Gen 4 Glock 20 FTF Issues

[aOWENc]

Good morning All,

My brother and I have identical Glock 20 Gen 4s with KKM barrels. We are both experiencing the same problem with FTF that I am assuming is coming from it being under sprung. We have used a variety of ammo (mostly 180s over 1250) both handloads and Underwood ammo. The slide will frequently fail to travel all the way into battery, it seems the slide is outrunning the magazine. There is visible damage to the factory recoil spring assembly where the rear flat area of the guide rod is getting deformed, this also leads me to believe we need heavier springs.

What is the best option for a new recoil spring assembly? I have heard Jager guide rods and ISMI springs, but many people have issues with the ISMI springs it seems. Wolff doesn?t appear to make a spring for the Gen 4, please correct me if I am wrong. Any help with this would be greatly appreciated! Thank you,
Alex

[DoubleA]

I?ve used a 22# ISMI since day one and never had problems with hot 10mm, 9x25 or 357sig. Mine is a Gen 3 so the assembly is different. I do know that they make parts to use a Gen 3 assembly in a Gen 4. As far as modifying a Gen 4 assembly I?m not sure because it never applied to my situation.

[RedTeam98]

Great choice on barrel KKM
I replaced my G20 Gen 4 with a NDZ stainless rod and 22 pound spring to shoot those 200gr bullets at 1200 FPS plus. Works great !

[Kenk]

Afternoon aOWENc, is the rd count pretty high on you and your brothers G20?s? Also, would both guns function 100% when they were newer using hotter 180?s? The reason I ask is that my G30S just started acting up one day. With mine, the rds kept getting hung up on the feed ramp. At that point I talked with Glocks CS, and sent it in. A couple weeks later my 9 year old G30S was back home. Glock replaced the majority of the parts for free, and now works flawlessly. Just another option if changing out the spring setup doesn?t correct it.