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Discussion Starter · #1 ·
So after dry fitting, sandblasting, re-fitting, squaring, I started riveting the plates together. Used a 20T press, tried different jig set-ups, worked great. Then I set the top cover rivet, the pain-in-the-rear one near the top of the backplate. I modified the bucking bar to go between the top cover rivets. Everything looked good and measured square. Then did the front top plate rivets.

RSP Top rivet



LSP Top Rivet - close match to originals.



But then this happened:



Backplate would not fit. Dry fit, no problem. Rivets pulled sides in tight and it would not fit without a lot of force.

So first thought - I'm out of square or backplate groove is not milled deep enough. I press fit the backplate to check alignment. Notice that the end of the right and left sides are not the same. I had measured the square from where the backplate fits into the groove and not to the end of the plate. Panic started to set in.



RSP view:



LSP view - I can see more metal from the back of the side plate and backplate:



I realized the LSP and RSP were slightly different lengths. I spent several hours getting out all my fixtures out for moving metal and experimenting on ways to fix this. Checked and re-checked the internals, barrel alignment, etc. Internally everything fit. Trunnion was square. Used another backplate and verified it was not the backplate. Both would not fit and required pressing (i.e., mallet time).

I found out what I did and fixed it before doing something stupid. Probably should have posted the problem first. Could have saved half a day. I thought I'd ask the forum to see if you went through the same "Oh $hit" moments when doing the final assembly. Off to press in the trunnion and get this finished. BTW - anyone guess what I did? It's fixed (I'll post later what I did but its embarassing since I spent so long on the wrong solution).

DaveB
 

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...?

Never had that problem because the top plate and the bucking bar did not allow the side plates to buckle. At least they never did for me...LOL. My first thought was a burr on the back plate,as I've seen that a couple times before. Or the groove in one of the side plates was not sufficiently milled and had to have a swiss file job. Let us know...
 

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Discussion Starter · #4 ·
I'm still trying to figure out how it happened but I decided to check the inside channel with a gauge. Sure enough the top right channel was slightly pinched inwards. Pulled out a Cresent wrench, bent the edge slightly back to open the channel...



... and bam - the backplate fell into place.



Can't figure out how I did this but it took five minutes to fix. I was about to use a spreader to open the area up between the plates. That would have really messed things up. Lessons learned.

At least I got 'er done.



Decided to chamfer the edges on the KMP side plate and do a lot of little fitting clean-up.





I'll finish the small stuff next weekend. Then it sits until I get a tripod and belt loader. I'm not going to parkerize until after I get it dialed in at the range.

DaveB
 

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Anyone that has NOT had one of these O SH*T moments does not build, Looks like you made a nice recovery.

Good Job

Karl
 
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