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Post by borderregt on Jan 25, 2011 0:46:33 GMT -5
My SRC Mp40 has a bit of wobble where the upper receiver slides into the back of the lower receiver "cup". Any idea if this is normal or the best way to correct?
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Post by CharleyNovember on Jan 25, 2011 0:58:26 GMT -5
AGM version had the same problem. If you can slightly "bulge" out the sheet metal on the back of the upper reciever it will make it a tighter fit with the "cup" of the lower reciever. This should take up some of the slop.
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Post by jimmiroquai on Jan 25, 2011 5:23:50 GMT -5
This problem is a little different with the SRC MP40. In the AGM, the upper receiver is a bit more secured because it is one piece at the back. In the SRC, the back is split to accommodate the blowback feature. The top-rear of the upper receiver isn't really resting on anything hence the vertical wobble.  I'm still trying to figure out how to fix this. Possible solutions: 1) Get rid of the blowback feature and weld a plate at the rear to fix the split permanently 2) Somehow weld a tongue inside the lower receiver cup to act as a support for the upper receiver |
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Post by jimmiroquai on Jan 29, 2011 10:43:35 GMT -5
I've fixed the top flex. I just replaced the retaining screw of the rear "cup" with a longer one wrapped in electric tape. The upper receiver slides in between the rear cup and this longer screw for added support. No more flexing.  Simple fix.  |
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Ersatzjack
Corporal
"That silly Franz... he thinks we are winning."
Posts: 1,093
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Post by Ersatzjack on Jan 29, 2011 14:14:23 GMT -5
What I find interesting is how in a couple of days you went from: 1) Get rid of the blowback feature and weld a plate at the rear to fix the split permanently 2) Somehow weld a tongue inside the lower receiver cup to act as a support for the upper receiver To adding a longer screw with tape. And it worked! A perfect example of stepping back and looking at the problem the next or following day. It often works wonders. Nice job as usual. |
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Post by CharleyNovember on Jan 29, 2011 14:22:18 GMT -5
Excellent work and way to help a fellow WW2Airsofter out.
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Post by borderregt on Jan 29, 2011 14:43:45 GMT -5
What size screw did you use?
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Post by jimmiroquai on Jan 29, 2011 18:59:36 GMT -5
Ersatzjack - Haha. I was actually in the middle of hacksawing a metal piece for one of the earlier solutions when the idea struck. LOL! @cn - Thanks! It's a good thing this topic came up or i wouldn't have thought about fixing it. My pleasure. borderregt - I'm not actually familiar with the sizing nomenclature of screws but the one i used was 2 inches long and 1/8th" in diameter.
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Post by CharleyNovember on Jan 29, 2011 19:11:22 GMT -5
Most of the rest of the world simply uses the metric system if it was indeed 1/8inch it will probably be close to a 3mm. The sizing is simple. Bolts come in 2,3,4,5 mm and so on measured by how big they are. Only one type of thread. The American system can have one size but a bunch of different thread pitches and threads per inch. It's really irritating..I tould guess that since it was made in China it would be a metric bolt but Jim is the expert here as he has one in hand.
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Post by borderregt on Feb 1, 2011 12:23:54 GMT -5
The screw is a M4-70... I tried a M4-70 x 20 and it was just way to short, that was the longest I had so I'll go out to lowes and try to get a longer one, I'll also get a nut to snug it against the end cap.
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Post by borderregt on Feb 1, 2011 14:54:35 GMT -5
Ok, I used a m4-70 X 45 and that does the trick, you want to use a lot of electrical tape on the screw, you want it to be raised a little past the diameter of the head of the screw. I didnt and there is still a little play... but not much.
Great Idea BTW.
I think a L bracket anchored by the endcap screw would be the best fix ( as the L bracket would give you additional strength)
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Post by jimmiroquai on Feb 1, 2011 18:02:33 GMT -5
The L-bracket was what i was working on before the screw idea hit. I guess i just got tired of hacksawing. The only problem would be the very little space.
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Simple fix.
