MT-9 Shells - Slightly shorter for better feeding

Hello, 

This is a slight remix to the shells modified by Fiddesticks丶for the model "MT9加长弹匣+优化弹壳 MT9 Extended Magazine + Optimized Shell"

https://makerworld.com/en/models/234308#profileId-250882 

I have permission from the creator to create a remix, but the license type selected doesnt allow me to link. 

The MT-9 shells can have some problems feeding because there is not much space between the front of the mag and the front of the shell, leading to jams when loading. This version shortens the shells by 1.3 MM and allows for much more reliable feeding either by hand or by the stripper clips.

The shells are also about 0.3 grams lighter which helps them to eject a bit farther. This may not seem like much of a difference, but the stock shells are 0.8 grams, so 0.3 grams less is quite a reduction. This is achieved through a shorter model, as well as 2 wall loops (vs 4).

Additionally, the stock MT-9 mags can actually hold 8 shells if you remove the stopper. Given how short the mags are, this stopper isnt  needed to prevent the spring from binding or to keep the base plate on. I have added a thin .08 MM plate that can be used in lieu, giving space for two extra shells, for a total 8. 

NOTE: If you already have a lot of shells already, you can simply cut off with a hobby knife about 1.5-2 MM of length to facilitate better feeding. They will still be a bit heavier but will feed better.