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DelawareTacticalDynamics
September 18, 2017, 17:03
Bolt gap is measured between the bolt and carrier with a feeler gauge correct?

Grinder
September 18, 2017, 17:51
With the hammer dropped

BIG50
September 18, 2017, 19:41
Correct and you do not have to drop the hammer some people like to drop the hammer they think it gives you a better lock up.

DelawareTacticalDynamics
September 18, 2017, 20:14
Looks like .013 on mine which is in the ideal range right?

hkshooter
September 18, 2017, 20:42
Looks like .013 on mine which is in the ideal range right?

On the low end but in the range.

BIG50
September 19, 2017, 08:39
0.13 is good and safe i like it at 0.19

hansellhd
September 19, 2017, 12:46
Looks like .013 on mine which is in the ideal range right?

Yes don't worry about it.

Min= .004

Max= .020

Ideal= .014

If I see a gap @ .010 I would install +2 rollers. Below .010 +4 rollers.

cjjtulsa
September 19, 2017, 16:42
On the low end but in the range.

Most data I've seen says the low spec is .004"? I've got at least one at .010", and though I've considered some +2 rollers soon, it still runs great. I wouldn't even mess with .013".

hkshooter
September 19, 2017, 20:07
Most data I've seen says the low spec is .004"? I've got at least one at .010", and though I've considered some +2 rollers soon, it still runs great. I wouldn't even mess with .013".

I'd like to see your data. .004 is practically no bolt gap at all. .010-.018 ideal, .010-.020 is the range. Thousandths, not millimeters.

http://img.photobucket.com/albums/v298/hkshooter/HK_BOLT_GAP_zpsgbqbturq.jpg (http://smg.photobucket.com/user/hkshooter/media/HK_BOLT_GAP_zpsgbqbturq.jpg.html)

michael_g927
September 21, 2017, 21:42
Every time i attempt to buy 91 types online, it seems like the other guy has no concept of measuring this. It has likely costed me at least a few rifles i probably should have bought.
Seems like guys cant agree on, Hammer forward", or "hammer rearward", on the measuring technique.
Does anyone have any definitive publication on this?

michael_g927
September 21, 2017, 21:44
Haha, i just read HKshooters attachment. What is the source of that? Id love to put this one to rest once and for all.

HK556WI
September 22, 2017, 06:29
Haha, i just read HKshooters attachment. What is the source of that? Id love to put this one to rest once and for all.

Right out of the H&K G3 armorers manual.

cjjtulsa
September 22, 2017, 12:25
I'd like to see your data. .004 is practically no bolt gap at all. .010-.018 ideal, .010-.020 is the range. Thousandths, not millimeters.

http://img.photobucket.com/albums/v298/hkshooter/HK_BOLT_GAP_zpsgbqbturq.jpg (http://smg.photobucket.com/user/hkshooter/media/HK_BOLT_GAP_zpsgbqbturq.jpg.html)



Got my data from H&K; I also have printed copies from the link you posted, and you'll notice it says that the low end of "ideal" is at .010", not the minimum bolt gap. Here is a shot of another G3 manual I've seen, also by H&K:

https://image.ibb.co/gtG4eQ/HK_Bolt_Gap.jpg

michael_g927
September 28, 2017, 11:32
Does anyone have factory proceedures to actually do the measuring? I have heard arguements for both hammer forward and rearward. Wondering what safety position has to do with all of this?
Thanks in advance fellas.

BM59
September 30, 2017, 14:06
I have 0.30 mm on both my V93s and 0.20mm on my V53 - equal to 0.011 and 0.07 inches. The V53 has double striped rollers (plus 2) , not sure if I’d switch with +4 or change locking piece. How do I measure wear of the LP (is a #8 by the way)?

Klaus Von Richter
October 03, 2017, 06:31
.004 is the minimum per HK. A lower bolt gap will give you slightly less recoil . I wouldn't recommend setting up a build to start with .004. A lot of people don't understand how delayed roller system works.

I personally am fine with a gap between 5-10 thousandths on a used gun.

michael_g927
October 03, 2017, 08:30
Where are the actual proceedures to measure written ?

cjjtulsa
October 03, 2017, 08:46
.004 is the minimum per HK. A lower bolt gap will give you slightly less recoil . I wouldn't recommend setting up a build to start with .004. A lot of people don't understand how delayed roller system works.

I personally am fine with a gap between 5-10 thousandths on a used gun.

I think one of us has it backwards: I'm pretty sure a smaller bolt gap will recoil harder, a larger bolt gap recoils less. My recoil softened when I added +2 rollers to open the gap a bit.

Klaus Von Richter
October 04, 2017, 09:00
I think one of us has it backwards: I'm pretty sure a smaller bolt gap will recoil harder, a larger bolt gap recoils less. My recoil softened when I added +2 rollers to open the gap a bit.

I'm not an HK certified armorer, so maybe someone with more experience can chime in. They way it has been explained to me by people with greater experience than I is that less bolt gap means more engagement of your rollers in your trunnion and locking piece which means your bolt doesn't unlock as soon which ( needing more force to unlock) which means your carrier is recoiled with less force. Where a greater bolt gap means less engagement of your rollers, requiring less force to unlock, which means more force is transmitted to the bolt carrier causing harsher recoil. Anything under .004 causes the bolt head to hit the carrier and will wear parts out faster and cause harsh recoil as well.

I'm not an expert by any means, I have built several HK style rifles. Maybe someone like GP can help enlighten us both with his experience. Also something like recoil can be pretty subjective.

BM59
October 04, 2017, 09:34
I'm not an HK certified armorer, so maybe someone with more experience can chime in. They way it has been explained to me by people with greater experience than I is that less bolt gap means more engagement of your rollers in your trunnion and locking piece which means your bolt doesn't unlock as soon which ( needing more force to unlock) which means your carrier is recoiled with less force. Where a greater bolt gap means less engagement of your rollers, requiring less force to unlock, which means more force is transmitted to the bolt carrier causing harsher recoil. Anything under .004 causes the bolt head to hit the carrier and will wear parts out faster and cause harsh recoil as well.

I'm not an expert by any means, I have built several HK style rifles. Maybe someone like GP can help enlighten us both with his experience. Also something like recoil can be pretty subjective.


That's my understanding too, small bolt gap should not affect safety but rather cause wear. What I'd like to understand from the experts is when to act on rollers and when considering a change of locking piece. My V53 has +2 rollers already and if I want to increase bolt gap beyond 0.007 should I just go +4 or try another locking piece - and is switching the LP just a 'drop-in' change?

hueyville
October 04, 2017, 10:16
I have always been told hammer down but can't tell anyone for sure. I just check them, buy, testfire, tweak till fits roll desire and put back for day need rifles can shoot till pile of ammo ends or barrel melts. Otherwise are heavy and require a dog to find my brass so they are more of the "break glass in case of emergency" rifles at the Ponderosa.

cjjtulsa
October 04, 2017, 14:15
From a post discussing this from 2011 on the HKPro website, from Jeff Walters (Ghilliebear2000) of Parabellum Combat Systems:


hope this helps
no bolt gap hard recoil less lockup
large bolt gap easy recoil lockup is longer.

I'd also like to see gunplumber chime in; I've heard people explain it both ways.

michael_g927
October 04, 2017, 22:22
Jeff is damn near as good as hearing it from Bill Flemming himself!!! Jeff builds around 150 rifles a year. They are exquisite! Of course they better be at more than 2k!!

Herr Walther
October 05, 2017, 05:49
Every time i attempt to buy 91 types online, it seems like the other guy has no concept of measuring this. It has likely costed me at least a few rifles i probably should have bought.
Seems like guys cant agree on, Hammer forward", or "hammer rearward", on the measuring technique.
Does anyone have any definitive publication on this?

A lot of guys nowadays don't even know which end of a hammer to use. :facepalm:

michael_g927
October 05, 2017, 12:09
Just makes it hard to throw a grand at someone when they dont know how to tell you the status of their rifle.
Jeff got an SAR in his shop this year. Looked good. Measured up bad. Seems like he said the trunion needed to be reset. I could be misrecalling. As it turned out, the rifle lived its life as a Flemming sear host.
So what was a nice rifle at a good price, turned into a nice looking costly repair. Luckily Jeff is a manufacturer. So after doing a major surgery (something VERY few companies can do) he was able to make a new rifle outta it. The finish and tig work was exquisite!
Keep in mind, these SARs are 30 years, 3 decades old.

Klaus Von Richter
October 05, 2017, 14:36
I could be wrong but in the link to HKpro ghille seems like he was referring to no bolt gap not the lower end of spec.

Is the same discussion here is a good post by holescreek, he has help me multiple times on WeaponsGuild with HK builds. I consider him an expert on HK weapons.

https://i.imgur.com/d87I5IF.png