Well a few days have passed and I have completed the further development of the PM5 saga. Whilst it has always been my aim to be able to return the gun to stock, I must admit to a couple of minor infractions. Although I would never drill or file in the pressure areas, I felt justified in a little magazine fettling, they were so individual where welded and formed that I needed to standardise the fit. Some would jam solid while others would slip through, upon adjustment to my work different ones jammed! Score 1 for a friend who suggested numbering the mags! Prior to continuing, I re-assembled in stock form and tried the first magazine that I worked on, it actually inserted and ejected better than before so I felt justified in gently bringing all the mags to the same dimensions. The Valtro PM5 is, in its stock form, a rattly piece of kit with very wide tolerances, I needed to tighten everything up for successful operation as a competition gun. My second "adjustment" was to drill a 4mm hole in the magazine release lever so as to facilitate a lightweight ambidextrous attachment, again, justified by it having no detrimental effect either in function or aesthetically when in stock mode.
Of course there are no standardised mag wells made for the Valtro, I looked at the Saiga one and decided that it would need so much cutting that it would be easier and far cheaper to fabricate, using materials I already had, with a view to manufacturing a "pretty" one once I had worked out all the bugs (and there were many, with more to find i'm sure)
Anyway here is the working prototype, a composite of aluminium, plastic and steel :
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- v52 (2).JPG (94.18 KiB) Viewed 84883 times
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The main mag well is formed of two sections of cut aluminium box section, one inside the other to arrive at the correct dimensions. this is then attached to the recovered side-plates from the earlier version. All held together with M5 machine screws tapped and thread-locked in place. A plastic outer cover hides my machine and file marks. Mounted within the box are three "bales" type small cabinet latches with spring loaded 6mm ball bearings. These guide the magazine thru the well by running in the rim line on each side and on the rib at the back. Due to there now being no forward mag retention shelf, the magazine needs to be kept pushed forward so as to remain in position and to ensure reliable feeding. The bearings help but the springs are inadequate when fighting the pressure of the magazine spring when the bolt is closed (top shell pressing on the underside of the bolt carrier)
This foxed me for a while and I tried many ways to combat the pressure of the magazine spring to no avail. Then whilst jamming a piece of scrap in the rear of the well so as to cycle the action, it dawned on me, a small brass ramp epoxied to the rear of the magazine to engage as the magazine located and latched, problem solved! The function is now rock solid when the magazine is in place and lets go nice and smoothly when the mag release catch is pushed. I added a steel strength plate where the new magazine ramp engages to prevent the aluminium from fracturing.
Another area I addressed was the trigger housing front locating pin looseness. As previously stated, I am using the existing fittings to mount my mods and there was some random movement at the front of the trigger unit ( which also includes the rear mag catch and release lever) I replaced the spring pin tube with a tight fitting plastic tube which I then tapped to M5 for my mounting bolt, again nothing permanent but a fix which cured all the looseness at the trigger/mag release.
The reworked feed ramp (which was a noticeable improvement on the stock item in the previous incarnation) was modified from the earlier version by cutting off all the spring area and replacing with a solid block of aluminium with stainless steel wear faces. the front face of the mag well connects flush to this block. (picture on next page due to 3 pic limit)
All seems to be in order now, just need some range time to thoroughly check everything out. I am hopeful and hope that my confidence in this gun will bear fruit, its a great shooter, just trying to make it competitive. I'll update when trials done (wife and work permitting!)