In an earlier thread I posted that I had 2 failures to fire out of 50 rounds in my circa 1997 G27 2.5 after Glock upgraded parts to current spec when getting replacement night sights 3 months ago. The ammo was Blazer aluminum 180's. The 2 failures were back to back at about round 44 & 45. It was a high strike on the primer both times. The rounds fired after reassembly of the slide and RSA. Glock kept my original RSA. Today I recieved a 2011 version RSA that I won on eBay. I could ride the Gen 4 RSA, marked 08, with the muzzel pointing upward, no magazine and unloaded, and get the slide to stick about 10% of the time at the last 1/8" of travel. The 2011 version has noticable more force and does not stick. So I took a photo of both and sure enough the 2011 version is a tad longer. Looking forward to trying this replacement spring out.