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I was comparing HK pistols in the store the other day, and they were kind enough to let be do a pretty detailed disassembly/inspection. The biggest difference I saw was the longer, double recoil assembly on the USP full size, and the single spring with buffer on the Compact and all other guns (as well as some slide rail changes). Why did HK not adapt the original RSA to all the other models. Supposedly this this was at the heart of the USPs exceptional recoil impulse, longevity (I understand one is at 297K+ rounds), and allowed to easily hand really hot +P+ 9mm and .45 (and even .45 super) out of the box with no damage. I can kind of understand why its missing from the subcompacts, etc, due to size (though I would think HK engineers could have made it work), but I'm at a loss for the full sizes, especially HK45. I am curious as to whether this is an actually engineering issue, or simply financial/marketing.

Thanks.
 

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Cheaper to produce, mainly.

Some competitors feel the single spring shortened produced a stronger, but shorter recoil impulse, resulting in faster sight realignment. Personally, I don't buy that.
 

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Cheaper to produce, mainly.

Some competitors feel the single spring shortened produced a stronger, but shorter recoil impulse, resulting in faster sight realignment. Personally, I don't buy that.
Only way to know is shoot it on the timer vs. same caliber other pistols and see if your splits are slower. Even then there may be other factors.
 

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Only way to know is shoot it on the timer vs. same caliber other pistols and see if your splits are slower. Even then there may be other factors.
Exactly. Because the HK45 grip is so drastically different. I don't think there can be a reproducible experiment. Unless... Someone makes a dual spring for the HK45 or a single for the USPf.
 

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P2000SK has the dual stage RSA so it's not a question of size. One of my little complaints about my VP9 is it's not as butter smooth and effortlessly easy to rack the slide like it is on my USP and it has more felt recoil, though is "snappier" and faster on target as measured by shot timer. Whether that's because of single vs dual stage recoil spring or the myriad of other differences between the two platforms I don't know, but the USP is a joy to shoot.

I'm partial to it and the P2000SK as my go-to guns and I don't think it's coincidence the dual stage RSA is a common feature between them.
 

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Shot my new P2000SK for the first time today (finally got free on a warmer day), only put about 50 rds. through it but have to say that despite it being such a stiff new spring in a small/light gun… I was very impressed with how well it shot for a subcompact, thought I did get brass to face a few times (probably let my grip weaken combined with strong spring).

That said, I do remember reading they went to the flat spring w/ bushing in order to make the USP Compact due to the shorter RSA required on the short slide. Makes perfect sense seeing as every model that has been released which is direct descendent of the USP Compact (HK45/HK45C/P30/P2000) has used this configuration.
 

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Maybe a dumb response, but since HK is still producing the USP line, they didn't stop using the USP recoil system, right?
 

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Maybe a dumb response, but since HK is still producing the USP line, they didn't stop using the USP recoil system, right?
Good question, as my USP SD in 9mm. With a born on date of 2014, has the dual recoil spring, but I dont know if that is because the SD is suppressor ready from the factory.

My USPc in 45, with a born on date of 2000 has the single spring with the bushing.

My P2Ksk in 9mm is by far the easiest subcompact to shoot that I have ever owned or shot. The P30sk is a close second, but has better ergo's for many. The grip becomes too fat my liking though.
 

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My HK45s are smooth enough, I consider then buttery smooth, so not sure if dual spring all that necessary.

The ergos likely have something to do with perceived recoil as well, USP feels like a 2x4 in my hand.
 

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If HK would of used the same RSA, the question would be.. "why did HK use the same RSA on the HK45 than the USP, you would figure that that they would make it differently since it's a new gun"

I did feel a big difference between my USPc45 and my new HK45.. i was expecting recoil to be much smoother on the HK45 because of it's size but no.. it's pretty harsh (for me) i did feel it coming back on target faster than my usp. I've been shooting 9mm exclusively for the last year, im thinking that's why i felt the HK45 recoil so harsh, i need to shoot it more.. the recoil impulse on the HK45 feels like your shooting.45acp +P+.

My opinion.
 

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It may partially have to do with getting the bore/axis slide height lower to the frame which is a shame since bore axis and recoil is subjective and I did notice that the 9mm P30 has a lighter recoil impulse than the VP9 which may be due to the P30's bushing on guide rod even though it has a slightly higher bore axis.
 

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The only USP's with Recoil Reduction System are Full Size USP/MK23/P2000SK.

USP Compact does not use it.
 

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It may partially have to do with getting the bore/axis slide height lower to the frame which is a shame since bore axis and recoil is subjective and I did notice that the 9mm P30 has a lighter recoil impulse than the VP9 which may be due to the P30's bushing on guide rod even though it has a slightly higher bore axis.
Or it could just be the recoil spring is still new on the VP9...
 

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Members of the HK Shooting Team used to use 9mm Experts until the P30L came along. One of them noted long ago that the dual spring system caused the muzzle trajectory to be a figure-8, whereas the single spring system allowed the shooter to keep the recoil in the vertical plane. That ever so slight difference in recoil characteristics caused a very slightly longer target reacquisition time for the USP vs the P30L, something probably only a professional shooter could really notice.
 

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Members of the HK Shooting Team used to use 9mm Experts until the P30L came along. One of them noted long ago that the dual spring system caused the muzzle trajectory to be a figure-8, whereas the single spring system allowed the shooter to keep the recoil in the vertical plane. That ever so slight difference in recoil characteristics caused a very slightly longer target reacquisition time for the USP vs the P30L, something probably only a professional shooter could really notice.
Well that's interesting. If that is true it sounds like it just comes down to a slight speed advantage vs a slightly more robust longevity. I would also consider that perhaps modern polymer design and construction of pistol frames have improved enough since the early 90s so that the dual recoil seen in the full size versions is no longer relevant/necessary. Personally I would prefer the longevity; the USP/MK23 reliability is legendary.
 

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Well that's interesting. If that is true it sounds like it just comes down to a slight speed advantage vs a slightly more robust longevity. I would also consider that perhaps modern polymer design and construction of pistol frames have improved enough since the early 90s so that the dual recoil seen in the full size versions is no longer relevant/necessary. Personally I would prefer the longevity; the USP/MK23 reliability is legendary.
OR the same or even better longevity with the buffer system. No way of knowing for sure without someone spending a really really lot on ammo LOL. In any case I am not losing any sleep over it one way or another or letting it affect my preferences of HKs..
 

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Someone please post pictures, so I can reference to my pistols.

I own a couple, and am curious to the difference.

Hk45 uses the one spring w plastic buffer, and USP/mk23 use the dual spring ?
My p30 is single spring w buffer, and p30sk is small dual spring.

More info please.....


What a good album!!!!!!! Jamming Mama's Boy's plug it in album! Any fans???
 

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OR the same or even better longevity with the buffer system. No way of knowing for sure without someone spending a really really lot on ammo LOL. In any case I am not losing any sleep over it one way or another or letting it affect my preferences of HKs..
I know of no statement from anyone of any diminution of reliability because of the different recoil spring systems. Who was it, Larry Vickers ?, who shot through over 90k rds with a HK45, and the recoil spring and buffer were not among the parts that failed.

This type of question about relative reliability is simply a scenario that has imaginary plausibility, but has never been an issue with these pistols' longevity or reliability. I could not recommend to anyone to take on the lifetimes of rounds needed even to attempt to measure a difference.

Shoot your pistols and let the recoil springs, whichever system they may be, do their job. If one does break, a replacement is not very cher.
 
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