Upgrade barrel & compatiblity post.
/long post allert/
As some of you previously reported you haveing hard time to install aftermarket barrels.
I just installed my hybrid 6.04 and figured what is causing the issue.
The inner barrel mounting/alignment surface is slightly shifted in some brand of barrels, this is a 0.5-0.8mm difference compared to the stock silverback barrel.
Previously this does not caused an issue, since most chambers has less stricks mounting clips allowing such play going unnoticed.
The chamber shells of the MDR sits really tight around the barrel. If you install an aftermarket one it's highly possible that the sifted surface will not let you close the chamber shells OR if you press the barrel further in the chamber, that puts more pressure on the bucking lips, combined with the stock rubber 70° hardness the nozzle can not feed. Resulting in jamm.
There are several solutions for the problem. The most simple is keeping the stock barrel because it's not bad
You can also slightly file your new barrel to have a proper placent in the chamber without excess pressure on the bucking. (It's literally less than 1mm)
The ideal solution in my opinion if you choose a bucking which is softer or slightly thinner on the front.
My personal solution was installing a 50° silverback MDR rubber (not to confuse with silverback SRS rubber) this softer rubber let me press the inner barrel slightly furter in the chamber, close the shells and preventing feeding issues. In the current external temperature I expect it perform better than the stock rubber too. This rubber should be available at distributors afaik.