I have read that the .458 SOCOM is very similar to the 45/70.  Does this mean that no one builds an upper specifically for the 45/70?  I already have a Marlin lever action 45/70 and really like it.  It would be nice to not have to stock another caliber.

Have also looked at the .50 Beowulf.  Have seen that people mention both the 'wulf and the SOCOM are relatively short range loads...what kind of effective range do they have?  250yds?  500 yds?

Sorry for the newbie BB AR-15 questions.  :)

The only issue I see is that .45/70 Gov is a rimmed round, which would probably require more of a redesign of basic AR components than things like .458 SOCOM.

It means that ballistically the .458 SOCOM is about like a mid level .45-70, not that you can shoot .45-70s in the AR.  The AR mag well is way too short for that.  For the AR the COAL is about 2.250 inches, the case alone for the .45-70 is 2.100 inch and by the time you add any bullet you are way over the length of the mag well.  
I shoot a 300 gr. X bullet out of my 15 inch Contender .45-70 at 1980 fps which is a hot load for the Contender, but not an overly hot load for the .45-70 in something like the Ruger No. 1.  One can easily hit 2100 fps with the Ruger No.1.  
That same bullet out of the 16 inch .458 SOCOM is going 1755 at the listed maximum load.

Using proper load build-up some people have gotten pretty aggressive loads with the 45 SOCOM.  Some that rival hot 45/70 loads.  I don't recall his screenname, but someone was using a certain powder and compressing it and then actually firing it.........

Keith,

I have a 458 Socom and a Marlin in 45-70.  What the others posted is correct.  BY the 45-70 comparison, it gives a lot of shooters a guage by which to make comparisons.  As you have a 45-70, you get the idea.  Where the comparison starts to fall off is with the heavier (longer) bullets.  They start to crowd the case, and you start falling behind the 45-70.  I have a 20" barrel, and have no problem getting the 300's over 2000 fps.  I actually load it a bit slower, out of respect for the bolt and brass.  

As to the range, it is really only limited by your ability to drop slow moving bullets into your target.  Good sights, trigger, technique and especially ranging.  I did a little playing around with the ballistics of a couple of 300 grain loads the other evening, and found that with my Nightforce clicks and moa lines on the reticle, I "theoretically" can get out to about 750 yards.  Thats shooting, not necessarily hitting.  I also found that at 500 yards, the 300 grain bullet is still moving about 900 fps.  Can anyone say warm 45 Colt load?  Would there be enough energy to take a deer or antelope.  You bet.  Can I humanely hit something that far.  Not a chance.  Does give me something to work towards.  I see lots of long range steel well before any long range game shots.

If you handload for your 45-70, you probaly already have lots of bullets that will already work for the 458.  This is what really settled it for me, the choice of bullets.  I also wanted the Pac-Nor barrel that I got from Marty.  Mines a tack driver with the premium barrel.  I would really take a hard look at the quality of components between your choices, it you want to stretch out your range.  With the 50 or the 458, your gonna need new brass and dies for sure.  As to which, do a little homework.  Both really do very similar things to targets.  It's just how you want to get to your target.


Shivan, forgot to add that I do not think compressed loads are necessarily bad, if they are still within safe limits.  I like H322 with mine, as my recipe gets powder slightly into the neck area.  This does two things for me.  One, it keeps the powder column uniform which I think helps my ES.  The other thing that it does is keep my bullet (theoretically) from possibly getting cramed into the case when chambering, for my loads that I do not crimp.  Crimping with a semi is very hotly debated, and I certainly have found that the crimp groove on 458 bullets rarely line up with my OAL in my 458.  No problems yet, and I am a very paranoid handloader.  I save my ball busting loads for my FA 454 Casull.  That gun is way overdesigned, the 458 Socom is not.


Craig

Have seen a conversion of a AR10 to think a .450 marlin, think the company  is accuracy systems inc.