Moly polishing/coating barrels is basically applying molybdenum dry film lubricant onto the barrel's inner surfaces. I am not really sure about the benefits of such application even though theoretically it could decrease friction and wear between the barrel and the projectile. With real steel, barrel pitting is indeed a problem with chromium molybdenum steel barrels. Stainless steel barrels do not seem to be affected, but frequent cleaning is recommended. Firing only moly coated bullets is required as well, but I don't think we need to worry about that for airsoft with the plastic rounds and low temperature exhausts. The potential benefits might be worth exploring for the adventurous types though. Tongue
11 March 2004
By Ron Gaitten
* Moly destroys your barrel by attracting and trapping water in the barrel causing severe pitting.
* Even if you live in a dry climate, temperature changes experienced during the hunting season (gun inside warm house - gun outside in the cold) causes the metal to sweat.
* My barrel was destroyed by pitting after only 154 rounds 40 of which were moly coated (fail safe). I had cleaned every 10-20 rounds with Hoppes9 and Shooters Choice, both good cleaners, with the patch and brush method. It didn't get it out.
* Moly is EXTREMELY hard to get out. Plug the barrel and soak with Kroil overnight. Then scrub with a mix of JB-Bore Compound and Kroil for 5-20 short stroke technique passes. USE A BORE GUIDE, quality rod and jag, and be careful around the crown (don't bang the heck out of it). Finish with a solvent of choice and good oil. Hoppes9 or Shooters Choice mops out the JB well. If you choose, you can use something a little stronger like Montana Extreme for a final solvent pass. Extreme copper solvents like Sweets 7.62 although are great at removing copper are probably not necessary with this cleaning process as the copper should have been mechanically removed by the JB/Kroil mix.
* A moly conditioned barrel will not shoot Std. copper bullets accurately (relative term).
* Stainless barrels are effeted too.
* This does not apply to "Lubalox" (found on Win. ballistic tip) or the Barnes coatings. However, I still advise caution.
Inner Barrel Length Guide
590mm = 23.228" PSG1
534mm = 21.023" SIG550
509mm = 20.039" M16 series and AUG
472mm = 18.583" FAMAS
469mm = 18.464" G3 series
455mm = 17.913" AK47/47s
407mm = M14 Socom 16
369mm = 14.528" HK51
363mm = 14.291" M4, SR16, XM177, SIG551
300mm = 11.811" Thompson
285mm = 11.220" MC51
247mm = 9.724" CAR15, P90, SIG552, G36C, AK Beta
245mm = 9.646" UZI
229mm = 9.016" MP5 series
141mm = 5.551" MP5K PDW
110mm = 4.330" MP5K
444mm = 17.480" M60
422mm = 16.614" M249
395mm = 15.551" APS2 SV