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45-70 minimum case length?


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I recently posted about a trade of my 45-70 375gr FTX LeveRevolution ammo for empty cases.  That's no longer in play, but there were comments that I didn't quite follow.


It is known that Hornady uses specially shortened 45-70 brass for its 375gr FTX LeveRevolution due to the length of the polymer tip. While new Starline brass -- as an example only -- is approximately 2.095-2.102 OAL, the Hornady brass is approximately 2.045 OAL, .050-.057 shorter.

 

As long as my dies are set for the Hornady brass length and I make sure I don't mix other brass (such as R-P, Starline, Federal, etc) in a single loading session, does this short brass actually matter much for general steel plate plinking inside 100 yards, mainly for Plainsman Matches? I'm not talking about precision long range target shooting; in fact, I'm specifically making light loads with Lyman #457191 292gr coated bullets over a light (30gr volume) charge of Triple Seven FFg.

 

Some folks have said things like "the Hornady brass is shorter than SAAMI spec" and this is puzzling to me. I am not aware that SAAMI specifies a MINIMUM case length. And 45-70 cartridges vary greatly in COAL depending on the bullet used; for example, Lyman 48th Ed. specifies COAL of 2.835 for the #547125 500gr RN and COAL of 2.550 for the #457191 292gr FP-BB bullet.

SO -- is there some SAAMI-specified MINIMUM length for a 45-70 case? If so, what is it and where does it say so?

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As shown above the case length dimension is 2.105-.020 or IOW a minimum of 2.085 and a maximum of 2.105.

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41 minutes ago, Nostrum Damus SASS #110702 said:

I recently posted about a trade of my 45-70 375gr FTX LeveRevolution ammo for empty cases.  That's no longer in play, but there were comments that I didn't quite follow.


It is known that Hornady uses specially shortened 45-70 brass for its 375gr FTX LeveRevolution due to the length of the polymer tip. While new Starline brass -- as an example only -- is approximately 2.095-2.102 OAL, the Hornady brass is approximately 2.045 OAL, .050-.057 shorter.

 

As long as my dies are set for the Hornady brass length and I make sure I don't mix other brass (such as R-P, Starline, Federal, etc) in a single loading session, does this short brass actually matter much for general steel plate plinking inside 100 yards, mainly for Plainsman Matches? I'm not talking about precision long range target shooting; in fact, I'm specifically making light loads with Lyman #457191 292gr coated bullets over a light (30gr volume) charge of Triple Seven FFg.

 

Some folks have said things like "the Hornady brass is shorter than SAAMI spec" and this is puzzling to me. I am not aware that SAAMI specifies a MINIMUM case length. And 45-70 cartridges vary greatly in COAL depending on the bullet used; for example, Lyman 48th Ed. specifies COAL of 2.835 for the #547125 500gr RN and COAL of 2.550 for the #457191 292gr FP-BB bullet.

SO -- is there some SAAMI-specified MINIMUM length for a 45-70 case? If so, what is it and where does it say so?

Right or wrong, I use short brass for Plainsman. Not as short as Hornady, but I had a bunch of used brass that was all different lengths. Just trimmed em all to the same length and no issue I'm aware of.

Edited by Eyesa Horg
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Since 45-70 bullets are quite long, using short brass is not an issue other than crimping.   Some of my deer loads, almost half the case is taken up by bullet.   For those even 1/4” shorter would still work fine as it would still leave enough case for a full caliber of bullet to be in the brass.   For bullets like that you could really long throat a barrel and then gain a lot of powder capacity.   Not sure I could handle the recoil.  

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Griff, what is the source of that drawing?  Is it SAAMI or just one of the manufacturers?  As I mentioned above, Lyman 48th Ed. specifies COAL of 2.835 when loading the Lyman #547125 500gr RN bullet, much longer than the 2.550 MAX COAL shown in that drawing.

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2 hours ago, Nostrum Damus SASS #110702 said:

So, to sum it up, if I only shoot 45-70 single shot rifles -- my Trapdoor Springfield and 1885 High Wall -- there is no problem at all reloading the short Hornady brass.

 

 

The MAX OAL in the SAAMI specifications is determined by how long a loaded cartridge can be and still cycle in a semi-auto, pump, or lever action firearm. It gives makers of firearms and ammunition manufacturers something to design to. Notice that the bottom drawing shows chamber dimensions.

 

AFAIK within the Leveroution ammo series all the cases are shorter than SAAMI specification. Be it 45-70, 44 magnum, 357 Magnum etc.

 

Single shot or repeater doesn't matter. What gun you are using is immaterial. 

 

What matters is if you change the distance between the BASE of the bullet and the BASE of the cartridge. Hornady made their brass shorter in that ammo series so that they could properly crimp the cartridge. If they had used standard length brass they couldn't have crimped the finished cartridge.

 

 

In other words; As long as the OAL of the finished cartridge matches what your loading manual says for that bullet and powder charge the length of the brass doesn't matter.

 

What does matter is making the finished cartridge shorter or longer than the OAL your reloading manual calls for. This changes the internal volume of the loaded round and can cause your firearm to rapidly disassembly itself. 

 

An example would be pushing the bullet deeper into the shorter case so that you can crimp it in the crimp groove. or making the OAL longer so that the crimp is not in one of the lube grooves.  

 

Edited by Sedalia Dave
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Right, SD.  And with Triple Seven it really doesn't matter at all because Hodgdon says do not compress it and do not use fillers, just cover the powder with a fiber wad; tiny changes in internal empty space won't matter.  That allows setting COAL appropriately for the crimp to be made at a good spot.

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