Barrel length & recoil (slide speed)

[S.P.F.]

I have a Glock 27 subcompact .40, which I adore. I also have a 9mm conversion barrel for it. When I shoot 9mm, the extraction is kinda weak (on light 115 gr, cheap ammo), and only throws the brass a couple inches. Occasionally I get an incomplete extraction, causing a stovepipe jam. It is sometimes suggested that one switch to a lighter recoil spring, to speed up the slide on 9mm conversion shooting.

However, I was wondering about a different solution. I also have a Glock 23 compact .40. I was thinking about getting a 9mm conversion barrel for it also. If I were to then use this (longer) conversion barrel on the model 27, theoretically the exit velocity of the bullet should improve significantly, with additional energy as well. The question I have is whether there is also increased recoil energy, that will speed the slide and improve extraction. Anyone know?

[JTROKS]

How about switching to a 9mm extractor and ejector? I've done all that conversion with my G23 and G27. The last one was with my G35. I'm very happy with the G35 conversion and switched to the 9mm extractor and ejector. I hardly shoot the G27 and 23 in 9mm so I sold/traded the conversion parts.

[S.P.F.]

I would see the logic in considering changing extractor and/or ejector if my conversion were something I would do with some degree of permanence, but that is not what I do.

I shoot both 9mm and .40 in the same shooting session, and changing barrels is a matter of seconds, that does not require small part manipulation in less than ideal lighting, as is a range stall. Anyway, I have examined the geometry of these components, and the .40 ejector and extractor should work just fine, and not contribute to any significant ejection distance issues.

My question is more of a physics question. All other things being equal, does a longer barrel accelerate a slide more?

[tophatjones]

My question is more of a physics question. All other things being equal, does a longer barrel accelerate a slide more?

The short answer is that you've got to test it to see if it'll work.

When the gun is fired, the barrel and the slide are locked together for about a tenth of an inch until the barrel's lower lug contacts the cam that will tilt the barrel downward. The intertia of the combined mass of the barrel and slide is similar to a heavy blowback slide, which slows slide velocity and delays extraction of the case.

A longer barrel means the bullet will exit the barrel at a higher velocity and theoretically the slide will travel at a higher velocity as well, but the larger mass of the longer barrel and longer slide will also retard the slide velocity to a degree.

[S.P.F.]

Tophat,

Only the barrel is longer, if I put the G23 barrel on the G27.
Kinda like a P38 barrel.


Yes, indeed, if using a longer & heavier slide, then the question becomes very much as you indicate.

[Sleighter]

I don't understand shooting both 9mm and .40cal in the same shooting session from the same gun. It sounds like you need to decide on a caliber or buy a 2nd gun.

[JTROKS]

It will slow down the slide velocity due to the heavier mass of the longer barrel. I'm not sure if you'll be able to tell the difference.

[S.P.F.]

Sleighter,

The purpose of range practice is to shoot better, and to build confidence in the capabilities of the gun. Since I may one day have to rely on the gun for more intrinsic reasons, I choose to become proficient in all of the capabilities of the weapon system. That sometimes entails using both barrels, to save trips and range fees.

The singular practical purpose of a second caliber is to provide options, specifically without having to have a second gun, unless I want that second gun to have other characteristics besides simple caliber change. That is why I have the G23 in addition to the G27 already. Yes, if I were more wealthy, I suppose more Glocks might make more sense.

I like to keep my BO bag at a reasonable weight, too. LOL

[tophatjones]

Tophat,

Only the barrel is longer, if I put the G23 barrel on the G27.
Kinda like a P38 barrel.


Yes, indeed, if using a longer & heavier slide, then the question becomes very much as you indicate.

Gotcha. But my answer still stands. Only way to know is to test it. The larger mass of the barrel may offset any theoretical gain in slide velocity from increased projectile velocity. The mass of the barrel is a significant factor affecting slide velocity in a short recoil design. If this was done with a blowback pistol, then the answer is yes.

[5ZS]

No one will know is the honest answer.

Either lower the spring weight or raise the 9mm power, is my suggestion.
As the spring wears down, it might get better.

Yes, in theory a longer barrel will net you more velocity, thus giving you more rear ward reaction.
Is there a enough difference from 3.42" to 4.01" in 9mm to make the ejection better. My gambling money is on no.

http://www.ballisticsbytheinch.com/9luger.html

Pssss...changing spring is apart of the barrel changing process, I would rather test my theory there.

[S.P.F.]

I think you guys may be right. I'm probably going to buy the G23 to 9mm conversion barrel anyway. I'll know the answer when I give it a go, then buy a 2 lb lighter spring for the G27, in addition to the one I already think I'll need for the G23.

But yes, I had already thought of, and used hotter or more grain weight ammo. My main objective is to have an all-purpose, any ammo-will-do system. I already very much like that using .40, these Glocks eat anything, which not many autos will do.

I appreciate the thoughtful answers.

[caliberetta]

I have a G27 with a Lonewolf 9mm conversion barrel and 9mm magazines.

I've shot about 1200 rounds through it, about 500+rds in 9mm, and 700+rds in .40.

I have some basic add-ons/upgrades: sights, 9mm barrel, 9mm magazine, GAP floorplates, grip tape, and a polished feedramp. The gun is otherwise stock in the G27 .40 configuration.

I've have not had not a single problem shooting the 500+rds of 9mm, in several different kinds of common ammo, including reloads from Freedom. The casings eject where they should. I also often use the .40 magazine.

I'm perplexed why you're having issues with the 9mm only. I don't have much ideas to offer as the Glock platform is relatively new to me and I'm still learning, however I can tell you for sure that the 9mm can run right on a converted Glock 27, as I have experienced for myself.

What brand is your 9mm barrel?

[Saym14]

I don't think exit velocity is the issue. It's likely more of the initial energy when the barrel unlocks. What happens with heavy or plus p ammo?

[jimsguns]

Your weak ejection issue has nothing to do with barrel length or slide speed. The fundamental issue is that the .40 to 9 conversion barrel is essentially a jimmy-rigged / MacGyver'd barrel to make a gun designed around the .40 S&W dimensions to function with a geometrically different 9mm cartridge. Obviously, the 9mm is quite a bit smaller in case diameter than the .40 and with that comes two issues not completely solved by a conversion barrel - extraction & ejection. Both of these functions are case diameter dependent and require different extractor and ejector designs (parts) to be 100% reliable. The conversion barrels seek to find a 'middle ground' where both ejection and extraction can occur - although not 100% reliable and never should be employed in this configuration for self-defense purposes (only target shooting/ plinking). To achieve functionality, the conversion barrel chamber is actually offset slightly to the left (looking down on a Glock) biasing the 9mm cartridge towards the ejector that is mounted in the frame so that it can make contact with the smaller diameter 9mm case and perform its function (note the ejectors on a 9mm and .40 have different geometry/ different p/n). The downside of biasing the chamber/ cartridge towards the ejector side is that you are also pulling the case rim away from being fully under the extractor claw. The result is a reduction in operational reliability (extraction) and coupled with the offset chamber, a weaker ejection. If your purpose of use for your G27 is self-defense in .40 S&W and the conversion barrel is just to give you a cost effective alternative for range shooting then just live with the light ejection and occasional functional issue. If you intend to use 9mm as your go-to defense cartridge then you need 100% reliability so either make the full conversion to 9mm (Glock 26 OEM slide assy - barrel, extractor & recoil spring - AND the frame-mounted ejector) or buy a G26. Hope this helps.

[S.P.F.]

Saym14,

Ejection is fine with heavier or more powerful 9mm. But that usually translates into a few more $$ a box. But, yes it is a (partial) solution.