Re: 930 spx chamber/gas port/spring question
BenSamp – glad the polishing went well! I was having that grooving/binding issue as well on the tube and made the aluminum insert (dia =0.993”) shown in the picture to slide in the gas block (with the gas piston out). I would use it to slightly reposition the seal until I found the sweet spot. I saw another post on this forum where he (SoCal Choppas) used a deep well socket to slide in and work the alignment:
viewtopic.php?f=14&t=2202&hilit=craftsman&start=75
On mine, it seems like it wanted to be tweaked slightly towards the barrel and then the barrel subassembly would just pop right on and off the tube – no binding at all.
I made it out to shoot today - after polishing the gas block and cleaning up the gas ports. I put about 125 rounds through it using 5 types of ammo and was pleased overall with the results – almost there!
- Cheap Federal Value-pack multipurpose 2-3/4”, 8shot, 1-1/8oz, 1200fps (low aluminum base)
- Winchester Super Speed X game loads 2-3/4”, 6shot, 1oz, 1350fps (low aluminum base)
- Winchester AA super sport clays 2-3/4”, 8shot, 1-1/8oz, 1300fps (low brass base)
- Winchester Rifled Slug value pack 2-3/4”, 1oz, 1600fps (high brass)
- Winchester Magnum Buckshot value pack 3”, 15 pellets, 1210fps (high brass)
I fired from the shoulder (or as close to the shoulder as possible) keeping the gun tight with the gun in 4 different positions (upright-normal, turned 90deg ejection port down, upside down, and 270deg with ejection port up). I then fired in the same orientations limp-wristing by really only holding the forearm and letting the entire gun pretty much float. I had NO stuck cases and those that didn’t eject would extract very easy with the charge handle (cycling the next round in). Here are the results:
Federal Value Pack - Light recoil as expected:
From the shoulder location fired reliably in all positions - no failures of any kind
When limp-wristing, it failed to eject cases about 90% of the time, insensitive to position.
Winchester Super Speed X game loads – Recoil about same maybe a little more than Federal:
From the shoulder location fired reliably in all positions - no failures of any kind
When limp-wristing, it failed to eject cases about 70% of the time, insensitive to position.
Winchester AA super sport clays – Recoil about 10-15% more than Federal:
From the shoulder location fired reliably in all positions - no failures of any kind
When limp-wristing, it failed to eject cases about 10% of the time, insensitive to position.
Winchester Rifled Slug value pack – Recoil about 50% more than Federal:
From the shoulder location fired reliably in all positions - no failures of any kind
When limp-wristing, it fired reliably in all positions - no failures of any kind.
Winchester Magnum Buckshot value pack – Recoil about 80% more than Federal:
From the shoulder location fired reliably in all positions - no failures of any kind
When limp-wristing, it fired reliably in all positions - no failures of any kind
Overall, I was very pleased with the results and I have pretty much figured out this shotgun. I still want to make sure that it is 100% reliable with all ammo while shooting from all types of holds (ie the limp-wrist condition) so my next step is to investigate replacing the Blue gas block spring with the Red spring – will call Mossberg and see if I can get them to send me one.
Something else I noted (an anticipated results) from my tests is that there is a big difference between the low brass and low steel base shotshells. The brass definitely extracts much better and I expect it is because when the cases deform plastically to the barrel contour when firing, the brass cases contract/release with about half the force as steel since brass has a lower modulus (Steel is much much stiffer and will want to stay ‘inflated” in the chamber).
So for now I am going to stick with the Winchester AA (it’s only about a $1 more a box at wal-mart) to assure the shotgun cycles in the most reliable fashion possible.
To me it is much more important to have a firearm which can be discharge/cycle reliably without regard or thought of its position or type of hold! Has anyone tired their 930 SPX with both the Blue & Red springs and noted the differences?