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Old March 27, 2006, 12:08 PM   #1
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Different Powder's Effects on Forcing Cone/Top Strap Erosion

I've noticed a small groove on the top strap of my S&W Model 28 between the cylinder and forcing cone. I'm guessing this is what I've heard referred to as flame cutting? I've also heard of erosion, which I'm guessing is mainly of the forcing cone. Usually when I hear these terms, I also hear them used in conjunction with powders like H110 and W296. I actually know one reloader who strongly prefers 2400 over H110 and W296 because of this.

I mainly shoot 2400 and Blue Dot in my model 28, although I've recently loaded up some with H110. The funny thing is that I've shot many more full-power loads in my .44 Colt Anaconda (and I use primarily H110 there), and I see no evidence of any erosion anywhere on that gun.

Is there something about about H110 and W296, like maybe that they burn hotter? Or maybe is it simply that by their nature they must be pushed close to max pressures?

I'm guessing that it's nothing to do specifically with H110/W296, and more to do with a particular gun seeing more ammo loaded to high pressures, regardless of powder type. Of course, I'm pretty new to reloading, so I thought I'd post this question here for you more experienced types.

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Old March 27, 2006, 12:26 PM   #2
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About 20 years ago I was shooting my 686 a lot and experimenting with loads for it. I picked up an article that described top strap erosion and its causes. In that writer's opinion, it was caused by the flame but also contributed to by the fillers in some powders. The opinion was that some fillers were abrasive and accelerated the wear. It was also stated that the erosion was fairly rapid on a new weapon but slowed after a period of time.

I shot my 686 for a full 20 years before recently selling it. After about 10,000 rounds of full .357 mag loads (mostly 2400 powder) the erosion appeared to be very minimal. I always kept an eye on cylinder gap to make sure it wasn't excessive so maybe that helped too.

Don't profess to be an expert on this, but this was my experience.
My definition of Gun Control--- A steady grip and hitting your target.

"In God we trust, all others are suspects."

"If I shoot all the ammo I am carrying, either I won't need any more, or more won't be of any help".

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Old March 27, 2006, 12:30 PM   #3
Steve in PA
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The flame cutting will get to a certain degree, then stop.
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Old March 27, 2006, 09:35 PM   #4
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The forcing cone cutting will not stop like the top strap erosion, but it really isn't a big deal.

You can send it to S&W and have the barrel set back for a nominal fee, and you can do it a couple times at least. Shoot on and be happy, don't worry about the flame cutting.
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Old March 28, 2006, 07:27 PM   #5
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So most people here don't think there's much to the theory that H110 and W296 are more prone to cause cutting/erosion than other powders? What swmike writes about is sort of along the lines of what I was wondering.

I also thought it was so odd that my Anaconda showed no evidence of it whatsoever, and the cylinder/cone gap is much bigger than on my model 28.

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Old March 29, 2006, 12:08 AM   #6
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Running your gun at max pressures will cause flame cutting. 45 Colt at 30,000 PSI is less likely to do it than a 357 at 40000 PSI.
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Old March 30, 2006, 06:21 PM   #7
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The larger B/C gap is what kept your Anaconda from damage. When the B/C gap is small, the gas and flame velocity is higher. This results in an increase rate of gas cutting. As the gap gets bigger, the gas velocity falls off. The rate of flame cutting decreases. Putting you finger over the garden hose end, will increase the water velocity in the same way...even though the pressure remains constant.
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Old March 30, 2006, 07:11 PM   #8
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Ahh--okay. 918v and mbartel, those are both excellent points.

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