Underwood 220gr Hardcast (New Load)

[TheOtherMike]

Thanks for the feedback.

I'll give it a go and if it seems like a workable setup, then I'll step up the RSA.

[TheOtherMike]

I tried the 220gr HC today with a 6" KKM barrel.

Shot 10 rounds. First 5 were one round in the mag at a time. Everything looked OK to me as I collected each case after firing.

Then I loaded 5 in the mag. I had a failure to feed on the 2nd or 3rd round. Corrected and continued. I was only able to recover 2 more cases. 1 had no primer - probably the round leading to the FTF. I decided to stop there.

I measured the 7 recovered cases (of 10 fired):

  .431
  .432
  .432
  .431
  .431
  .432 *blown primer
  .432

I have 140 more of these rounds. Am I correct in assuming the experts here would recommend not to fire any more?

[ETA: These are the older, hotter 220gr rounds.]

Would it be possible to remove some of the powder and "reload"? (I have not started reloading so I have no idea.)

Would the stock Gen3 barrel be any better/safer? (Thinking that the looser chamber and shorter barrel may result in lower pressure.) Oops, forgot there's no jacket - my primary reason for getting the KKM.

Other options?

[Yondering]

3 thoughts -

- I would not continue shooting any load that caused a blown primer. That's a very definite sign of over-pressure, unless it's really weak brass. Even if you never had any other pressure issues, gas leakage around the primer will cause erosion of your breech face.

- Single case measurements after firing aren't worth much; you need to measure before and after, and compare the difference against a known good max load in the same brass.

- The Glock barrels do just fine with lead - if the bullet fits, meaning it should be slightly (.001-.003") larger than the bore. The 9mm Glock barrels tend to be a couple thousandths large, which I suspect is the main cause of the "no lead in Glocks" idea. Your .40/10mm barrel may or may not be oversized.

[4949shooter]

3 thoughts -

- I would not continue shooting any load that caused a blown primer. That's a very definite sign of over-pressure, unless it's really weak brass. Even if you never had any other pressure issues, gas leakage around the primer will cause erosion of your breech face.

- Single case measurements after firing aren't worth much; you need to measure before and after, and compare the difference against a known good max load in the same brass.

- The Glock barrels do just fine with lead - if the bullet fits, meaning it should be slightly (.001-.003") larger than the bore. The 9mm Glock barrels tend to be a couple thousandths large, which I suspect is the main cause of the "no lead in Glocks" idea. Your .40/10mm barrel may or may not be oversized.

Bingo. The signs are telling you to stop shooting it.

I would contact Kevin and see if he will replace your ammo with the newer, reduced load. He should be understanding if you explain the circumstances to him.

Glad you didn't have anything worse happen!

[TheOtherMike]

Thanks guys.

For the record, the case diameter of the unfired Underwood 220gr HC rounds is .421.

[mt10mm]

Why does this look to be only a glock issue? Do any of the S&W/EAA or other shooters have these same issues? When I was have my problems with the 4th gen G20 I looked for problems with other platforms and didnt find as many. Dont get me wrong I love my G20 but maybe Glock needs to address possible issues with the G20 platform.

[The_Shadow]

TheOtherMike, Is this the Glock 20 3rd or 4th generation?
What RSA spring rate are you running?  Factory stock? Other?

I have been trying to study these issues, Semi Autos are very dynamic in their functions.  Positive lockup and dwell time in battery all affect the performance.  I just installed a Wolff Gun Springs 22lb non captive RSA in my G-20SF and did some crude testing with a digital scale the results can be seen here; http://10mm-firearms.com/gunsmithing/wolff-gun-springs/msg27957/?boardseen#new

Underwood's ammo as measured in the pull-downs are shown to be loaded above loadings in most manuals if not all.  However some guns will handle the loadings just fine.

[4949shooter]

Why does this look to be only a glock issue? Do any of the S&W/EAA or other shooters have these same issues? When I was have my problems with the 4th gen G20 I looked for problems with other platforms and didnt find as many. Dont get me wrong I love my G20 but maybe Glock needs to address possible issues with the G20 platform.

I honestly think it has something to do with the polymer frame. We don't see any other manufacturers with *completely* successful polymer10mm platforms. The polymer flexes under recoil, even as evidenced by the 9mm +p+ video posted by someone here (Shadow?).

I am happy to have found a workable setup with my Gen 3 SF and 22 pound RSA. I won't be getting the Lone Wolf barrel until probably June, but I am planning on testing the Underwood and Buff Bore 220 hardcast loads with this barrel in my Glock.

The Glock is a tough pistol for sure. It is used by military units and police departments here and in other parts of the world. That having been said, I don't think Glock ever intended for "nuclear" level loads to be fired through their tens. From Glocktalk I learned they test their 10mm pistols with CCi 200 grain Blazer. Not exactly a hot load. 45+p level maybe, but not true 10mm.

[Intercooler]

   I shoot high pressure in my XD. When I let the slide stop go it chambers but... It has a weak pressure holding it shut. It sometimes doesn't seem to push the slide forward solidly as much as I like and I give it a nudge. So far I have been pretty lucky it has stayed in battery (talking 9mm here) and know it might bite me at some point in time. High pressure rounds seem better suited in hammer fired pistols. 

[TheOtherMike]

I setup my G20SF specifically for this 220gr HC ammo with a 6" KKM and a 20lb. captured RSA with a stainless rod.

Everything else I have run through the G20SF was with stock setup.


Not clear to me what issue is being attributed to Glocks/polymer frames.

Also not clear what the RSA has to do with overpressure concerns.

Hope someone can explain.

Thanks!

[Intercooler]

  A neat experiment would be to hang or attach a pull gauge onto your slide and see what force in LBS it takes to pull the slide back against the striker. I can do this with one of my hammer fired pistols if it holds on the site correctly. Let me go see.

[Intercooler]

   I just tried the Limited Pro several times and the slide overcomes the hammer and starts the slide movement back at ~ 12 LBS. Can someone with a Glock give it a whirl? My guess is about 6 LBS, but since I'm curious I'm going back to pull the XD 

[Intercooler]

  The XD had moved in the 4-5 LB range, but noticed it moved pretty freely before that nice movement backwards. It has a DPM recoil reducing guide-rod assembly in it too.   

[4949shooter]

I setup my G20SF specifically for this 220gr HC ammo with a 6" KKM and a 20lb. captured RSA with a stainless rod.

Everything else I have run through the G20SF was with stock setup.


Not clear to me what issue is being attributed to Glocks/polymer frames.

Also not clear what the RSA has to do with overpressure concerns.

Hope someone can explain.

Thanks!

The polymer frame flexes under recoil. There was a slow motion video posted somewhere of a Glock 19 firing +p+ ammo. You could see how much the frame flexed in the video and that was only 9mm!

I do believe with full power 10mm ammo the Glock framed flexes in a similar manner, though probably to a greater degree. This in my opinion can cause malfunctions. In my case, a 22 pound RSA solved the problem.

[DarnSkippy]

Here is my experience with the UW 220gr HC 10mm load.

Pistol: gen3 Glock 20, factory recoil spring, KKM 5.3" barrel.  I chose this barrel length to line up with the end of the SureFire X300U light mounted on the gun, which gives more holstering options.

Test 1: UW 220gr Hard Cast, bought in October 2013, shot in mid December 2013; temp = 55 degF

1264
1244
1263
1256
1256

avg = 1257, sd = 7.14; can't recall if this brass showed overpressure signs

Test 2: UW 220gr Hard Cast, bought in October 2013, shot in mid January 2014; temp = 53 degF

1296
1271
1273
1272
1274

avg = 1277, sd = 9.45

Some of these rounds had mild smilies (even with the KKM barrel) and one blew out a primer.  I called Kevin about it in February 2014.  He replaced it all with ammo from newer batches, and sent me a shipping label to return the unfired rounds from what I had bought in October 2013.

Test 3: UW 220gr Hard Cast, lot #B0901-003 received in February 2014, shot on March 9, 2014; temp = 68 degF

1177
1215
1179
1189
1195

avg = 1191, sd = 13.68; brass looks good with no apparent signs of overpressure

So it looks like the UW 220gr HC load has certainly been toned down, especially since the higher velocities were recorded in weather that was 15 degF colder.  I put this gun together for use out West against large animals when I have no other option.  I'm now unsure if the load is powerful enough for that, though it's no good for the gun to blow up, of course.