We all enjoy our 1917 style 45ACP revolvers, whether it’s a model 25, 325, or 625, for their versatility & big-bore thump. Many of us like them even more when they’re flavored in 45 Colt. Unfortunately it seems S&W doesn’t like stamping 4-letter words on its revolver barrels so they’ve been far & few between, by comparison.

Sadly, just reaming out a 45ACP cylinder to accept the longer 45 Colt cartridge won’t work. Converting a 45ACP (rimless) revolver to shoot 45 Colt (rimmed) is involved, mainly stemming from the gross headspace needed for the moon-clipped rounds as well as the 45ACP’s cylinder’s shorter length & its related extended barrel breach.

The 45ACP is typically loaded with 230gr bullets as a standard max weight though heavier can be found from specialty vendors. Heavier bullets in 45ACP cases just take up too much of the small case’s volume, in my opinion.

The 45 Colt’s ample case length is better suited for 250gr & heavier bullets but at the moderate power level they operate at in the 625 it’s really too much case capacity. Fully charged they often still have too much unused space.

The shorter overall length of the old .45 S&W Schofield would be helpful but it’s still the same problem of trying to adapt a rimmed cartridge to a rimless setup.

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I got the idea, which is somewhat of a compromise but still the best of both worlds, rimmed & rimless, for use in a 45ACP M625.

Enter the 45 Winchester Short Magnum (45WSM). (That's what I'm calling it for now anyway. )

You get there by trimming a Starline 45 Winchester Magnum (45WM) rimless case (1.198") down to 45 S&W Schofield length (1.100") & reaming the 45ACP cylinder's chambers to the appropriate depth, to accommodate the 45WSM's extra case length, using a standard 45ACP reamer. That's it.

With them loaded up to 45 Super power level (25K-28K psi) there would be no safety issue since the cylinders can already handle that.

Furthermore, you would not have to worry about a dangerously high power 45WM (41.5K psi, SAAMI) round accidentally finding its way in to one of the modified chambers as they're too long to allow the cylinder to close if it's only reamed to accommodate a 45 Schofield’s length.

As in the 45ACP you can still shoot the taper crimped 45WSM rounds individually (without moon-clips & extracted individually) or with moon-clips.

Use cannelured and heavier 45 Colt bullets with a roll crimp along with moon-clips.

Of course, moon-clipped 45ACP rounds can still be shot in the modified cylinder's chambers, as well as 45 Auto Rims, if desired.
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Details on how I did it:
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I bought a new stainless M625 45ACP cylinder from MidwayUSA, #666363 (S&W# 412200000) for $118, for the conversion. Of course my original cylinder could have been used as well for the conversion but I wanted to error on the side of caution & use a second cylinder.

Also, as a general rule, I prefer not to shoot short cartridges in chambers intended for longer ones (no 38 Specials in my 357 cylinders, or 40 S&W in my 10mm Auto cylinders), so having a dedicated separate cylinder for this longer cartridge seemed appropriate here.

Modern 625 cylinders are ~1.539” long overall, as this one measured, & it weighs in at 7.3oz as it comes out of the box, only equipped with an extractor.

Four out of six of its throats checked at ~.4528” diameter while the remaining two were tighter on the inside diameter at ~.4522”.

The head end of its chambers ran ~.4790” while the mouth’s end ran ~.4745”.

Their chambers’ shoulder depth averaged .823”.

These measurements are nominal & compare similarly to the other 45ACP cylinders I have.

I have potentially three 45ACP revolvers for the project: 325NG, 325TR & a 625PC. Unfortunately using the heavier weight 625PC (39oz.) was out for this conversion because S&W uses a shorter than normal cylinder (1.425” long) in them.

The other two have standard 1.539” long cylinders so I picked the longer barrel (4” -vs- 2.75”), and slightly heavier weight (31oz –vs- 27oz), 325TR for the conversion. (One day I’ll find a 5” M625 I’ve been wanting. )

The new cylinder installed in the 325TR revolver easily using the extractor from the 325TR’s original factory cylinder as well as all the other related hardware.

It required no adjustments as the endshake was nominal (like the original’s) and the gross headspace (.097”) & the barrel-cylinder gap (.005”) were also the same as the original’s.

I calculated that a mid-length 45WSM case (1.095”), being .202” longer than a mid-length 45ACP case (.893”), should have the new 45WSM chamber’s shoulder cut to 1.024” deep. (Of the four 45ACP cylinders I have on hand their shoulders averaged .822” deep.)

To be cautious (you can always cut deeper later, if needed, but you can’t add back metal) I decide to go with a shorter shoulder depth of 1.019” initially.

It’s a conservative depth that would also help insure that individual rounds could be fired without moon-clips while headspacing on the chamber shoulder only, as in a semi-auto pistol, which I like to do for casual shooting.

For the job I purchased a standard 45ACP finishing reamer (FA45AUTO), with a solid pilot for Cylinders (not Barrel for semi-autos) from Dave Manson Precision Reamers ($75 + shipping), after confirming with them that it’s cutting depth was adequate for this job.

The reamer’s maximum cutting depth is more than adequate at ~1.160”.

The solid cylinder pilot’s diameter is .4512” & would be fine with my new cylinder’s existing throats. I didn’t see a need to buy the more expensive finisher version with removable pilot & a pilot pack.

The finisher is 5” long, has a 7/16” shank with a 3/8” square drive on the end.

Dave Manson was out of stock at the time I called but they allow back-orders. He said they should have one made & ready to ship in 3-4 weeks max. Mine shipped in just 2 weeks.

Reaming the new cylinder’s chamber depth, by hand in a vise, isn’t difficult but takes some time (at least it did for me). Establishing the new cut is rough for a handful of turns but smooths out & remains so for the rest of the way.

Use adequate cutting oil, moderate pressure, & frequent cleaning of the chamber & reamer to remove the cutting’s chips, will ensure a good finish & longevity of the reamer.

As you near the desired depth, be patient & don’t rush the process. It doesn’t take much to remove more than you expected or wanted. Each chamber took me approximately 25-30 mins.

So how did this part of the process come out?

The new throats are all uniform now, after reaming, at .4529", inside/outside diameter.

The new chamber mouths are unchanged at .4745".

The new chamber heads are now .4810" (+.002" from new), within 45WM SAAMI specs.

Chamber shoulder to cylinder face depth averaged ~1.0145"

Headspace clearance = .014" (shell head to frame, with a 1.094" case headspacing on the chamber's shoulder). This is roughly what was the headspace clearance for a moon-clipped 45ACP round in the factory cylinder.

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Now to conjure up some 45WSM ammo for it.
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COAL:
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My COAL” of 1.475” for the 45WSM is based on the 45WM having a SAAMI max COAL of 1.575" & since I removed almost 0.100” from it that seems appropriate.

However, since this will be used in a revolver, & not a pistol, the OAL” of the cylinder will have the final determination of it's ultimate maximum length. I come up with ~1.610” as a maximum COAL, if other factors allow.

Case Capacity:
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A mid-length (1.095”) 45WSM case, cut from a brass Starline 45WM case, will hold 34.3grs of H²O. (Starline’s nickel cases run a tad more at 34.5grs/H²O, for some reason.)

This is 25.6% more volume than a 45ACP case.

In other capacity comparisons, the 45WSM has:
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1.5% less volume than a 41 MAGNUM
9.7% less volume than a 45 WIN MAG
18.9% less volume than a 45 COLT

7.9% more volume than a 10mm MAGNUM
28.9% more volume than a 357 MAGNUM
42.3% more volume than a 10mm AUTO


Accuracy:
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Using .4512” Hornady 230gr HAP bullets (.648” long) in my work-up loads, so far, it’s been every bit as accurate as before the modification using Unique, Power Pistol & Blue Dot powders loaded to a COAL of 1.435”.

At just under (100) work-up loads thru it, & all fired without moon-clips, I’ve not had any issues.
Some of these used Zero’s 185gr JHP in 45 Super equivalent work-ups also.

I also have (500) .4528” Acme 250gr Hi-Tek coated L-RNFP bullets to work with next. Proportionally these bullets seat more of their .656” length in the case when seated & roll-crimped at the cannelure (.352” deep). COAL is 1.392”

My next L-SWC bullets will have longer noses & seat more of their weight outside of the case.

I’ll be continuing with more range time as I finalize loads.

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What’s in the name:
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I searched & couldn’t find where this had been done before (apologies if I missed it), and if not, it needed a name.

45 WSM: 45 Winchester Short Magnum seemed the most obvious, since it’s just a shorter version of the 45 Winchester Magnum, also because of the new rifle cartridge trend to name shorter versions “WSM”s.

Some other possibilities:

45 SLA: 45 Super Long Auto, being essentially a longer version of the 45 Super.

45 SCA: 45 Short Colt Auto, being essentially a shorter rimless version of the 45 (Long) Colt but for use in a semi-auto.

45 SWA: 45 Smith & Wesson Auto, seeing S&W doesn’t have a .45 semi-auto cartridge with its name on it.

Maybe they should?

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Waiting for the break of day

That took some serious effort but the results look excellent.

Your project is intriguing and I see what you’re doing; but I’m a little bothered that you’re apparently creating an auto cartridge that won’t work in any autos. (Due to length I mean, the same way that many 40’s have frames too short to be converted to 10mm.)

But I suppose that’s only a marketing concern... follow your bliss and kudos for creating something new!

It looks like you did a lot of thinking on this so please do not take offense to my question.

I understand that using 45 Super brass does not satisfy your desire for more case capacity even if it can be loaded to higher pressure.

However, why not just re-chamber the revolver to .460 Rowland?
The case is .957" in length, commercial brass is readily available so you do not need to spend time trimming 45 Winchester Magnum brass and there is established loading data available at 44 Magnum style performance levels.

Obviously the .460 Rowland does not give you as large of a increase in powder capacity, but it is a lot less work

If you are just looking for 45 Super performance you could load the 460s light.

.460 Rowland ammunition is currently available from several of the smaller boutique ammunition companies



The .460 Rowland gets past this since conversions of auto loaders exist for this cartridge.

The 460 Rowland conversions also provide proof that a 45 Winchester Short Magnum conversion of 45 ACP auto loaders can realistically be achieved.

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"Acta non verba"

How's COAL compared to 10mm...and do S&W full-size .45 ACP
barrels swap into their 10mm slides (if there's enough reamable
chamber-length )?

I'm unfamiliar with load data on these various .45 magnum-type cartridges, but the Sierra book has .45 ACP revolver loads using 240 grain bullets at up to 1,100 fps using the plain .45 ACP case. The same loads should also work well in Auto Rim brass. Granted, these loads are likely below the level of the hotter .45 cartridges described, but are well above standard .45 Auto load data.

My question is why? Many other calibers will fill the bill for those wanting more power. Pandemic boredom is striking everywhere. Have a ggod time with your research.

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USMC 69-93 Combat Pistol Inst.

How about .45 Schofield Rimless? Sort of early 20th century. If you had wanted to go with the full length .45 Winchester Magnum, there would have not been much likelihood of loading a factory one in the revolver. The case design that Winchester uses is different from Starline’s and the Winchester case won’t fit in the moon clips.

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S&WCA 1729

Yeah, I am aware of the 460 Roland but as I've said before, for me, it's 40K psi max is a bridge too far in my 625. Others do it but not me. I have plenty of factory big bore magnums made for high pressure already.

If that (potential) max pressure was agreeable with me in my 625 I'd have just reamed it to accept the 45 Win Mag, which runs at basically the same pressure.

My intent wasn't to make a shorter high pressure cartridge but to just have a case with some breathing room when heavier deep seating bullets are used but still maintain a 45 Super maximum pressure threshold, with the extra powder volume, that could be easily adapted to work with the vast number of M25/325/625 made in 45ACP.

The 460 Rowland is pretty slick in semi-autos but even though the case is slightly longer, in them, it still has to adhere to the same max COAL" as the 45ACP (1.275") & can't use it's potential extra capacity (empty it only has 5.6% more volume than a 45ACP).

In a revolver application that COAL" wouldn't be a problem but it wouldn't be as significant a volume gain compared to the 45WSM.

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Waiting for the break of day

The max COAL of the 10mm Auto is 1.260".

The max COAL of the 45ACP is 1.275".

The max COAL of the 45WSM is 1.475".

The max COAL of the 10mm Magnum is 1.555".

The max COAL of the 45 Win Mag is 1.575".

The later are both magnum revolver cartridge lengths. Large semi-auto pistols have been made for them but any 1911 sized frame & magwell are too small for them.

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Waiting for the break of day

Sierra #v5 & #v6 do have some great load data for 45ACP revolvers & I do like their 240gr JHC bullets.

All my 45ACP(+P) & 45 Super loads are loaded in S-L 45 Auto Rim brass (which are stronger than their 45 Super cases), which I prefer to use in my revolvers.

And while they're an awesome combination they're still restricted to the same limitations of the 45ACP platform, thus my reasoning for the 45WSM alternate cylinder for my 325TR.

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PS: It's worth noting that Sierra used a 7-1/2" bbl. Freedom Arms revolver to obtain the velocity data in their 45ACP Revolver Loads section & the data was not updated from v5 for v6. The other 45ACP load data sections were updated in v6 & use a universal 5" barrel for their testing. That makes a difference in velocity.

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Waiting for the break of day

Yes, I'd noticed that actual 45 Winchester Magnum brass has a slightly larger extractor groove diameter (.415" -vs- .400") but I've never run across any of them.

Starline's 45 WIN MAG brass is the more common find (even they're limited) but they do use the same extractor groove diameter (.400") as the 45ACP.

That difference aside, they still could be loaded & shot individually, without moon-clips, if the chambers were reamed to 45 Win Mag depth.

Which, again, is why I opted for the shorter Schofield's case length for the 45WSM in the 625s.

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Waiting for the break of day

Well, I tried to address that exact question preemptively already.

I guess you didn't read the whole thread.

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Waiting for the break of day

I have 3 that will chamber the 45 winchester magnum. That was not the intent when I made them. But, when you take a 45 colt and machine it to accept 45acp in full moon clips you end up with a gun that chambers 45 acp, colt and WM. I have some WM brass but never load it to WM levels

Having a gun that will chamber a round with more pressure than is good for it is not a problem. Some of my older guns would not like +P+ ammo, but would chamber it.

I have always enjoyed the descriptions and articles about wildcatting cartridges that I would see in magazines even though I have never been a reloader or really knowledgeable about any of this. I think it’s interesting to see inside the process of how new cartridges get developed.

Thanks for all the work and an interesting write-up! I hope you will keep us up to date of continued developments.

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Possum—The other white meat!

Very nicely thought out....did I miss something as I didn't see any velocity listings....

Bob

Cool............

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dd884
JMHO-YMMV

The same bullet at the same velocity will give you the same energy, but...

The 45WSM holds 25.6% more powder than a 45ACP case. Powder is power. More power, more velocity. Different result.

I'll just say that in the longer case (45WSM), with the same bullet (230gr HAP) seated to the same depth (.308"), & using the same powder (Power Pistol), but with more of it to obtain the same pressure (~25Kp) as in the shorter case (45 Super), you can expect ~100fps more (= ~115ft/lbs more) due to the higher volume of gases produced.

And with higher pressures/heavier powder charges, different weight bullets & slower powders, the affect is greater.

Isn't that the reason why a 357 Magnum (35Kp SAAMI max) can throw a 125gr bullet faster than in a 9mm Luger (35Kp SAAMI max) can?

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Waiting for the break of day

I recently had the opportunity to load up some Rim Rock 45 Colt 270gr Keith L-SWC bullets (that I added gas checks to) & tried them with several different powder combinations.

Seated to a COAL of 1.470", & roll-crimped, they filled out the 45ACP cylinder nicely but still had room to spare.

One caveat on this subject:

45 Colt chambers are reamed differently, & to looser dimensions, than 45ACP chambers are.

Attention must be given when trying to load 45 Colt sized bullets in 45ACP/45WSM reamed chambers as the typically fatter 45 Colt bullets will receive interference from the tighter chamber dimensions (mainly the case mouth end) as well as from the tighter throats found in 45ACP cylinders.

45 Colt bullets need to be sized appropriately when used in these chambers.

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The meplat on this cast Rim Rock 270gr Keith SWC-FB is .348".
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The .452" meplat on this Rim Rock 225gr DEWC-FB is the apex.

It's seated .466" deep in the case.
(That would use 69.2% of a 45ACP's case capacity & 55.2% of the 45WSM)

The 270gr SWC seats .422" deep.
(That would use 62.7.2% of a 45ACP's case capacity & 50.0% of the 45WSM)

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Waiting for the break of day

Some recent chronograph tests have netted Power Pistol propelled 230gr JHPs in the upper 1100 fps range at +700 ft/lbs and some Blue Dot loads over 1200 fps.

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Waiting for the break of day

I initially considered just doing it this way too but even knowing I'd never buy any factory 45 WIN MAG ammo, & that I'm the only one who shoots my guns, I just didn't feel comfortable going that route now, for my use, or later down the road when I'm not around & can't oversee it's use.

When the brass for the 45WSM is cut to 45 S&W Schofield (aka:45 Short Colt) length, at 1.095" (min 1.090" - max 1.100"), and the chambers' shoulders are reamed to the proper corresponding depth, an inserted factory length 45 WIN MAG cartridge will be too long to be able to close the cylinder on, thus avoiding that potential over-pressure situation.

No matter what the case capacity size is people still have to reload responsibly, of course.

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Waiting for the break of day

I get it and like what you have done. Made a round and chambers that make the most out of an acp cylinder. Main reason my guns can use 45WM is because they started out as 45 colts and were then made to fire rimless brass. All my guns use .452 bullets. Most of my 45 Colt cylinders started life as 44 mag cylinders which I reamed to 45 colt and a .453 dia plug gauge will not go in the throats.

People need to take some responsibility for what they stick in guns though. Doing it the length you did to prevent chambering 45 Win Mags is fine, but some knuckle head can still stick in a 40k 45 Roland. Trying to make things idiot proof only goes so far and idiots know no bounds.

There is a lot of wasted cylinder in a factory 45acp cylinder that one can put to use.

One of the things I learned from this thread is that Winchesters 45 Win Mag bras won't go in clips, I bought 200 rounds of Starline brass and had been using it with no problems.

LOL, ain't that the truth!

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Waiting for the break of day

I acquired a 5" 625-4 from a collector here in town with the intent to to turn it into a Rowland. That's off the table now but this sounds like a viable option. I wanted it for a bit more portable hiking/hunting backup revolver around my cabin. I have a 629 that I put a 7.5 slab side on but it's too heavy and awkward for this purpose. I carry a L frame now for this purpose and without it would have had to let the biggest buck I've taken walk, but that's a whole different story. Guess I'll just trade off the 625 for a 4 or 5" 29 seris.

The 4" 325TR that I ended up using for this project is definitely portable & at 31ozs empty (8oz lighter than my 4" 625-8PC) it's pretty light too.

My 4" 329PD, with the titanium cylinder installed, weights 25.2oz empty.

I swapped out it's Ti cylinder for a Ss cylinder which bumped it's weight up to 28.8oz.

But I do love 5" barrels for general purposes though.

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Waiting for the break of day

I like the whole concept of the .450 WSM bringing the .45ACP into the 21st century and offering the possibility of a revolver that can be used with full moon clips and standard .45 ACP ammo in the same firearm. Not all situations call for a semi-auto. There are some situations when a revolver can be a superior weapon in my humble opinion no matter how much I LOVE a custom Colt 1911 .45ACP!

Thanks, for the thread and the great info.!

I'm a big guy and am more concerned with how the gun hangs on target in my hand, recovers for repeat shots, and just just over all feels to me. I like a litle on the heavy side and bull barrels. It's just a personal preference but then I don't think a .44 Mag with standard loads recoils bad. Yes, I know I am strange; I just have been shooting almost since I could walk. The first center fire handgun was a .45 ACP; Colt 1911 (my Grandfather's).

You are talking my language as my dream concealed carry revolver would be a short barreled Doubletap .450 Shot Magnum Cartridge/.45 ACP. Loaded with either their 200gr. or 230gr. bonded HP loading it should be a formidiable street loading for self-defense.

I like the S&W 629 .44 Magnum 2.625" barrel length at 37.4 oz. however I would prefer it had been cut for full moon clips, its chambers more chamfered for fast relaoding with said moon clips. My problem with the 629 is the lack of load development by major companies for lower end .44 Magnum loadings specificly designed for law enforcement/self-defense use as compared to say the 9mm/.45 ACP/.357 magnum loadings.

That is the reason I thought a Doubletap .450 Shot Magnum Cartridge/.45 ACP revolver similar to the design of say a PERFORMANCE CENTER MODEL 629 would serve a good law enforcement/civilian self-defense purpose.

LOL, you're seriously making me consider trying the 45WSM cylinder in the 325NG, just for giggles.

A revolver like you described would be cool too!

Too many fun options, if we only could.

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Waiting for the break of day

Looks like you've done some well-planned and interesting work to boost the power of some .45 ACP revolvers. I admire that.

At my age, I value simplicity. With this old model Ruger Blackhawk, I can shoot .45 ACP, .45 Super and special .45 Colt loads that would make the .44 magnum guns blush with envy. Changing from one cylinder to the other takes just a few seconds.



Those same hot .45 Colt loads can also be loaded into these older large frame Vaqueros, and with Ron Power kits they can be indexed and loaded like the old model Blackhawks from half cock. The older Blackhawks and Vaqueros were built like tanks and can easily take the increased pressures achieved through handloading.

John

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- Cogito, ergo armatus sum -

Would the M625 cylinder bought from Midway for this project fit my Model of 1955/25-2 SN 4584XX made in 1978 or 1979?

Maybe someone else can confirm but I'll say No, for at least this reason & probably more:

This modern cylinder has a "D" shaped extractor shaft, to keep it aligned. I'm sure ones made in the late 70's still had round shafts with a pin in the extractor star to keep them aligned.

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Waiting for the break of day

Having cut my teeth on Ruger Blackhawks while growing up, back when that's the most I could afford, & just barely, I can't tell you how many times over the years I've come within a hair of purchasing the one for sale I was inspecting. They definitely cover a lot of bases.

I'm sure if I had bought one I'd still have it, & cherish it, but at this point in my life I'm not changing horses. I'm getting close to the finish line.

A 45WSM cylinder can still shoot 45ACP or 45 Super with moonclips, 45AR loaded as hot as you like, or the 45WSM with or without moonclips.

No cylinder swap needed.

And I've got my S&W 460 MAG for anything hotter.

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Waiting for the break of day

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Recently I started doing some load comparisons between my 45WSM & the 45 Colt with the same bullet & powder used in them.

In this one I used Hornady's 230gr HAP bullet which I used extensively in working up loads in the 45WSM & have found it to be a very consistent bullet at a reasonable price.

While the bullets weren't seated to the exact same depths in both cartridges (my bad) there was about .020" difference.

I was curious of what the difference would be between the two different size cases (the 45WSM has 18.9% less volume than the 45 Colt) with the same powder weight in them.

The 45 Colt loads are (+P) load & are less than 23K psi loads per Handloader #337, which is the same pressure as SAAMI 45ACP +P loads.

The 45WSM loads should be in the mid to low 45 Super pressure range due to it's smaller case volume.

The M25-13 has a 5" bbl. while the 325TR has a 4" bbl.

The Power Pistol loads with 11.4grs had a difference of 130mv & 145me in favor of the 45WSM.

The Power Pistol loads with 12.0grs had a difference of 150mv & 175me in favor of the 45WSM.

Big difference.

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Waiting for the break of day