GS Double Diamond .40cal to 9mm Conversion Barrels for Glock Gen1-4

I bought the .40 caliber to 9mm conversion barrel that was made by Double Diamond to change my duty weapon from a .40 caliber to a 9mm platform. I have shot approximately 200 rounds through this barrel and am truly impressed by the accuracy of this barrel. I can definitely shoot better with this barrel. I would highly recommend this barrel to anyone who wishes to go from the G22 (.40 caliber) to the 9mm. Thanks GlockStore!

it worked with everything i put in it from steel cased to aluminum cased and brass.i also ran some federal 9BPLE +p+ hollow point ammo and it worked 100%. thank you glockstore for selling this barrel at a great price.

I have 2 Glock 23's with 9mm conversion barrels. I took them both to the Henk Iverson H.I.T.S. Pistol course on Sept. 30th. I shot the Double Diamond 9mm conversion straight out of the box all day long... 500 rounds of FMJ. Last Tue shot our Tuesday Night Steel match with various JHP and FMJ loose from my bag... 100 rounds without any issues. As a side note, I had purchased two G-19 extractors, just in case but have not needed them. The other G23 9mm conversion (not Double Diamond) has more than 2,000 rounds through it with no issues. I have saved more than the cost of the barrels in ammo savings.

I bought one of these for my G35. Works perfectly with factory and handloads; didn't have to change extractor or ejector. I do use G17 magazines, but no other changes. Accuracy is excellent and happens to print to same point of aim as the .40 factory barrel. I couldn't be more pleased and plan to add one of these conversion barrels to my G23 as well. Can't say enough good things about this barrel!!!

Received one of the last generation barrels recently for my Glock 23. What a difference. The .40 barrel would throw rounds in a varied grouping but once I got this sighted in, shoots a very nice group at 25 feet. Would recommend highly. Sidenote, threaded DOES come with a thread protector already. Add a little blue loctite to keep it in place.

600 rounds through it so far and zero problems. I did replace the extractor and ejector with Glock 19 oem parts. No FTF or FTE problems at all. Also no problem with brass hitting me in the face. Beautiful fit and finish. Thank you Glockstore!

Got to take this for a walk at charity event shoot for 4 days.
Threw this in my G22 Gen3 and fed it S&B 115gn fmj. The barrel was machined true, could ragged hole at 7yds. Good enough for my eyes.

Downside: In 800 rounds I had 14 Type 3s. Could be a lot of things including the ammo, however, my G19 Gen2 ate the same amount of the same ammo and got 1 Type 3. In this case, maybe not the ammo. Could have been tired hands.

Take Away: I wouldn't use it for carry, but for range work I think it's awesome. Besides, Type 3s are my favorite. Finger magic.

I'm completely satisfied with this conversion barrel and with the CustomerService I received from the glock store. I waited for a sale and got the barrel for 116 bucks with free shipping and after ordering I live chatted with Conor An he told me it ship towards the end of the week I ordered it on a Tuesday it shipped on Thursday and got it Friday... since installing (in my glock 35 G4) i have put about 100 rounds through it no problems great fit and finish and very accurate... I have nothing negative to say if you are thinking about buying this barrel you wont regret it

Since I converted my Glock - 23 from a 40 cal to a 9 mm it works like a charm. At first I had a feed problem because of the new Gen 3 lower but it went away after a few rounds

Great quality, perfect workmanship. Accuracy on par with Glock factory barrels. As good ( maybe better?) than my Glock 26.

Very nice barrel but needed a little fitting around the top lip over the chamber to fit into my slides. Otherwise happy with the purchase

I purchased this conversion barrel for my G23 and I can confirm that the pistol functioned FLAWLESSLY!!! The only other amendment was the addition of G19 magazines. I experienced no FTF, FTE, no malfunctions whatsoever!!...I was originally going to purchase the 9mm specific extractor just to be safe, but never got around to it. Went to the range this morning for yearly quals, and brought my MCK with the G23 (9mm convert) and it shot beautifully!!

I carry a Glock 27 and I also have the 40 to 357 sig conversion barrel. both perform flawless with standard 40 cal mags!

I have these very 9mm conversion barrels in both my Glock 23 and 35, and they work great. Be aware through that the dimensions are tight in the chamber and my carry ammo won't readily cycle through them. Apparently my carry ammo is just a thousandth or two wider than the range ammo I use. Speaking of range ammo, I can use 9mm to the extent of my budget and FMJ range ammo runs through the barrels perfectly, saving me a ton of money. Good accuracy too, when I do my part.

Love the conversion barrel for my glock 27. No problem so far.

Works perfect my Glock GEN 5 22 converted to 9 mm
Thanks