hoot to shoot! 

Good luck,

Jeff

[Graybeard]

28,000 is DOUBLE trapdoor pressure levels.

[Lloyd Smale]

these loads are stout and pushing into ruger #1 territory. I guess ill just leave them on the shelf. I need a #1 in 4570 anyway. Allways wanted one but never got around to it. I was just hopping to get away with it to clean up some brass but i guess its not worth taking the chance.

[Lone Star]

28,000 is DOUBLE trapdoor pressure levels.

This is another of the confusing part of the .45-70 pressure rating.  According to SAAMI, .45-70 ammo intended for all .45-70 firearms in good condition cannot exceed a MAP of 28,000 cup.  But, most factory 405-grain ammo is loaded to ca. 20,000 cup.  The 300-grain stuff is higher, around 25,000 cup.  Just for fun, here are the pressures that three major handloading manuals list for the three pressure levels:

Trapdoor
Hornady - 25,000
Speer - 21,000
Lyman - 18,000

Marlin
Hornady - 40,000
Speer - 28,000
Lyman - 28,000

Ruger
Hornady - 50,000
Speer - 35,000
Lyman - 40,000

Not much agreement there.  BTW, it is the maximum internal area of the case that determines the case head thrust, not the rim size.  I work with contained pressures all the time, that is the truth.  Doubt me - call JD Jones.  He's written about it extensively for over 20 years and will be happy set you straight. 


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[poncaguy]

I've been shooting factory rounds in my 16" Contender pistol for years, no problems...........now would kinda be a dumb time to ask if they were safe in it. Comments?

[Lloyd Smale]

factory loads for the most part are real tame and should be fine in any gun. There loaded for the pressure limits of the old springfield falling block guns so as long as your not talking garretts or buffalo bores ammo they would work in any gun.

[Hopalong7]

Lloyd, I asked TC many years ago what to shoot in my then new 16" Contender barrel.  Answer was to strickly limlit to Trap Door loads and they highly reccommended not to use any bullets heavier than 405.  I've enjoyed shooting mine in pistol configuration for many years.  But...since my barrel was 16 1/4" long I had to try it as a carbine just once...fired two rounds( these were only 300gr trap door loads too )...never tried it again.That little carbine whipped the #$%@ out of this old man(and I was a good bit younger then).             GOOD SHOOTIN', Walt