Reply To: Edgun R5M, my well-intended mistake

Forums PCP Airguns Edgun R5M, my well-intended mistake Reply To: Edgun R5M, my well-intended mistake

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kiba
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Just a quick report… finally had a chance to reassemble and test fire the rifle tonight after adding the secondary spring under the pivoting latch.

Factory spring on the right, new secondary spring on the left. The secondary spring fits inside the factory spring, then you reassemble the latch.

 

You have to size the secondary spring carefully. Too tall and it coil binds and won’t let the pivoting latch open enough to snap over the fixed latch in the frame. Also, you have to make sure it’s short enough to let the pivoting latch open enough so that the 2x cocking levers can pivot rearward fully and hit their stop pins; if you leave the spring too tall it will coil bind and stop the rotation of the pivoting latch before the 2x cocking levers hit their rearward stop pins and all the cocking effort will be put into the ramps on the cocking levers and the pivoting latch that’s bottomed out against the fully compressed and bound spring. Took a couple tries of trimming ¼ coil at a time until everything worked as it should without coil bind. Once the 2x cocking levers can pivot all the way rearward to their stop pins, the new secondary spring is trimmed short enough.

The good news: 2x fills (80 pellets or so) at 63 ft-lb with zero instances of bolt blow back. We'll see how it holds up long term, but for now it looks like the second spring was a simple and easy fix.

One lesson learned from disassembly/reassembly…when removing or reinstalling the barrel, you need to insert something about .230" diameter into the transfer port in the frame to keep pressure on the front o-ring on the brass breech extension on the barrel, or else the front o-ring bulges/extrudes into the transfer port and gets cut. The brass breech extension o-rings are metric, 13.1 x 1.6mm… I would not suggest removing or reinstalling the barrel without having spare o-rings on hand, it is very easy to cut the front o-ring in the transfer port.