Sixty rounds in your Glock?

9mm Extreme Extension Glock – Taccom3g:

(a) TACCOM 9mm Extension for the 33 round 9mm Glock magazine.

The manufacturer claims:

We’ve come up with an extension and spring that will feed your PCC efficiently. Made from 6061 aluminum, it will take the abuse of competition and keep on running. The internals of the extension are smooth to allow for both the follower and the rounds to flow effortlessly thru for thousands of cycles. Easy to assemble too!! 

Manufacturer also offers some supplementary advice:

Note: Keep in mind that the end user must chamfer the inside of their magazine as well as their follower so that you get a smooth transition when the follower re-enters the magazine.

An idea whose time has not come?

The curmudgeon in me refers back to Viet Nam where we couldn't get the 30-round "banana" magazines for M16's (apparently those of us 'in the field' had second or third call on equipment, including magazines, boots and replacement arms ... right after the Officers and the REMFs stole the good stuff) and in fact we used the straight 20-round magazines but downloaded them to 18 rounds, because the springs lost their resiliency when kept fully loaded for days at a time.

So I'm historically dubious about claims exceeding my experiences. These magazines are obviously not intended for the kind of abuse and poor maintenance suffered during a combat tour.

My experience competing in IPSC matches / "Open Division" was that the 25-round magazines had to be treated with kid gloves.  We removed the springs (or at least the end caps) from the magazines so the springs were not under any tension between usages ... which is to say, right up to Match Day.    That kept their 'strength' up so there were more or less reliable, but we still tended to down-load the magazines by a round or two.

But that was way-back-then, and the manufacturers claim here that:

We’ve come up with an extension and spring that will feed your PCC efficiently. 

By that I presume that advances in metallurgy have resulted in springs which WILL perform reliably under the most grueling of conditions.

Actually, I doubt that.

On the other hand, I recall a couple of very smart fellows who once said: "640 kilobytes of memory should be enough for anyone", so I suppose it's possible that I've misjudged modern technology.