Glock 20 recoil spring for hot HC ammo

Kenk · May 06 2019 05:38:59 PM MDT

I'm starting to wonder if it's the weapon itself. I have shot several boxes of Underwood's 220 Grain Hard Cast Flat Nose through my G20 gen 4 with no issues, as well as with a KKM barrel
Thanks

Ken

The_Shadow · May 06 2019 06:05:27 PM MDT

I have measured the Underwood 220 WFN Hard cast cartridges with Meplat 0.280", C.O.A.L. 1. 2520" - Meplat 0.2810", C.O.A.L.: 1.2660".
Based on troubles others have had with WFN bullets with even wider Meplats they were loaded seated to 1.2420" to improve feeding situations.

You should see if you can improve feeding by having them seated slightly deeper (shorter COAL) to help with the tipping angle as the cartridge strikes the roof of the chamber and the head tries to slide up the breech face to fully chamber.

Iceman · May 06 2019 07:12:28 PM MDT

Quote from: The_Shadow on May 06 2019 06:05:27 PM MDT
I have measured the Underwood 220 WFN Hard cast cartridges with Meplat 0.280", C.O.A.L. 1. 2520" - Meplat 0.2810", C.O.A.L.: 1.2660".
Based on troubles others have had with WFN bullets with even wider Meplats they were loaded seated to 1.2420" to improve feeding situations.

You should see if you can improve feeding by having them seated slightly deeper (shorter COAL) to help with the tipping angle as the cartridge strikes the roof of the chamber and the head tries to slide up the breech face to fully chamber.

I don't think it was that kind of FTF; mine were always "bolt over round" FTFs where slide causes nose down in mag jams, caused by round not up high enough when slide comes forward.

Roguer · May 13 2019 05:04:30 PM MDT

Just wondering if there is any difference in performance between an after market single spring RSA that is captured and non captured ones. Hope I was clear in my asking.

mcseal2 · May 14 2019 05:53:10 PM MDT

After talking to KKM they recommend trying Double Tap ammo. I have some on order. I have my doubts that it will work though, the HC failures occur with the factory barrel also and either the 22lb or factory recoil spring.

Underwood Extreme Penetrators have fed flawlessly (40 rounds) and Fiocchi 180gr JHP's (300+ rounds) have fed without a single malfunction. That is with any combo of barrel, recoil spring, and mag spring I have tried. Not sure what the deal is.

Geeman · May 14 2019 06:57:26 PM MDT

My Gen4 didn't like the UW 220 HC.

Everything else runs fine.

Greg

Kenk · May 14 2019 07:00:14 PM MDT

Evening mcseal2,
Have you discussed this with Glock?, letting them know the two types of ammo that function properly, and that the rest have reliability issues. My G20 / gen 4 eats everything, and begs for more. This is also the case with my KKM barrel / factory recoil set up. Something just seems off. I have owned numerous Glocks over the years, and have all been extremely reliable. Just my 2 cents

Ken

powerstoke250 · May 15 2019 04:19:19 PM MDT

I rarely post, but I had a great experience today. I've been trying to figure this same issue out as well for awhile. G-20 Gen 4. Finally bought another G-20 Gen 4 about 6 months ago to see if it was just the first gun. Both guns perform just about identical. My original is 3+ years old. Have tried recoil springs in various weights, Wolff Mag springs, etc. Nothing seemed to make a difference. I know the common denominator is the shooter... but I think I have good enough technique that, that is not the entire issue. I have/shoot 3 diff M&P 45's as both my carry and home defense units and have no issues with them. My accuracy is decent. Was trying to get UW HC to shoot (220gr and 200gr). After the new gun I decided to give up on UW and try working up my own load using Montana Bullet 200gr HC (have been following a couple of other threads on here discussing COAL, tipping etc. where others have had success). But unfortunately that also has not been working. Typically have jams starting with the 1st to 5th round, usually multiple per mag for any of the more powerful loads. Lighter loads, both my target reloads or factory have always worked fine.

Saw this thread this morning, Iceman's post in particular. I have several extra stock mag springs left from the Wolff spring replacements I did so doubled up on the mag springs in two of my mags (I have 9 mags now, so it's not a specific mag issue) and headed to the range. Got 13 rounds in the mag with a 14th in the chamber. UW HC 220 and my latest reload attempt at 1.215 COAL 8.0gr Long Shot and every Mag I shot worked great until either the last or second to the last round. Shot 6 mags and every one had a jam at the end, but performed without any problem until then. For me this is a success story. I have wanted this as my woods carry gun. 11 reliable rounds is OK by me (1 in the chamber, 10+ from the Mag with one or two left). Hopefully will never get to the jam except at the range if this continues to hold. Interesting thing is that today on my reloads (shorter length than the UW) the jams were all nose up against the top back of the barrel, never entered the chamber. Normally the jams have been nose up, but part way into the chamber with the breach face a little over the round as Iceman described. I had a 22 lb recoil spring in, and am going to get a hold of a 19 or 20 lb spring. Will also lengthen the COAL on my reloads a bit and see if that helps in combo with the beefed up Mag spring. Shooting the gun, there was no detectable difference to me with the extra spring strength when there is no FTF.

Thanks for sharing your experience Iceman, you helped me. I've been thinking of getting rid of the Glocks and trying a different make in 10MM, but I really like that I can swap in a 6 inch barrel if/when I want to (by the way, in my experience 220gr UW HC do not tumble with the 6inch barrel in either my glock or kkm barrel, a whole other topic).

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powerstoke250 · May 17 2019 05:21:58 PM MDT

Just got back from the range again. Offsetting the doubled up mag springs by 1 coil fixed my jamming on the second to last round problem. I suspect there's a release of tension on the Mag walls on those last two rounds as they line up one on top of the other in the narrower neck at the top of the mag. I figured offsetting the springs might reduce that at the longest extension of the spring. Appears to work.

Kenk · May 17 2019 09:36:13 PM MDT

It's always nice to get to bottom of these frustrating issues, nice job!

mcseal2 · May 21 2019 07:26:24 AM MDT

Good info thanks guys.

I've tried the double mag spring without success. I have not talked to Glock but did talk to Underwood and KKM. KKM recommended trying Double Tap ammo, they said that is what they test with. I have some on order so I'll try it as soon as it shows up. The only thing I've had success with so far is the UW Extreme Penetrator 140 grain. Underwood considers that a bear worthy load. KKM also said they would polish the feed ramp more if the DT ammo doesn't work. I still have my doubts that the feed ramp is the problem since it occurs with either the factory barrel or the KKM barrel and both the factory and 22lb recoil springs.

powerstoke250 · May 21 2019 02:51:30 PM MDT

Sorry the double mag spring doesn't work for you. I've been back to the range with it 2 more times now and have not had a single jam (I don't recall ever getting through a complete mag of Underwood without a jam before). I bought some of the wolff brand springs ($2 ea. if you buy 3 or more). I got the 9 coil, that are what get used in the G 29 among others. I cut one more coil off the bottom of the 9 coil reformed that bottom loop and added that in with the Stock G-20 mag spring and did not offset the springs, both were flush up against the follower. Set two mags up that way and both functioned today with my peppy'r reloads, no problems. Still could only get 13 rounds in the Mag. Also, the first time I tried this I had a 22lb recoil spring in. The last two have been the stock recoil spring. So for me, recoil spring does not appear to be the issue. I hate having to rig this, but if it works... you don't know how much time I have spent trying to get this to work. Way to much.

On another note. Since I am focused in on all of this right now, I went out yesterday and bought an SA XDM 10MM 5.25. Took that with me today and shot one mag of the Underwood hardcast and 4 mags of my reloads. No problems at all!! I am going to give it a few more tries and if the experience holds I plan to pick up an XDM 4.5" as well. I do admit that part of my particular problem could be my technique and perhaps the XDM is just more forgiving.

I was talking to a guy as we left the range today. He had a new 9MM he was shooting today and I mentioned that I was there with the XDM for the first time. He said he had tried 10MM several years ago with a gen 3, G-20. Said he finally sold it, because he could not deal with the constant jamming... he offered that comment up before I had ever mentioned my problems with the glock.

4949shooter · May 21 2019 02:59:23 PM MDT

Powerstroke I think you hit the nail on the head.

With the light weight of a Glock 10mm, technique is very important. This has been my experience as well.

Enjoy your new Springfield..

mcseal2 · June 18 2019 03:48:57 PM MDT

My G20 is off at the gunsmith's now with some of the HC ammo. I'll see what he figures out. The other 10mm I traded for, a Sig Tacops 1911 is feeding everything fine so far. Maybe it was just me. The HC ammo in the G20 didn't seem to kick noticeably more than the 180gr at 1250fps JHP ammo I shot through it, and I never had a failure to feed in around 400 rounds of that through the G20. Would bad shooting form cause jams with one and not the other?

4949shooter · June 18 2019 06:09:17 PM MDT

Quote from: mcseal2 on June 18 2019 03:48:57 PM MDT
My G20 is off at the gunsmith's now with some of the HC ammo. I'll see what he figures out. The other 10mm I traded for, a Sig Tacops 1911 is feeding everything fine so far. Maybe it was just me. The HC ammo in the G20 didn't seem to kick noticeably more than the 180gr at 1250fps JHP ammo I shot through it, and I never had a failure to feed in around 400 rounds of that through the G20. Would bad shooting form cause jams with one and not the other?

Short answer is yes. The Sig is an all steel 1911. Steel frame 1911's are not prone to wrist technique issues. Glocks (my favorite pistols) can be prone to this due to their lightweight polymer frames. This has been my experience with them.Full power 10mm requires a tight wrist lock.