FtF 10.5 inch MRP Update

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[ARCHIVED THREAD] - FtF 10.5 inch MRP Update

Posted: 12/27/2005 2:38:51 PM EDT

What would cause a 10.5 inch MRP upper to function perfectly on lower #1, and FtF most of the time on lower #2. Lower #2 functions fine with other uppers. The only difference is lower#1 standard trigger and lower#2 is RRA NM 2 stage. Buffers and springs are same and swapped between lowers. Bolts are M-16. Mags were checked in each and perform in other weapons flawless. What lower parts would contribute to this problem?

Posted: 12/27/2005 7:09:28 PM EDT

[#1]

does the other questionable lower work with other uppers?

check the distance of the bottom of the mag catch slot to the top of the lower and the width of the mag catch slot.

how does the FtF(eed?) manifest itself?

Posted: 12/28/2005 5:09:34 AM EDT

[#2]

Quoted:
does the other questionable lower work with other uppers?

check the distance of the bottom of the mag catch slot to the top of the lower and the width of the mag catch slot.

how does the FtF(eed?) manifest itself?

Tweak
Yes, the lower DOES work with another upper. I will check the measurements today. The Failure to Feed is occuring as the round starts to go up the feed ramp. It stops at feed ramp then when charging handle is pulled and released it feeds on up into chamber.
Thanks, Clippen

Posted: 12/29/2005 7:35:03 AM EDT

[#3]

Quoted:
does the other questionable lower work with other uppers?

check the distance of the bottom of the mag catch slot to the top of the lower and the width of the mag catch slot.

how does the FtF(eed?) manifest itself?

Tweak-
The bottom of the mag catch slot to the top of the reciever is 2.4cm. Do you mean the wdth of the magwell, or pull mag catch and measure mag catch slot?
Thanks, Clippen

Posted: 12/30/2005 7:28:02 PM EDT

[#4]

width of the mag catch slot and catch help too, your slot location is already .00388 lower than the largest permissable, the call is 0.9375" +/- 0.0035"

2.4cm = 0.94488"

0.9375" = 2.381cm

Posted: 1/2/2006 10:04:15 AM EDT

[#5]

Tweak I remeasured with better caliper and got 0.9390 to the best I can tell.

Posted: 1/2/2006 2:11:10 PM EDT

[#6]

that's within rage. barely what is the width of the slot and the catch?

Posted: 1/15/2006 6:39:03 PM EDT

[#7]

I finally got to work on this weapon again. I swapped out the trigger group, bolt catch assy. and the mag catch assy. not one FTF in three hundred rounds. One problem, it won't srtip the first round from a 30 round mag downloaded to 28, using the bolt release. It will finish the feed on the first charge with handle. This happened on all mags, everytime. What should I look for. Clippen

[ARCHIVED THREAD] - FtF 10.5 inch MRP Update

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