Side Plate, Another Anomaly?
- Thread starter Retired W4
- Start date
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As I recall these have what looks like two firing pins so it can shoot 9 mm machine gun ammunition with its harder primers.
So I suspect the sliding hammer block might be shaped differently from other models. Is that true? If so that might explain the difference of machining at top of the sliding bar groove in the side plate.
I don’t have a 547 so that’s just my best guess.
So I suspect the sliding hammer block might be shaped differently from other models. Is that true? If so that might explain the difference of machining at top of the sliding bar groove in the side plate.
I don’t have a 547 so that’s just my best guess.
OP
Thanks Jim. The hammer block looks like the standard one but someone has had the side plate off previously. The other pin, above the firing pin, looks like a device to press on the rear of the case, possibly to stop rearward movement when firing. Now I'll have to take the side plate off my 4" SB to compare. These things are very different from other hand ejectors by S&W.
That's exactly what it does. S&W calls it a limit pin. I've read that they added it during development because of pierced primers. I'm sure it relates to the funky extraction system.
Jim Watson
Member
As I understand it, the "limit pin" is to drive the round all the way into the chamber against the stepdown to the throat so it is fully supported against the firing pin blow. Those French submachine gun primers are tough.
OP
OP
Ok, that settles it. My 4' has the same side plate cut and same bent hammer block. Why, I don't know, but it is.
OP
Apparently the bend is so the block clears the firing pin retainer. The retainer is similar to the retainer on a 1911 except it holds two pins in. I have install hundreds and hundreds of side plates before but these are a real pain with that bent hammer block.. Never again. Oh, I still have to put the 3" back together. 
