The O-ring engagement was among a few of HK's innovations with the USP line of pistols. They claim it provides better accuracy by allowing the barrel to fully lock up with the slide. There is some debate to the validity of the claim, but nonetheless, only a select number of models were fitted with an O-ring barrel.

The following models were delivered from the factory with an O-ring barrel:

• Mark 23
• USP Tactical 40/45 + Compact (Not the USP-SD)
• USP Match
• USP Expert
• USP Elite
• HK 45 + Compact

So the standard USP does not have an O-ring barrel. Which makes perfect sense because the barrel does not protrude enough past the slide for an O-ring. However, the USP-SD has plenty of barrel length yet does not have the O-ring like it's bigger brothers (the .40 and .45). Is it possible to add an O-ring a USP-SD barrel? You would think so right?

Well the answer is no, and here is why; HK barrels are hammer forged. Once they are forged they are then cooled to a temperature that makes them even more resistant to wear. Once completely cooled the metal is so hard it cannot be cut or threaded as the barrel will break any tools used to do so. It's like trying to cut a diamond with a hack saw. This why you really do not need thread protectors for the tactical barrels. Due to the hardness, if you ever manage to cross-thread your suppressor with an HK barrel, the suppressor mount would be re-threaded. Not the barrel.

If you are after a custom barrel for your USP with an O-ring engagement, check out Jarvis barrels. They are high quality, match grade products that drop right into HK pistols with no problems. They produce a variety of barrels with different lengths and features.

The short answer is no. Dry firing a Glock does not hurt the firing pin or any other part of the gun. Over time, the trigger spring and recoil spring may wear, but much slower than it would from live fire.

Dry firing a center fire pistol or rifle will not hurt the gun. The only exception is a rimfire gun as the firing pin will strike the side of the chamber when no round is present. This will eventually dull the firing pin or damage the chamber wall. Although, some guns like the Ruger 22/45 can be safely dry fired due to careful design improvements.

So today I was going to shoot my USP-SD. To make a long story short, my grip slipped as I went to take it off the pistol stand (unloaded) and I dropped it about 4 feet off the ground. No big deal, I picked it up, then notice something different with the sight picture... I had no rear sight.

I looked along the ground, and sure enough, I found the rear blade which was part of the rear sight. Upon careful examination, I realized that it must have fallen just right and cracked in half. At one time I had questioned how durable the adjustable sights would be if challenged. Unfortunately, today I found out. Although they are high quality and made from metal, they will break if dropped or bent in just the right (or wrong) way.


I contacted HK customer service with the picture above. I stated exactly what happened and they gave me an RMA number. I shipped the slide only, and HK promptly put in a new sight mailed it back. It's no secret that HK pistols are expensive, but HK provides some of the best customer service in the business.