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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The 34gr JSBs are shooting very well out of my R5M at 895fps… more accurate than the 25gr pellets, especially at longer ranges. I shot out to 150Y last weekend to verify drops and was very happy with them. Had a couple 125Y 5 shot groups that were about 1". It was the first time I've ever shot the 34s, I've been using the 25gr pellets for years with my previous R3 and R3M.

 

While the 34gr JSBs shoot great, the higher muzzle energy and regulator pressure compared to the 25gr pellets has revealed another problem… occasional bolt blowback when firing, maybe 4 shots in 10. The bolt doesn't blow completely out of battery and dump air on your cheek and drop velocity when it happens, but the cocking carriage does come unlatched and the bolt and carriage moves back about 1/2". When it happens accuracy isn't effected and the Labradar doesn't show any velocity loss so there isn't any air loss, but it is an annoyance.

 

I took the rifle apart on Sunday to see what the problem might be and what could be done. Step one is adding a secondary spring to the pivoting latch in the cocking carriage to hold the latch more firmly in the closed position. That's done, but unfortunately I nicked an o-ring on the brass breech adapter when sliding it past the transfer port in the frame and am waiting for replacement o-rings. The original o-rings measured to be 13.1 x 1.6mm; I had 13 x 1.5mm o-rings on hand but they slide into the frame with almost no resistance so they may leak.

Once I get the correct replacement o-rings we'll see if the second latch spring fixes the blowback issue or if I'll have to start looking for another fix… I have two more ideas in mind that may help if the spring alone doesn’t solve the issue, one is easily reversible with no permanent mods to the rifle, the other would require modifying the pivoting latch in the carriage and the fixed latch in the frame.