Build guides
Straight answers to "will this fit?" for the most common pistol and rifle builds. Every chart is checked part against part with the same rules the builder uses.
Glock
- Which slides fit a Glock 19 frame?Will a Gen3 slide fit a Gen4 Glock 19? A fit chart for G19 frames, slides, barrels, recoil springs and trigger parts across Gen3, Gen4 and Gen5.
- Which red dots fit a Glock slide?RMR, RMSc, Acro or MOS? See which pistol red dots mount directly to each Glock 19 slide, which need an adapter plate, and which sights co-witness.
- Glock 19 threaded barrels: which thread, which slide, which sightsThreaded Glock 19 barrels come in 1/2x28 and M13.5x1 left-hand. See which muzzle devices thread on, which slides take each barrel, and which sights clear a can.
- Can you put a Glock 48 slide on a 43X frame?The Glock 43X and 48 share one frame, so either slide fits. See which barrels, recoil springs and red dots go with each slimline slide.
Sig Sauer
- Which slides fit which Sig P320 grip modules?Full, Carry, Compact or Subcompact? A P320 fit chart for grip modules, slides, barrels, recoil springs and magazines, checked against measured lengths.
- Mixing P365 and P365XL slides, grips and barrelsWill a P365XL slide fit a standard P365 grip? A fit chart for P365 grips, slides, barrels, recoil springs, magazines and RMSc red dots.
AR platform
Updated Oct 4, 2026.