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I BLEW MY O-RING!

2555 Views 18 Replies 14 Participants Last post by  amstaffHK
So I was cleaning my Mark 23 yesterday and realized the slide didn't feel quite right. I noticed the missing o-ring. What would cause this? The gun has about 1000 rounds through it tops.
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High wear item, just replace as needed.
Need one, I have a few. PM if in need.
The gun came with like 5 of them. I thought they were soposed to last like 10,000 rounds?
Just curious...

Was it black or green?
The gun came with like 5 of them. I thought they were soposed to last like 10,000 rounds?
Too many variables to say they last over 10,000 rounds. Solvent, removal for cleaning, small nicks or cuts from handling...etc. Enjoy your blown o-ring, but don't go around telling too many folks...
It was green, but I replaced it with a black one.
Mine came with a bunch of green ones.. but i know they make black as well. Is there any difference other than the color. I've seen both for sale (i think the sae price) on hkparts.net.
Usually when you buy a new pistol you get about 2-3 of them with the pistol, but o-Rings are cheap and easy to replace.
If there was no lubricant on the oring, it may have been rolled by the friction to the point of failure. Rebuilding automatic transmissions, they have numerous orings and its easy to damage during assembly if there aren't lubed. I was disappointed when my P30 arrived and the barrel wasn't cut for an oring.
Take a cotton ball and rub it over the inside of the hole for the barrel on the removed slide. If there are any burrs, you will be able to see with the cotton ball. Those burrs will destroy an O-Ring. If there are burrs, a little sanding until smooth will make everything better.
If there was no lubricant on the oring, it may have been rolled by the friction to the point of failure. Rebuilding automatic transmissions, they have numerous orings and its easy to damage during assembly if there aren't lubed. I was disappointed when my P30 arrived and the barrel wasn't cut for an oring.
Frankly, I'm glad the engineers found a way to keep the accuracy in the P30 WITHOUT the O-ring. Less parts especially disposable ones makes a better design. So, you are deployed in the sand box. During a mission, your O-ring goes away. You tell the BG to take a time out while you change your o-ring? Hans & Kurt took care of that scenario for you.
I see your point...

My understanding of the O-ring, is that it's for "enhanced" lock up and accuracy. As you may know, the weapon will still fire accurately, with or without the o-ring.
Those in the sand box with a busted o-ring should be just fine. :)
I see your point...

My understanding of the O-ring, is that it's for "enhanced" lock up and accuracy. As you may know, the weapon will still fire accurately, with or without the o-ring.
Those in the sand box with a busted o-ring should be just fine. :)
You're correct. In a discussion detailing the development of the HK45, Larry Vickers and Ken Hackathorn had this to say:

Ken: We took the USP45 barrel which they’ve already got in production and just added the o- ring because we know that enhances accuracy. So we kind of spec’d those things out. Of course as time went by, what everybody discovered is if you take the o-ring out the difference in accuracy is going to be minor.
Larry: The o-ring; why not, there is no downside to the o-ring.
Ken: Because if the o-ring came off, the gun still shot great and was still accurate and reliable.
I think technically you shouldn't need an o-ring. Why does the USP-45T have one but the USP-SD doesn't? Its the same gun in a different caliber. I doubt HK would design or sell a 9mm version of a 45 that wasn't as accurate.
I think technically you shouldn't need an o-ring. Why does the USP-45T have one but the USP-SD doesn't? Its the same gun in a different caliber. I doubt HK would design or sell a 9mm version of a 45 that wasn't as accurate.
Common misconception, they aren't actually the same gun. They do not have a match trigger in the SD either.
Too many variables to say they last over 10,000 rounds. Solvent, removal for cleaning, small nicks or cuts from handling...etc. Enjoy your blown o-ring, but don't go around telling too many folks...
+1 and I have heard up to 20,000 rounds as well. If your o-ring is breaking at a 1000 rounds from new then I think your MK23 is lacking some serious lubrication in that area. JMO
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