.45LC +P in 1873 gun, cont'd
I'm bringing this up again, just to address some of the points raised by TSR in the last post on this.
Bottom line here is that nobody thinks its a good idea to use the so-called .45+P rounds in an 1873 replica carbine.
quote:TSR1965
My good friend, I think you need to research some more of the rocks and dynamite loads that are available from the high end factory loads like Double Tap, Buffalo Bore, and other's. They have energy figures near 454 Casull(standard loads). By no means should these be put in an 1873 Winchester, or any modern replica of it. To do so, could warrant a visit to you...professionally speaking. No sense in pushing the wire.
I don't make house calls. . . [;)]
Well, you're right that the Buffalo Bore and the like offer .44 magnum-like performance. I knew these loads were pretty stout, but I didn't realize quite how powerful they actually are!
In my opinion, calling .45LC rounds that operate at 25,000+ PSI "+P" is misleading to the point of being dangerous. By convention, ordinary +P rounds are only loaded to 10% higher pressures than similar non +P rounds, and they are supposed to be safe in modern guns. All of the SAAMI rated +P rounds are loaded this way. These "heavy" .45LC +P rounds are much more powerful than the convention, something that might not be obvious. It would be pretty easy to one of these hot rounds to accidentally get chambered in the "wrong" gun and cause a major problem.
Even so, these magnum .45LCs are still only operating at between 25,000-30,000 PSI as I indicated in the last post. Here is the reference you asked for:
quote:Double Tap:
http://www.doubletapammo.com/php/catalog/product_info.php?cPath=21_38&products_id=131
.45 Colt +P 255gr SWC Hardcast 50rds. $44.95
Using a Keith-style SWC hardcast bullet, this loading makes your .45 Colt a very effective hunting weapon. These loads are safe in all Ruger revolvers, BFR revolvers, TC Contender, Colt Anaconda, and Freedom Arms firearms. These loads are safe in all modern Model 1892 leverguns as well as all Winchester & Marlin 1894's. DO NOT USE IN ANY OTHER FIREARM. THESE ARE NOT STANDARD PRESSURE CARTRIDGES! Operating at 27,500PSI
Now Buffalo Bore's info:
Buffalo Bore: Heavy .45LC+P
Heavy .45 Colt +P Ammo - 300 gr. J.F.N. (1,325 fps/M.E. 1,170 ft. lbs.) - 50 Round Box - (Big Game up to 1000 lbs.)
These Heavy .45 Colt +P loads are safe in all LARGE FRAME Ruger revolvers. (includes Blackhawk, Super Blackhawk, all pre-2005 Vaquero, Bisley, Redhawk)
These Heavy .45 Colt +P loads are NOT intended for the New Model Vaquero (small frame).
These loads are also safe in all modern Model 1892 leverguns
as well as all Winchester & Marlin 1894's
So I don't have a pressure quote on the Buffalo Bore rounds, but I think its probably fair to say that with similar ballistics, they're operating at fairly similar pressures.
Note that the true .454 Casull is SAAMI rated at *65,000* PSI and is significantly more powerful than .44 magnum.
I don't see how its possible to get comparable ballistic performance as a .454 running at 65,000 PSI from a similar .45LC round operating at only 27,500 PSI. The only way that can be true is if you're comparing the .45LC+P to fairly watered-down .454 rounds.
In any case, since the manufacturers of this ammo give a short list of guns that they say are OK with this ammo, and the 1873 replica isn't on that list, I'd say that's a pretty good reason not to try it!
Repeating myself from the last post, even if these guns might withstand the pressures, I wouldn't try it, and I don't see any good reason to take a chance. If you want that sort of ballistics, there are plenty of guns out there that can handle this ammo.
Being Devil's advocate, I'm not convinced that one round of 27,500PSI .45LC+P is necessarily going to instantly detonate a modern gun capable of handling 35,000PSI .357s, that's all. If the gun design can actually handle .357s, then it necessarily has to be fairly tough, and probably quite a bit tougher than the original 1873 guns.
quote:The reason they get away with the 357 Magnum, is this thing called force, or thrust. There is not as many square inches of surface area in a 357 as a 45 Colt or 44 Magnum. All that PSIG is converted back into force when it meets surface area to do so. The 1892 design is much more robust than the 1873.
So you raise two different issues here.
Addressing the second one first, yes, the 1892 and 1894 gun designs are far stronger, and per the +P ammo manufacturers, its OK to use the .45LC+P in those rifles. That's the way to go if you want more oomph from a .45LC gun.
On pressures, back to elementary physics, pressure = force/area. Reversing that, force = pressure x area.
Since a .45 chamber is larger than a .357, as you say it will have a larger surface area. Therefore, at any given chamber pressure, the walls of a .45 will experience a greater peak force in pounds than a .357.
The problem with this blanket statement is that, as above, the pressures we're comparing aren't equal.
For illustration purposes, lets estimate the ACTUAL forces involved. I think its fair to say that as a pretty close approximation, the surface area of a chamber wall is going to be equal to the external surface area of the cartridge.
Since both .45LC and .357 magnum cartridges are straight-walled, we can get a pretty good estimate of the cartridge wall surface areas just by taking the circumference of the cartridge (IE Pi x the diameter) multiplied by its length.
So, the .357 cartridge is .379" wide and 1.29" long. Crunching numbers the .357 chamber should be (3.1416)(.379)(1.29)= 1.536 square inches. Multiplied by 35,000PSI yields 53,760 pounds of peak force on the chamber walls.
45LC is .480" wide and 1.285" long. Therefore the .45 chamber is (3.1416)(.480)(1.285) = 1.938 square inches in area. Multiplied by 27,500 PSI yields 53,287 pounds of peak force.
In short the peak force on the chamber walls from a max-loaded .357 and the Double-tap .45LC+P should be virtually identical.
Biggest practical difference, I think, is that because the .357 cartridge is narrower, the thickness of its chamber is likely to be greater, and the increased amount of steel in the thicker .357 chamber wall should mean more resistance to force.
I can't speak to the quality of steel involved, but it might also be possible that the .357 is built out of hardened or tougher steel compared to the .45LC as well.
So those are probably the reasons why Chaparral arms can "get away" with an 1873 carbine in .357 magnum.
Bottom line here is that nobody thinks its a good idea to use the so-called .45+P rounds in an 1873 replica carbine.
quote:TSR1965
My good friend, I think you need to research some more of the rocks and dynamite loads that are available from the high end factory loads like Double Tap, Buffalo Bore, and other's. They have energy figures near 454 Casull(standard loads). By no means should these be put in an 1873 Winchester, or any modern replica of it. To do so, could warrant a visit to you...professionally speaking. No sense in pushing the wire.
I don't make house calls. . . [;)]
Well, you're right that the Buffalo Bore and the like offer .44 magnum-like performance. I knew these loads were pretty stout, but I didn't realize quite how powerful they actually are!
In my opinion, calling .45LC rounds that operate at 25,000+ PSI "+P" is misleading to the point of being dangerous. By convention, ordinary +P rounds are only loaded to 10% higher pressures than similar non +P rounds, and they are supposed to be safe in modern guns. All of the SAAMI rated +P rounds are loaded this way. These "heavy" .45LC +P rounds are much more powerful than the convention, something that might not be obvious. It would be pretty easy to one of these hot rounds to accidentally get chambered in the "wrong" gun and cause a major problem.
Even so, these magnum .45LCs are still only operating at between 25,000-30,000 PSI as I indicated in the last post. Here is the reference you asked for:
quote:Double Tap:
http://www.doubletapammo.com/php/catalog/product_info.php?cPath=21_38&products_id=131
.45 Colt +P 255gr SWC Hardcast 50rds. $44.95
Using a Keith-style SWC hardcast bullet, this loading makes your .45 Colt a very effective hunting weapon. These loads are safe in all Ruger revolvers, BFR revolvers, TC Contender, Colt Anaconda, and Freedom Arms firearms. These loads are safe in all modern Model 1892 leverguns as well as all Winchester & Marlin 1894's. DO NOT USE IN ANY OTHER FIREARM. THESE ARE NOT STANDARD PRESSURE CARTRIDGES! Operating at 27,500PSI
Now Buffalo Bore's info:
Buffalo Bore: Heavy .45LC+P
Heavy .45 Colt +P Ammo - 300 gr. J.F.N. (1,325 fps/M.E. 1,170 ft. lbs.) - 50 Round Box - (Big Game up to 1000 lbs.)
These Heavy .45 Colt +P loads are safe in all LARGE FRAME Ruger revolvers. (includes Blackhawk, Super Blackhawk, all pre-2005 Vaquero, Bisley, Redhawk)
These Heavy .45 Colt +P loads are NOT intended for the New Model Vaquero (small frame).
These loads are also safe in all modern Model 1892 leverguns
as well as all Winchester & Marlin 1894's
So I don't have a pressure quote on the Buffalo Bore rounds, but I think its probably fair to say that with similar ballistics, they're operating at fairly similar pressures.
Note that the true .454 Casull is SAAMI rated at *65,000* PSI and is significantly more powerful than .44 magnum.
I don't see how its possible to get comparable ballistic performance as a .454 running at 65,000 PSI from a similar .45LC round operating at only 27,500 PSI. The only way that can be true is if you're comparing the .45LC+P to fairly watered-down .454 rounds.
In any case, since the manufacturers of this ammo give a short list of guns that they say are OK with this ammo, and the 1873 replica isn't on that list, I'd say that's a pretty good reason not to try it!
Repeating myself from the last post, even if these guns might withstand the pressures, I wouldn't try it, and I don't see any good reason to take a chance. If you want that sort of ballistics, there are plenty of guns out there that can handle this ammo.
Being Devil's advocate, I'm not convinced that one round of 27,500PSI .45LC+P is necessarily going to instantly detonate a modern gun capable of handling 35,000PSI .357s, that's all. If the gun design can actually handle .357s, then it necessarily has to be fairly tough, and probably quite a bit tougher than the original 1873 guns.
quote:The reason they get away with the 357 Magnum, is this thing called force, or thrust. There is not as many square inches of surface area in a 357 as a 45 Colt or 44 Magnum. All that PSIG is converted back into force when it meets surface area to do so. The 1892 design is much more robust than the 1873.
So you raise two different issues here.
Addressing the second one first, yes, the 1892 and 1894 gun designs are far stronger, and per the +P ammo manufacturers, its OK to use the .45LC+P in those rifles. That's the way to go if you want more oomph from a .45LC gun.
On pressures, back to elementary physics, pressure = force/area. Reversing that, force = pressure x area.
Since a .45 chamber is larger than a .357, as you say it will have a larger surface area. Therefore, at any given chamber pressure, the walls of a .45 will experience a greater peak force in pounds than a .357.
The problem with this blanket statement is that, as above, the pressures we're comparing aren't equal.
For illustration purposes, lets estimate the ACTUAL forces involved. I think its fair to say that as a pretty close approximation, the surface area of a chamber wall is going to be equal to the external surface area of the cartridge.
Since both .45LC and .357 magnum cartridges are straight-walled, we can get a pretty good estimate of the cartridge wall surface areas just by taking the circumference of the cartridge (IE Pi x the diameter) multiplied by its length.
So, the .357 cartridge is .379" wide and 1.29" long. Crunching numbers the .357 chamber should be (3.1416)(.379)(1.29)= 1.536 square inches. Multiplied by 35,000PSI yields 53,760 pounds of peak force on the chamber walls.
45LC is .480" wide and 1.285" long. Therefore the .45 chamber is (3.1416)(.480)(1.285) = 1.938 square inches in area. Multiplied by 27,500 PSI yields 53,287 pounds of peak force.
In short the peak force on the chamber walls from a max-loaded .357 and the Double-tap .45LC+P should be virtually identical.
Biggest practical difference, I think, is that because the .357 cartridge is narrower, the thickness of its chamber is likely to be greater, and the increased amount of steel in the thicker .357 chamber wall should mean more resistance to force.
I can't speak to the quality of steel involved, but it might also be possible that the .357 is built out of hardened or tougher steel compared to the .45LC as well.
So those are probably the reasons why Chaparral arms can "get away" with an 1873 carbine in .357 magnum.
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Excellent summary (to original post). I've always been an advocate of the total surface area of the pressure as an important aspect. Also happy to see that you've brought up the greater amount of steel (in the same firearm) in a .357 vs. 45 chambering.
Sidenote: Buffalo Bore didn't (wouldn't?) get back to me vis-a-vis my question regarding the use of their +P .45Colt cartridges in my replica Colt Lightning rifle.
Open question: would the Colt Lightning (modern steel reproduction-Taurus) be about the same strength as the 1892 Winchesters?
Thanks, Joe0 -
Actually the part that is most detrimental in the process is the FORCE on the breech face. With the surface area of the 357 compared to the surface area of the 45 Colt, against the breech face, that is the force being applied to the action itself, not just the chamber area. It is the force that is being applied against the lock up mechanism. Much like the Thompson Center Contender versus the Encore. They did not chamber 308, 243, 30-06 head sized rounds in the Contender, because there was too much force or thrust on the breech face. The Encore has a lot more meat back there to suck up the extra thrust provided by those rounds. Yes, there were larger diameter rounds chambered in the Contender, but they had much lower pressures. Same applies to the 1873 action, as it has no dual vertical locking bolts to engage the breech bolt. It has just the toggle link.
Hope this makes sense for you two.
Beany, your formula for surface area is a bit incorrect. It is Pi x radius x radius. Not that it makes a difference in this case,as we are talking about force against the breech face, not the whole surface area of the chamber.
Best0 -
For Joe, I don't know the answer to your question about the Colt Lightning.
quote:Originally posted by tsr1965
Actually the part that is most detrimental in the process is the FORCE on the breech face.
No argument. I agree that breech locking strength probably is the true limiting factor here, rather than absolute metal strength of the chamber.
But by the exact same principles, if the breech of this rifle is strong enough to handle a full tilt .357 magnum round at 35k psi it "should" also be strong enough for .45LC+P at 27.5k psi. How do I know this with no math?
Pascal's law states that pressure transmitted within a fluid is transmitted equally throughout the fluid in all directions.
In this case, the "fluid" is the expanding gas within the cartridge case. So the pressure exerted to the rear of the chamber is going to be identical to the pressure exerted on the chamber wall. It should also be identical to the pressure exerted on the base of the bullet.
Note that we are talking about PEAK pressures here. The overall pressure curves of a .357 and .45LC+P are necessarily different (if they were identical, the .45LC+P wouldn't be more powerful), but the key consideration in gun strength is its ability to withstand the momentary peak pressure.
Anyway, since I've already shown that the force on the SIDE of the chambers is similar between the .45LC+P and the .357, and since I believe that the cartridge rims are roughly proportionate in diameter between the two cases, then I can estimate that the peak forces operating on the two cartridge bases should be fairly similar as well.
But why guess. . .lets do the math. . .
Base of .357 case = 0.440" diameter
Area of base of .357 case = (Pi)(D/2)^2 = 0.1521 sq. inches.
Force = pressure x area = 35,000 x 0.1521 = 5323.5 lbs.
Base of .45LC case = 0.512" diameter
Area of base of .45LC case = 0.2058 sq inches.
Force = 27,500 x 0.1000 = 5659 lbs.
So the .45LC+P should exert only about 6% more force on the back of the breech, and I'd say that's roughly comparable.
As a minor consideration, I'm not 100% sure that the force is truly transmitted through the ENTIRE case rim. Since for example, the pressure doesn't actually enter the solid part of the rim, that solid part might realistically just be considered "along for the ride". If you were to factor this out (say using inner case diameter as a substitute for case rim diameter), I think you'd find that the two rounds were even closer in rearward forces. I'll leave the calculation here as an exercise for the reader! [}:)]
That quibble aside, and again being Devil's advocate, I'd say that *IF* this rifle can truly handle full tilt .357s, then I don't see why it would instantaneously "kaboom" from .45LC+P loads which exert nearly identical peak internal forces.
Now, that said, the fact is that there are some guns labelled ".357 magnum" that in reality can't handle .357 magnum rounds in quantity, let alone full tilt .357 loads operating at max SAAMI pressure.
In this particular case of a 19th century design originally intended to run black powder rounds at 15,000 PSI (or less) I'm actually a bit skeptical about its safety and durability running .357 loads. So while "on paper" a similar gun in .45LC should be able to handle the +P rounds, in practice. . .I'm not that comfortable.
There is a difference, also, in a gun being able to fire ONE high-pressure round, and 1000 of them. Even if the gun could safely handle a few .45LC+P rounds, that sort of pounding just CAN'T be good for it.
quote: With the surface area of the 357 compared to the surface area of the 45 Colt, against the breech face, that is the force being applied to the action itself, not just the chamber area.
See above.
quote:Beany, your formula for surface area is a bit incorrect. It is Pi x radius x radius.
I like the tactful way you say "a bit incorrect". That's like "a bit pregnant". [;)] In this case, I don't think I'm pregnant. . .
Pi x the square of the radius will yield the area of a two dimensional circle. So if you wanted to calculate JUST the surface area of a cartridge base (like I did above) then yes, the formula you listed would be correct.
On the other hand, to compute the surface area of the SIDE of a THREE DIMENSIONAL CYLINDER (which is what I did to estimate the chamber wall surface area), you need to multiply the CIRCUMFERENCE of the cylinder (ie Pi x D, or alternatively Pi x 2r) by its overall length.
So I think I did use the correct formula to prove the point I wanted to make above.
quote:
Not that it makes a difference in this case,as we are talking about force against the breech face, not the whole surface area of the chamber.
Well, again, assuming the two cartridges are roughly proportionate in shape (and they are), then the peak forces against the side and rears of the respective chambers should also be roughly proportionate.0 -
In all honesty, I really think that those advertised pressure's are not realistic. The performance level being attained, they have to be higher. Plus, it is the dwell time of the pressure on the pressure curve. To attain that performance, they have to be using a ton of slow burning powder, to apply higher pressures over an extended amount of time. Then you can also argue, you only have so much time in a short barreled handgun, but when that is applied to a 22-24 inch rifle barrel, the dwell time is much longer.
Best0 -
quote:Originally posted by tsr1965
In all honesty, I really think that those advertised pressure's are not realistic.
Its a very good question.
I don't know exactly how double-tap came up with its published pressure figure of 27500PSI. but I'd actually be fairly surprised if if that number were NOT pretty close to the true peak operating pressure (ie within a few percent).
Again, I got a separate reference estimating roughly the same operating pressure independently.
I also think the companies that make this ammo necessarily have a pretty good idea of what pressures their rounds put out (if not an exact measurement), and roughly how strong the common make guns are in terms of what actual pressures they can handle.
Double-tap would potentially be opening itself up to serious liability if it significantly understated the operating pressure of its rounds. There is no reason why the company has to publish that number; neither Grizzly nor Buffalo Bore do for their respective versions of the .45LC+P round.
So I think its fair to say that Double-tap didn't just pull the number from you-know-where. There is zero reason to lie about it or make up a number, and quite a few good reasons NOT to do that. Either they directly measured it, or they extrapolated it based on burn rates, measured velocities, and/or other data.
I believe that one of the reasons you can get better-than-expected performance from .45LC at low pressures is because the case was designed for black powder rounds and is cavernously huge. The larger case volume of .45LC vs .44 magnum lets you get similar ballistics at lower operating pressures.
This is sort of the natural inverse of shrinking down a .45LC case and increasing the pressure to get the same ballistics, namely the .45ACP!
I'm also pretty sure that Buffalo Bore and the like use special proprietary (ie not available to the general public) powders to maximize pressure/time curves while keeping peak pressures low. I know as a fact that CorBon has been using these for some time.
For example, Buffalo bore in particular has a .45LC load it explicitly states is absolutely within SAAMI spec (ie 14k psi) and that should be safe in ANY post-war .45LC gun, that launches a 255 grain bullet at 1000 fps from an ordinary revolver. Note that THIS load is quite a bit better than an ordinary .45LC factory load, and it *SHOULD* be safe in an 1873 replica carbine!
Anyway, is it so crazy to think that if you were to exactly double the peak operating pressure (from 14 to 28000 psi) you should be able to get exactly double the muzzle energy? In this case doubling the muzzle energy of a 255 grain bullet at 1000 fps would require increasing the velocity by 41% to 1410 fps.
And. . .surprise. . .Buffalo bore also sells a 260 grain "heavy .45LC +P" that is supposed to do 1450 fps. So that is effectively 100% more energy (or very slightly more) and still potentially within our guesstimate pressure range for the .45LC+P of 30k psi or less.
quote:The performance level being attained, they [pressures] have to be higher.
Well, I don't think they do, that's the point.
Again, the key is a combination of a large case volume (that reduces operating pressures) plus special powders that work at lower pressures.
Remember, by ITSELF the peak pressure isn't a good measure of performance. What really matters is the total force exerted on the bullet base. That's going to be proportionate to the area under the curve of time vs. chamber pressure.
That curve is going to be dependent on several things, but probably the single most important factor is the burn characteristics of the specific powder used.
Its not just that the powder has to be slow-burning, but that the burn characteristics have to be exactly matched to the load and round for optimal performance. I bet that Buffalo Bore, Double-tap, etc did quite a bit of experimentation with powders and primers before they optimized these rounds for commercial sale. In short, these companies are specifically tuning the rounds to get maximum performance at specific pressure levels.
As another relevant consideration, these rounds probably SEEM hotter than they are for their pressures, because you're mentally comparing them to the ballistics from factory loads and published reloads, both of which are probably watered down a good bit from theoretical SAAMI max loads for a variety of reasons.
quote:
Plus, it is the dwell time of the pressure on the pressure curve. To attain that performance, they have to be using a ton of slow burning powder, to apply higher pressures over an extended amount of time. Then you can also argue, you only have so much time in a short barreled handgun, but when that is applied to a 22-24 inch rifle barrel, the dwell time is much longer.
I think you're saying essentially the same thing as I did above, that the key is not the peak pressure in particular, its the total pressure x time its acting. Or more precisely, since the absolute pressure varies with time, its the area under the curve of pressure vs. time.0
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