Day 41, 42, 43, 44 - 1st, 3rd, 8th & 9th April
Well big update time! We decided to review the M2 and discussed what improvements it needed.
Our first port of call was the ROF, which had seriously dropped (if you watch the other videos you'll notice it's a lot faster), this was because the M90 AEG spring had lost a lot of it's ummm springyness (technical term :P). It quickly became apparent that there were a few issues:
So we fixed those springs.
The AEG spring return guide: you can see the spring is looking rather sorry for itself. Later I was playing with it and it snapped in several places
We opted for a bigger spring and got an M135 chopped down to fit:
The next stage was a lot more complicated. Our original 'design' (cough) meant the barrel was permanently fixed in and the AEG barrel & hop-unit were a bit of a nightmare to reach. We also had an issue of accuracy because the AEG barrel wasn't brilliantly supported. This meant we had to revisit the entire forward section and even the hop-unit.
Work starts on the new hop-unit. We're using alloy-bronze (only because we got a few big lumps of it for free and it's a ton easier to work with than the bigger lumps of stainless we also got :P)
Sometime later, the barrel holder and ammo feed part of the hop-unit is made:
lacking a mill we opted for a ball-bearing hop-unit design, we'd have liked to have gone with a nub system but there was neither the room nor the tooling available.
A carefully drilled & tapped hole later: one AEG barrel, hop-rubber and adjustable hop-unit. We replaced the previous barrel as it'd gotten a little damaged.
The hop-rubber made life a little complicated, the barrel is 8.5mm but with the hop-rubber on it it's closer to 9.5mm. This meant the unit had to have a 9.5mm hole at the front which would lead to a bit of barrel wobble. To fix this a small bush out of mild-steel was made (as you can see it got a bit hot in the lathe)
The bush was cut to be flush with the hop-unit after the pic was taken
In the middle of all that happening, we notice that the wood could do with some touching up:
They get a new coat of varnish:
With the varnish dry the cocking handle gets a spring installed (made out of the old M90 recoil spring).
We decide to the use the rest of the .50 rounds to dress up the ammo box some more:
So now work starts on the barrel assembly socket, using mild-steel this time. We did want to have some bayonet type system making the whole barrel easy to drop in like the real M2 but again lack of a mill prevented us, we opted for a screw system.
With the socket complete the barrel screw is done in alloy-bronze
But alas it's not that easy, there needs to be a flat face to the barrel socket otherwise it's going to interfere with the feed-plate. With no mill the lathe is made to improvise:
It didn't come out brilliantly but it did the job. The barrel socket, barrel screw and hop-unit altogether:
Point of no return is reached when we cut out the "mid-barrel"
The hop-unit/recoil-slap plate stop is made
Putting the system together, note: we had to chop the recoil-slap plate down even more.
With everything properly aligned the slap-plate is tack-welded in:
The barrel socket is tack-welded in,
We then made sure everything was properly aligned then went to town with the welder.
Making the barrel bush, we put a 14 CCW thread on here, the idea being we would later make a tracer unit and/or sound amplifier. Sadly there's not a lot out there that's <24mm for it to fit inside the barrel.
The barrel bush is finished and put on the barrel - held in place with E-clips
It was initially planned to make 4 rollers and fabricate the barrel bush in such a way that it's act like a roller bearing but it was decided that this would be too finiky, especially without a mill on hand. So we opted for a nylon outer bush, thankfully we've a nice big bar of that :)
It fits and glides down the barrel beautfully, should see an end to any accuracy problems we had.
The barrel assembly is complete, we put a screw in the threaded section so the barrel could be fully locked in:
The M2 waiting for it's barrel:
Everything goes together smoothly:
The hop-unit goes flush with the stop plate but in this picture the nozzle/feed system is pushing it forward a little
And the feed-plate with hop-up adjustment hole goes on, the feed plate is what locates the hop-unit fully in place:
We did want to give it a respray but we're out of time this week.
But does it work? And if so does it work well? We hear you say... well you'll have to wait till Sunday evening ;)