Therer is no jammer position. I am afraid I don't know what a jammer is? It is the ST rusher position, (which is on others plays the defensive line) They do not function primarily has blocking for the returner. On punt returns these players function primarily as kick blockers attempting to block the punt. You may not include defensive backs ie CB SS FS LBers or any offensive player in these 4 positions.. I'm not sure why anyone would use an offensive lineman in this position. I feel offensive linemen would be too big and too slow to be effective?

The gunner positions 1-4 are the players that Block for your returner. They are generally faster and smaller players that can get back downfeild to set up blocks for your returner. In the CSV the punt return play is a defensive play but many use Wrs and Rbs as returners and I don't care about that. No DB's or offensive players on the line during punt returns. ...............................MM

The "jammers" play on the punt return team and block (supposedly) the gunners. Technically, it is not a real position, but like Will, Mike, Sam, Wedgebuster, or Monster, in RL, it is a position some people play. As far as I know, you can do whatever you want in this regard, as long as you don't put those people on the line. IMO that was not unclear at all.

Jammers are the two guys out wide on both sides who try to slow down the gunners.

The image is protected, so I won't post it here, but there's a good example on this page, third pic down...
https://steelersdepot.com/2015/12/football-101-special-teams-nomenclature/

I am only talking about the 4 players on the punt teturn team located in the center of the feild. I don't care about any other positiion. You may not play any Defensive back CB SS FS or any player under 276 lbs in those 4 positions. Thank you for explaining Jammers as I had never heard that term. Again you want faster players on the outside so they can get back downfeild and set up blocking for your return man. I don't see where it much matters in MFN? Punt Returns we neutered several versions ago................................................................MM