new 400 corbon barrel

[analog]

Hi all,

I just picked up an Accumatch 400 corbon barrel for my G21. It is the threaded one, with compensator that screws onto it.

I got a chance to go shoot it tonight, and had some trouble with "failed to fire". I shot about 60 rounds, and out of those 60, had about 8 or 9 "clicks". For each one, I waited about 30 seconds, with gun pointed down range, then, racked the slide, and ejected the round. Each round had an indention on the primer, but did not go boom.

Now, I have never had this happen when using regular 45ACP, generally Wolf.

For the hell of it, I put one of the rounds that failed to fire back into the gun, and tried again. That time, it worked! So, I retried each of them again, and they all fired.

So, question is, do I need to upgrade my firing pin in anyway?

Thanks!

[WalterGA]

I own several Accu-Match barrels exactly like yours. On a couple, minor fitting was required. Check to see if the barrel hood is flush with the top of your slide. If not, you'll need to do a little judicious filing. Also, the compensator is pretty effective at slowing slide speed. You might need to experiment with different recoil spring weights. Your compensated barrel will also cause your Glock to be more susceptible to "limpwristing".

I'm sure you're aware that .400 Cor-Bon won't feed properly from pre-ban mags. You'll have to use Klintonista mags.

Accu-Match has been out of business for some time. How did you happen to find an Accu-Match barrel??

[analog]

Yeah, I used my tyrannical 10 rounders, I didn't have any feed problems. I shot about half the rounds without the compensator, and had the same failure to fires.

Once I did put on the compensator, I did notice that a couple of times, the spent brass wouldn't eject completely and get lodged between the barrel, and the slide. Probably my lazy grip is the culprit there.

I picked up the barrel from an eBay auction. I was surprised as heck to see it, but, for $80 with the compensator, I figured, why not. Only thing missing is the set screw for the compensator. WalterGA, you don't happen to know where I could find one do you?

So far, I REALLY like the load on these 400 corbons. Just gotta get them reliable ;)

Thanks for the info. I'll inspect the seating of the barrel more closely when I get home tonight.

[WalterGA]

Analog: The setscrew is a 10-32 setscrew. The problem is finding one short enough. If the screw's even a few thousandth's too long, the guide rod will bind on the screw during cycling. I've rounded off a couple of those setscrews and they're tough to extract. Had to have two of them drilled out. If somebody made a torx-head setscrew that size and short enough, that'd be ideal.

I've been able to find the 10-32 setscrews at a local hardware store. I grind 'em down to the proper length.

I had one of my .400 Cor-Bon Accu-Match barrels reamed to .40 Super. Great accuracy and a little hotter than .400 Cor-Bon. Problem is finding dies at a reasonable cost.

I'd also advise you to be particularly careful about bullet setback. I blew up my first G21 using the exact setup that you have.

[analog]

Thanks for the info on the set screw... Let the hunt begin!

please forgive the newbie question, but what is bullet setback, and how do I look out for it. I don't want to be blowing up my Glock. She is currently my only one, and I would hate to be without her.

[WalterGA]

Bullet setback is when the bullet strikes the feedramp with enough force to push the bullet back into the case, causing a potentially dangerous overpressure situation. Not as likely to happen with factory loads, but it's more likely with bottlenecks, eg., .400 Cor-Bon than straightwall cartridges, as the bottlenecks don't offer much neck surface area for really good neck tension.

In my case, the round had actually jammed on the feedramp. I took a quick glance, but didn't look closely enough, popped the bottom of the mag, which chambered the round. I realized the error of my ways immediately, as I pulled the trigger.

The reason I suggested that you make sure that your barrel hood (the rearmost upper portion of the barrel that contacts the rear of the ejection port opening) is flush with the top of the slide is that could be the cause of your failures to fire. If your strikes are a little off-center and your shots tend to be high, that's something to look for. Also, the new .400 Cor-bon rounds probably use small rifle primers, which are harder than small pistol primers. Just make sure that your recoil spring is o.k. and that your G21's striker channel is clean and dry. There should be no oil at all in the striker channel.

[analog]

Well I finally pulled the new barrel out and compared it to my orignial 45acp barrel. The 400 cor-bon is much tighter, and doesn't completely seat. So, I bet that is the problem.

Thanks for pointing me in the right direction WalterGA!

[WalterGA]

", and doesn't completely seat. So, I bet that is the problem..."

On a couple of my Accu-Match barrels, I used a flat, medium, diamond E-Z Lap hone to take a little material off of the cut just in front of the chamber area. Just do a little at a time, until you get the fit as you like it. Before filing on that horizontal cut, I'd check to see if the barrel hood is a little long, which'll have the same effect on ill-fitting.

[KK20]

80 dollars for the barrel-- wish i saw that

:)