Originally Posted by
turnburglar
3. Seat Depth: If you want to mess with ANYTHING I would experiment with seat depth. I used to think "Just load to mag length" like most of you seem to. My buddy with the most experience taught me the error in that. Really long story short, with seat depth you are either jumping, kissing, or jamming. A lot of F class shooters try and kiss. This is dumb with high volume gas guns as the chamber is in a constant state of erosion. This only leaves jamming and jumping for gas guns. My guess is at mag length you are jamming massively into the lands. The magic of jumping is that the amount of jump stays fairly consistent over the life of the barrel. Also it produces stupid accurate loads once you figure out the jump for each bullet.
First off, I’m not an expert on precision loading, so I hope I’m not saying anything too stupid. I’m following this thread to learn.
With that said, I don’t think any of my chamber/bullet combos will touch the lands and still come close to fitting in a USGI mag. In other words, I suspect most everyone here is “jumping” rather than “jamming”. I measured some of my 5.56 and Noveske Match Mod 0 chambers recently with that Hornady length doodad, and found that I’m jumping 60 thou or more at mag length.
Hoping to learn more.
RLTW
Former Action Guy
Disclosure: I am affiliated PRN with a tactical training center, but I speak only for myself. I have no idea what we sell, other than CLP and training. I receive no income from sale of hard goods.
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