K-Frame Forcing Cones

[Hapworth]

Good replies in this thread, and plenty more in the many other threads discussing this very issue. Suggest a search.

Bottom line: you're likely safe shooting any common .357 load you like; you're probably especially in the clear if you keep it 140 grain and above.

My understanding is that the 125 grain "hot" loads of today are pale compared to their counterparts from 50 years ago when the forcing cone problems started cropping up and, and that those problems were largely associated with especially hot Treasury loads that briefly became popular in law enforcement circles, and are now long gone.

 

[nipster]

As I mentioned in my post, this is the first one of these that I have come across, and I have owned a lot of K frame 357's and shoot 357 magnums out of them alot.

For the most part, I thought it was an internet wives tale until I found one for myself. I still have no reservations shooting them.

 

[Doug.38PR]

I ask this question about the M-19 some years ago. Answers were mixed. Some say the force cone would crack after so many thousands of 125 gr Magnums, others said they've been shooting thousands 125 gr Magnums in their 19s and 66s for decades without any problems.

It either will or it won't.

 

[STCM(SW)]

The 110 gr Super Vel rounds were hot when they were around. I still have a few I found a couple of days ago.
I've seen more examples of top strap being eaten from loads useing H110/WW296.

 

[jack the toad]

My guess is few if anyone on this forum have ever experienced this problem. If someone has actually had this happen to a k frame that they own, I'd like to hear about it.

I've never experienced the problem but I was aware of the warnings in the pre-L frame days so I took necessary precautions. I've seen several K's with cracked cones that were for sale and I considered buying until I saw the crack.
As to what load caused it, I don't know but in my opinion it is a real concern.

 

[aphelion]

As to what load caused it, I don't know but in my opinion it is a real concern.

It doesn't really matter what load. If the barrel is too thin, it is more prone to cracking, whether the bullet weight is 125 gr or 158 gr. The issue with 125 gr and lighter bullet loads has to do with increased rate of erosion. As the forcing cone erodes it become thinner yet, and will aggravate the problem with the thin barrel. But if too much material has been removed, it can crack there sooner or later no matter the bullet weight. As I said, if you see a specimen with too much steel hogged off that area, I'd avoid it if you want to fire magnum class loads through it.

 

[Senor Chisme]

My guess is few if anyone on this forum have ever experienced this problem. If someone has actually had this happen to a k frame that they own, I'd like to hear about it.

In 1978 I purchased a Model 65, had adjustable sights installed, and carried it on duty with the US Border Patrol. When I transferred to Chicago, I had it chopped to 3”, round-butted, and carried it for another three years. During those nine years, we qualified 4 times a year. The qualification course was the old PPC course. We fired 60 rounds (48 rounds of wadcutter and 12 rounds of magnum.) I don’t know if they were 125 or 110 grain loads. We were also issued 3 boxes of wadcutters each quarter for practice. Practice, for me, consisted of rocks, cans, jackrabbits, and coyotes in the brush and later in Chicago, paper punching. I used up all the issue ammo plus a lot of purchased and handloaded ammo.
When I transferred to Dallas, we were transitioning to semi-autos and the gun was retired to a house gun. I still took it to the range a couple of times a year with both wadcutters and magnums (both 125 and 110 grain.)
After I retired, I joined a local Sheriff’s department where I carry a .45 ACP. I still took my 65 to the range a couple of times a year to qualify with it using all magnums. Sometimes I would use 125s and sometimes 110s. A couple of years ago, during qualification, the cylinder became extremely difficult to open. Upon closer examination it was discovered that the forcing cone had split at 6 o’clock. It is impossible to guess how many rounds have been fired through this gun. However, I can positively state the majority (by a wide margin) have been wadcutters.
By the way, I had the barrel replaced with a 3” Ladysmith barrel. Looks kind of cool.

 

[ColColt]

This is what the forcing cone looks like on the 2 1/2" 66-4 I picked up today.

 

[ralph7]

I'll be receiving a 66-4 about the middle of next weeks but am beginning to get questions in my head about shooting 357 Mag's though it much since I've read here and there about forcing cones cracking...usually at about 6 o'clock. Not that I plan on a lot of full bore fire snorting 357's but was curious as to the credence of and number of these occurrences. I'm sure it has happened as I saw at least two pics from different people showing it. If this had been a serious problem I feel sure S&EW would have addressed it long ago but would like some comments/feedback since this is my first K-frame and don't know it's strengths/weaknesses.

I'll primarily be shooting lead SWC's for the most part so, this shouldn't be a real problem for me-just curious about the forcing cone issue.

well, don't shoot it at that time, then.

 

[18DAI]

That forcing cone looks fine ColColt. Shoot whatever you wish in that fine 66. Just keep it clean and the forcing cone free of carbon and lead buildup.

Do this and your great grandchildren will be enjoying that 66 decades from now.

I've only been issued/shooting/accumulating/examining K-frame magnums for about 44 years. In all that time I've never seen a 66 with a cracked forcing cone in person. Only a photo of one, on this board. That was after six years of asking if anyone had ever seen or even heard of a 66 with a cracked cone.

I'm with Sebago Son. Better chance of seeing aliens, IMO. Enjoy your 66!! Regards 18DAI

 

[Amityslim]

After reading the range of opinions on this subject over the past few months, and with new-to-me 4" 66-2 and 19-4 beauties, I decided to work up a lighter load for a steady diet and to shoot 158 gr. fullhouse loads occasionally. Very probably over-conservative, but there it is. I want to be sure to pass these on. Different story if Smith still made them. Tried a 158 gr. 13.5 gr. 2400 load which chronographed at 1100 fps and was most pleasant. May bump to 14 or 14.5, but honestly, 1100 fps is probably good enough for most of my outdoor use, not living in grizzly country. Skeeter claimed that most magnum loads chrono at about 1200 fps out of 4" barrels but I haven't tested that.

The 19 gr. H110, 140 gr. XTP load goes through my 686, and nicely.

 

[M2MikeGolf]

Keep the gun clean. Don't forget the forcing cone area of the barrel. If you don't have a Lewis tool, get one. Limit the use of lightweight magnums. Drew may have overstated his case "just a little" , but in general, if your gun (I take it you are buying a used gun that has been fired) has not been abused before it gets to you, you are not likely to have much trouble with it - as long as it gets proper usage and care.

I think M29 has made an important point. For all the reports of cracked cones, I have never really heard or read a detailed report of variables. I purchased an old M1917 once and cleaned it thoroughly (I thought). It grouped erratically with FMJs and after a super close inspection of the throat around the barrel, I realized there was ancient lead that had built up there, virtually undetectable at even close inspection. After some serious scrubbing, I had removed all of this old lead, and realized that this could cause some serious back pressure, it's simple physics, combustibles in smaller, confined space, increased pressure (ask the explosives expert about that, and it all makes sense). My guess is that after leading the throat on these K-frames, then firing high pressure light loads just increased the pressure around the throat causing the cracks. Since most probably clean their revolvers well, that would explain the low numbers of reports of this problem. After reading how some clean their weapons on other threads, I realized that this could easily be causing this issue. If 125 gr loads contribute to this problem, I don't see an issue, most (if not all) fixed sight .38/.357 S&Ws are regulated with a 168 gr. load, and I see no real advantage to the lighter since there are simply myriads of 158 grain styles and loads, proven ones to boot. It's all I would ever shoot anyway, J-Frame/K-Frame or even N-Frame.

I have a 547 which produces almost .357 pressures (look it up in the SAAMI if you don't believe me). Ever hear of one of those cracking cones? Maybe it's because most commonly purchased and used 9x19 ammuniton is jacketed. Anyway, it's just my theory on it, I have no proof other than an uninjured firing hand to prove it.

 

[Match10]

You have more to worry about from an alien invasion from mars than if your Model 66 barrel is going to crack.

This. Just shoot it!

 

[ColColt]

It's going to have it's debut at the range next Friday. That'll give me this weekend to make up an assortment of rounds and several different powder combos that have worked well with other revolvers. I seldom use jacketed bullets-primarily 150-170 gr lead bullets. I still think I'll stir clear of any fire breathing 357 loads. I'll feed those to the other animals.

 

[rigrat]

So I guess even shooting 38 or 38+ loads with less than 140 grain bullets wouldn't be advisable?

 

[ColColt]

I have a tendency to believe at least some of the cracked cones were due to shooting lead a lot and not getting the barrel/forcing cone cleaned out and it just kept building up. that for sure will cause more pressure. I shoot lead nearly exclusive and after each range session clean them the same day. I usually don't have leading problems at least that a little Chore Boy wrapped around a wire brush and or some Lead Remover by Shooter's Choice won't take care of. If sized properly for you gun -mainly the throats and not using BHN22 bullets in a load that only develops 17-20,000psi, I think leading will either be minimal or not at all.

 

[aphelion]

Lead bullets, whether cast or swaged have nothing to do with it. 38 Special class loads have nothing to do with it. If there was too much material removed from the barrel during fitting, leaving that area thin and poorly supported, cracking becomes more likely with higher pressure loads. If the forcing cone has sustained a lot of erosion, leaving that area thin, it becomes more suseptable to cracking with heavy loads. Thinner = weaker, it is as simple as that.

 

[ColColt]

True but, you can bet an accumulation of lead plays a big part as well-smaller area for bullet to travel though=greater pressure.

 

[roaddog28]

Its likey a person will have a heart attack and die before cracking a forcing cone on a model 19. Use the recommended round which is a 158 gr magnum and clean the forcing cone of lead deposits. Also, it would take many thousands of rounds for a K frame magnum to wear out with end shake. The K frame magnum is not a fragile revolver. In my opinion it still the besting all around magnum S&W ever made.
Regards,
Howard

 

[Laurent]

In 1978 I purchased a Model 65, had adjustable sights installed, and carried it on duty with the US Border Patrol. When I transferred to Chicago, I had it chopped to 3”, round-butted, and carried it for another three years. During those nine years, we qualified 4 times a year. The qualification course was the old PPC course. We fired 60 rounds (48 rounds of wadcutter and 12 rounds of magnum.) I don’t know if they were 125 or 110 grain loads. We were also issued 3 boxes of wadcutters each quarter for practice. Practice, for me, consisted of rocks, cans, jackrabbits, and coyotes in the brush and later in Chicago, paper punching. I used up all the issue ammo plus a lot of purchased and handloaded ammo.
When I transferred to Dallas, we were transitioning to semi-autos and the gun was retired to a house gun. I still took it to the range a couple of times a year with both wadcutters and magnums (both 125 and 110 grain.)
After I retired, I joined a local Sheriff’s department where I carry a .45 ACP. I still took my 65 to the range a couple of times a year to qualify with it using all magnums. Sometimes I would use 125s and sometimes 110s. A couple of years ago, during qualification, the cylinder became extremely difficult to open. Upon closer examination it was discovered that the forcing cone had split at 6 o’clock. It is impossible to guess how many rounds have been fired through this gun. However, I can positively state the majority (by a wide margin) have been wadcutters.
By the way, I had the barrel replaced with a 3” Ladysmith barrel. Looks kind of cool.

That's very good info. That barrel looks real thin. On the second pic, it appears to be filed at 6 o'clock: is it factory original?

L.