USP 40 Full size and the recoil buffer spring

[warpedcamshaft]

I've been putting a bunch of time in on the USP 40 full size lately.

I have noticed that the recoil buffer spring makes this firearm recoil "differently," and cycle slow compared to some other pistols (several video frames longer depending on ammunition used. 180 grain ammunition adds a couple more frames to the video compared to 165) Also... and correct me if I am wrong, I believe that the recoil buffer spring system died with the USP. In subsequent platforms, HK uses a different buffer assembly.

A few weekends now, I have been capturing high speed video of the pistol during drills. I've noticed that on frame by frame video, the pistol cycles much slower than Glock 19, 23, 17, HK45, or Walther PPQ. I have also noted that site tracking is much harder for me on the USP full size. (I may post some of this video eventually)

After scouring the internet for information about the USP shooting characteristics, I found some interesting information from Bruce Gray. Apparently, he was taking the buffer spring out of his USP 9mm during competition in the Limited class. He also mentioned that "all spring loaded recoil buffers make a given pistol flip higher and return the sights less consistently."

To me, the USP seems limiting in the "shootability" category compared to other designs, and it seems my observations are somewhat validated by Bruce Gray's observations.

I think I am going to sell the USP 40 in the end, but I was curious if anyone else with time on the USP has had a similar experience with the recoil characteristics.

[montrala]

Basically you are right and what Bruce Gray said is truth. So you can omit my outburst below ;)

USP recoil spring system was developed to reduce felt (and actual) recoil of .45 +P rounds. It does great job on .40SW as well, on 9mm it's function is barely noticeable.

It is very hard to mimic USP recoil system work by hand. This is because with hand on pulls on slide, when shooting recoil pushes barrel. USP system works this that for initial recoil barrel with slide travel together with recoil assembly, compressing small (internal) spring. When guide rod hits end of it's travel, barrel starts to unlock and slide travel back compressing main spring, until is hits small spring bushing, compressing small spring again (when slide unlocked, recoil assembly moved forward, so small spring can be compressed again). So this is 3 step recoil system - by hand only 2 last steps can be felt, unless you push on barrel, them 1st stage can be felt. From engineering point of view it is ingenious system. From shooter point of view it seems unnecessary. When USP Compact was developed (initially it was supposed to be free recoil system) simpler system with flat recoil spring and polymer recoil buffer was introduced. This system proved to work as good at taming recoil as USP one, so from this point any new HK design (except P2000SK) got this new recoil system.

For several years I was using USP Expert in .40SW in IPSC competition, then I changed to custom built STI 2011. Expert definitely cycled slower than STI and after some time and lot of work to find proper setup to make STI work, it allowed me to shoot little faster that I did with Expert. What I learnt on STI using different recoil systems is that additional springs do make sight tracking harder and make slide cycle less consistently. This is what happens in USP. USP system works great for separated, aimed shots, but for string of rapid shots it is less than ideal.

Now I use HK P30L (9mm) in IPSC and IDPA (and as CCW).

[moonshot]

I'm not sure if this is even the same system, but I had a USP compact in 40 several years ago with a plastic disc as part of the RSA, supposedly there to soften the recoil and/or extent the lift of the frame.

I felt that gun had far more pronounced muzzle jump than other 40's I was shooting, but I attributed this to higher bore axis on the HK, even though that HK fit my hand like a glove.

For this and other reasons I sold my USPc.

[warpedcamshaft]

Basically you are right and what Bruce Gray said is truth. So you can omit my outburst below ;)

USP recoil spring system was developed to reduce felt (and actual) recoil of .45 +P rounds. It does great job on .40SW as well, on 9mm it's function is barely noticeable.

It is very hard to mimic USP recoil system work by hand. This is because with hand on pulls on slide, when shooting recoil pushes barrel. USP system works this that for initial recoil barrel with slide travel together with recoil assembly, compressing small (internal) spring. When guide rod hits end of it's travel, barrel starts to unlock and slide travel back compressing main spring, until is hits small spring bushing, compressing small spring again (when slide unlocked, recoil assembly moved forward, so small spring can be compressed again). So this is 3 step recoil system - by hand only 2 last steps can be felt, unless you push on barrel, them 1st stage can be felt. From engineering point of view it is ingenious system. From shooter point of view it seems unnecessary. When USP Compact was developed (initially it was supposed to be free recoil system) simpler system with flat recoil spring and polymer recoil buffer was introduced. This system proved to work as good at taming recoil as USP one, so from this point any new HK design (except P2000SK) got this new recoil system.

For several years I was using USP Expert in .40SW in IPSC competition, then I changed to custom built STI 2011. Expert definitely cycled slower than STI and after some time and lot of work to find proper setup to make STI work, it allowed me to shoot little faster that I did with Expert. What I learnt on STI using different recoil systems is that additional springs do make sight tracking harder and make slide cycle less consistently. This is what happens in USP. USP system works great for separated, aimed shots, but for string of rapid shots it is less than ideal.

Now I use HK P30L (9mm) in IPSC and IDPA (and as CCW).

Great post, thanks for the info.

[warpedcamshaft]

Got a chance to put some rounds through a P30 this last week.

The P30's recoil buffer system "returns" the front sight very nicely and has a much different feel from the spring buffer system of the USP fullsize.

[montrala]

The P30's recoil buffer system "returns" the front sight very nicely

This is what I call good tracking.