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Locking piece swaps and bolt gap.

ak4784

KC Weapon

Joined: May 2004

Posts: 17366

EE: 100% (1)

MO, USA

Posted: 6/20/2026 6:42:19 PM EDT

Are you guys checking bolt gap after swapping out locking pieces?

I went ahead and ordered some feeler gauges so I can check once I get everything assembled. They were cheap, so why not.

I am just curious if you guys are checking this and if anyone has ever found a gap out of tolerance?

Thanks

osprey21

Known Assoiciate

Joined: Jan 2001

Posts: 168924

EE: 100% (297)

FL, USA

Posted: 6/20/2026 7:28:25 PM EDT

[#1]

I always have.

Now with more political fatigue.

chargerdude70

It is what it is!!

Joined: Mar 2014

Posts: 2670

EE: 100% (56)

MI, USA

Posted: 6/20/2026 7:29:54 PM EDT

[#2]

Yes, check gap between LP changes. Takes little time for the insurance.

Yes, have had tolerance variations between LP's, especially if going between brands. Was it enough to warrant new rollers, no. But again, it never hurts and takes such little time to check. It's a good thing to do after a cleaning and keep a record.

ak4784

KC Weapon

Joined: May 2004

Posts: 17367

EE: 100% (1)

MO, USA

Posted: 6/20/2026 8:51:40 PM EDT

[#3]

I’m reading that gap below 0.010 and above 0.020 is bad. Sweet spot is in the middle.

Sound about right?

chargerdude70

It is what it is!!

Joined: Mar 2014

Posts: 2671

EE: 100% (56)

MI, USA

Posted: 6/20/2026 9:24:15 PM EDT

[#4]

My HK SP's came in at around .018" when new.

willi3d

Member

Joined: Oct 2012

Posts: 9064

EE: 0% (0)

FL, USA

Posted: 6/20/2026 9:43:30 PM EDT

[#5]

Quote History

Originally Posted By ak4784:
I’m reading that gap below 0.010 and above 0.020 is bad. Sweet spot is in the middle.

Sound about right?

View Quote

Optimum for a new gun is nearer the top of the range as bolt gap goes down as the gun wears. It doesn’t normally increase.

LineHaul

Joined: Jan 2021

Posts: 1605

EE: 100% (17)

NC, USA

Posted: 6/20/2026 10:47:49 PM EDT

[#6]

Harbor freight has feeler gauges for $4.99….
I checked the bolt gap on my ap5sd at .015 oem
.014 after installing a rcm 80* lp

56cbr600rr

Member

Joined: Sep 2013

Posts: 1463

EE: 100% (29)

GA, USA

Posted: 6/21/2026 12:01:28 AM EDT

[#7]

My ap5 was .018 My sp5 was .014.

southerncross

Enhanced

Joined: May 2008

Posts: 24829

EE: 100% (1)

GA, USA

Posted: 6/21/2026 7:19:36 AM EDT

[#8]

I checked both my AP53 and my 91 when I got them. I changed the locking piece and rollers on my 53 when I put the suppressor on to get the gap back in range. Its pretty simple once you understand what to do and how to check.

TEAM GIMMICK 2026

2manytoys

Member

Joined: Dec 2001

Posts: 5808

EE: 100% (270)

WV, USA

Posted: 6/22/2026 9:40:38 PM EDT

[#9]

Quote History

Originally Posted By ak4784:
I’m reading that gap below 0.010 and above 0.020 is bad. Sweet spot is in the middle.

Sound about right?

View Quote

Acceptable bolt gap on aHK91 is between .004 and .020. Anything in that range is ok. .012 is right in the middle of that.

Gopherboy128

Collector of Guns

Joined: Jan 2011

Posts: 9363

EE: 100% (30)

WA, USA

Posted: 7/7/2026 1:10:51 AM EDT

[#10]

Yes, its quick and easy to do with tapered feeler gauges. Beating up my roller-locks isn't something I want to do, and can be avoided fairly easily by checking the gap after swapping rollers or locking pieces around.

[Insert Witty Comment Here]

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Locking piece swaps and bolt gap.

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Locking piece swaps and bolt gap.

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Locking piece swaps and bolt gap.