N frame Endurance Package

[Frank237]

Anyone know if the Endurance Package upgrades, that started with the M-29-3's back in 1987, did they make it across the entire model line?

Meaning to the K and L frame guns as well?

FN in MT

 

[Joed49]

The Endurance package was only for the .44 Mag to my knowledge. It was done to fix the problem with heavy loads in that line. Some shooters noticed that upon firing the cylinder would rotate backwards from all the power.

The original N frame is an old design that was not intended to handle all the power a .44 mag could generate. S&W beefed up the frame and made it work with the .44 Mag but in all honesty the N frame was designed for the 44 Spl. Eventually with heavier bullets and hotter loads the problems started. The Endurance package was S&Ws answer.

 

[muddocktor]

I have seen later engineering revisions of the Model 27 that have the extended stop cut in the cylinder as compared to the earlier models, but don't know if the other modifications of the Endurance package were carried over to the 27 line also.

 

[RodSS]

Model 25s also

I read somewhere that the Model 25 .45colts also got similar treatment starting with 25-7.

 

[muddocktor]

Yeah, looking on GB at a NIB 25, it also has the longer stop cut in the cylinder too. I also found 1 25-7 with an unfluted cylinder and it had the regular stop cut and it was 45 Colt.

EDIT: Also found a 25-9 that was made for the "12 Revolver" set in 1990 and it does have the longer cylinder stop cut.

 

[Dennis]

My 25-9, 27-5, and 24-3 have the longer slots. My 3 29-3s do not.

 

[RO73]

I'm picking up my first 29-3 later this week and I have a question. How do I know if it has the endurance package. It's a 29-3 classic with the unfluted cylinder.

P.S. This will be my 2nd S&W revolver so I'm still learning. Thanks for any information you can provide.

 

[Laketime]

oIt will have an E following the 29-3.The endurance package is really only intended for silhouette shooting needs.The loads needed to knock over Rams at 100 yards or more.This is the only group of shooters who were experiencing problems with the original guns.Before this sport took off ,there had been little if any complaints about the durability of the 29.I had three early 70,s model 29-2's which had several thousands of magnum rounds through them and we're still tight.

 

[brucev]

Lets see... I just pulled my 21-4 Thunder Ranch out of the holster. I'm holding it up in comparison to my 28-2 that I just pulled out of the other holster. The 28 has the normal cylinder stop cuts. The 21-4 has the longer endurance type cuts. Cool. Guess this means I can go play Elmer Keith w/ the 21-4??? Maybe.

 

[RO73]

oIt will have an E following the 29-3.The endurance package is really only intended for silhouette shooting needs.The loads needed to knock over Rams at 100 yards or more.This is the only group of shooters who were experiencing problems with the original guns.Before this sport took off ,there had been little if any complaints about the durability of the 29.I had three early 70,s model 29-2's which had several thousands of magnum rounds through them and we're still tight.

Thank you!

 

[klw629]

I have seen 629-2 with the E after the 2 is that meant to designate the endurance package.

 

[muddocktor]

I have seen 629-2 with the E after the 2 is that meant to designate the endurance package.

Yes, in the 629 series, the Endurance package started being applied with the 2-E models according to the SCSW.

 

[k22fan]

The SCSW writes the 629’s dash 2 indicated the frame got the new yoke retention system, the radius stud package and a floating hand. Floating hands turned out to be a bad idea and were later dropped entirely by S&W. According to the SCSW again, the 629-2E got a hardened yoke and frame. If all the details in the SCSW could be taken as gospel, longer stop notches and the bolt block were the “endurance” upgrades that deserved a dash increase to 3.

I believe longer stop notches were phased into the entire N frame line but not all of the endurance enhancements were. The bolt block required an additional milling cut and parts I’ve never read of being in S&Ws chambered for cartridges that recoil less than .44 magnum. On the other hand model 357 light weight .41 magnums recoil more than all steel N frame .44 magnums so it’s logical they're in them as well as other aluminum framed magnums. Hopefully someone with more knowledge will tell us which ones.

When 300+ grain magnums were fired in .44s that had end shake frames were recoiling back away from cylinders so far that the front of the stop notch depressed the locking bolt allowing the cylinder to rotate the wrong chamber into line with the barrel. Long stop notches were S&W’s cure. The bolt block prevents the cylinder latch from moving back under even heavier recoil. It ended the problem of cylinders flying open.

The endurance package made 29s and 629s able to handle more recoil, but not higher pressure. In and of themselves, longer stop notches weaken cylinders since the notches are directly over the thinnest part of chamber walls in 6 shot S&Ws.

Since I don’t need really heavy recoiling .44 loads the more important part of the endurance package for me was smaller chamber throat diameters and smaller forcing cones. I don’t have to compete in 220 meter silhouette matches to appreciate more easily attained accuracy.

 

[kingston]

It's my understanding that beginning in 1990 all M29-5 and M629-3 had the full endurance package.

 

[ISCS Yoda]

It's my understanding that beginning in 1990 all M29-5 and M629-3 had the full endurance package.

Okay, I have to ask, I don't quite have the ability to simply look at my guns and see these things. I have a 25-5 in .45 Colt. What am I looking for/how do i tell if it has this "package"?

Thanks.

***GRJ***

 

[k22fan]

Okay, I have to ask, I don't quite have the ability to simply look at my guns and see these things. I have a 25-5 in .45 Colt. What am I looking for/how do i tell if it has this "package"?

Thanks.

***GRJ***

The 25-5 was superseded by the 25-6 during 1988. The SCSW credits the 25-6 with two upgrades that in 29s and 629s preceded the endurance package, the front side plate screw with a hardened spring loaded yoke retaining pin and radiuses on the studs where they project from the inside of the frame. With the side plate off you can look for those. While you’re in there the absence of the a bolt lock (cylinder release latch lock) should be obvious. Long vs. short cylinder stop notches should also be obvious but it would take a hardness test and comparison to other frames to tell if the frame and yoke were heat treated.

I doubt any 25-5s had any endurance package upgrades. The metal in the bottom of N frame .45 Colt cylinder stop notches is very thin. That’s where 6 shot S&Ws deform first. My guess is if you pushed your reloads too far you’d get dimples under the stop notches before endurance package features would do you any good. The bottom line is your 25-5 was engineered to have S&W’s margin of safety firing a cartridge with a 14,000 psi SAMMI maximum average chamber pressure, not the .44 magnum’s 36,000 psi.

Incidentally, some time ago I reloaded 340 grain bullets in my 25-3 .45 Colt. The perception was standard .44 magnum recoil without the loud blast. I did not experience the cylinder skipping, flying open or anything else the endurance package was designed to correct. I had no idea how much of S&Ws safety margin was left and recommend you pursue more prudent activities.