Thought I would share this with anyone that might be looking at a conversion barrel for one of their guns. I have a gen4 G22 and bought a KKM conversion barrel and 9mm magazine so I could use "cheap easy to find 9mm " . Lone Wolf and others make similar conversion barrels. I had asked KKM if I needed a different recoil spring and they said it works for some and others have said they need a spring. I found out that the recoil spring is the same for the Gen3 G17 and G22 but NOT for the gen4.

 

When I tried it when I first got it with the G22 recoil spring I had something like 20 out of 50 rounds either fail to eject or fail to feed. I never had an issue like this with .40 cal in the gun. Today I received a G17 recoil spring and gave it a try at the range. Put another 50 rounds of 9mm through the gun without the slightest problem. So, if anyone is having issues with a conversion barrel in a gen4 Glock I would recommend the equivalent 9mm version's recoil spring.

this is good to know, i have a glock 23 4th gen. coming my way soon and was looking into doing this, I wonder if the g23 is affected?

Yes Howard, the Gen 4 spring change is a good idea. They are different between the 9mm and 40 cal in either the large (17,22) or the medium (19,23) frames.

 

Also keep in mind that the 40/357 ejector is different from the 9mm/380. By the accounts I've read, frequently the incorrect ejector does not have a significant effect. But, in some pistols because of tolerance variance, it may make a difference. And the ejector is relatively cheap and easy to change.

 

In case you have a problem.

Yep. That's why Glock had to do an exchange program on their Gen 4 RSA's. Originally the Gen 4 .40 and 9mm pistols used the same weight RSA. It was soon found out that it was ok for the .40 but caused the 9mm's to have all kinds of ejection problems.

 

And where the hell are you getting "cheap easy to find 9mm"!!

Yes Howard, the Gen 4 spring change is a good idea. They are different between the 9mm and 40 cal in either the large (17,22) or the medium (19,23) frames.

 

Also keep in mind that the 40/357 ejector is different from the 9mm/380. By the accounts I've read, frequently the incorrect ejector does not have a significant effect. But, in some pistols because of tolerance variance, it may make a difference. And the ejector is relatively cheap and easy to change.

 

In case you have a problem.

 

My understanding is you are correct about the ejectors, but it is not an issue. The .40 cal ejector is straight while the 9mm ejector is at a roughly 15 degree angle. This is compensated for by the conversion barrels being shifted slightly towards the ejector. If you look at the conversion barrel you will see it is wider on one side than the other to compensate for this.