I started reading another thread about Wolf barrels and the leading problems with Glock barrels, and found the reference to the unsupported chambers. I wrote the reply below, but figured it would be better to start another thread, as this will probably draw a lot of fire, so let her rip!

Have a Glock 20 (10mm) and have started shooting cast bullets over the last couple months. Stock barrel, with Wolf spring kit through out. Have had no leading problems with the stock barrel, and towel dropped Lyman 401638, 175gr TC, from WW.
But I do have a question, http://shootersforum.com/images/smilies/confused.gifevery one is referring to an unsupported chamber in their stock Glock barrels.
My chamber measures .429, new ammunition measures .423, my reloads measure .423, and fired factory and reloads all come out .427 to .428. None of these look pregnant. Where the **** were your barrels made and what dimensions are they?
I just checked a friends S&W manufactured .40 S&W, and it has the same dimensions as my 10mm, except for chamber length, and cases come out of that gun with the same OD as those from my Glock.

I would really like to hear some reply's to this.

I also pickup a lot of range brass and have to date, not found any .40 S&W brass that looks pregnant and at least some portion of this brass has come from Glock's.

Welcome to the forum. Rules are to join in and play nicely with the other children. Other rules are in the stickies in the General forum.

Standard 1911 barrels and many others have "unsupported" chambers. This just refers to the mouth of the chamber that extends from the feed ramp leaving a short length of case head brass exposed instead of giving it 100% support as an integral ramp barrel will do. There is a good set of photos of it here (http://38super.net/Pages/supported.html) for a .38 Super showing supported and unsupported chambers. If you load to high enough pressure or if you have extraction that is not adequately delayed by the lockup, you will see a bulge form at the unsupported location, as it is the weakest point and pressure tends to expand things at the point of least resistance.

If your loads are well within reasonable pressure limits, I don't see why you should see a bulge, pregnancy, or a Budweiser tumor there, either? As to leading, watch for it. It can be hard to see. If you have a friend with a Foul Out electrolytic bore cleaner, let him use it on the barrel just to be sure nothing comes off on the rod? If not, you are good to go. You've got the right load, bullet, and lube. In fact, you might want to post those details for some other frustrated Glock user to emulate?

I can't add much to what Nick has said, but the bottom line is that you need to keep the reloads in the mid or low range if you want to get the most of your brass.

My 1911 has a fully supported chamber and I have no problems with premature case failures, but I know several Glock guys that have had blowups, and one guy that has had 3. Granted he's not been hurt by them, but he was using Bullseye powder and I wonder if that had contributed to the issue.

hmmmm....would this be my chance to say something to the effect that I knew them plastic fantastics were no good ? mebbe I better not..... ;)


kidding, gents, just kidding..... heh heh....

OK! I just went and removed the slide from my Glock 20 with an empty case in the chamber. This barrel has a ramp and looks more like the .38 Super on the right (supported), in the example shown here, http://38super.net/Pages/supported.html.
My next question is, did Glock make different styles of barrels for different model or even different years? I purchased this gun new in 1993 and have fired thousands of lead bullet threw it, most home cast with home made lube.
I will try my hand at a photo of my barrel and post it here?
As for the load, it is 7.5gr of Accurate Arms # 5, CCI 300 primer, Federal brass cases, 175gr towel dropped Lyman 401638 from wheel weight alloy, the bullet is seated out a little over length to 1.275". I got a velocity of 918 FPS the last time I fired this load, but after a lot of examination with a bore scope, I still do not find any lead, I have used a Hoppe's lead remover in the barrel with a clean screen onto white paper with no lead appearing on the paper. The bullet is lubed with a home made lube of beeswax, anhydrous lanolin, Murphy's oil soap, and Neets Foot oil. If any one is interested in the recipe I will gladly post it. This lube is soft and a little sticky, but works good in my handguns and my 45-70.
Thanks for the info.
I will try to be a nicer player ib the future!

You are definetly in the safe range, thats barely above 40 S&W velocities.

No Glock has a fully supported barrel, typically the 10mms do have a little more support, but the 10mm case is a lot thicker in the web area than 40 S&W is. The biggest problem with the 10mm guns is that they put a Glock Smile in the cases, which does shorten case life.

I loaded and shot many many hard cast rounds out of a Glock 17 and 19. I have never had problems with the cases bulging or any pressure issues. I don't try to magnumize ANY of my handguns except those that were designed specifically for magnums like .357's. I'm perfectly happy with 1000 fps loads in cast using hard cast slugs. I'd rather use a heavier slug (124+gr 9mm) than a lighter one when shooting cast. They were reliable and more than accurate enough for combat pistol competition at my level.

I stopped using Bullseye quite a while ago. Yes it is a very "cheap" powder to use giving you many more loads from a pound of powder than some others. I did find that it is sporadic on pressure and velocity. Some early manuals like the Hornady vol 2 tended to have over heavy loads in bullseye. It is also disgustingly easy to get double or other over charge loads due to the very small loading volume of the powder from a powder measure. I got better luck using a powder like red dot for pistol cartridges. It is still a small weight but the powder is bulkier making an over charge easy to spot.