Differences between Gen 4, Gen 5, and FBI M pistols

Glock logo17M/19M & Gen 5 changes from the Gen 4 pistols include:

  • No finger grooves.
  • Flared mag well.
  • Ambidextrous one-piece slide stop lever – on many of the ‘M’ guns, it’s also an extended ambi slide stop. That extended ambi slide stop lever is part # 33797, and is available for sale to certified armorers. It now appears that the extended ambi slide stop lever is on the Gen 5 G34.
  • Front of the slide is rounded to match the Gen 4 subcompacts and long slide models. When first introduced, the Gen 5 and ‘M’ frame weren’t beveled to match. That has since been resolved in newer pistols.
  • Land and groove rifling instead of polygonal
  • Gen 5 GMB (Glock Marksman Barrel) barrel has a target match crown (FBI ‘M’ guns don’t). Barrels cannot be swapped with other generation guns – mainly due to the differences in locking blocks and newer, longer, RSA.
  • Same style firing pin safety (angled instead of flat) as the Glock 43
  • Return to two-pin frame due to a redesign in the locking block that removes the need for the third pin as well as Glock’s plan to only have Gen 5 in 9mm.
  • Slide lock spring similar to Glock 43 (coil vs leaf), and the slide lock is moved slightly rearward.
  • Return of cutout on bottom of front strap to assist with stripping magazine (such as due to a double feed) that were originally in Gen 1, Gen 2, and early Gen 3 full sized guns. Early prototypes did not have this cutout, which is why it’s not visible in some early pics. This cutout is on the 17, 19, and 34, but not the 26. The 26 has the extended toe similar to the MHS and 19X frames.
  • Tougher finish applied to the same Melonite metal treatment process. This finish is dubbed nDLC (diamond like coating) that is similar to the black nitride finish. Glock refers to it as an ion bonded finish, and will only be available on Gen 5 guns.
  • The upper cartouche, the flat area on the upper right grip area that show where the pistol was made, has been moved down and combined with the lower one, which contains the patent number
  • Mags have an orange mag follower
  • Mags have extended front lip to aid in reloading
  • Mags have a slightly rounded base plate (bottom front edge)
  • There are no front serrations, as some people claim, or as some photoshopped pictures suggest. Glock added an LCI to the guns many years ago to negate the need for press checks.
  • ‘M’ guns come with 6 magazines. Gen 5 guns come with 3.
  • Gen 5 is available with polymer sights or several night sight variations, including factory and Ameriglo ‘Bold’ night sights. The new sights are narrower than previous models. ‘M’ guns have slightly different sights than the Bold sights. Differences being FBI sights have a ‘U’ shaped notch in the read sight, whereas the Bold have a square notch. Both rear sights are serrated, and the night sights don’t have a white or colored ring around them (this is often referred to as ‘blacked out’). Both the Gen 5 Bold sights and the FBI sights are available with  a .125 orange front sight as well as a more traditional .140 width sight.
  • Glock had said no plans for MOS guns, but they are now releasing the Gen 5 G34 in MOS.
  • Glock said originally that the Gen5’s will only be offered in 9mm, but São Paulo Police Department (Brazil) is now testing the Gen 5 G22.
  • New striker, but same spring cups, spring, and sleeve
  • New extractor
  • New slide cover plate
  • New trigger mechanism housing
  • New trigger bar, but the Gen 4 dimple is removed (since the Gen 5 went to the angled trigger safety, the hump is no longer needed)
  • Gen 5 doesn’t use the ‘S’ shaped coil trigger spring, like the previous generations, instead going to a setup like the slimlines
  • G19 and G26 come with a smooth trigger (like the 17) instead of the previous grooved trigger.
  • ‘M’ guns have the nDLC finish on some internals (at least the trigger bar),  Gen 5 guns do not.
  • ‘M’ guns appear to have an extended mag catch as stock, vs. a normal mag catch for the Gen 5 guns
  • Gen 5 are currently available in black. ‘M’ guns are available in several color molded frames.
    • Black is standard issued to all agents.
    • BFG is issued to FBI SWAT
    • FDE is issued to FBI HRT
  • Gen 5 guns have a ‘5’ rollmark on the top of the barrel. ‘M’ guns have a ‘5M’.
  • Gen 5 G34 doesn’t have the cutout on the top of the slide like previous version, yet still maintains good balance due to a re-engineering of the materials used in the slide.

The new mags will work in previous generation pistols, and vise versa, with the exception of the 21SF with picatinny rail & ambi mag catch.

Keep in mind that the ‘M’ pistols are Glock’s specific response to the FBI requirements for a new pistol. Just because any of these features exist on these guns does not mean that they will appear in any other non-‘M’ guns in the future.

The following pictures of the Gen 5 G26 and G34 are from Glock.

Roll marks on slides and/or frames

Glock logoThis is a living post and will be updated as I get more info.

Here is information about the various roll marks you may see on Glock barrels, slides, and/or frames.

The pentagon indicates polygonal rifling, which all Glocks except the 17M and 19M use. Those two use land & groove rifling (a requirement under the FBI contract). A pentagon without a dot in the middle means the barrel is from grade 5 steel. Pentagon with a dot in the middle indicates grade 6 steel. Neither symbol has anything to do with +P and/or +P+ compatibility. For +P and +P+ info, see https://us.glock.com/customer-service/faq. The Austrian government eventually required the 3D in the oval, which replaced the pentagon symbols. NIST (National Institute of Standards and Technology) created a 3D ballistics database for research to positively identify bullets fired from specific barrels. The 3D database will help draw positive matches between a fired bullet and the barrel it was fired from. Barrels marked with a 3D are in the database. Ballistic experts can strategically identify the correct source, but it’s not 100% accurate. For more info about the database, see https://www.nist.gov/news-events/news/2016/07/nist-3d-ballistics-research-database-goes-live. It’s important to note that the evolution of these symbols should not be interpreted as there are issues with the components with previous marks.

The “AT” indicates it was made in Austria. Newer barrels made in Smyrna, GA have a “US” and a little outline of the state of GA.

From 1982 to 1991, Glock 17 pistols were assembled & test fired in Austria. (Later pistols were also assembled and test fired at Glock Inc. in Smyrna, GA.) Those barrels have an eagle roll mark. The eagle with the number 2 in the center is Austria’s coat of arms. The number 2 in the center of the coat of arms means it was proofed at the firing proof house in Vienna, Austria. You’ll also see this mark on frames from the same period.

The ‘NPv’ is the Vienna proof house roll mark for ‘smokeless powder proof for parabellum pistols’. The pistol was tested using a round loaded to at least 130%. Normally, Glock guns are tested with 120% loads. The markings are proof marks and inspectors marks as required on Austrian pistols that they met the 130% requirement. Many of those NPv marked guns have “Glock Inc, Smyrna GA” stamped on the bottom of the trigger guard.

Sometimes, you’ll see three letters after the NPv on Austrian made barrels. Those are date stamps to indicate when the BARREL was test fired (note that does NOT necessarily mean when the pistol was built). Eventually, Glock did away with those three letter codes. Unofficial information I have to decipher those three letter codes that are on the barrel (not the serial number) are:

The first letter is for the month:
E…Jan
L…Feb
N…Mar
B…Apr
S…May
Z…Jun
G…Jul
P…Aug
I…Sep
C…Oct
V…Nov
A…Dec

The last two letters are for the year:
O…0
W…1
K…2
R…3
F…4
M…5
H…6
Y…7
T…8
D…9

For those with the ‘CIP over N’ roll mark, see https://en.wikipedia.org/wiki/Commission_Internationale_Permanente_pour_l%27Epreuve_des_Armes_%C3%A0_Feu_Portatives and http://www.mdwguns.com/cip.html

Gen 5 pistols have a ‘5’ to the right of the ‘3D’ mark on the barrel. ‘M’ guns have a ‘5M’ to the right of the ‘3D’ mark.