Recently got an Olight PL-2 Valkyrie 1200 lumens for my gen-4 G20 setup for the outdoors. This G20 never had a FTF or any other issues the way it is setup (stormLake barrel + 17-lb stainless steel recoil assembly), neither with regular loads nor with hot loads. Although it has shot a lot less hot loads (BB UW, etc) over time then regular loads (Sellier and Bellot, Magtech, regular Sig, etc.). Yesterday I decided to take it for a whirl with the newly bought PL-2 Valkyrie so I get used to the new weight up front and make sure no issues. All the regular loads shot with no issues. Plus 1 box of UW X-penetrators 140 grain also shot without any issues whatsoever. But for some reason the Buffalo Boar HCFN (220 grain) and Underwood HCFN (both 200 and 220 grains) had massive FTF issues. Every about 2-4 rounds a next round would be stuck either 1/2 way in (or less or more then 1/2 way). Wished I took some pictures. I replaced the recoil assembly and the barrel with the stock ones, and nothing changed with above. I also noticed that my PL-2 Valkyrie light had burn marks on top of it where it sits right under the muzzle. Please see attached photo. The FTFs only happened with the HCFN rounds both from UW and BB, So my thinking now is: The light did not allow the hot loads to exhaust as quickly hence adding more pressure and making the slide move back more quickly then usual hence causing the FTF. I did not suspect this yesterday at the range (outdoor one) as my brain was little dehydrated .. otherwise I should have tried without the light on. The 20 rounds 140 grains UW X-penetrators although a hot load but had no issues might be explained by the lesser weight of the bullet hence causing less reaction backwards?? Not really sure though. Freak coincidence: something new changed with the gun aging (maybe my 17-lb springs are less then 17 lbs now and just happened to show up yesterday.) So i ordered a 22 lb spring after doing some research and heading to the range again hopefully next weekend assuming I receive the new spring by Friday. I will first try without the light and with the old setup. If anyone had experienced burn marks on any of their lights as mine did please let me know. I did not think that is the norm but suspecting it was caused by the heavy/hot loads. Thanks for your opinions and happy glocking. Will update again after my next range outing.