Lightening cuts on slides for RDS, yay, or nay? plus a breech face question

[DacoRoman]

OK my quest for knowledge continues.

BTW mods, if this better belongs in the RDS forum, please move.

I'm trying to join the ranks of the pistol RDS community.

If I send a Glock slide for an RDS mill job, should I be looking at getting lightening cuts to offset for the increased weight of the RDS? Not necessarily a complete cut either, but just some material to lighten the slide. In fact I'd rather not have a complete fenestration, but if it makes the gun run better with lightening ditches, or whatever you'd call them, I'd totally be open to do it.

So yay, or nay, to lightening ditches, or even complete fenestrations?

Or will a Gen3, 4, or 5 slide run completely fine, with an RDS, with only the mill job and no other chop shop action?

Also! Do any of the common aftermarket RDS slides, from Primary Machine, Agency Arms, et. al., have breech faces optimized to keep brass out of the glass?

[Ed4032]

I’m in the same place on this. Does it really make that much difference?

[JCN]

Note that a Glock MOS doesn’t have any additional lightening when you put an optic on over running without it. Just the absence of the plate.

If you run weak ammo, you might need a lighter recoil spring to account for the slower slide speed in relation to the mag springs. But I wouldn’t intentionally lighten the slide to compensate.

Having run a competition gun with 3 oz taken out of the slide to make weight for division versus having a slide with all the weight plus the optic...

The heavier slide combo is softer shooting.

[GJM]

My sense is that most optic cuts remove enough metal to offset the weight of the RDS, and most lightning cuts are primarily cosmetic. I do like forward serrations so I don't have to grab the optic to work the slide.

[luckyman]

My sense is that most optic cuts remove enough metal to offset the weight of the RDS, and most lightning cuts are primarily cosmetic. I do like forward serrations so I don't have to grab the optic to work the slide.

Yeah I can’t find the data now, but I looked at this at one time and was surprised how much the optic cuts did to semi rebalance the overall weight.

[WobblyPossum]

Also! Do any of the common aftermarket RDS slides, from Primary Machine, Agency Arms, et. al., have breech faces optimized to keep brass out of the glass?

If you’re referring to the breechface cut/notch found in newer production Gen5 guns, I don’t believe that any of the aftermarket slides incorporate it and I haven’t heard of anyone offering to machine it into existing slides. The cut is nice to have since it really seems to improve consistent ejection but the guns without them (millions of Glocks prior to the Gen5 guns) seem to run just fine.

[Lon]

I’ve never cut lightening cuts into any of the slides I’ve added RDS cuts to (4 total - 2 Sig, a CZ and a Glock) and have never had an issue. The brownells RDS slide I bought had the lightening cuts purely for cosmetic reasons.

[DacoRoman]

Note that a Glock MOS doesn’t have any additional lightening when you put an optic on over running without it. Just the absence of the plate.

If you run weak ammo, you might need a lighter recoil spring to account for the slower slide speed in relation to the mag springs. But I wouldn’t intentionally lighten the slide to compensate.

Having run a competition gun with 3 oz taken out of the slide to make weight for division versus having a slide with all the weight plus the optic...

The heavier slide combo is softer shooting.

Good info, thanks. And presumably Glock would have lightened the slide more if it was a requisite for rds reliability I’m surmising.

Copy regarding recoil impulse but did you feel like you could pull faster splits with the lightened slide ?

And to expound to others’ potential experience, has anyone noticed slower splits when running a heavier/rds slide ?

[DacoRoman]

My sense is that most optic cuts remove enough metal to offset the weight of the RDS, and most lightning cuts are primarily cosmetic. I do like forward serrations so I don't have to grab the optic to work the slide.


Yeah I can’t find the data now, but I looked at this at one time and was surprised how much the optic cuts did to semi rebalance the overall weight.

Roger that, makes sense and good to know .. it will sure save me some money too!

[JCN]

Good info, thanks. And presumably Glock would have lightened the slide more if it was a requisite for rds reliability I’m surmising.

Copy regarding recoil impulse but did you feel like you could pull faster splits with the lightened slide ?

And to expound to others’ potential experience, has anyone noticed slower splits when running a heavier/rds slide ?

That’s a very complicated question.
With my very heavy TSO slide, I can do 0.09-0.11 splits.

There’s a lot more than slide weight to fast splits.

The short answer is that if your springs and ammo all work together it doesn’t really matter.

I prefer heavier slide myself.

[DacoRoman]

If you’re referring to the breechface cut/notch found in newer production Gen5 guns, I don’t believe that any of the aftermarket slides incorporate it and I haven’t heard of anyone offering to machine it into existing slides. The cut is nice to have since it really seems to improve consistent ejection but the guns without them (millions of Glocks prior to the Gen5 guns) seem to run just fine.

Yes that’s what I was referring to.

A bee was placed in my bonnet about that and I didn’t want to send a gen 3 or 4 slide for milling if it was going to bounce brass into my glass ... I did many searches to look for reports of that specific problem, but uncovered no reports of such a thing, not to say that it doesn’t happen possibly, but not enough to get people to noticeably complain about it.

I did find a YouTube review of an early Gen 5 with very weak ejection, mostly with Blazer Brass, that would eject straight back along the slide and hit the shooters arms, the trajectory very suspicious for potential glass hits if an rds was present. I wondered if this is why Glock modded the breech on Gen5 MOS’s.

Part of me wants to ignore the fear that Gen 3’s especially would suffer from that problem, because I was inclined to convert a Gen 3 for RDS. However, I think I’ll take the opportunity to sell/trade a Gen3 G19 and Gen3, or 4, 17 for their Gen5 counterparts, with the serrations and the breech mod, and have the Gen 5s milled, for extra functional insurance as it were.

Actually out of the Gen 3 & 4 G17, which would you fellers keep, I’m very curious to know? I’m inclined to keep the Gen 3 because I have a ton of spare parts for the 3’s, but I’m conflicted regarding which one to replace!

[DacoRoman]

I’ve never cut lightening cuts into any of the slides I’ve added RDS cuts to (4 total - 2 Sig, a CZ and a Glock) and have never had an issue. The brownells RDS slide I bought had the lightening cuts purely for cosmetic reasons.

10-4, good validation thanks. Did you notice recoil or split times differences post RDS’ing?

[DacoRoman]

That’s a very complicated question.
With my very heavy TSO slide, I can do 0.09-0.11 splits.

There’s a lot more than slide weight to fast splits.

The short answer is that if your springs and ammo all work together it doesn’t really matter.

I prefer heavier slide myself.

.09-.11 splits ! Yowza! That’s amazing. At my best I was happy when hitting .18s splits with a stock Glock 19 or 17. So it sounds like with my skill level I won’t likely even be able to tell :D.

Good info, thanks !

[JCN]

.09-.11 splits ! Yowza! That’s amazing. At my best I was happy when hitting .18s splits with a stock Glock 19 or 17. So it sounds like with my skill level I won’t likely even be able to tell :D.

Good info, thanks !

0.18 splits with a stock Glock trigger is about as good as I would be able to do too.

The 0.09-0.11 splits is with a very short reset 1.5# competition single action trigger. That’s like best case mechanical situation.


https://youtu.be/Gy8Yj6Q8Ssk

[DacoRoman]

0.18 splits with a stock Glock trigger is about as good as I would be able to do too.

The 0.09-0.11 splits is with a very short reset 1.5# competition single action trigger. That’s like best case mechanical situation.


https://youtu.be/Gy8Yj6Q8Ssk


I see! Thanks for the video, that's some darn fast shootin' anyway!

[Lon]

10-4, good validation thanks. Did you notice recoil or split times differences post RDS’ing?

I saw more accuracy w jail bait splits (<.16 seconds). I adjusted my recoil spring so the pistols track better. The only stock spring I run w an RDS pistol is on my work pistol.

[GJM]

If you want to effectively operate, you need a slide like this.

71627

[DacoRoman]

I saw more accuracy w jail bait splits (<.16 seconds). I adjusted my recoil spring so the pistols track better. The only stock spring I run w an RDS pistol is on my work pistol.

Very interesting. Can you please expound on that a bit, which weight spring on which gun ? Thanks!

[DacoRoman]

If you want to effectively operate, you need a slide like this.

71627

That’s got so many cuts, I can’t even see it.. it must be one of those ghost guns.. gives splits so fast you travel backwards in time! And you can use it as a camping stove to cook winnies! Meal Team Six is all over these apparently ... :D

[Sig_Fiend]

My vote is NO on excess slide cuts. Also, if you're just starting out, an easy route to figure out what you like and what's going to work for you would be a Glock gen5 MOS + FCD (Forward Controls Design) adapter plate for either an RMR or Acro. Quality parts, and you won't be locked into something you find you don't like.

For reference, here's a few item weights to put things in perspective:

Trijicon RMR (https://www.trijicon.com/products/product-family/trijicon-rmr-RM06-RM07-RM09?mount[]=Not+Included) (any) - 1.2oz
Holosun 407C (https://holosun.com/index/product/item/cid/11.html) / 507C (https://holosun.com/index/product/item/cid/3.html) - 1.5oz
Holosun 508T (https://holosun.com/index/product/item/cid/1.html) - 2oz
Holosun 509T (https://holosun.com/index/product/item/cid/12.html) - 1.72oz (Still a bit suspect. I bet they flipped the weight between this and the 508T on accident, but can't weigh mine at the moment.)
Aimpoint Acro P1 (https://www.aimpoint.com/products/red-dot-sights/acro-p-1-35-moa-red-dot-reflex-sight-with-integrated-acrotm-interface) - 2.1oz
FCD OPF-G MOS RMR adapter plate (https://www.forwardcontrolsdesign.com/OPF-G-RMR_p_224.html) (steel) - 0.83oz
FCD / TangoDown MOS Acro adapter plate (https://www.forwardcontrolsdesign.com/OPF-G-ACRO_p_265.html) (steel) - Unknown, but probably 0.8-1.2oz I would think. I have one buried in my gear box and will weigh it if I can find it.


Moral of the story, we're talking about a difference of possibly 1-2oz in weight over say a stock gen5 Glock with MOS cover plate. A lot of the slide cuts I've seen on the market, just my personal opinion, but I feel like they do little except potentially affect the long term integrity of the slide. If you want front slide serrations because you don't already have them, that's at least a functional improvement.

[Lon]

Very interesting. Can you please expound on that a bit, which weight spring on which gun ? Thanks!

Here’s a good article from Dave at CGW about recoil springs weight: https://cajungunworks.com/how-to-select-the-proper-recoil-spring/

Bottom line for me: over the last 27 years of competition shooting I’ve found that most factory weight springs tend to be heavier than they need to be. Which causes more slide “bounce” up and down than is optimal. Tuning the recoil spring (which usually means lowering the weight) reduces that “bounce” so that the sights track better (they don’t move up and down as much). I’ve consistently found 12-14 pound recoil springs to be the sweet spot for me. Consistent extraction, cycling and ejection through a wide variety of ammo in all shooting environments.

And just an FYI, for the last 10+ years my competition guns have been my carry and duty pistols for the most part. I know competition shooters w full blown race guns that are running sub 10 pound recoil springs. But I wouldn’t recommend that on a carry/duty pistol.

Hope that helps.

[DacoRoman]

Here’s a good article from Dave at CGW about recoil springs weight: https://cajungunworks.com/how-to-select-the-proper-recoil-spring/

Bottom line for me: over the last 27 years of competition shooting I’ve found that most factory weight springs tend to be heavier than they need to be. Which causes more slide “bounce” up and down than is optimal. Tuning the recoil spring (which usually means lowering the weight) reduces that “bounce” so that the sights track better (they don’t move up and down as much). I’ve consistently found 12-14 pound recoil springs to be the sweet spot for me. Consistent extraction, cycling and ejection through a wide variety of ammo in all shooting environments.

And just an FYI, for the last 10+ years my competition guns have been my carry and duty pistols for the most part. I know competition shooters w full blown race guns that are running sub 10 pound recoil springs. But I wouldn’t recommend that on a carry/duty pistol.

Hope that helps.

Most excellent info, thank you very much sir !

[DacoRoman]

My vote is NO on excess slide cuts. Also, if you're just starting out, an easy route to figure out what you like and what's going to work for you would be a Glock gen5 MOS + FCD (Forward Controls Design) adapter plate for either an RMR or Acro. Quality parts, and you won't be locked into something you find you don't like.

For reference, here's a few item weights to put things in perspective:

Trijicon RMR (https://www.trijicon.com/products/product-family/trijicon-rmr-RM06-RM07-RM09?mount[]=Not+Included) (any) - 1.2oz
Holosun 407C (https://holosun.com/index/product/item/cid/11.html) / 507C (https://holosun.com/index/product/item/cid/3.html) - 1.5oz
Holosun 508T (https://holosun.com/index/product/item/cid/1.html) - 2oz
Holosun 509T (https://holosun.com/index/product/item/cid/12.html) - 1.72oz (Still a bit suspect. I bet they flipped the weight between this and the 508T on accident, but can't weigh mine at the moment.)
Aimpoint Acro P1 (https://www.aimpoint.com/products/red-dot-sights/acro-p-1-35-moa-red-dot-reflex-sight-with-integrated-acrotm-interface) - 2.1oz
FCD OPF-G MOS RMR adapter plate (https://www.forwardcontrolsdesign.com/OPF-G-RMR_p_224.html) (steel) - 0.83oz
FCD / TangoDown MOS Acro adapter plate (https://www.forwardcontrolsdesign.com/OPF-G-ACRO_p_265.html) (steel) - Unknown, but probably 0.8-1.2oz I would think. I have one buried in my gear box and will weigh it if I can find it.


Moral of the story, we're talking about a difference of possibly 1-2oz in weight over say a stock gen5 Glock with MOS cover plate. A lot of the slide cuts I've seen on the market, just my personal opinion, but I feel like they do little except potentially affect the long term integrity of the slide. If you want front slide serrations because you don't already have them, that's at least a functional improvement.

Most excellent info, thank you very much sir! I’m shocked that the 509T is lighter than the 508T btw!

Y’all have convinced me to go optic cut only..I’ll most likely be trading up to a Gen5 19 and 17 with the forward serrations and sending them to Agency for the AOS cut only.

[GJM]

A 509T on my scale is 2.3 ounces.

One issue I have run into with lighter recoil springs is a possible reduction in reliability -- because some light pressure on the slide with your thumb might cause the slide to not go fully into battery.

[Darth_Uno]

I've run multiple 19 & 17 Suarez, Grey Ghost, KE Arms and Faxon slides without lightening/windows to seemingly no detriment. All with factory spring weights. I've also had a few with windows that didn't seem to do any worse, or better.

If you think they look cooler on Instagram, knock yourself out. The reduced mass/cycling speed argument is internet psychobabble*.

*Glock intentionally cut a hole in the 34 slide, but that's a different animal

[Joe in PNG]

I once got some impressive splits from a Glock 18, but didn't have a timer handy.
Didn't get much accuracy either.

[Wondering Beard]

I once got some impressive splits from a Glock 18, but didn't have a timer handy.
Didn't get much accuracy either.

In slight thread drift, I once fired (OCONUS) a G17 converted, through one of those gizmos that replaced the slide end plate, to have a full auto capability and it happily fed 124gr through 60gr loads without a hiccup.

As to lightening cuts, I'm loath to create entrances for stuff to get inside my gun if that gun is meant for serious social purposes. I don't see reputed personal defense instructors with loads of experience with red dots have such cuts on their instruction and/or carry guns, so I see no reason to do it.

[YVK]

My CO match CZ slide is all cut with windows and stuff; it weighs 16.5 oz with a steel guide rod/spring and SRO attached. I've shot it with recoil springs from 8 to 12 lbs and have had no malfunctions.
A stock irons-only CZ slide with a steel guide rod is 18.4 oz, at least mine is, and I've shot it with 9-12 lbs recoil springs and have had no malfunctions.
That have made me to conclude that CZs, n=3 study size, don't care if slides are lightened or not.

I've heard an opinion that Glock slides should not be excessively lightened so my aren't and are running fine.

[GJM]

My CO match CZ slide is all cut with windows and stuff; it weighs 16.5 oz with a steel guide rod/spring and SRO attached. I've shot it with recoil springs from 8 to 12 lbs and have had no malfunctions.
A stock irons-only CZ slide with a steel guide rod is 18.4 oz, at least mine is, and I've shot it with 9-12 lbs recoil springs and have had no malfunctions.
That have made me to conclude that CZs, n=3 study size, don't care if slides are lightened or not.

I've heard an opinion that Glock slides should not be excessively lightened so my aren't and are running fine.

I have run light recoil springs in Shadows without issue. I have run lighter than OEM recoil springs in Glock and M&P pistols with issues, that after returning to a stock RSA went away.

[DacoRoman]

Thanks to all for the great input. It was very helpful and enlightening...forgive the pun ;D.

I went and got me a Gen5 G19 and 17 yesterday and will be sending them for optic cuts only. Well...maybe I'll succumb and have a pair of Lighting Bolts cut on each side of the slide :D ...just kidding.

[GJM]

Sig's idea of a pro cut optics slide for a P226, which is a darn shame as I would like one.



71752




And, HK's idea of an optics slide.


71753

[DMCutter]

I would not dress one of my 229s in anything that tacky. That's like painting orange flames on the side of BMW M3.

[DacoRoman]

Wow Sig.. please offer that slide in that rainbow trout finish you might still have and I won’t be able to resist myself... not.

That HK looks all business on the other hand.

What is that strange cut out in the very front of the Sig Slide, I’ve never seen that before. Bottle opener?

[Sig_Fiend]

Henceforth, I declare nose cuts like that SIG slide to be referred to as "frontal slidebotomies". ;)

Consumers and popular social media channels are to blame for products like that SIG slide. Current day SIG US is an ROI-focused business. They wouldn't produce products like that for long if people didn't buy them. I do, however, blame SIG for not clearly delineating between products that should probably be marketed as "recreational" vs. serious-use.

And hey, if someone wants to buy that because they think it looks cool, more power to them! I just wish people would ask more questions, such as DacoRoman has, to better understand the implications of things like that on a defensive or competition gun.

As far as that weird nose cut on the SIG slide, near as I can tell there's no legitimate and functional reason for that. It's purely aesthetics, if a person even finds that attractive. I believe I've seen a few guns cut that way with matching compensators that have grooves that lock into the cuts. There are what I would consider far more robust methods of achieving that with a compensator though. For example, Parker Mountain Machine's comps for Gen5 Glocks take advantage of the bevel on the nose of the slide to keep the comp aligned. Aesthetic AND functional!

71774 71775
Pcis courtesy of Parker Mountain Machine (https://www.parkermountainmachine.com/store/p393/PMM_Glock_19%2F19X%2F45%2F17%2F34_Gen_5_Compensato r.html). Not my pictures.

SIG could have easily achieved this with many of their P-series slides, albeit probably at a shallower angle. Alas, that would not be Gucci enough for some people...

[DacoRoman]

Henceforth, I declare nose cuts like that SIG slide to be referred to as "frontal slidebotomies". ;)

Consumers and popular social media channels are to blame for products like that SIG slide. Current day SIG US is an ROI-focused business. They wouldn't produce products like that for long if people didn't buy them. I do, however, blame SIG for not clearly delineating between products that should probably be marketed as "recreational" vs. serious-use.

And hey, if someone wants to buy that because they think it looks cool, more power to them! I just wish people would ask more questions, such as DacoRoman has, to better understand the implications of things like that on a defensive or competition gun.

As far as that weird nose cut on the SIG slide, near as I can tell there's no legitimate and functional reason for that. It's purely aesthetics, if a person even finds that attractive. I believe I've seen a few guns cut that way with matching compensators that have grooves that lock into the cuts. There are what I would consider far more robust methods of achieving that with a compensator though. For example, Parker Mountain Machine's comps for Gen5 Glocks take advantage of the bevel on the nose of the slide to keep the comp aligned. Aesthetic AND functional!

71774 71775
Pcis courtesy of Parker Mountain Machine (https://www.parkermountainmachine.com/store/p393/PMM_Glock_19%2F19X%2F45%2F17%2F34_Gen_5_Compensato r.html). Not my pictures.

SIG could have easily achieved this with many of their P-series slides, albeit probably at a shallower angle. Alas, that would not be Gucci enough for some people...

Sweet looking pistol. How does it run? I need to learn about comps/Roland specials at some point too!

[Sig_Fiend]

Sweet looking pistol. How does it run? I need to learn about comps/Roland specials at some point too!

That's not mine. Those pics are from PMM (linked in the caption below the pics).

Glocks comps can work and can help improve performance. They can also narrow the window of operation such that ammo choice becomes even more critical and your options become less flexible. To some degree it's like experimenting with striker spring or recoil spring weights. For some shooters, there's certainly performance improvements to be had. However, the trade off is potentially reducing margin for error in ammo quality and reliability. Stuff like that is not even worth considering, IMO, until a person can perform at a high level on some of the popular standards tests and drills (http://pistol-training.com/drills) out there.

[JCN]

71825

This one is mine. It shoots high power ammo as soft as gamer ammo.

[DacoRoman]

That's not mine. Those pics are from PMM (linked in the caption below the pics).

Glocks comps can work and can help improve performance. They can also narrow the window of operation such that ammo choice becomes even more critical and your options become less flexible. To some degree it's like experimenting with striker spring or recoil spring weights. For some shooters, there's certainly performance improvements to be had. However, the trade off is potentially reducing margin for error in ammo quality and reliability. Stuff like that is not even worth considering, IMO, until a person can perform at a high level on some of the popular standards tests and drills (http://pistol-training.com/drills) out there.

I’m trying to get out of a 2 year hiatus from pistol shooting, and to start with I’d like to just get to a sub 1 sec draw from aiwb and .18 splits using a regular ol’ Glock. I wouldn’t want to complicate my life with delving down the rabbit hole of Roland specials but I have to admit that it’s a really cool concept.