Drilling a third gas port for light loads?

[Jogar80]

Well I’m back to the drawing board guys. I have posted before about how I bought my 7 yr old an SA-20 so he can join me on my dove hunts. He had tried a 28 gauge this season and liked it, but I bought him a 20 gauge, thinking it was something that would better serve him for the long run and for a wider range of hunting duties. I thought I could probably get the gun to cycle some 3/4oz loads at 1200 fps to replicate the 28 gauge but it does not cycle the loads. Oddly enough, if I unseat the barrel by 3/32” the gun will even cycle fiocci trainers which are 3/4oz at 1075 fps. I have tried running the gun in with a few hundred rounds of heavy loads, extensive cleaning, polishing contact surfaces, clipping the recoil spring a bit, and having a lighter spring made for it. The lighter spring allows the 3/4oz loads at 1200 to eject (BARELY) but the spring does not have enough tension to load the next round fully into battery.

Due to the difficulty of getting parts for this gun, I do not want to open up one of the gas ports and then be stuck with a gun which is only for light loads. I was thinking of adding a third gas port for use with light loads. This way, when my boy gets older or stronger, we can simply plug that hole and not have to worry about getting another barrel.

Does anyone have any advice on size for the new gas port? Or reasons why this would be a bad idea?

Thank you all for any help!

 

[megawatt]

I remember talking to Jim Fuller of Rifle dynamics years ago. Back when he was doing alot of work with Saiga shotguns.

Customers were always wanting the Saiga to run on birdshot. He finally got the correct size of port and or number of ports to add (forget what the solution was). It was a challenge. Too big a port and crap would go in the hole. Too small of a port then it gets clogged up too easy. Small port- Maybe it works great for a few shells but then it would get clogged up and not run.

I will just say fooling with the port size or number of may cause headaches for you. Good luck.

 

[Jmm14534]

My $0.02 is your plan only makes sense if you have 2 identical barrels. One can be the experimental barrel and one that puts the gun back to factory configuration.
If you don’t have 2 barrels and really want to proceed why not just start by increasing the diameter of the existing holes a little bit at a time?