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Discussion Starter #1
Looking for some help with LEM trigger pull weights. I currently have a AF dated USP compact in .40 with the heavy LEM trigger setup. I want to use this pistol for CCW but I just can't seem to get adjusted to the heavy LEM trigger. My groups with this setup are all over the target which doesn't give me the confidence to use it as a CCW piece.
Now I know there's a learning curve with the LEM trigger but I can shoot one giant ragged hole with my Glock which has a 6lb trigger.
I don't really want to do a full blown light LEM setup as I think it would be a bit too light for me. Is there something in between light LEM and heavy LEM that will retain the reliability that I need for a CCW piece?
Let me know what I need to do. Pointing me to parts and/or part numbers would be greatly appreciated.
Thanks is advance for your input and help.
 

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Discussion Starter #2
Ok, after doing some reading it looks like I want the Todd Green Special LEM trigger setup.

Can anyone confirm for me the part numbers I need (firing pin block spring and hammer spring) for this setup? Again, I'll be installing this in a USP Compact .40.

Thanks
 

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You'll need the light FPBS 209296 and V1 hammer spring 215694. Keep the heavy TRS that came with your heavy LEM.
 

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Tony I have the TGS on my USPc and I love it. Heavy LEM was too heavy and light was mushy. Best mod I ever did! Let us know what you think after you complete the job.
 

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I have the light FPBS only, left the heavy TRS. This is considered a V4 and it is inbetween heavy and light. I don't like messing with the hammer spring. You stated that reliability is important; messing with the hammer spring WILL affect reliability. You are shaving off of a margin of error that HK built into the gun. The stock spring hits the primer harder than needed for most ammo, if you go lighter, you are hitting lighter. Will it work with your ammo, maybe/probably. But maybe not. HK built in that margin of error and I for one don't want to mess with reliability in a fighting gun.

Consider a Variant 4 before replacing the hammer spring.

Btw, I used to have a USPc I got used. Had light primer strikes, eventually I realized the hammer spring was not stock. Replaced it and problems went away. Just some food for thought...
 

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I have the light FPBS only, left the heavy TRS. This is considered a V4 and it is inbetween heavy and light. I don't like messing with the hammer spring. You stated that reliability is important; messing with the hammer spring WILL affect reliability. You are shaving off of a margin of error that HK built into the gun. The stock spring hits the primer harder than needed for most ammo, if you go lighter, you are hitting lighter. Will it work with your ammo, maybe/probably. But maybe not. HK built in that margin of error and I for one don't want to mess with reliability in a fighting gun.

Consider a Variant 4 before replacing the hammer spring.

Btw, I used to have a USPc I got used. Had light primer strikes, eventually I realized the hammer spring was not stock. Replaced it and problems went away. Just some food for thought...
The hammer spring that he was told to use by TooSixy (part number 215694) is the stock hammer spring that the DA/SA USP Compact is equipped with. It is not a "lighter than factory" Compact spring by any means. It is actually the same hammer spring used in the Match Trigger kit. I use this spring in all of my USPs. I've been using it for years, and have never encountered any issues with it, let alone any light primer strikes.

The "not stock" hammer spring that you had in your Compact was just that...a non-Hk spring causing firing problems in an Hk. You should be fine with any hammer spring that Hk offers.

Just my 2 cents...
 

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I have the light FPBS only, left the heavy TRS. This is considered a V4 and it is inbetween heavy and light...
+1 from me, all of my H&K pistols are setup this way.. (LEM TRS, LEM HS, DA/SA FPBS, Match sear spring)
Add the USP match sear spring (nickle plated) if you want to further smooth the break.
 

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Discussion Starter #11
Strider45, I see what you're saying. I would think that if the recommended hammer spring is the same one that's in the SA/DA USPc I should have no problem with reliability. Question though, when I pull up that part number it shows a "match hammer spring". Is that what comes standard in the DA/SA USPc?

Also, if I just replace the FPB spring it would only add about 1/2 pound to the trigger pull weight compared to the TGS?

Sorry for the questions. Still learning and trying to make informed decisions.
 

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The USPc and the Match Hammer spring are the same one. The pull for each Variant is going to differ slightly but it should be between .5 and 1.5 lbs difference between V4 and TGS.
 

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Strider45, I see what you're saying. I would think that if the recommended hammer spring is the same one that's in the SA/DA USPc I should have no problem with reliability. Question though, when I pull up that part number it shows a "match hammer spring". Is that what comes standard in the DA/SA USPc?

Also, if I just replace the FPB spring it would only add about 1/2 pound to the trigger pull weight compared to the TGS?

Sorry for the questions. Still learning and trying to make informed decisions.
Yes...the Match hammer spring is actually the Compact hammer spring. With regards to the FPB spring, I'm not sure on the exact weight...but it will not add any weight, it will lessen the trigger pull weight, if you install the lighter one. I'm thinking that this is what you were asking...
 

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Discussion Starter #14
Yes...the Match hammer spring is actually the Compact hammer spring. With regards to the FPB spring, I'm not sure on the exact weight...but it will not add any weight, it will lessen the trigger pull weight, if you install the lighter one. I'm thinking that this is what you were asking...
Maybe I worded it wrong. I was asking the difference in trigger pull weight between the V4 and V-TGS.
 

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Maybe I worded it wrong. I was asking the difference in trigger pull weight between the V4 and V-TGS.
What is V-TGS?

Maybe some clarification is needed here. V1 is light LEM, it includes light TRS and light FPBS. V2 is heavy LEM, it includes heavy TRS and heavy FPBS. V4 is medium LEM, it includes one of each.

The Todd Green Special, from what I understand, is a V4 with a lighter hammer spring (or the hammer spring from a different gun?). As previously posted, I don't mess with hammer springs, personal choice. Besides the reliability aspect, I can't tell a DA that my gun is a H&K Variant 4, I have to say I modified the gun, etc etc.

When I went from V2 to V4, I would estimate I lost about a pound from the trigger pull weight. I didn't measure, but it feels much closer to a standard striker gun's pull weight (Glock, etc). Maybe a bit lighter than Glock.
 

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What is V-TGS?

The Todd Green Special, from what I understand, is a V4 with a lighter hammer spring (or the hammer spring from a different gun?). As previously posted, I don't mess with hammer springs, personal choice. Besides the reliability aspect, I can't tell a DA that my gun is a H&K Variant 4, I have to say I modified the gun, etc etc.
V-TGS is Todd Green Special. You are not actually using a lighter than factory hammer spring or a hammer spring from a different gun. You are using the stock hammer spring from the DA/SA version of the gun you own, reguardless of model. The hammer spring is going to hit exactly as hard as it does in SA of the DA/SA counterpart. If you don't feel comfortable changing the hammer spring that is completely fine. But for the purpose of full disclosure, there is no reliability issues with using the stock DA/SA hammer spring in a LEM pistol.
 

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V-TGS is Todd Green Special. You are not actually using a lighter than factory hammer spring or a hammer spring from a different gun. You are using the stock hammer spring from the DA/SA version of the gun you own, reguardless of model. The hammer spring is going to hit exactly as hard as it does in SA of the DA/SA counterpart. If you don't feel comfortable changing the hammer spring that is completely fine. But for the purpose of full disclosure, there is no reliability issues with using the stock DA/SA hammer spring in a LEM pistol.
Well, when I said "different gun", I think the DA/SA version of your gun qualifies. Sort of. If the springs aren't any different, what is the benefit? The DA/SA spring has to be lighter for there to be a benefit, right?

So that begs the question, why are there two different hammer springs if they work exactly the same way, but one apparently results in a better trigger pull? It seems to me that HK or someone knows something and decided there needed to be a different spring for LEM triggers, for some reason. I'd love to know why.
 

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So that begs the question, why are there two different hammer springs if they work exactly the same way, but one apparently results in a better trigger pull? It seems to me that HK or someone knows something and decided there needed to be a different spring for LEM triggers, for some reason. I'd love to know why.
And that my friend is why HK is weird. The stock spring worked perfectly fine on the DA/SA variants, but for some reason, they decided to install a heavier hammer spring in the LEM. My best guess is that since you would never be doing a DA pull, they increased the weight for an even stronger hit on the primers (even though i have never heard of a SA/DA having light primer strikes for no reason) because the shooter really wouldn't make much of a difference. A 5lb pull and a 7.5lb pull are not that far apart. But an 11lb pull and a 13.5lb pull feel much different (even though the difference in the weights are exactly the same).
 

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I have the light FPBS only, left the heavy TRS. This is considered a V4 and it is inbetween heavy and light. I don't like messing with the hammer spring. You stated that reliability is important; messing with the hammer spring WILL affect reliability. You are shaving off of a margin of error that HK built into the gun. The stock spring hits the primer harder than needed for most ammo, if you go lighter, you are hitting lighter. Will it work with your ammo, maybe/probably. But maybe not. HK built in that margin of error and I for one don't want to mess with reliability in a fighting gun.

Consider a Variant 4 before replacing the hammer spring.

Btw, I used to have a USPc I got used. Had light primer strikes, eventually I realized the hammer spring was not stock. Replaced it and problems went away. Just some food for thought...
+1 I found the trigger rolled better with the original hammer spring. V4 may be the way to go. I carry v1 tho
 

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And that my friend is why HK is weird. The stock spring worked perfectly fine on the DA/SA variants, but for some reason, they decided to install a heavier hammer spring in the LEM. My best guess is that since you would never be doing a DA pull, they increased the weight for an even stronger hit on the primers (even though i have never heard of a SA/DA having light primer strikes for no reason) because the shooter really wouldn't make much of a difference. A 5lb pull and a 7.5lb pull are not that far apart. But an 11lb pull and a 13.5lb pull feel much different (even though the difference in the weights are exactly the same).
Interesting. More energy on the primer is ALWAYS good. It's not for when things are clean and good, it's for when the gun is clogged with mud and dirt and maybe not all of that force is actually making it's way to the primer. It's all about margin of error. I can see why they would say, hey, we can get away with a heavier spring here for even more reliability.

Isn't the hammer spring primarily compressed at all times on an LEM? I just looked at my P2Ksk and the spring appears compressed. So how do you get a smoother trigger pull by changing out the hammer spring, if it is compressed during the movement of the action and not by the trigger?
 
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