Bryan Austin
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.45 Colt Chamber Pressure for Model 25
- Thread starter TheTinMan
- Start date
AJ
US Veteran
That is what I was trying to say in my original ost. But others told me that I was wrong. Post #2, maybe I worded it wrong?
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OP
There is one difference that 44MAG N-frames have that not all N-frames have & that's the bolt block added as part of the Endurance Package to keep the cylinder from unlocking & rotating back a chamber under recoil.
I've not made a full inventory check for this feature on all of my N-frames but while I do know that my modern 41MAGs (57/357/657) also have this I can say that my .45s & 10AUTO N-frames do not.
So far I haven't remembered to check my .357s while they were apart to verify them.
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329PD bolt block - disengaged
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329PD bolt block - engaged
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I don’t want to beat a dead horse but do want to clarify when and in what models this “bolt block” mechanism was added. Am I correct in thinking now that it was not part of the endurance package introduced with the 29-3E/629-2E? If so when did appear?
Any production line set up to run garbage one day, and good stuff the next, would eventually only produce garbage, and the company would go out of business.
I would think as long as the recoil shield is hard enough not to deform due to cartridge pressure, that's probably all the hardness needed for the frame. Raising hardness reduces the fatigue life of a part. Each round fired, stretches the frame, but since the material is in the yield range, that's not a problem. Only becomes an issue when the fatigue life is low, because frame cracking would be a problem.
I will also state, if someone wants 454 Casull performance, go buy a pistol built for a 454 Casull. Trying to find the design limits on something that was never designed or built for a high pressure cartridge, its your money. And you are free to do whatever you want. So blast away, and see what happens.
I ain't going to do it.
No one is looking for 454 Casull performance. Just stepping up the MODERN 45 Colt to moderate pressure levels. Going from 750fps to 1000fps with a 255 slug with the colt. A 454 Casull moves a 260 gt out at 1800 fps Big difference
Endurance Package
The Endurance Package came in segments, on succeeding revisions, for the 44 Magnums that provoked the change. It consisted of five significant changes as detailed in the attached articles: -1) yoke bearing surface increased, -2) yoke heat treated, -3) radius stud package, -4) longer cylinder stop notches, and -5) the bolt block.
As already mentioned it's apparent not all of the features are applied to all caliber/cartridge N-frames, namely the bolt block.
While I strongly suspect all of the others are I can tell you that the longer stop notches are oddly not on my 45ACP Performance Center 625-8, mfd. Feb-2016.
The cylinder on this model is unique to it & is not the standard length as other 45ACP revolvers, it being ~1/8" shorter. Why the stop notch difference is anybody's guess though.
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Handloader# 241 excerpt:
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John Taffin "Book of the 44", excerpts between the red lines
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625PC with standard length cylinder stop notches (not Endurance Pkg length)
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The Endurance Package came in segments, on succeeding revisions, for the 44 Magnums that provoked the change. It consisted of five significant changes as detailed in the attached articles: -1) yoke bearing surface increased, -2) yoke heat treated, -3) radius stud package, -4) longer cylinder stop notches, and -5) the bolt block.
As already mentioned it's apparent not all of the features are applied to all caliber/cartridge N-frames, namely the bolt block.
While I strongly suspect all of the others are I can tell you that the longer stop notches are oddly not on my 45ACP Performance Center 625-8, mfd. Feb-2016.
The cylinder on this model is unique to it & is not the standard length as other 45ACP revolvers, it being ~1/8" shorter. Why the stop notch difference is anybody's guess though.
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Handloader# 241 excerpt:
.
.
.
.
John Taffin "Book of the 44", excerpts between the red lines
.
.
.
625PC with standard length cylinder stop notches (not Endurance Pkg length)
.
.
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Some Thoughts on the .45 Colt
Everything I've read says cylinders fail at the cylinder lock notch, due to there being very thin metal there. When the cylinder fails, the top strap fails as well.
14,000 psi vs 23,000 psi (pressure limits on .45 Colt and .45 Auto). The .45 Auto is 0.04" smaller in case base diameter than the .45 Colt, so the bottom of the cylinder notch may be 0.02" thicker in the .45 Auto cylinder than in the .45 Colt cylinder, or 7%. The argument for using the .45 Colt at .45 Auto pressures may break down a bit due to this.
The .45 Colt pressure limit is low because pre-1900 revolvers lacked "modern steel." So it seems to follow that using modern steel with greater tensile strength will permit higher pressure loads. The tensile strength for "modern steels" varies by far more than a factor of two, depending on treatment. So its possible that better steel will support a greater pressure limit. It's also possible that a stronger steel may be used on .44 Mags or .45 Autos than on .45 Colts (or not).
Mr. Linebaugh's words comparing the relative performance of .45 Colt and .44 Mag are true.
Bryan Pearce's experience with the .45 Colt revolvers carries great weight. I do believe that any modern .45 Colt revolver taken to 23,000 psi will survive, safely. For 20 years, my Father shot 9 gr Unique w/ 260 gr KT semiwadcutter in his 1939 SAA. I have the gun. It's pretty loose compared to a new SAA, and that may be because the load overstressed it, or just because its a Colt with softer part steel. The load came from Phil Sharp, and like most of his loads tended to push things.
A revolver will usually be proof-tested at something like 2 times its book pressure. So the question would appear to be more wear and tear than failure. Though that takes us right back to Elmer Keith's early experiments, where he tested quite a few .44 Spls, to failure.
You are undoubtedly safe at 14,000 psia for the .45 Colt. You're likely safe at 23,000, though you may wear your gun a bit with prolonged use. Modern Colts and S&Ws probably ought not be loaded to pressures exceeding 23,000 psi.
The final point is: why? A .45 Colt 260 gr at 960 fps may be had at about 14,000 psi. My Father shot a 2000 lb horse through both shoulders with one; the factory load stopped at the skin on the opposite side, his handload penetrated completely and he found it stuck in the fence plank beyond. This is a lot of penetration and very good performance. With a proper bullet and placement, it will stop a charging grizzly. What more is needed from a sidearm?
Everything I've read says cylinders fail at the cylinder lock notch, due to there being very thin metal there. When the cylinder fails, the top strap fails as well.
14,000 psi vs 23,000 psi (pressure limits on .45 Colt and .45 Auto). The .45 Auto is 0.04" smaller in case base diameter than the .45 Colt, so the bottom of the cylinder notch may be 0.02" thicker in the .45 Auto cylinder than in the .45 Colt cylinder, or 7%. The argument for using the .45 Colt at .45 Auto pressures may break down a bit due to this.
The .45 Colt pressure limit is low because pre-1900 revolvers lacked "modern steel." So it seems to follow that using modern steel with greater tensile strength will permit higher pressure loads. The tensile strength for "modern steels" varies by far more than a factor of two, depending on treatment. So its possible that better steel will support a greater pressure limit. It's also possible that a stronger steel may be used on .44 Mags or .45 Autos than on .45 Colts (or not).
Mr. Linebaugh's words comparing the relative performance of .45 Colt and .44 Mag are true.
Bryan Pearce's experience with the .45 Colt revolvers carries great weight. I do believe that any modern .45 Colt revolver taken to 23,000 psi will survive, safely. For 20 years, my Father shot 9 gr Unique w/ 260 gr KT semiwadcutter in his 1939 SAA. I have the gun. It's pretty loose compared to a new SAA, and that may be because the load overstressed it, or just because its a Colt with softer part steel. The load came from Phil Sharp, and like most of his loads tended to push things.
A revolver will usually be proof-tested at something like 2 times its book pressure. So the question would appear to be more wear and tear than failure. Though that takes us right back to Elmer Keith's early experiments, where he tested quite a few .44 Spls, to failure.
You are undoubtedly safe at 14,000 psia for the .45 Colt. You're likely safe at 23,000, though you may wear your gun a bit with prolonged use. Modern Colts and S&Ws probably ought not be loaded to pressures exceeding 23,000 psi.
The final point is: why? A .45 Colt 260 gr at 960 fps may be had at about 14,000 psi. My Father shot a 2000 lb horse through both shoulders with one; the factory load stopped at the skin on the opposite side, his handload penetrated completely and he found it stuck in the fence plank beyond. This is a lot of penetration and very good performance. With a proper bullet and placement, it will stop a charging grizzly. What more is needed from a sidearm?
This thread is interesting. I appreciate the technical data, and own a M25-5 (with correct throats and perfect blueing). I also have a newer flattop NM Blackhawk in .45LC on the mid-size frame. My experience is that both revolvers will shoot a 255-260 gn cast bullet over 8.5 gn of Unique or BE-86 without any short term problem. This feels like a Tier 2 load, though I have seen various tables that show it to be something else. On the other hand, it is not a fun load to shoot in either revolver, and I stay at 8.0 gn of Unique (or BE-86) in these two guns. I bought a large frame NM Blackhawk in .45 LC, and replaced the grip frame with a steel frame, to shoot the 8.5 gn load. It is a heavier gun, with a larger grip than the flattop. No qualms.
The 8.0 charge under a 255 gn cast .45LC bullet is still a heck of a lot of gun, for hunting, target or self defense. Loading an 1873 bullet to .44 magnum levels is interesting in an academic way. But as a 71 y/o retired guy, I cannot afford to buy another M25, so I want to be careful of this one. I also have two beautiful Model 15-4s. I baby those, too, for the same reason. But your guns, your loads.
I am not able to do more than put my blind faith in the technical data here (not an engineer), but noticed that it was not expressed in powder, bullets, and weights; rather as units of pressure and thickness of steel. But in terms of recoil, the .45LC tells me not to try and prove anything in my nicer revolvers, and to accept it for what it is - a historic 1873 cartridge that still gives good service. I cast these bullets in a Lyman Keith mold, tumble lube with hoarded Johnson's floor wax (LOL), use a powder that Phil Sharpe used before my father was born, in one of the most beautiful revolvers made, and feel blessed to do so.
The 8.0 charge under a 255 gn cast .45LC bullet is still a heck of a lot of gun, for hunting, target or self defense. Loading an 1873 bullet to .44 magnum levels is interesting in an academic way. But as a 71 y/o retired guy, I cannot afford to buy another M25, so I want to be careful of this one. I also have two beautiful Model 15-4s. I baby those, too, for the same reason. But your guns, your loads.
I am not able to do more than put my blind faith in the technical data here (not an engineer), but noticed that it was not expressed in powder, bullets, and weights; rather as units of pressure and thickness of steel. But in terms of recoil, the .45LC tells me not to try and prove anything in my nicer revolvers, and to accept it for what it is - a historic 1873 cartridge that still gives good service. I cast these bullets in a Lyman Keith mold, tumble lube with hoarded Johnson's floor wax (LOL), use a powder that Phil Sharpe used before my father was born, in one of the most beautiful revolvers made, and feel blessed to do so.
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The three-tier approach to .45 Colt loads generally works. Except that there is not a lot of readily available data for the Tier-2 loads, which would be appropriate for the S&W revolvers.
There is data out there in a number of magazines and online articles, but I say it’s not readily available as I have never seen any of this mid-range data in a published reloading manual. Searching through years of articles is not the same as just flipping through a book to a section that would be found between Colt SAA loads and “Ruger Only” loads.
Some manuals list pressures for their min & max loads. However, I have not seen manual listing a range of pressures for any given bullet/powder. The min/max pressures can be used as a general guideline, but keep in mind the progression of pressure increase to powder charge is not going to be linear.
Similarly, there are a few computer models that can estimate chamber pressures for a given load. But again, these only provide estimates.
This is not to say one should not use this info and work up carefully. Just noting some of the potential shortcomings with this approach.
I have an M25-15 that generally only sees Tier-1 loads. I have other revolvers that are capable of safely handling higher pressures. But if I didn’t, I would not be uncomfortable loading somewhere between the published SAA-appropriate loads and the Ruger-only loads.
There is data out there in a number of magazines and online articles, but I say it’s not readily available as I have never seen any of this mid-range data in a published reloading manual. Searching through years of articles is not the same as just flipping through a book to a section that would be found between Colt SAA loads and “Ruger Only” loads.
Some manuals list pressures for their min & max loads. However, I have not seen manual listing a range of pressures for any given bullet/powder. The min/max pressures can be used as a general guideline, but keep in mind the progression of pressure increase to powder charge is not going to be linear.
Similarly, there are a few computer models that can estimate chamber pressures for a given load. But again, these only provide estimates.
This is not to say one should not use this info and work up carefully. Just noting some of the potential shortcomings with this approach.
I have an M25-15 that generally only sees Tier-1 loads. I have other revolvers that are capable of safely handling higher pressures. But if I didn’t, I would not be uncomfortable loading somewhere between the published SAA-appropriate loads and the Ruger-only loads.
Chuck Taylor did a series of books where he tested guns in Alaska. I was surprised as he used Ruger loads in his test of the 25-5 and had no problems. I would however expect it would contribute to frame stretch and other problems.
I have pin gauges and have found that initial portion of S&W 45 ACP chambers are the same dia as 45 colt chambers for all intents and purposes. Interestingly they both can vary by .001
The notch is the week point, BUT, the length of the notch also comes into play. The wider or longer the notch the greater the unsupported area surrounding it. An endurance package cylinder is weaker than the earlier cylinders simply because of the longer notch. Don't think so? Try making the notch the full length of the cylinder and see what happens. S&W engineers were well aware of this FACT when they made the chances and did it anyway because they KNEW the cylinder would still handle it.
There is no way a 45 colt frame will suffer frame stretch at 25,000psi and a 44 mag firing rounds at 36,000 won't . It is silly to even believe that. Both will eventually shoot loose. But only after about spending a lot more for ammo (even reloading) that the value of the gun. 10,000 rounds x 10 cents is $1000. Then a shim or 2 and barrel set back might be in order and your forcing cone will probably need it anyway
The notch is the week point, BUT, the length of the notch also comes into play. The wider or longer the notch the greater the unsupported area surrounding it. An endurance package cylinder is weaker than the earlier cylinders simply because of the longer notch. Don't think so? Try making the notch the full length of the cylinder and see what happens. S&W engineers were well aware of this FACT when they made the chances and did it anyway because they KNEW the cylinder would still handle it.
There is no way a 45 colt frame will suffer frame stretch at 25,000psi and a 44 mag firing rounds at 36,000 won't . It is silly to even believe that. Both will eventually shoot loose. But only after about spending a lot more for ammo (even reloading) that the value of the gun. 10,000 rounds x 10 cents is $1000. Then a shim or 2 and barrel set back might be in order and your forcing cone will probably need it anyway
grice
Member
Yes they are!
Outpost75
Member
People don't understand that the 23,000 figure for .45 ACP+P is NOT a machine loading limit, but represents the maximum probable individual pressure or PMax, defined as the sample mean X-bar plus 3 standard deviations. X-bar+3 Sigma.
Unless a load has excellent MEASURED (not a Quickload estimate) ballistic uniformity you should limit loads to pressure tested data from powder and bullet manufacturers which do not exceed 20,000 psi. Heavier loads are not "dangerous" when used in moderation, but WILL accelerate wear, impairing reliability, maintainability and durability.
In revolvers barrel-cylinder gap has as much influence on velocity as barrel length. In cartridges similar to .38 Special or .45 ACP loaded with faster burning powders similar to Bullseye, TiteGroup, 231, WST the expected Delta-V is about 10 fps for each 0.001" change in B-C gap from Mean Assembly Tolerance. A 4-inch gun at minimum pass 0.004/ hold 0.005 will likely produce higher velocity than a 6-inch gun at maximum pass 0.008 / hold 0.009". These days S&W does not repair an OFG ( open front gage) up to 0.010" - they ship'em.
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