Here is some info. about the Gen 4 Glocks.
There are 3 parts that have been upgraded by Glock since the release of the Gen 4. If you contact Glock, they will usually replace the parts for free. I suggest going to a local GSSF match and have the Glock Armorer on site replace all 3 parts for free. First Part: RSA
The first part that you need to make sure you replace is the Recoil Spring Assembly. The early models of the Gen 4 had a spring that was a little too tight or the tension was a little high. This was more of an issue with the 9mm than it was with the .40 S&W.
The latest RSA should have the following numbers on the flat plate of the base. 0, 4, 3. The 0 is on the left, the 4 on the right and the 3 on the bottom. If you have this RSA, you have the new and improved version that prevents any potential issues.Second Part: Ejector
The next part you want to change is the Ejector. Glock has a new ejector that prevents the rounds from hitting your head every now and then. This is not a big issue, but it happened enough that people complained and Glock fixed it. I would get hit by one in every 50 or so rounds. With the new Ejector, I have not experience any issues. In fact, the new Ejector shoots the casing almost at a 90 degree angle from the slide. Your shooting butty next to you should be aware of this. Third Part: Connector
The next part you need to replace is the Connector of your trigger assembly. The new connector is called the Dot ( . ) Connector. You should see a small dot on the end of the connector for verification. What this does is smooth out the trigger by reducing the pull by .5 lb. This may not sound like much but the new shape to this connector also makes the trigger a little smoother than the original. I have taken mine to the range and test this new connector out and it's nice. The trigger pull is lighter and smoother.
That's about it. Once you replace these 3 parts, you have all the latest components. I think Glock will send them to you free of charge if you contact them. I am a Glock Armorer but had all mine replaced at the last GSSF match I attended, so it was extra simple for me.
As for my G19 Gen4. I have 2,450 rounds through it. In total I have 3 FTE's. I think it was my fault and possible the White Box ammo I was shooting. In all 3 cases, I feel that I may have limp wristed my grip, so I think it was user error more than anything else.
I look forward in putting another 650+ rounds through it during the Close Range Gun Fighting Class on July 28th in San Antonio, Texas.
I am going to attempt an IDPA match before then but in any case, my G19 Gen4 will have over 3,000 rounds through it by the end of this month.
Hope the information can help someone. If you need pictures, let me know and I will do my best to take some good ones and post them on this thread.