I am thinking of packing my model 66-1 (pinned, and recessed) this year for hiking season. What are folks opinions on running Underwood 140gr Extreme Penetrator ammo in it. The biggest critter I have to worry about here in western WA is our little black bear.

I have no idea what the answer to your question is. I did not want you to think you were being ignored.

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police651

I think it's a bit hot for a K frame. I would never use it in my gun.

If you were going to use a lot of it for an extended period of time, you might have concerns. For carry and self defense only, you may be okay, but contact Underwood to see what they think. Do it by email so you have something in writing in case things go south. Of course, your gun must be in good shape. Good luck.

I'm not familiar with Underwood, but I've had experience with a number of boutique ammo makers. Now, there are more powders available now than there were back then. That said, if you find someone claiming higher velocities at SAAMI pressures, there's a definite possibility of some creative writing.

You've got a nice gun, there's little reason to risk damaging it with hot loads. The key to your solution is shot placement and projectile integrity, not wantum ballistics. Pick a major name 158 or maybe 180 gr hollow point/soft point and go with that.

It may be safe to do, yet based on my experiences with the Underwood .357 Magnum 158Gr. JHP rated at 1,475 FPS in an L frame I would not want to shoot much of any of there Magnum ammo in a K frame.
Your Model 66 will be happier and so will you if you shoot Hot 38 special or mid-range .357 Magnum ammo.

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Always Stay Strong!

I doubt any commercially available ammo will harm your revolver if the ammo is used in moderate amounts.

As a practical matter, I can’t imagine why you think you need boutique ammo for your application.

Any commercially available 158 gr 357 mag ammo will suffice.

Neither you nor the bear will notice a difference.

My 66 No Dash and I are happiest with a steady diet of .38 special and some commercial 158gr .357.

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Thanks for all the replies. I typically carry Remington green, and white box .357 125 gr semi JHPs in it. That is what the sights are zeroed for. I am looking for something that penetrates better, and does not have a drastically different point of impact. I'll send underwood an email, and then give them a try. I don't see myself shooting more than 40 rounds of them in my life.

If you want penetration, get you a hard cast bullet and stoke it with some 2400 or H-110

Lookat Buffalo Bore. Tht tell you what guns their loads are safe in. I've shot lots of Underwood in N frames, and I don't think I would care to shoot much of it in a K frame. It'll be hard to control for a fast second shot.

With bears in mind you want the best penetrating bullet you can find. The Federal 180 grain Cast-core is by far the only big factory bullet that meets that criteria. Or as mentioned before look at something similar from Buffalo-bore. Adjust your sights for that load.

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Billy
Gunsmith, M/C mechanic

You do know that 125 gr. 357 in an old K frame magnum is a no no don't you???

If not you do now. K frames magnums were built to shoot 38 specials, 38+P and 158 gr. 357 magnums. Story is the 125 gr. 357 magnums led to cracks in the forcing cone. Might just be a story or a wive's tale like low number 1903s but I'd hate to find out the hard way. There's plenty of threads here to back it up.

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LIVE FROM THE DAWGHOUSE

My first center-fire revolver was a Model 66-1 with six-inch barrel purchased in 1980. I shot various bullet weights including some warm .357 reloads. One day it lost the timing and I sent it back to S&W for repair. It got a new non-recessed cylinder; they said one of the chambers was swelled. Not really noticeable to the naked eye. Back in the late 80’s, it cost over half the purchase price for the repair and probably reduced the current value by half as well.

Got a 686 and considered that a more robust solution. I retired the Model 66 and haven’t shot it in over 20 years.

I've shot Underwood and never had a problem, but with Buffalo Bore I've had issues with very hard primers that are difficult to ignite.

I have not shot any nuclear strength Underwoods in a K frame, but I've shot 158gr American Eagle JSPs in my M19 at the range. They only reach about 1250fps according to the box, but they were plenty hot for that K frame. I didn't shoot very many before I transitioned back to .38 SPL. I'd definitely get some big squishy rubber grips if I planned to shoot much hot ammo in it. The Pachmayr Diamond Pros seem to be the squishiest grips I've seen.

I emailed underwood. Looks like I am good to go with this ammo.

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I am aware that steady diets of 125 gr in old K-frames is not the best idea. Mine mostly sees wimpy .38 specials, but I carry the 125gr green, and white box .357 Mag. JHPs. I have zeroed the weapon with these loads, and have shot a couple of boxes through it. I am aware that some K-frame guns have been trashed by a steady diet of hot .357 rounds. I am also aware of how "knowledge" gets spread on the internet like old wife's tales.