Glock 21 gen 3 vs gen 4

Disclaimer: I am far from a handgun expert. I've noticed a lot of threads about these two guns cropping up recently, and since at the moment I happen to have both in my posession (I sold the G21 Gen 3 but am waiting on paperwork to come back before I transfer it) I figured I would do a quick write up. I do not fancy myself an uber gun reviewer (Nutnfancy, who by the way I'm not a huge fan of.) Also, sorry for the pictures, they are not the greatest. So, just keep in mind that these are just my opinions, and hopefully I can answer some questions from people less familiar with these firearms. So, take it for what its worth!

A lot of people have been asking about these two firearms.

In the picture above, on the left is the Gen 4 G21, on the right, the Gen 3 G21. In my opinion, there are 4 major differences. They are the grip size, magazine release, texture, and recoil spring assembly. Some will say that the finish is different, but I believe that current model Gen 3s also use this newer finish, so I won't include it. The newer finish is more of a matte black vs the older, slick, somewhat shinier black. I have read that it is because U.S. produced Glocks cannot use Tennifer due to environmental regulations, so they are now using Melonite. Take that for what it's worth, I'm not 100% sure.

1. Grip size:

Above, the Glock 21 Gen 4 is on the left, and the Gen 3 G21 is on the right. It is probably pretty difficult to gauge the difference in grip size from that picture. The Gen 4 Glocks have interchangeable backstraps. The Gen 4 G21 with the smallest backstrap (Which is actually no additional backstraps) is the same size as the Gen 3 G21 SF (Short Frame) model, and is 3mm shorter than the standard G21 frame. If the grip size is the biggest deciding factor for you (as it was for me,) I suggesting going to a local shop that has both, and holding them. Some people say that the grip size difference between the Gen 3 G21 and the Gen 4 G21 (or Gen 3 G21 SF) is almost nothing, and it makes no difference to them. Others say it makes a huge difference. I'm in the latter category. I noticed a distinct difference, and my preference is for the shorter grip. I find that I can more easily control recoil and get faster follow-up shots since I have a better grip on the firearm.

Note: The Gen 4 G21 does have 2 additional backstraps you can use to make the grip thicker, but unless you are giving this gun to your pet gorilla, you probably won't use them.

2. Magazine Release

Here is a picture of the magazine release on the Generation 4 G21 (and other Gen 4 Models)

Here is a picture of the magazine release on the Generation 3 G21 (and other Gen 3 Models) below:

The differences between the mag release are that the Gen 4 mag release is noticeably wider/longer, the texture is slightly different. Also, it is reversible. If you are a lefty, the choice will be pretty clear for you. I have another Gen 3 Glock, and I have to say I have no problems with the Gen 3 (and earlier generation) magazine releases. I find I can access them relatively easily, and they work fine. The problem arises with the bigger models, like the Glock 20 and Glock 21. The grips are so big that I had trouble reaching the magazine release. I would have to use my support hand to sort of roll the gun in my strong hand to hit the release. Not the end of the world, but I much prefer the larger, and more easily reached magazine release on the Gen 4.

For those curious about how difficult it is to reverse the magazine release: It is very easy. I had to replace the magazine release spring on a different Glock (which are the exact same set of steps required to reverse the mag release on the Gen 4) and it took me five minutes, and I had never done it before then. All you need is a small flathead screwdriver and a pair of needlenose pliers. Guides can be found online.

3. Texture

Here is an example of the texture on the Generation 4 Glock 21:

Here is an example of the texture on the Generation 3 (and earlier generations) Glock 21 below:

Sadly, I do not have an example of the RTF2 texture that Glock offers. I believe they do still offer it. But basically, the Gen 4 texture is a happy medium. It's less aggressive than the RTF2, but more aggressive than the standard Gen 3 (and earlier generation's) texture. I found the old texture to be way too smooth. That's just for me though. It wasn't such a problem on smaller framed guns, but with the thicker guns like the G21 and G20, I find that the more aggressive texture noticeably increases my control of the weapon. I can get back on target much quicker, and I don't notice the gun jumping quite as much. This is probably a combination of both the smaller grip, and more aggressive texture, but the more aggressive texture definitely helps. The RTF2 is quite aggressive, and I imagine that if you were to carry it IWB without an undershirt, it would rub you raw. But you probably won't drop it.

If you like the Gen 3 gun but want a better purchase on the gun, you can always add things to assist you. Talon grips are a very popular option. But I found them unnecessary for me with the Generation 4 texturing.

4. Recoil Spring Assembly

I did not snap pictures of the new recoil spring assembly, but they are readily available online. Basically, the old RSA was a single spring on the guide rod. The new RSA uses a double captive recoil spring. Glock claims that it reduces felt recoil. I have to say that after shooting both, I could not discern any noticeable reduction in recoil. Perhaps there is a difference in other calibers, or maybe others can feel the difference between the two in the G21's, but I could not. The new RSAs cost more to replace, but are supposed to last twice as long. So it is a trade-off.

Edit: Magazines: I forgot to add that the Gen 4 Glocks come with three magazines, and the Gen 3 Glocks come with two. Not really a difference between the firearms themselves but I figured I should add that.

That's pretty much it. Maybe it'll help some people out who are in between, or are new to Glocks altogether. Maybe not. But I figured I'd throw it out there!

Excellent write-up! Thanks very much for taking your time to do it.

This 'ought to be made into a sticky for at least a while till the "21" buzz blows over.

Dual recoil spring definitely makes a big difference in G23 Gen3 vs Gen4. I can't say much for G21 gen4 either.

I just bought the 21 Gen 4 and chose it because it comes with 3 mags instead of two. I had the mags shipped to a friend in PA. I already had several Glock 21 mags that I carry as spares for my 30S. Great gun, I love it. Also have a 17, 19, and a 26.

I just bought the 21 Gen 4 and chose it because it comes with 3 mags instead of two. I had the mags shipped to a friend in PA. I already had several Glock 21 mags that I carry as spares for my 30S. Great gun, I love it. Also have a 17, 19, and a 26.