M&P Smokeless/Forcing cone improvements

[BMur]

I’ve been working on finding exactly when the early M&P hand ejectors were converted to smokeless powder then more importantly when the improvement was made to the forcing cone to handle various “increased”powder loads.

The first change was definitely in 1902 the same year the first Smokeless bullet was introduced: Photo 1

It’s the next change that took a lot of research to confirm.
By my research notes that change took place in late 1914/1915 time frame. Approximately serial number 250,000 range.

A significant beefing up of the forcing cone shows up in that serial number range. See photos.
I knew it took place but wasn’t sure when it occurred.

In my opinion any hand ejector model manufactured prior to 1915 should only use low standard smokeless pressure loads that were listed at that time in early reloading manuals.

Later hand loads increased to as much as 18,000 psi. That is an increase from the early smokeless loads around 11,000 psi.

The early loads did NOT list a variety of bullet weights and powder selection like later listings. This was the source of forcing cone failure on the early guns. Put simply; too much pressure from more modern loadings.

Murph

 

[Alk8944]

The K-Frame Military and Police revolvers were never "converted" to smokeless powder. The cartridge is what was converted. Even the Model 1899 guns are perfectly capable of firing standard pressure, modern (current) production .38 Special ammunition. Where did you get the idea that there ever was an issue with forcing cone (barrel shank) failures with smokeless powder factory ammunition?

Standard pressure smokeless powder .38 Special ammunition has always, and still is, loaded so as to be compatible and acceptable to use with standard firearms of this caliber, no matter when they were produced! The exception to this is, naturally, +P ammunition which of course is not standard pressure!

The first major change to the M&P revolvers was the Model 1903 First Change. The diameter of the barrel shank was increased and the frame "lunette" accordingly. In all my S&W reference material this change is mentioned, but no reason given for it.

What I believe is probably the fact that the thickness of the barrel shank of the 1899 and 1902 models was actually less than the thickness of the cylinder charge hole walls, which may have been perceived as a weakness. As a result the barrel was changed to make the walls of the barrel shank at least as thick as the cylinder walls. Look at your own photo of the breech end of the barrel shanks and you will easily see how thin it was!

The other change that many assume was for strength is heat-treatment of the cylinder. This occurred approximately 1918. My impression of this has been that the steel of the cylinders was relatively soft which resulted in battering of the cylinder stop notches when the gun was cocked, especially during fast double-action shooting. The heat-treatment was to harden the cylinder to reduce damage to the stop notches. Please understand this is strictly my opinion! Again though I do not recall ever seeing any reference anywhere to the reason for this change! I have proposed this before on this forum and have never been contradicted though.

As to your assertion that the barrel shank of the K-frames was "beefed-up" about 1914 or 1915, this is completely false! The diameter of the barrel shank of the Model 1902 First Change guns is is identical to even the most current production S&W revolvers! I own a Model 1902 1st change made in 1905. In the past I have installed a very late (1929-1930) production .32-20 barrel in that frame and it fit perfectly! If, as you say, the barrel shank was "beefed-up" in 1914-15 the shank of that barrel would have been far too large for my 1905 dated frame! Your "research" needs a little work!

 

[quinn]

Great research, and I think important info for those of us with earlier guns lik possibly Triple Locks. Thanks for this information and points to ponder! As someone who has had his nose in old reloading manuals for years and shooter of eraly cartridge guns we may not all agree on the technical evolution but this provides things to consider.

 

[Alk8944]

To add to my first post, your assertion "The early loads did NOT list a variety of bullet weights and powder selection like later listings. This was the source of forcing cone failure on the early guns. Put simply; too much pressure from more modern loadings." is also patently incorrect!

The first .38 Special ammunition was loaded in 1899 by U.S. Cartridge Company as I recall. It was a black powder load of 21 grains, presumably FFFg grade. The bullet was a 158 gn. RN lead bullet. While there may have been alternate bullet weights after that they would all have been lighter. Bullet weight can have an effect on pressures, but not reducing it! I believe you also mentioned handloads! That isn't germane to this issue!

I believe you are confusing the early .38 Special guns with much more recent barrel shank failures of .357 Magnum K-Frame revolvers with light, hand-loaded, bullets. Again, these are not germane to your original assertions.

 

[BMur]

Research

Thanks Quinn,
Never ceases to amaze me how honest research can create such an explosive result.
The change is only obvious when you have an open mind and actually perform the research.

The forcing cone issue is common knowledge to early model collectors. A great example is the 22 Lady Smith.
However, the larger caliber M&P’s also went through the exact same transition and also suffered forcing cone damage from TOO HOT STANDARD SMOKELESS LOADS of later production.

TYPICALLY AND INCORRECTLY ATTRIBUTED TO DOUBLE CHARGES.

The typical history of pistols depicts a very common theme. HOTTER LOADS WITH LATER PRODUCTION MODELS of the same caliber.

All you have to do is actually read through early hand loading catalogs from 1891-1950 and see it clearly published. It’s this kind of research that starts you looking for the manufacturing transition that must have taken place to handle the increase in pressure given the same caliber on the exact same M&P platform.

The entire purpose isn’t to upset ANYONE. It’s to realize as was mentioned by Randy that the earliest guns were NOT DESIGNED to handle modern max loadings.

My research only reveals a definite change in the 1915 time frame which makes perfect sense to eliminate the forcing cone issue.

I have an 1899 M&P in my collection that dates to 1900. I will post a photo comparison of that original forcing cone next to an M&P barrel in the 250,000 serial number range (1915).

The obvious difference is amazing and should be alarming to those who own and shoot the early guns. I shoot my 1899 model one often but NEVER exceed 11,000 psi loading.

My typical load is 148 grain WC in front of 2.5 grains of bullseye.

Later standard loading actually list 3.5 and up to 4.2 grains of bullseye powder! That’s WAY TO HOT FOR THE MODEL 1 M&P!
Murph

 

[BMur]

Cone comparison

Here is a photo comparison of a Model 1 M&P in 38 Special caliber stamped on the barrel in the 7,000 serial number range.
The comparison barrel is also marked 38 Special from a commercial model (NOT A VICTORY) in the 250,000 serial number range.

I also reviewed a few of my Modern reloading books and very clearly published pressure curves as high as 18,200 psi are listed as Standard loadings for 38 Special. That is way too hot for early guns.

If modern loading manuals list this kind of pressure it would suffice to say that you could easily find yourself purchasing todays modern manufactured ammo that achieves this pressure as well.

Way too hot! My 1899 will never see that while I’m alive.

Murph

 

[glowe]

The problem is not with the gun, but with the advancements in cartridge design. From the beginning, the K frame has been rated for pressures of 16,000-17,000psi. That number has never changed for the standard loading of this cartridge. SAAMI today stated the same standard pressure for the standard 38 Special. It is the error of the owner to use ammunition that was not designed for the gun and not the gun. Same issue with the 22 HE. Designed to shoot 22 Long, but in use at the time that the 22 Long Rifle came out. Owners used them in the little 22 with expected results - blown forcing cones. What I do not see from your in-depth research is any confirmation of forcing cones on early K frames bursting. You just say it, but where is the documentation??

 

[BMur]

Thankless

SAAMI STANDARDS did not exist prior to 1926. Look it up for yourself.

The transition I am documenting took place 10 years BEFORE SAAMI STANDARDS.

Prior to 1926 we have many reloading manuals for reference and none of the many many in my collection come close to 17,000 psi or cup.

In fact I would like to see your research that proves black powder can achieve 17,000 psi in The M&P model.
My references reflect 9-11,000 psi MAX!

Murph