Will an optic cut make my Glock less reliable?

[Snidely Whiplash]

I searched and couldn’t find a similar topic ; not sure if my search skills are weak or if it’s a non-issue.

As I explained in another post, I recently purchased an MOS Glock and, assuming the red dot experiment works, I’ll be thinking hard about adding red dots to my current Glocks. I was exploring the slide optic cut option and one reputable service listed a disclaimer indicating that they test and fully stand behind their optic cut etc. but that “any modification has the potential to affect reliability”.

Is this a real concern? I wouldn’t want to chance making one of my Glocks less reliable, they have had zero malfunctions after a couple of thousand rounds each. Maybe this is just legalese and I’m worrying over nothing?

[LockedBreech]

I searched and couldn’t find a similar topic ; not sure if my search skills are weak or if it’s a non-issue.

As I explained in another post, I recently purchased an MOS Glock and, assuming the red dot experiment works, I’ll be thinking hard about adding red dots to my current Glocks. I was exploring the slide optic cut option and one reputable service listed a disclaimer indicating that they test and fully stand behind their optic cut etc. but that “any modification has the potential to affect reliability”.

Is this a real concern? I wouldn’t want to chance making one of my Glocks less reliable, they have had zero malfunctions after a couple of thousand rounds each. Maybe this is just legalese and I’m worrying over nothing?

As a lawyer I have some casual familiarity with CYA language. That's what that seems like. They don't want some dude getting an optics cut and then getting mad because his gun won't eat garbage steel case perfectly.

I'm sure there are ways to screw up a slide with a milling, but that's the likely reason for the disclaimer.

Edit: Based on the posts below, it really can impact reliability. Shows what I know!

[GJM]

Probably won't effect reliability. However, folks on PF have had cases where reliability changed post an optic installation. Sometimes a screw is too long and touches the extractor bearing rod/spring, sometimes it might be a heavy optic, sometimes it might be for a reason unknown. Small probability, though, and that is why we test function while zeroing the optic.

[JCN]

I searched and couldn’t find a similar topic ; not sure if my search skills are weak or if it’s a non-issue.

As I explained in another post, I recently purchased an MOS Glock and, assuming the red dot experiment works, I’ll be thinking hard about adding red dots to my current Glocks. I was exploring the slide optic cut option and one reputable service listed a disclaimer indicating that they test and fully stand behind their optic cut etc. but that “any modification has the potential to affect reliability”.

Is this a real concern? I wouldn’t want to chance making one of my Glocks less reliable, they have had zero malfunctions after a couple of thousand rounds each. Maybe this is just legalese and I’m worrying over nothing?

Yes it is.

If you use a stock (stiff) RSA, add a huge mailbox optic on top, then shoot weak target ammo you might get a stovepipe unless you decrease the strength of the recoil spring.

It’s all just physics. Not a big deal.

[Clusterfrack]

I searched and couldn’t find a similar topic ; not sure if my search skills are weak or if it’s a non-issue.

As I explained in another post, I recently purchased an MOS Glock and, assuming the red dot experiment works, I’ll be thinking hard about adding red dots to my current Glocks. I was exploring the slide optic cut option and one reputable service listed a disclaimer indicating that they test and fully stand behind their optic cut etc. but that “any modification has the potential to affect reliability”.

Is this a real concern? I wouldn’t want to chance making one of my Glocks less reliable, they have had zero malfunctions after a couple of thousand rounds each. Maybe this is just legalese and I’m worrying over nothing?

I think this is a legitimate concern, although as LockedBreech said the warning is likely just legal ass covering.

I have not observed reliability issues with full-size Glocks milled for optics. My P-07 milled for the Holosun 509t2 has been as boringly reliable as normal. Ejection is still in a neat pile of cases, and limp-wristing doesn't cause malfunctions. I would do significant tests on any gun that's to be used for life safety purposes.

[WobblyPossum]

RJ had a G48 that was reliable until he had it milled for an optic and then it began having problems. It’s a realistic concern because you’re changing the weight of the slide by removing metal and then adding weight that may or may not be about the weight of the metal you removed. It’s less of a concern on the double stack Glocks than the slimline ones since the slimline guns are often already operating on the ragged edge of reliability with their tiny little recoil springs.

[mizer67]

I comp'ed a G19 recently. It was reliable with the comp. and no red dot. Unreliable with both.

Ejection is marginal with just the comp. alone, so it was riding the edge of reliability (with a 15 lb. spring). Likely solvable with a 13 lb. spring.

[Utm]

I have 6 slides that have been milled and I have not experienced any reliability issues but that's sample size of 1

[757_Magnum]

I have three G19s, one G45, and one G26. All are gen 5 with stock RSA wearing RMRs, milled by Jagerwerks and Maple Leaf Firearms. Two of the G19s have carry comps, and all have more than 2000 flawless rounds through them. I mainly run my own full power 147 gr reloads, but the comped G19s have also gone through a couple hundred rounds of aluminum cased 115s I was given.

[RJ]

RJ had a G48 that was reliable until he had it milled for an optic and then it began having problems. It’s a realistic concern because you’re changing the weight of the slide by removing metal and then adding weight that may or may not be about the weight of the metal you removed. It’s less of a concern on the double stack Glocks than the slimline ones since the slimline guns are often already operating on the ragged edge of reliability with their tiny little recoil springs.

Correct. The post and related discussion starts here:

https://pistol-forum.com/showthread.php?41318-Any-other-Glock-48-fans&p=1218805&viewfull=1#post1218805

I subscribe to HCM's theory there "is no free lunch" with the slimlines, and that Glock's choice of the G43 RSA for the G48 narrows the allowable timing window for some ammo. I had the slide milled, taking out the rear dovetail, so perhaps that was why it did not run well. I was bummed because I liked everything else about that gun. So I sold it.

[Darth_Uno]

For the most part, you won’t see many issues with 19’s or 17’s. The only booger I’ve had directly relaated to optics is using too long of a screw that hindered the extractor. Which wasn’t the optics fault at all.

You see far more problems when you monkey around with triggers, springs and connectors. With or without an optic.

[HeavyDuty]

I have six Glocks with red dots, and thankfully haven’t seen reliability issues with any - but I haven’t done high round count shooting with any of them.

The ones with the highest round counts are the direct milled 26.5 with RMRcc and direct milled 43 with RMRcc. I shot them enough to be comfortable with function, about 500 rounds each. Ammunition was just too hard to find to do more than that at the time.

[maximus83]

No failures yet with a new G19.5 (Holosun 507c) and a G45 (Trijicon SRO). Both have just north of 500 rds total, and 300+ with the optics mounted.

I have had a few times with each gun when the slide failed to lock back on empty. But this is a separate issue, it happened before and after the optics were added. It was caused by my grip as my strong hand thumb sometimes contacts the slide release. Still learning to get a repeatable index--basically a training issue.

[vcdgrips]

I can tell you that I know of a metro PD gunsmith is very aware of thread depth and shape of screws on the right side of many optics such that he has been known to take off a thread or two and taper it ever so slightly to mitigate against real or perceived ejection issues associated with a screw bearing down on internal slide components of a Glock.

[HCM]

Correct. The post and related discussion starts here:

https://pistol-forum.com/showthread.php?41318-Any-other-Glock-48-fans&p=1218805&viewfull=1#post1218805

I subscribe to HCM's theory there "is no free lunch" with the slimlines, and that Glock's choice of the G43 RSA for the G48 narrows the allowable timing window for some ammo. I had the slide milled, taking out the rear dovetail, so perhaps that was why it did not run well. I was bummed because I liked everything else about that gun. So I sold it.

As I recall, it was not the optics cut itself, but the added weight of the optic that pushed your G 48 out if it’s window of reliability.

[JCN]

RJ had a G48 that was reliable until he had it milled for an optic and then it began having problems. It’s a realistic concern because you’re changing the weight of the slide by removing metal and then adding weight that may or may not be about the weight of the metal you removed. It’s less of a concern on the double stack Glocks than the slimline ones since the slimline guns are often already operating on the ragged edge of reliability with their tiny little recoil springs and wimpy ass target ammo.

Fixed that for you!

Most of the optic weight reliability issues don’t come into play until people start shooting 380 ACP powered ammo.

I never noticed an issue with a G34 MOS with optic shooting Syntech 150 with a stock RSA… but it promptly stovepiped in newer shooters hands when they had even a hint of limp wrist.

[diananike]

I had about 1500 rounds without cleaning before having a failure to eject with my G48 MOS with 407K. I had another failure within a hundred rounds of the first one. After that I cleaned it and haven’t had a malfunction since in the last 500rds.

My G19 was cut by a reputable Canadian gunsmith and has a 407C. About 2000 rounds through that one. I think I only cleaned it once after a single malfunction.

I’m not sure about 43s but I just got one and am planning on having it cut and compensated so Ill find out soon.

[diananike]

Double post