Aluminum Bronze Sten Breech Block

[Vincent]

My aluminum bronze Sten breech blocks arrived today…. and I thought some of you might like to see before and after pictures.

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Should have the after pictures up in a day or two.

Information

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[Vincent]

Attachment 66212Attachment 66211Attachment 66214
It still needs cleaning up, but you get the idea.

[browningautorifle]

First I've seen. Now I see. I knew they were supposed to be lighter...

[Vincent]

Yes, that one is lightened for a Mk2(S) sound suppressor. I will do the next one like the Mk6, by drilling out the return spring spigot….. and probably a bit more.

[browningautorifle]

That's the one I meant, the lightened one...I knew they'd been turned a bit but hard to visualize.

[Sarge]

They also jack up the rate of fire. Seems like I have one of those in my parts box, but never saw any reason to use it.
Sarge

[Vincent]

The only good reason I know of is to use with a suppressor and that’s the plan.

[Sarge]

OK, what don't I know? What is the benifit of a higher rate of fire with a suppressor?
Of course I guess I should talk since I have a suppressed MAC 10, 9mm, but then I don't know of any way to slow the MAC down or I might.
Sarge

[Peter Laidler]

The lighter weight is so that the breech block will operate with the lower velocity of the bullet that HAS to be travelling at LESS than the 1000 ft/min or so speed of sound.

[browningautorifle]

the bullet that HAS to be travelling at LESS than the 1000 ft/min

So, if you use it with standard ammo in a standard gun, you get a higher rate of fire. These are all meant to operate with the parts as issued. I once made up a set of drive springs for an M3 greasegun using the butt springs from a Bren. When I touched off, it sounded like an Ingram...ran about 1000 RPM instead of 300. Neat.