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

Hey guys,

After gaining some advice from some guys on the forum (thanks again!) I loaded my first 10mm ammo and had some surprising results. I loaded 25 rounds using a ladder test and fired them from my Glock 20 with a KKM barrel in the stock length. Chronograph was 10 feet from the muzzle, 53 degrees outside.

These are handloads for my gun, work up in your gun to ensure your safety.

Powder: Longshot
Bullets: 180 gr FP Coated Lead from Hoosier Bullets
Primer: CCI Large Standard
Brass: Mixed (mostly S&B)
OAL: 1.260"
Crimp: .421"

8.8 Grains: 1268, 1272, 1266, 1264, 1254 AVG: 1262
9.0 Grains: 1313, 1319, 1281, 1304, 1293 AVG: 1302
9.2 Grains: 1288, 1310, 1325, 1324, 1354 AVG: 1320

I loaded up to 9.6 grains, but didn't shoot the 9.4 or 9.6 loads because I exceeded what I was hoping to get to when just using 9.2 grains of Longshot. This was very surprising to me as I didn't expect to get over 1250 FPS with anything but the 9.6 load. Brass on the 9.2 loads didnt show any obvious over pressure signs, but there were slight dents in the case mouth and a weird scuff on the side of the brass that I will try to photograph later.

The recoil was also significant and much more than the Underwood JHP I shot. I'm not sure why these were so much hotter than I was expecting. I plan to measure the dimensions on the bullets I was using later to see if anything is weird. All the of the loads shot very well with the 9.2 being the best.

The Underwood 180 gr Nosler JHP that quotes 1250 FPS produced the below results:
1182, 1212, 1196, 1171, 1192. I was really hoping these would hit 1250 but they shot great so I'm not worried about it.

Thanks for all the great replies guys.

I just loaded 25, I started at 8.8 grains of Longshot per Graybeard's advice and worked up to 9.6 grain in .2 increments.

I kept the OAL length at 1.260 as this passed the plunk test and spun freely in my chamber.

I'm going to the range after work with the chronograph to test these and will report back with any data that I get.

Hey everyone!

I used the search function and found some results on this, but I'm a new reloader  and was hoping someone could maybe give a but more of a definitive max charge or starting point for my particular setup.

I'm shooting a Glock 20 with a KKM Barrel. I just got a chronograph as well so I'm looking forward to reporting back with whatever results I get.

I was hoping to pick up some blue dot and Accurate #9, but my local store only had a few pounds of longshot so that's what I'm rolling with.

I'll be using mixed brass and Remington large Pistol primers.

For bullets I have some 180 grain coated FP from Hoosier Bullets. He's a preacher that lives about an hour away from me in Indiana, and he makes a great product for a really good price.

I'm currently planning on starting at 9.0 grains and doing a plunk test with my barrel, my manuals show a minimum OAL of 1.250" for 180 grain lead. I will then work up a latter test and hopefully be able to get 1250 FPS safely.  How does this sound to people with a lot more experience than myself?

Any additional advice or recommendations would be greatly appreciated. Thanks guys!

Note: I accidentally posted this in the general reloading section before I noticed there was a 10mm loading section. Mods please feel free to delete my original post in the normal reloading section. Sorry for the confusion.

I just put that exact same ammo on the chronograph today out of my Glock 20 with a stock length KKM Barrel.

Velocities were as follows: 1173, 1173, 1192, 1165, 1176 FPS, chronograph 10 feet in front of muzzle.

My box says 1200 FPS, so they are really close to advertised velocities and very consistent. Probably would have easily been over 1200 FPS if I was using 5in + Barrel.

This ammo was purchased in May 2020.

Hope this helps!

That offhand shooting is seriously impressive.

I also went with the RMR and X300 on my 9mm carry gun, 5000 rounds down range so far and both are dead nuts reliable. I plan to send my G20 to get milled for a dot when Jagerwerks runs their Black Friday sale.

If it were any other caliber I would say no, but with the costs of 10mm brass and the way the Glock Barrel bulges the brass I would say it is a fantastic upgrade. I hate the idea of changing out internals with non OEM parts, but so far the KKM Barrel has been 100% reliable. I only have 200 rounds through it so I would not consider carrying the handgun until I shoot the barrel more and confirm it's reliability.

My stock G20 badly bulged factory federal 10mm, I didn't even attempt to shoot a higher pressure Underwood or handload through it as it was destroying the brass. Accuracy is also better, plus now I can shoot cheap coated lead bullets without worrying about the polygonal rifling in the Glock OEM barrel. I say go for it, but put 500 rounds through it before you rely on the firearm with the KKM Barrel.

Yes! Which is really disappointing to me because I love their range ammo for handguns. The 38 specials S&Bs seem slightly larger around the rim than all my other 38 special brass and I have to sometimes use vice grips to get the case out of the shell holder, which of course destroys the brass.

Hey everyone!

I used the search function and found some results on this, but I'm a new reloader  and was hoping someone could maybe give a but more of a definitive max charge or starting point for my particular setup.

I'm shooting a Glock 20 with a KKM Barrel. I just got a chronograph as well so I'm looking forward to reporting back with whatever results I get.

I was hoping to pick up some blue dot and Accurate #9, but my local store only had a few pounds of longshot so that's what I'm rolling with.

I'll be using mixed brass and Remington large Pistol primers.

For bullets I have some 180 grain coated FP from Hoosier Bullets. He's a preacher that lives about an hour away from me in Indiana, and he makes a great product for a really good price.

I'm currently planning on starting at 9.0 grains and doing a plunk test with my barrel, my manuals show a minimum OAL of 1.250" for 180 grain lead. I will then work up a latter test and hopefully be able to get 1250 FPS safely.  How does this sound to people with a lot more experience than myself?

Any additional advice or recommendations would be greatly appreciated. Thanks guys!

Hey everyone!

My name is Alex. I'm a 21 year old college student that's been into shooting and hunting for years but just recently got into the 10mm and reloading.

I just bought a G20 and a KKM match barrel in the factory length. I also just picked up a chronograph and a variety of powders to start out with. I'm looking forward to picking up some knowledge from everyone and hopefully giving some back eventually!