Frame bridge wear question

original: forum.m1911.org
Retrieved: December 01, 2011
Last Post: July 25, 2009

Slopoke
25th July 2009

After 2000 rounds I notice the very front of the frame bridge on my RIA is showing a slight hump / metal build up on the surface, presumably where the barrel / link hinge makes contact when the slide opens. Just curious if this is a concern.


Hawkmoon
25th July 2009

Can you post a photo? If the area is where I visualize from your description, there should be a chamfer along that corner/edge.


Slopoke
25th July 2009

Here are a few close-up pics. It does not seem too bad, but you can definetly feel a "lip" when you run your finger over the edge. Also not sure if it has always been this way and I just noticed, or if this is the result of wear.


Hawkmoon
25th July 2009

Looks like whatever chamfer might be there was cut by hand with a dull file.

I'd send the photos to Ivan and ask him what Arnel thinks.


Slopoke
1st August 2009

Arnel said the bridge should be filed to clean it up. He offered to have me send the gun back to him but I went ahead and touched it up myself no problem.


Lazarus
1st August 2009

Are these photos actually showing evidence that the barrel is stopping on the frame bed? Use your calipers to measure the depth of the frame bed from the top of the frame rails. I would look for at least .077". Let's see a photo of the bottom of your barrel.


niemi24s
1st August 2009

Here's one of the OP's pics after a little adjustment...

PICTURE 404

...showing evidence of barrel feet/VIS contact.

From that, looks like his linkdown timing's OK - feet hit VIS first, then the barrel drops to the bed.

But (me not being real familiar with a non-bow tie VIS)... do you think the feet are hitting the VIS a little too far down?


Slopoke
2nd August 2009

Quote:
Are these photos actually showing evidence that the barrel is stopping on the frame bed? Use your calipers to measure the depth of the frame bed from the top of the frame rails. I would look for at least .077". Let's see a photo of the bottom of your barrel.

Don't have time this weekend to snap a pic of the barrel, but I can say that the it has matching marks to what you see on the top of the frame bed. However as Niemi24s points out you can see that the feet make good contact with the side of the bed. I am not an expert here but do trust Arnel's input that all is ok. I will try to measure the frame bed depth just to be sure.


Lazarus
3rd August 2009

I'm not sure you can determine that the timing is correct by seeing a mark on the VIS. If there is an obvious gouge on the frame bed, the barrel is not politely dropping down onto the bed; it is slamming onto the bed at some time during the linkdown. But, the photo shows that the mark is near the rear of the bed, so it is possible that the barrel needs some dressing in this area. Or, it is possible that the bed is not deep enough. Interesting that the recommendation was to file on the bed first without taking some measurements or checking the wear areas with black marker.


niemi24s
3rd August 2009

Quote:
I'm not sure you can determine that the timing is correct by seeing a mark on the VIS.

Good point. It might be that the barrel is contacting the VIS and bed simultaneously as the result of a link that was just a tad too short.

If this is the situation, the link would (I think) be a little on the tight side when the barrel's fully down and aft - instead of being totally loose.

Is this what you're saying?


Lazarus
4th August 2009

Quote:
It might be that the barrel is contacting the VIS and bed simultaneously as the result of a link that was just a tad too short.

I was thinking it would be possible for the barrel to hit the bed first, but still be free of the upper lugs. Then the barrel would continue moving rearwards unit it hit VIS. If that scenario is possible, it seems like the link would be in tension, trying to pull the bottom of the barrel apart. (VIS set too far rearward?)


niemi24s
4th August 2009

Quote:
I was thinking it would be possible for the barrel to hit the bed first, but still be free of the upper lugs. Then the barrel would continue moving rearwards unit it hit VIS. If that scenario is possible...

That scenario is not possible. During linkdown, the link is in tension and if it hits the bed first the barrel cannot go any farther aftward to make VIS contact - unless the link breaks.

The reason VIS contact won't be made is because the barrel cannot go any farther down (it's already on the bed) and it can't go any farther aftward (the link's still in tension).

The upper lugs could still be vertically disengaged in either scenario.


Slopoke
5th August 2009

Quote:
If this is the situation, the link would (I think) be a little on the tight side when the barrel's fully down and aft - instead of being totally loose.

..just to chime in here the barrel is totally loose when the barrel is fully down.


niemi24s
6th August 2009

Quote:
just to chime in here the barrel is totally loose when the barrel is fully down.

If you meant to say the link is totally loose when the barrel is fully down and aftward, that's good.

That can only occur if the barrel hits the VIS first and then drops down to the bed. It's the only way the tension can be relieved in the link without putting the link into compression.

Just whittle off the "lip" with a good knife or scraper and blaze away with her!


Slopoke
7th August 2009

That's it, I think I am in good shape.


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