Thanks for your question. I know a little about barrel performance in a semi-auto, but it's only a little. I did however talk to Dave Sevigny from Glock and told him about your questions and got his input.
Dave has a couple Open Glock pistols and shoots them in the Steel Challenge. Dave's gun was built by S&J Customs (www.GlockJockey.com
) and the comp he runs is aluminum and is their 5 Port model
. It's their 'do all' comp but they do offer an 11 Port model
which is sport specific for USPSA Open Major or Steel Challenge depending on how you set up the gun.
Dave told me he's got somewhere between 15K to 20K rounds through the gun and it has been exceptionally reliable. Dave is also using a factory ammo load from Atlanta Arms & Ammo
. His load is 115gr running out the barrel at about 1050fps for a power factor of 120-122. Remember, this is his steel gun.
Dave suggested I talk to S&J Customs to get some more data or you and I talked to John Nagel, their designer and pistolsmith.
I told John about your gun and he had a couple comments. First, he says the G34 is not the best slide to use for an Open gun running Major. That is because the slide is lightened to reach the same weight, 11.7oz, as the slide on a G17. The stock slide is not ideal for your competition application. There are aftermarket slides that are better for your set and you'll want to consider that as you proceed.
As for the aluminum comp, John says the life expectancy is about 25K rounds. After that point the first port gets worn out. But he said that for a shooter below the level of Grand Master, like Dave, or Master, may not be able to notice the impact on their shooting performance. John has customers who tell him they can't tell the difference from their old comp and a new one. You will want to consider that when you consider your comp.
The most important thing that John pointed out was the weight is the real issue. In their experience, the max weight you want to put on the end of the barrel and still get the gun to run reliably is 1.5oz. This means you're looking at an aluminum alloy comp. Going any heavier will create what John calls the 'bump factor' where the barrel essentially bumps, or bounces on the locking block. This can lead to stove piping or short cycling. So whatever you go with in a comp, keep it under 1.5oz.
I'd suggest talking to a couple other Open Glock shooters to get their input as you'll have additional issues with springs and tuning the ejection to avoid the sight mount system. Hope this helps and good luck with your Open Glock. - ERHARDT