1911 (Spartan) mainspring housing retention pin difficulties

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echerub

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Hi folks

I'm trying to change the mainspring housing on my Spartan - from the stock plastic one to a metal STI one in order to install a magwell - but I can't get the retention pin in. In fact, I can't get it back in to the original MSH either. With or without the main spring assembly in place, I push the MSH as high up as it'll go - and the holes all look aligned to my eye - but then the pin doesn't go in. Light tapping with the hammer & punch doesn't do anything.

Is it supposed to take a lot of force to get it back in? It's not the retention nubbin in the middle - the pin just isn't even going into the MSH itself yet. It looks like it might just be nicking the front edge of the metal MSH because I see a bit of wear on the front edge of the opening. That might have been from my attempts to push the MSH up with the spring installed and inadvertently lightening up a bit on the tension while reaching for/using the hammer.

Any advice for a newbie 1911 owner here?

Thanks!
Len
 
The pin is supposed to be quite round nosed on one end and have a dished out area on the other for the punch or other tool used to push it out and back in the hole. If your pin doesn't have these shapes it might have bruised and distorted the plastic in the old MSH and possibly the new metal one as well. Check for burrs of metal in the holes. If you have any you can use a stout but small knife to lightly cut away the metal. Or lightly use a counter sink tool to remove those burrs as well. Or perhaps you've caused a burr on the nose of the pin itself. You'll want to check each and all of the parts closely for any signs of such damage.

If this isn't the case with the new MSH then you've run into one of the little manufacturing differences from one brand to another and you'll need to drill out the hole to a size which is a few thou larger. Or LIGHTLY file or Dremel out the hole.

The key here is to closely examine all the parts to see which fits OK into the other. Look for signs of the small sorts of damages which could produce the issue. The fact that you used a punch and hammer even lightly could have caused the problem. So that's the first thing to check for.

In any case you want to think of and use the least intrusive solution first and work up from there as needed. Start with assuming that you damaged the holes or the pin and check for that. From there move on to the MSH's.
 
Hmm. I'll have to look very closely at the pin and the holes later. When I try inserting into the frame holes alone or the MSG alone, the pin goes in no problems. But when I put everything together even though it all *looks* aligned perhaps there's something just a little off.

The pin does have a slightly rounded end and an end with a depression, but the rounded end has really sharp/hard shoulders.

Yep, hammer is decocked :)

If I can't see anything from a closer inspection, I'll try the lube and if that doesn't work, use the Dremel with a very light touch.
 
If the pin fits both by themselves then LEAVE THE DREMEL ALONE! ! ! !

Instead use this as a trick. From the opposite side insert a pin punch that is a little on the small side so it fits easily. Then use that to pry a little to get the holes to line up. Then insert the real pin from the other side. Once it's inserted far enough to hit the detent ball at mid way you can remove the "prybar" and things will line up.

Another option would be to get a common wire nail that is a few thou smaller than the hole. Mount it in a hand drill and while spinning it "lathe" a long taper on the pin. Use it as a tapered alignment forcing pin and you push it through until the end is flush. Then use the real pin to push the aligner through as the retainer pin seats into place.
 
I didn't get a chance to do anything with the Spartan yesterday, so your warning got to me in time! :)

I'll give the opposite-side punch method a try!
 
I had same problem. The holes were slightly offset. I used a carbie drill bit smaller than the diameter of the MSH's hole to widen the affected area. Tiny little bit at a time, checking fit constantly. Fits like a glove.
 
The mainspring pushes down on a cone shaped bottom plunger that protrudes into the cross pin hole. Most crosspins have a groove in the centre to "lock" it in place. As long as the pin goes in half way you can hit it quite hard and it will go fully into place. That cone end has all the force of the mainspring pushing down on it so it ca take a substantial hit to move it. I usually lay the heel of the pistol on the bench and hit it will a 4oz brass hammer.
 
juancarlos said:
Is the hammer cocked? That will stop you from being able to reassemble.
Click to expand...

+1

Mainspring housing pins are always a lot easier to get back "in" when the hammer is uncocked.

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The new MSH may be binding on the grip safety.
If that is the case, then messing about with the MSH pin hole, will only cause other issues.
Be certain that the grip safety operates correctly, with adequate clearance for the top of the MSH.
If removing material from the MSH, make sure that the shape profile of the part is not altered.

Sometimes supposedly "drop in" 1911 parts, actually need fitting!

Just sayin', Eh!:)
 
Sometimes the issue is a slightly long hammer strut....this forces the msh out of alignment and you need to compress it while inserting the pin. already some good suggestions ie slave pin, punch to align the hole, etc.
This is actually a good thing for the gun as there is no free play in the hammer when it's down. EGW sell a longer hammer strut for this very reason.
 
Okay, got everything solved. The problem was the channel in the MSH's themselves - plural because I was changing over 2 MSH's for 2 Spartan frames. Same problem in both cases. The STI steel MSH's retention pin channel was "off-centre" in relation to the retention pin holes in the frames.

I ended up Dremeling the channels a bit bigger "forward" and just testing often until the retention pin could go through all the way. I wish it was something simpler than that, but unfortunately it was definitely something that required "fixing" with a Dremel. I would have thought STI would align things right for the MSH to fit their own frames perfectly.

Thankfully the trigger I changed on one frame fit no problems!

I've spent all afternoon on this, but now I know my pistols a whole lot better and I feel good about that! :)
 
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