I first printed everything out of 3D Fuel PLa+ and when I assembled it and I inserted a 3D printed CMMG replica 22 mag, it snapped off the feed ramp at the base of the ramp. OK, so I’ll print the barrel adapter out of Fiberon PA612CF, anneal it for 12 hours, and let it sit out for moisture. Assembled everything today and the bolt wouldn’t fully close at first until I forced it closed. And…the feed ramp split at the base of the ramp again. It looks like the bottom of the metal reinforcement plate is striking the top of the feed ramp, as the Fiberon version now has a dent.
Another odd thing with both, the adapter pin holes for the handguard don’t anlign evenly with the cuts in the RS22 barrel. There is maybe an 1/16” (or less) of the barrel that shows on the feed ramp side of the pin holes. It takes a hammer to get one of the pins through both holes and the barrel cutouts. Additionally, dummy rounds would eject with the PLA+ barrel adapter but not the Fiberon one.
Anyone else experiencing this issue with the Wisp and an RS22 barrel?
Rs22 barrel should be the most stable attachment with the pins going all the way through the receiver. So is the play in the adapter to barrel or adapter to receiver? If there is any need for a brace than something isn’t fitting correctly.
It seems to be a bit of play in both the barrel to the adapter and the adapter to the receiver. PLA+ adapter is providing the tighter fit with the PLA+ upper. I decided to wrap a couple layers of teflon tape around the barrel, but fewer layers around the pin holes in the barrel. It Is now a much tighter fit in the adapter. I actually added additional layers another two or three times after test fitting each attempt.
I then wrapped the barrel adapter with a couple layers of teflon tape as well and it is much better than before. Instead of just under 1/2” horizontal sway of the barrel, it is now down to probably 1/8” or even less. It seems to be a tolerance issue…and that may be a result of the RS22 barrel itself since it was a $35 barrel shipped from Rossi. I further bubba’d it with a black ziptie around the barrel from each side of the end of the handguard and now it is really rocksteady. The two zip ties are pulling equally from both the right and left sides of the handguard. I know my experience is not what is intended, but it seems cable ties and pipe/duct clamps are a natural fit for 3D2A anyway.
As for settings, I printed all the Polymaker PLA+ with 300BLK’ settings. Now I just need to get to a range to finally test it with live ammo, as dummy rounds are functioning quite well. Again, this has been an educational and fun project that reminds me of working out the kinks in the first P80 I built.
I’ll need to tighten the adapter tolerances then.
How can I join the discord? Although it manually cycles fine with metal dummy rounds, the headspace must be too large for actual rounds. After detonation, the rear 1mm or so of the casing is bulging and preventing extraction. I’d like to see how the beta resolved the headspace issues.
Likely an issue with tolerance stacking. With rs22 it’s a bit harder to adjust since the barrel can’t be moved in easily. It would be best if I release bolts with different length options so people can choose the right one that fits.
Eventually I’m going to do a different design (replica this time) with a receiver in a chassis bolt action with a multi piece receiver so headspace can be adjusted easier.
Here are photos of one of the casings that got stuck, though I didn’t think they looked too bad. But there is a little bulge in front of the rim.
I’ve updated the files with alternate length bolts. The guide now also explains one way of measuring headspace since I got asked that a lot.
You’re amazing! I’ve already downloaded v1.1 and will print some of the longer reinforced bolts to see which does the trick.