Tuesday, May 19, 2015

Snub Guts

One thing I noticed when I was in the guts of the 2 snubbies of mine.  One had more of a MIM hint to it.

What do you mean, MIM hint?  T-Bolt?

Well, as you know Metal Injection Molding is cheaper way to go about making gun parts.  More expensive ways are forging then machining, or cutting the part from bar stock...

This is not a dig on MIM stuff.  MIM is perfectly fine for whole bunches of parts and still make a great gun.  And can be used with more and other gun parts to still make a decent gun.  Metallurgists can tell you the nitty gritty.

If they are the same, T-Bolt, then why bring it up?  

Well... it's not the same.  A forged frame has had its molecules messed with.  Aligned.  By the smashing while near molten.  It's a stronger part.  Hands down.  But do you need, say, an adamantium fountain pen when a Bic will do?  Or even a golf pencil?  And do you want to PAY for the adamantium pen?  S&W revolvers are expensive enough without doubling the price insisting on 1930s build methods.

So, how could you tell you had MIM parts, T-Bolt? 

The hammer and the rebound slide had hollows in them.  And mold lines in non critical areas that don't contact other parts.  With hollow there is less machining to do (unless you HAVE to cut the hollows in with the mill or trip hammer, of course, then it's a lot more work).  And you save a trivial amount of metal.  And lighten the parts a bit, but not much.  If you machine off less metal, you heat the part less with the tooling, and you get less warpage, too, when it cools off.  It's kinda a cool way to make stuff out of metal.  When it's done right.  And from what my little mind can tell, they did it right.
The trigger looks the same with both.  And looks case hardened.  Case hardening makes a finish that is attractive to some folks' sensibilities and does some things good for the part, but that's another kettle of fish... 

So, despite being made slightly different, is there really any true difference between your two identical models from slightly different generations, T-Bolt?

Naw.  None that I can tell.  And none that matters, really.

So what was the point in sharing this then, huh?

I just found it fascinating!


Angus McThag said...

I'd add that MIM got a bad reputation early on when people didn't make the connection that some parts should still be made the old fashioned way then went out and applied MIM to ALL of the small parts.

Since those missteps the MIM processes have gotten better and manufacturers have better learned where its use is inappropriate.

The reputation lingers though.

Tam said...

MIM hammers and triggers can be discerned at a glance. You don't even need to take the gun apart to tell if the trigger's MIM or not.

Is the backside of the trigger "skeletonized" or is it one smooth curve of metal like the front? If it's the former, it's MIM. If the trigger's MIM, then the hammer is too. :)

New Jovian Thunderbolt said...

Any idea what year the switch over was? If it was all at once, that is...

Tam said...

It happened over a few years around the turn of the millennium, just before the Lock Era.

P&R -> MIM -> Lock

I think the first MIM guns were the re-introduced Centennials in the mid/late '90s, but I'd have to check.

MIM era coincides with the switchover to frame-mounted firing pins because the old-style hammer with the riveted hammer nose (FP) wasn't a MIM-friendly part.

Incidentally, Smith is a model of how to do MIM right, unlike the CMC/Kimber fiasco. The number of rejected small parts during the QC process plummeted at Smith after they introduced MIM for small parts.