I think the Glock concern was more with loading lead bullets. I think the polygonal rifling strips lead off and then begins to foul very quickly. Then pressures can build and boom.
Other than that, I havent heard anything.
RipT
A few years back, a story was started that cast bullets should not be fired in Glocks. Dunno who started it, I heard it was Glock's north American distributor, but I can't confirm that. It has circulated the world and is believed by so many that it has become entrenched as a hard fact. It is BS pure and simple. Polygonal rifling is not new. It is just one of various rifling forms that existed a century ago, and I have inspected an early 20th century Westley Richards rifle with polygonal rifling. Conventional land and groove rifling became dominant probably because it was both succesful and easiest to produce with the cut rifling machines that dominated barrel production from late 19th to mid 20th century.
The important point to note is that all ammo of a particular calibre made in hundred of factories around the world must be made to tolerances to fire safely in any firearm of that calibre, also made in many factories. That is true whatever form of rifling that firearm may have. The same factory ammo is fired in Glocks of various calibres and in firearms with conventional rifling. To put it differently, Glocks fire exactly the same ammo as all other firearms. That includes handloads, because they must also be made to specifications that will function safely. Excessive leading in polygonal barrels ? Nonsense ! Leading is a function of alloy hardness, lube quality, velocity, and bore smoothness. As Glock bores are very smooth, leading should be less not more.
I am a commercial bullet caster. I cast more bullets in a year than most home casters will cast in a lifetime. Several of my customers have Glocks. One has three in different calibres. All have fired thousands of cast loads with no problem. Trust me, you can shoot cast loads in your Glock just as you can in any gun. The story to the opposite is pure BS with no basis. Beats me why otherwise intelligent reloaders believe it.
I strongly suspect that if it came from Glock, it was really just the usual voidance of guarantee if reloads are used. All gun manufacturers say that, and I suspect that Glock's was misinterpreted as being against only handloads.