I was reading the data in Spear #8 (1970) reloading manual and the question comes up re the strength of the acp re the ar. It has been stated in a recent post that they are identical.

The load data in Spear #8 is:
240gr lead/8.0 gr Unique max in the AR
230 gr lead/7.0 gr Unique max in the ACP
The manual mentions nothing about pressure.
Compare that with more recent manuals!!!!!

I rather suspect the difference is the application, revolver vs semi-auto rather than shell strength.

If you shoot an ACP revolver and want more poot this sure will put more lead in you pencil.

Bob

7 or 8 grains of Unique with the bullets indicated would be quite a hand full. I find that 6-6.2 grains of Unique and a 225 grain cast bullet gives 875 +- fps from auto or 1917 with either cartridge case. Enough for me.

Those loads are considerably higher than what is listed in Speer #14. I imagine the formulation for Unique may have changed over the years.

I think either case can handle the max pressure SAAMI gives for .45 ACP. Speer may have reduced these loads for lead bullets due to complaints about leading. I notice they have more powder in the loads they list for Unique/230 gr. jacketed bullets in #14, but still not up to the levels you quote from #8.

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You're shy a few manners.

The ACP/AR issue does have a lot to do with if you are using the ACP in an auto, or a revo. Most 1911 platforms use throated barrels instead of ramped which support the entire case unlike the throated barrel.

Something that a lot of handloaders are not aware of is that alot of bullet manufacturers, who put out load data back then, did not have pressure guns for all, or even most of the calibers that they provided load data for. Some of the newer manuals that used pressure guns for the data, even mention that their new data supercedes all earlier data for that reason. An example is the Speer number 9 and 10. They state that while loads worked up in their Blackhawk for the .45 Colt were not pressure tested, they were safe in their test gun. It happened a lot back then. I know for a fact, that most companies didn't have, and most still don't have a pressure barrel for the .340 Weatherby, which is why the loads shown for it rarely look much better than the .338 Win.

Then too, we live in a law suit happy society now.....

Gun4Fun is dead on, most of the data published years ago relied on objective observations like flattened primers, sticky extractors etc. Modern electronics have changed alot of the load data. The M25 being a Target revolver, should be loaded with target loads, not driven to extreme.
A good substitute for it that you can push max with is the recent Ruger convertible .45acp/.45Colt, I have some really great loads with 185g JHP's that sizzle without any pressure signs. Of course the AR is a different fish but with the 625's it could be pushed upwards over what the old Target model would be comfortable with. Remember tho' that the case is the weak link in the mix not the firearm itself.
RD

__________________
Got a Phd from Hard Knocks U

Yeah I tried some of the hot AR loads with a 255gr from the number eight. Holy recoil Batman and extraction was very hard and flattened primers as well. Needless to say I backed way off!

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Stay safe people!

I have used loads from the Speer #8 in the 45AR for years. Are they stout? Yep! You don't have to shoot every round at maximum. As for the semi-auto/revolver comments, I'm not sure I want to beat my auto up with the recoil seeing as they are recoil operated. If you shoot those heavy loads in an auto you need to do some spring changing, in my opinion.

The M625 will take what you can dish out to it from just about any manual, even the Speer #8. It is the same frame/cylinder as the M629 with .009" thinner walls.

If you look at the Speer #6 manual though you will see that they had pressure testing equipment long before the #8. I would find it hard to believe that they didn't use it when they produced the latter manual. Didn't print it, I understand that, didn't use it, don't understand that.

p.s. I have use the SR4756 loads out of my 625. They clock out of my barrel at 1100fps with a 240gr bullet. Serious indeed!

As I posted, a lot of the bullet companies did not have pressure guns for a lot of the calibers they provided data for. Whether or not you want to believe it is up to you, but it's a fact, and that info has been published in various manuals over the years, not to mention countless handloading articles.
Tha various 25/625 designs are rated by S&W for +P loads that are running 23,000 PSI, which is a pretty stout load for sure.

I am curious as to where you came up with .009" difference. That is only half the difference in actuallity.

I measured several of my 25's and 29's at their thinnest point at the rear face of the cylinder. The .44 cylinder's average .075" outside wall thickness, with a stop notch depth of .035" ave. That leaves .040" at the thinnest point of the notch, and the weakest part of the cylinder.

Two of the 25, .45 cylinder's average .066" outside wall thickness at their thinnest point, with a stop notch depth of .040", while my 25-7 averages .045" stop notch depth. The first two leave a wall thickness of .026", and the other .021".

So if you average the three, at .024". That is .016" less steel over the case at the thinnest point in the 25 cylinder's than in the 29 cylinder's, and .018" less steel surrounding the case in the .45's than in the .44's, and that is a considerable difference. I agree that the rest of the guns are the same, but the cylinder is what contains the pressures.

Tell Sackett and guns 4 fun are both way more knowledgeable than I am, for sure. I have never a big fan of bang to the wall handloads, so I can't comment on that kinda pressure.

Having sed that, I do like stout loads and for that reason, I am going to try a few loads out of #8 in 45AR and 44 special.

I let you know what happens when I get backfrom the hospital.

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Slim, U.S. Army, Ret.

Cal Slim,

Don't misinterpret my post above. The 25/625 platform is a strong design, but we need to look at actual numbers when we are talking warmer loads than are listed in todays manuals. I regularly use 23,000 PSI loads in my 25's, and the cases pop right out. I just don't push them beyond that level to keep from causing excess wear to the guns, and to provide a large safety margin.

This seems to be a hot button issue for you. And I don't want to add fuel to an already burning fire but......................

As to the point of pressure equipment. While it may be true that some of the bullet manufacturersdidn't have pressure testing equipment, it isn't true for the company that produced the manual in question, Speer.
Here is a picture from their #8 that clearly shows their pressure testing equipment. It may not be "electronic", of that I'm not sure. Copper crusher stuff most likely. Nonetheless, they had it and it would be inconceivable that they wouldn't use a tool that they had so readily available. Take a look:

BBHFarm Gallery :: Speer #8, Speer Inc, 1970 :: aaj

As for the measurements, I just used the measurements of a SAAMI standard designed test barrel chamber. Case in point: 45ACP chamber measures .4796" at it's nominal measuring point. The 44Mag's chamber measures .4589" and if you subtract the two it gives you a .0207" difference. Of course you have to divide that by 2 to get how much material difference is left in a standard chamber, which gives you .01035", that's 10/1000". Sorry about the discrepency of .001" or so but I was looking at the test chamber of the 45AR round which measures .4789" thus giving the original measurement difference of .009". That is of course assuming that the centerline of the chambers is the same.

I think they are. Could be .001" wrong there too though.

Calvaras,

There are folks that have done 45WinMag conversions on M625's for years and the maximum pressure for that round is 40,000CUP according to SAAMI. I looked in their latest publication on the matter and they don't list a "PSI" rating for the 45WinMag so I can't tell you what that is. 40,000CUP though is the same rating for other magnum rounds, like the 44Mag. It's maximum "PSI" number is 36,000PSI. Does that mean that 40,000CUP = 36,000PSI? As far as the rating it does, in actuality, I don't think anyone is sure!

Tell,

It is not a hot button issue for me, and there is no need to get all worked up about this, but we do need to look at realistic numbers. I don't know anyone who uses a test barrel to shoot their loads. We all use production guns and that is what I use for determing the dimensions. The numbers you are using are from only one side of the chamber. The walls encompass the case in a complete circle. You have to consider that the steel is .009" thicker all the way around which is .018" in any two opposite directions.

As far as pressure guns being used in the manuals, re-read my post. They did not have them for all of the cartridges they provided data for. Of course they had them for some, but not all. There is no way to know for sure which loads were pressure tested and which weren't, without them actually saying so in the text.

Gun,
When measuring the "dangerous difference" in the cylinder, wouldn't it stand to reason that it would be the difference from the outside of the cylinder or the lug notch to the outside of the chamber since that is the thinest part of the cylinder? If a gun is going to blow because of an unsafe round, wouldn't it take the lines a least resistance? Towards the thinest area? That is what you said in your previous post. That measurement is only half the difference of the size of the chamber as the centerline of the cartridges is in the same line in both guns, right?

The difference in the two calibers of material from the chamber to the outside of the cylinders on the two firearms I have is .011". Yours maybe different, that's fine. Everything made by man has it's tolerances. Seems like .002" is well within that range.

This guy probably knows more about this than any of us. Anyone interested in trying warmer than normal loads for their 45/ 45AR should read is comments on the S&W 25/625's. The first article is on the .45 Colt, but the chamber walls are the exact same as the .45 ACP/AR guns

Gunnotes...Smith & Wesson Mod 25-5

Scroll down to the bottom of this article to find the notes on the S&W 25 platform.
Linebaugh's Custom Sixguns - Heavyweight Bullets

Tell -
re-read the post with the figures in it. You will see that their is a difference of .016" at the thinnest point, which is the bottom of the cylinder stop notch. That is where almost all guns will let loose first, and that figure is quite a difference. That was taken from measuring 5 different guns, 2 29's from different time frames, and 3 different 25's from different time frames. The factory has been pretty consistant over the years in dimensions, I'll give them that.

I understand your logic, but in reality it doesn't work out that way the 5 guns checked. The stop notches are consistantly deeper on the 25's than on the 29's.

Just for the record-

I believe that the 25/625 will stand a bit more than 23,000 PSI, but that is still a very powerful load in a .45, and going beyond that just causes accelerated wear and tear. I just don't recommend it to anyone when there are more appropriate guns out there to do that. You can safely push 255 grain cast swc to 1,000 fps at 23,000 psi which is all that is needed for the lower 48. Why go further?

From the Smith area, and to this point I agree. The cylinders are designed to withstand about the same pressures. That is the only point I was speaking to:
I like this part of the article too:

Tell-I don't think I understand your post above.

According to Linebaugh, the frames are the same strength, not the cylinders.

The 25 cylinders are about 80% as strong as the 29's, and I came out at 77% using my guns, so we are close.

I think the frames were what you were referring to and not the cylinders, no?

And yes, on working up a load, we agree wholeheartedly.

That is the sole responsibility of the person doing the loading, and shooting. It should be undertaken with a great deal of care, and a good working knowledge of proper procedures and techniques, along with using known and published data.

Sierra Manual # 5 has a seperate section for 45 acp revolvers, if anyone would care to check more current load information. It says the data is for the revolvers listed, but am unsure if they mean the revolvers referenced in the introduction section, or the one revolver used for the testing.

RD:
I wanted to ask a simple, somewhat on-topic question -
Can you shoot .45 AR in a SA Ruger chambered for .45 ACP?

I never thought of this before, but my guess would be "No" since extraction amounts to "poke out" in a SA, it would probably be impractical and unsafe to make it handle .45 AR, unless that was all it was meant to handle.

__________________
You're shy a few manners.

One of the problems getting good data on the .45 Auto Rim is that SAAMI standards were set lower than for the .45 ACP because the original factory loads used soft swaged bullets that leaded the barrels badly at elevated (.45 ACP) pressures. So, you start out with a reduced pressure allowance for this reason. Most reloading data today is to SAAMI standards. This is way underpowered from what is safe. Further, Speer and Hornady data on heavy bullets are for soft, swaged, bullets and they have leading issues. Cast bullets of appropriate temper can be loaded heavier than swaged bullets with excellent accuracy and NO leading.

I agree with the 23,000 psi point. The problem is, no one is giving us pressure figures with these desirable heavy bullets (in my case the 454424 Lyman in the Auto Rim Cases).

However, Brian Pearce's article on the .45 Auto Rim (Handloader magazine #254 - August/September 2008) gives good data and he is a writer that I trust to give us the true skinny. John Taffin's information on the Auto Rim is also a good source:

SMITH & WESSON'S 625-2

The answer to the question about Auto Rim with the Ruger Single Action - the short answer is NO. The Auto Rim case rim is too thick. The Ruger does not have adequate headspace to allow use of the Auto Rim.

However, the .45 Cowboy Special has a .45 Colt rim with a .45 ACP body and THEY will work in the Ruger ACP cylinder (at least in two Ruger convertibles that I tried it in):

http://www.cowboy45special.com/

Dale53

As you must know Dale53,

I'm a huge fan of Pearce, an have quoted him here often. I didn't in this thread with the exception of the 23,000 psi for the .45's, but I'm glad that you did. He and Taffin are the finest writers in the business and I agree... they give the straight skinny when it comes to pressures and strength. A lot of what I have posted here comes from personal experiences, but a lot came from the two articles you listed. I have learned more from Pearce thn any other writer ever, and he backs it up with pressure tested data and common sense, which I really appreciate.

Thanks for mentioning those articles.

I would say that any serious handloader should subscribe to both Rifle, and especially Handloader, more than any other magazine. They will learn more there than here or anywhere else, and from men who have access to industry insider information that most of us don't, not to mention the pressure equipment.

I think the problem is with whom you are quoting. That is why I posted those excerpts from your source.

I didn't try to run the Linebaugh flag up this flagpole, you did and it seems like he is an extremely "confused expert".

Here is the whole section you asked us to read:
So as I read the article, the frame is weak but the cylinder is strong. Then as you reread it it seems like the frame is the issue.

Here is my point, and I want to make this as clear as possible. The Smith & Wesson M625 is as strong in the cylinder as a M629. Even the "expert" in the article above agrees to it. It is the hand and the extractor star and other delicate things that wear and THEN problems can arise out of untimed firearms. If you want your firearm to last longer use lighter loads.

Excuse the vernacular but "DUH"!

Tell,

You are trying to pick nits, and make your point by using a simple mistype.

Remember this-
Linebaugh himself is a master gunsmith, not a professional writer, and what he said about the frames and cylinders is an obvious mistype. You can see that from this section here-

This section below is obviously a mistype, and if you read all of Linebaugh's writings, that is perfectly clear.-

If you don't care for him that is your choice, but you'd be making a mistake to try to claim that he is a "confused expert". If you can show me someone with more practical experience and knowledge about the capabilities of a modern revolver, I'll be glad to listen to you. I would like to see some type of evidence to their credentials. Linebaugh's are well known and respected throughout the firearms industry.


Common sense dictates that a cylinder with 20% thinner walls cannot be as strong as one with thicker walls. It would defy the laws of physics. The weakest part of a S&W outside of the cylinder locking notch is always the numerous small parts used. That's something that can't be denied, and no one is. They have nothing to do with containing pressure though.

Here is a point that isn't about "nits". And we, us Americans do it all the time. We make "super humans" out of folks that we want to.

If he is going to be deemed as an "expert" he well better be able to communicate what he means to the public, wouldn't you think?

Could you see those statements brought up in a court of law? A still wet behind the ears defense attorney would chew it up and spit it out!

I'm not saying that he isn't knowledgeable or anything like that. It just seems that the source article you picked to show us the inadequacies of the M625 platform for heavy rounds is a bit confusing, at least to this simpleton.

Tell-

I am not trying to show the inadaquacies of the platform. To the contrary. You are new here, so obviously haven't read many of my posts. I am a big fan of any .45 caliber gun, and I love the Smiths. I have stated so many times here, and have posted many times about the so called weaknesses of the platform as being undeserved.

Still this is a public forum that even non memebers can read, and to post that the 625 is as strong as the 629 is inaccurate at the least, and may cause someone reading to try something risky or dangerous. Maybe even injure themselves. I wouldn't want that, and I don't believe that you do either.

One of the most used caliber revolvers in the past 150 years has been the .45 Colt (more use in the last part of the 18th century but also plenty since). The original specs with black powder would drive a 260 gr bullet through a horse at 100 yards.

The 625 .45 ACP can safely and easily drive a 260 gr bullet at the same level (reloads only). That should be enough for most work.
Add a Keith style bullet and you have about 25% more stopping power in the same package with safe pressures in the 625 .45 ACP.

A 250-260 gr Keith at 900 fps is the max that I will ask of my 625's. That will do what needs to be done. If I need more, I'll get one of my "heavy hitters".

YMMV
Dale53

They say one picture is worth a thousand words. I drew this picture in AutoCad with the exact dimensions I measured with micrometers.

The diameter of the cylinder is the same on both my M629 Classic and my M625-8, 1.712". I measured the outside diameter of the chamber diameter with inside micrometers for both calibers and drew the chambers accordingly. Then I drew the "notches" that I measured by calipers, which I know is not near as accurate, and put them in. In reality, they aren't needed to show my original statement of a difference of .009" difference between the chamber wall and the notch. Simply showing the difference would have sufficed.

I know my literary skills can be wanting at times as well. That is why I have drawn the picture. I also have a call into Mr. Linebaugh to have him clarify his statements.

I'm glad that you called Linebaugh. I was going to suggest that. I have talked to him a few times, and he was always very helpful and friendly.

Your drawing while very nice, shows little. Where are all the dimensions? I inclued all of them in my post and they speak for themselves. I took them as I said from 5 different revolvers, measuring each notch and chamber mouth wall.

I even went and pulled another .44 out just now to check it, and it is the same as the other two .44's. So now I have checked three .44's against three .45's, and the difference between outside chamber wall thickness is .009" in overall thickness. The .44's notch depth average is .042", leaving a metal thickness between the bottom of the notch, and the inside of the chamber wall of .024".

Again, the depth notch average on the three .44's is .035", leaving a metal thickness between the bottom of the notch and the inside wall of the chamber of .040".

.040" minimum thickness on the .44 minus the .024" minimum thickness on the .45's, equals a difference of .016" in favor of the .44 at the thinnest point on the cylinder.

I doubt that you will ever agree here, since you have debated strongly for your position. I have layed it out as clear as possible for you, and anyone who might be reading along, in the hopes of maybe saving someone from taking bad advice and pushing a fine .45 caliber handgun beyond its limits and getting hurt, or worse.

I will say no more here, as there is no percentage in it.

Dimensions coming up!
You know what?

I bet this isn't the first time you haven't taken it too well that you were wrong!

Just a guess though, me being new and all!

With all of the dimensions, sir.

Skeeter Skelton wrote once in the late 1970's that he thought of having the .45 ACP cylinder of his Blackhawk's chambers recessed for the thick rim of the .45 Auto Rim cartridge. Thus, with a quick cylinder swap, he could shoot the .45 ACP, .45 Auto Rim and .45 Colt. He said it might be frivolous, though, as there was precious little Auto Rim brass around then and it might be on it's way to becoming an obsolete cartridge.

Of course, he was incorrect about the future of the Auto Rim. Since Skeeter's death in 1988, S&W revolvers for the .45 ACP have become wildly popular and demand for the rimmed alternative round has soared. I am sure far more of it is sold, mostly as empty brass, loaded and shot today than at any time since it's introduction.

The first handloading manual I bought, about 1975, was the Lyman 45th Edition. The top loads in it for the Auto Rim are a 225 grain bullet (they used the Lyman 452374) over 7.0 grains of Unique for 988 fps, and a 238 grain bullet (Lyman 452453) over 6.8 grains of Unique for 981 fps, both fired from a S&W Model 25 with 6-1/2 inch barrel.

Oddly, in the .45 ACP section, they load the same 225 grain bullet over 7.2 grains of Unique for 967 fps, fired from a 5 inch Colt Gov't Model.

My most used Auto Rim handload is a cast Lyman 454424, a SWC weighing in at about 255-260 grains depending on metal used, over 6.2 grains of Unique for 825-875 fps, depending on the sixgun used. I use an RCBS special ordered roll crimp die with my RCBS .45 ACP carbide die set and RCBS Auto Rim shell holder. It about duplicates the ballistics of the traditional Winchester and Remington .45 Colt factory loads but uses a better bullet.

All three of the .45 caliber catridges discussed here are just great in the N frame S&W sixguns. If I NEED more power than a 255 grain bullet at 875 fps will give me, I need a .44 Magnum or a rifle.

And THAT likely wouldn't be too durn often.

Thanks for the information, Buff.

I just always assume any revolver that shoots .45 ACP will also fire .45 AR. Obviously, that's only true for Double Action Revolvers.

Skeeter Skelton's musings about having a special cylinder made are interesting but sound impractical, unless you just have money burning a hole in your pocket. I'm sure that the reason Ruger offered a spare .45 ACP cylinder to go with a .45 Colt SA is/was to take advantage of the availability / low cost of .45 ACP (at least back when it was the military service round and presumably available on the surplus market.)

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You're shy a few manners.

Just thinking out loud, but if one wanted to make a .45 cylinder that would handle the AR, it would appear that one could simply machine a .45 ACP cylinder down from the rear and then deepen the chambers accordingly. Is this a workable method? Would the AR cartridge fit through the loading gate on the Ruger single-action? Sincerely. brucev.

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<><

I think that's approximately right, except there is no reason to machine off the entire cylinder, IMHO. Just cut into each chamber far enough for the rim to seat "partially submerged". You would also have to ream each chamber a corresponding amount. I believe if you look at Buff's post where it says "... he thought of having the .45 ACP cylinder of his Blackhawk's chambers recessed for the thick rim of the .45 Auto Rim cartridge ... " that is what Skeeter Skelton was proposing.

As far as fitting through the loading gate:
The AR's nominal rim diameter is .516 in, whereas the .45 Colt's is .512. This is only four thousanths of an inch difference, and I imagine that Ruger allows a greater tolerance than that for clearance in the loading gate. Somebody who has one could check that. The AR has a thick rim, but not an especially wide one.

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You're shy a few manners.

There should be no reason to deepen or ream the cylinder a little. You are machining the back of the cylinder to allow the thicker rim to fit, the cartridge would still be sitting at the same over all depth. The ACP cases headspace on the mouth, which would not be affected by shortening the cylinder from the back. The thickness of the ARs rim is the sum of the thicknesses of the ACP case and the moon clip used for extraction.

Modern AR brass has the same inside dimensions as ACP brass and loading data can be used interchangably with each other. As Dale53 mentioned above the difference is because when SAAMI set the standards for the AR there was only one factory loading and it was loaded light because of the lead bullet fouling at higher velocity.

Just got off the phone with Mr. Linebaugh. What an individual!

Personable, intelligent, forthright, interesting, knowledgeable, and any other adjective you could use to define a real officianado of our sport. A real person, a standup kind of guy!

The first thing he would like to convey is that he is truly sorry for any confusion that his article caused. You can call him yourself to authenticate anything said here, and I encourage you to do just that. Don't take my word, ask him.

He made several statements concerning his article. He said that the cylinders of both the M629 and the M625 are made to withstand 40,000, and he got a little "fuzzy" as to whether it was CUP or PSI, blamed it on old age, I understood! Even with the "bolt notch" being dead center of the chamber! He said he has purposely destroyed cylinders in a special "handgun" he designed for that purpose and has NEVER, EVER, had one blow up at that point. They have ALWAYS, EVERYTIME, blown up at the base of the bullet, period, and he said he has destroyed a few, on purpose.

We spoke for about 30 minutes and he shared a bunch of his experiences, for the most part, I listened, willingly.

He made another statement that I found exceptionally interesting, given recent events on the forum. Do you know what that is?

I'll share it with you. He said that there is a greater danger of blowing up a firearm by deep seating a bullet over increasing a powder charge! I almost fell off of my chair!

He gave an illustration with someone from Carthage, Ill. This individual is a powder expert, blows holes with dynamite in granite to make little rocks out of big ones. It basically goes like this:

What happens if you take a certain pattern (he told me but old age again) boring and put a charge in the bottom of the whole with the normal type of packing and touch it off. He asked the expert in blasting: "What do you get?" The expert said: "Nice sized rocks that I can run through the crusher." Now Mr. Linbaugh asks him what he gets if he were to use the same charge, same boring pattern and pack the hole with the sealing agent only push it in with a D7 Cat. The expert said: "You better be far away and behind another D7 Cat to be safe!" Mr. Linebaugh, who volunteered this story without coercion, said that that is what you get when you deep seat a bullet.

Now, to clarify what he meant to say in his article and he plans on redoing it later. A Smith and Wesson BY DESIGN, with it's swing out cylinder, crane and such like will not stand up to the abuse that a single action will because of design of the frame, not the cylinder. The cylinder is capable of taking the full power loads, period, whether Ruger or Smith.

A Smith and Wesson will shoot itself loose in 1000 rounds where the Ruger will not. It comes from end shake, not cylinder damage. Again with full power loads.

His loads run about 30,000psi that he carries everyday and he says it will last a lifetime at that pressure!

Mr. Linebaugh is quite a personable individual! He says he doesn't have a TV, computer and something else I can't remember, he spoke so fast.

Give him a call!

What Skeeter meant was to take the existing, already supplied .45 ACP Ruger Blackhawk cylinder and add a counterbore to each chamber's rear, for the rim of the cartridge case. Picture an older S&W Magnum revolver cylinder's counterbore. It would be a fairly simple task for a well equipped machinist.

The only Blackhawk I have is a .357 that belonged to my late aunt and uncle, so I can't check the loading gate size question, but can't imagine they wouldn't fit. Blackhawks are good guns, I just never got into Ruger single actions.

Good catch Jellybean. I was thinking wrong about this. Of course the case length for both the .45 AR and .45 ACP is the same, so no need to lengthen the chamber.

I do agree with Buff (and Skeeter) that you would get a more elegant result by recessing the chambers to allow the .45 AR to seat in the chamber with the rim partially enclosed. Shortening the cylinder may be quicker and easier, but the end result would be less pleasing, to me anyway.

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You're shy a few manners.

There is a post in the Smithing section: "Cracked Cyl Wall mod 629-2E", that I think everyone here should read and give serious consideration to.