Creedmoor 45-90 Question

[Digger]

Hi Y'all,

I was browsing some Gunbroker ads for Creedmoors and I noticed a couple of 45-90s that said they could also fire the 45-70.  Is this a feature of those rifles, or can any 45-90 also fire 45-70?  Is it a question of how much powder you put in the same sized case?  If it's a feature of those rifles, would the dual chambering adversely affect the accuracy of the rifle?

Thanks,
Digger

[Mako]

Digger,
They share the same straight walled case base, just the length is different.  It's like .38 spl in a .357 mag chamber.  In the case of rifles maybe not ideal for accuracy, but the shorter will function fine since they head space off of the rim.

The .45-70 is basically a little over 2.1" long and I believe the .45-90 was called the .45 X 2 4/10" by Sharps.

~Mako

[Gripmaker]

Load bullet "out" in 45-70 to duplicate length of 45-90 or use longer bullet to gain same effect and you should eliminate the powder fowling problem shorter cartrideges cause.

[john boy]

Here's my take ... if a chamber is cut for a 2.4 cartridge - shooting 2.1 brass in it makes no sense.  Specific bullets will not be in the leede and accuracy will suffer because the chamber cut for the case is larger than the bullet diameter. Plus the bullet will have to pass over the cartridge shoulder cut and then wobble into the leede.  And if one wanted to shoot a bore riding bullet, how will it reach past the leading bore cut?
If it was common practice to do this - match shooters would use 45-70 reloads with the bullet seated way out or breach seat the bullet... and they don't.  A chamber is cut for a specific case length to PREVENT GAS LEAKING into the chamber which causes FOULING AND LEADING at the chamber end of the bore, so use the correct cases in the correct chamber cuts

But do what your want to ... it's your rifle.  And when the leading, fouling and poor groups happens - don't go posting on the forums that your rifle has a problem and asking what is the cause and what you should do to correct it!

[Fox Creek Kid]

You will RUIN your chamber. DO NOT do it. This question gets asked several times a year to the owner of Shiloh Sharps and he says no. Unless you want to rebarrel soon. It is not like shooting a .38 Special in a .357. Mag.

[Dick Dastardly]

.22 rimfire rifles have had shorts, longs and Long Rifle cartridges made for them for a very long time.  Some say "Long Rifle Only", but shoot the others just fine.  Some say they shoot all Three.  In the case of the .22, it's more of a feeding question.  Many shooters are very happy with .38 Specials shot of .357 Magnum guns.  I have several of these.  One, a Browning 92 in .357 Magnum has shot many SASS matches with .38 Special black powder ammo and absolutely no chamber problems.  I've shot Ruger 44 Magnum RVs for many many matches with 44 Special ammo.  No worries. 

Your 45-90 may, or may not, like 45-70 ammo.  You will have fewer and less sever questions about erosion, leading etc. with Holy Black than you will with heathen fad smokeyless powders.  As JB says, there is a risk.  I've seen lots of 45-70 ammo shot from 45-90 guns with no problems.  I've also seen some with chamber erosion that was bad enough that the barrel had to be either replaced or set back and rechambered.

Also, it depends on how much you shoot the shorter ammo in the longer chambered rifle, the pressure generated by your load(s) and how often you clean the chamber.

The risk is yours.  So is the benefit.  Does the benefit outweigh the risk?  Your decision. . .

DD-DLoS

[Mako]

You will RUIN your chamber. DO NOT do it. This question gets asked several times a year to the owner of Shiloh Sharps and he says no. Unless you want to rebarrel soon. It is not like shooting a .38 Special in a .357. Mag.

FCK,
I'm always willing to learn. Is there some mechanism other than gas erosion that causes this problem?  Not that it actually matters but I'm curious, are you're referring to Kirk or to Bob?

As always a humble student,
Mako

[Fox Creek Kid]

Mako, Kirk gets asked this question several times each year. Let's ponder for a moment: when the bullet loaded in a 45-70 is fired in a 45-90 chamber what happens? The bullet obturates to the greatest possible size in the CHAMBER after it has left the 45-70 case and not the barrel throat & leade where it should. Now you've got circa. 25,000 psi behind that bullet that is SQUUUUUEEZZZEEEDD back down to 0.458 when it leaves the chamber to be swaged into the throat. REMEMBER, the chamber is sized to fit the brass case & not the bullet. Let's add MINIMUM 0.010 either side for brass and another 0.002 either side so you can chamber a round. Let's call it 0.024 for sake of argument. So this bullet obturates from a sized diameter of 0.458 to (0.458 + 0.024 = 0.482) 0.482 and then when it hits the barrel leade it is SWAAAAAAAAGGGEEDD back down to 0.458. This is not good for your chamber nor accuracy in a rifle. Kirk Bryan does this for a living and adamantly tells customers NOT to do this. I'll take him at his word. 

[Delmonico]

The 45-2.1, 45-2.4 and the rest of that family are "NOT" straight cases, they are straight tapered cases, the 38/357 22 Short/22LR and others are straight cases. 

That is what makes it a bad idea.  Even if you don't damage the chamber you can get blow back and the case mouth expands far more than it needs to.

[john boy]

Kid - well said.  Thanks for filling the details with the dimensions and the swaging of the bullet.
And the bottom line still is ... Don't Do It!

[Mako]

The 45-2.1, 45-2.4 and the rest of that family are "NOT" straight cases, they are straight tapered cases, the 38/357 22 Short/22LR and others are straight cases. 

That is what makes it a bad idea.  Even if you don't damage the chamber you can get blow back and the case mouth expands far more than it needs to.

Delmonico,
While it is true that the .45 family is a tapered case you should remember your high school trigonometry.  There is only .295" difference in length between the two.  The base for both start at .505 and end at .480 at the mouth.  That translates to a .003" difference in diameters at the 2.105" length the .45-70 is with a constant taper from base to mouth.  You get more than that variation from one ammunition brand to another.  That argument doesn't hold water.  If your mouth can't obturate .003" then you have bigger problems than shooting "short" cases.

Also I'll bet you if you measure a "straight" walled .38 you will find most have larger bases than at the mouth.  Get your caliper out and measure any "straight" walled case and you will find they all have some taper.  Even more true with a reloaded case, the bases will always be larger.

According to printed materials such as the 4th edition of Cartridges of the World, "The .45-90 is practically identical to the .45-70, only longer. It is a common practice to fire .45-70 in these rifles when the proper ammunition is not available."  Not my words, Mr. Frank C. Barnes words.  Not everyone will agree with him, you might find yourself in that camp.

There are many facets to this diamond we call life,
Mako

[Mako]

Mako, Kirk gets asked this question several times each year. Let's ponder for a moment: when the bullet loaded in a 45-70 is fired in a 45-90 chamber what happens? The bullet obturates to the greatest possible size in the CHAMBER after it has left the 45-70 case and not the barrel throat & leade where it should. Now you've got circa. 25,000 psi behind that bullet that is SQUUUUUEEZZZEEEDD back down to 0.458 when it leaves the chamber to be swaged into the throat. REMEMBER, the chamber is sized to fit the brass case & not the bullet. Let's add MINIMUM 0.010 either side for brass and another 0.002 either side so you can chamber a round. Let's call it 0.024 for sake of argument. So this bullet obturates from a sized diameter of 0.458 to (0.458 + 0.024 = 0.482) 0.482 and then when it hits the barrel leade it is SWAAAAAAAAGGGEEDD back down to 0.458. This is not good for your chamber nor accuracy in a rifle. Kirk Bryan does this for a living and adamantly tells customers NOT to do this. I'll take him at his word. 

FCK,
While it is true you get some obturation, you won't get the full chamber diameter. There is only .295" difference in length which is only 64% of the caliber diameter.  The bullet doesn't leave the case, travel down the remaining portion of the chamber then finally enter the lead area.  With the longer bullets we use for long range rifles we have it in the case and in the lead at the same time even with the shorter case.  There is about .069" of lead at 12°45' from the .481 chamber to the .450 bore on the standard SAAMI .45-70 chamber spec.  I'm not sure what Shiloh Sharps uses.

I will agree it is not ideal, but 25KPSI on a barrel the girth of the Sharps is "nothing".  Erosion is primarily caused by particle and gas abrasion.  It is also the product of chemical reactions of the gases with the steel of the barrel.  Gale McMillan believes that's the primary factor in barrel throat erosion.  I'd have to say that Gale knows a thing or two about barrels.  The chemical reactions are with smokeless propellants, once again Black Powder comes out on the winning end in this one as it is relatively benign as far as reaction with the alloying elements in barrel steel.

Bob is known to be very "opinionated" I am not sure what the consensus about Kirk is.  No disrespect intended towards either of them, they make fine products and support shooters.

Regards,
Mako

[Fox Creek Kid]

Mako, you are correct in your length measurements. However, the front of the bullet will be swaged down while the rear is going through a rapid transition from 0.458 to circa. 0.482 which is not a good thing. I tried to keep this simple w/o mentioning what is known as bullet "finning" which happens in this situation. I had a rifle that did it. Accuracy was in the garbage as the "fin" created at the base of the bullet caused the projectile to "weather vane" as it went down range.

I have a rifle being rebarrelled as I type because the chamber is too long, cut by an out of spec reamer. It never shot worth a hoot. I got leading & bullet base finning upon examining fired bullets. Trust me, it doesn't work.

[Mako]

FCK,
I definitely believe you about the accuracy, and I'm sure that Kirk will tell people it's not a good idea.  I agree with both of you when it comes to fine or even decent performance from a nice Sharps .

Digger originally asked if it was possible to use .45-70 in the longer chamber and "would the dual chambering adversely affect the accuracy of the rifle?"  I took the question about ADVERSELY affecting accuracy to mean detrimental to the rifle itself, I believe that is how you took it as well.  I am of the opinion the effect on accuracy is transient if Black Powder is used, I believe your's and Kirk's is that it is long term.  I guess we can disagree on that.

Long term use of .38 spl in a .357 chamber is adverse if smokeless powder is used, but most of us would never know it.  The question is relative considering the audience and the purpose for which we use things. As I said before this is a Black Powder forum and at face value I still consider the answer to be "yes, you can shoot .45-70 in a Sharps chambered for .45-90, especially if you are using Black Powder."  Is it optimum?  Nope, but that wasn't the question.  Is it adverse to the accuracy?  Long term?  I guess it depends on who you ask.  For each shot? Yep, it will always be a substandard choice.

If we always agreed this would be a boring place.

Have a great week end,

Mako

[Delmonico]

Delmonico,
While it is true that the .45 family is a tapered case you should remember your high school trigonometry.  There is only .295" difference in length between the two.  The base for both start at .505 and end at .480 at the mouth.  That translates to a .003" difference in diameters at the 2.105" length the .45-70 is with a constant taper from base to mouth.  You get more than that variation from one ammunition brand to another.  That argument doesn't hold water.  If your mouth can't obturate .003" then you have bigger problems than shooting "short" cases.

Aceptable tolerances can make that a bit more.  But if you know a little chemistry and metalurgy, HS level again, you would realize that anytime you get less than a complete seal, you have highly oxidated hot gases going around and stiking the metal at around a 90 degree angle.  This removes a bit (read burns) of the steel each and everytime it happens.

This is what will ruin a chamber, would it do it with every gun, don't know, but in some situations it can happen.  Not my problem though becuause I won't do it.

[Jamie]

While wiser men with greater experience than I have answered the question more fully than I could, it might be worth a summation.  Obviously it is possible to shoot a 45-70 in a 45-90, so the real question that remains is why would you want to? If it was to save a hunt either because you failed to pack the ammo, had already shot all the ammo, or the airlines were collecting baggage for their own purposes, it would obviously be easier to come up with 45-70 ammo in a pinch.  On the other hand, even that might be a bust.  If you were just trying to save money with less powder, or cheaper brass, or to save your shoulder with less kick, it seems more reasonable to just buy a 45-70 in the first place. 
My dad would never shoot 22 shorts in his old Mossberg 46A because after a sparrow shooting foray with two boxes, he found that he couldn't chamber a long rifle.  A long time with a wire brush got the lead out of the front of the chamber that had built up, and he was back in business.  He decided that the savings wasn't worth the problem. 
A 38/357 or 44 Special/44Magnum situation is different, as others have observed in that the bullets themselves engage the rifling at the same time, regardless of the length of the case itself. Prior to the rifling they pass through the relatively less destructive chamber mouth and then enter the throat of the barrel. 
On a more historic note, I've read several times that the native Americans doing battle in the West, the Apaches in particular were prone to open up the chambers of their rifles in order to be able to shoot all straight cases of that caliber regardless of length.  It isn't hard to figure out why, is it?  Ammo supply was pretty limited for them.  Again, from what I've read, most of these "conversions" were a mistake as they rendered the gun impossible to reload due to expanding case mouths into inaccurately cut chambers. 
Really interesting responses - I learned alot, thanks guys!   

[Digger]

Really interesting responses - I learned alot, thanks guys!  

Hear, hear.  Second that.

Digger

[john boy]

OK, let me put one more nail in the coffin for the reason ... No
I have a 12ga SxS that I use for CAS shooting original gunpowder.  The chamber is reamed to shoot 2 3/4 and 3" shells.  Over repeated use shooting 2 3/4" shells, the chamber is now ringed on both barrels.  If you have never seen a ringed barrel, there are multiple etched circles in the steel before the reamed area where a 3" shell would end.  Apply the same concept of leaking gas shooting a 45-70 in a 45-90 chamber

[Mako]

OK, let me put one more nail in the coffin for the reason ... No
I have a 12ga SxS that I use for CAS shooting original gunpowder.  The chamber is reamed to shoot 2 3/4 and 3" shells.  Over repeated use shooting 2 3/4" shells, the chamber is now ringed on both barrels.  If you have never seen a ringed barrel, there are multiple etched circles in the steel before the reamed area where a 3" shell would end.  Apply the same concept of leaking gas shooting a 45-70 in a 45-90 chamber

John Boy,
Take this as it is meant, it's not meant to be condescending or insulting, but that makes absolutely no sense whatsoever...The exact same thing would happen to a 2 3/4" chamber.  Why would it be any different, explain that?  What is the difference between a 2 ¾" and 3" chamber?  I mean it literally, do you know the difference?  Is there some special feature we are unaware of?  Step back man and think about what you just said, think about it. The only difference between a 2 3/4" and 3" chamber is where the throat starts, there is no chamber step, no smaller "bore" diameter for the bullet to fit in.  It is a simple transition from the straight camber section including where the crimp opens directly to the slope of the throat and into the bore.

Match shotgun shooters all over the world have their throats pushed back, angles changed, chambers lengthened  which is just freebore added before the throat to give a gentler transition, lower pressures and improve patterns. And you are now telling us that their combined experience is wrong?  Elongating your chamber will cause erosion?  That's a new one to me.

You need to re-evaluate your hypothesis; it is seriously flawed and not supported by what shotgun smiths and clay shooters have accumulated in years of experience.

The "ringing" you see is not just caused by shorter shells in a longer chamber.  Furthermore the term "Ringed Barrel" actually means something.  It means you have a swell in the bore.  A permanent expansion of the walls that doesn't spring back.  This is not uncommon with steel shot loads in thin walled or older shotgun barrels.  I have seen ringed barrels, but they are not what you are describing.  What you are asserting is that you have erosion in your chamber.  I'll ask once again, if you get erosion in a 3" chamber, why wouldn't you in a 2 ¾" chamber?

And what is this, "Apply the same concept of leaking gas shooting a 45-70 in a 45-90 chamber"? There's no leaking gas, just as there is no leaking gas in a 3" chamber with 2 3/4" shells.  How did leaking gas become an issue with shotguns now?  The only argument that holds any water with the shorter rifle cartridge is the fact the bullet is not fully supported by a lead and throat in a longer chamber.  There is a definite step, the shell is Ø.480 and the bullet is Ø.458.  There is no such step with a shotgun chamber.

I'll see your one nail and raise you two pulled ones...

~Mako

[Ranch 13]

 Well speaking from experience. ( I have an Italian made rifle they either didn't chamber correctly or mis marked the barrel) You can shoot 45-70's with no disturbance to the gun.  How someever, accuracy will be not zactly what you'ld like after 10 or so rounds as the leading in the barrel will be severe. Going to a 462 diameter and hard alloy helps ,but not much.
You can easily load 70grs of 2f or Goex cartridge, a .030 wad and seat a Lyman postell or similar bullet to the driving band , and have firm contact with the powder, when the whole mess is stomped into Starline Brass. Leading will be eliminated, and recoil will be the same as shooting the 45-70.