reloading for glock

Question
In Richard Lee's Modern Reloading 2nd ed., in 40S&W specs,
he warns not to fire reloads in Glocks or similar guns that
"do not fully support cartridge due to intrusion of feed ramp". He doesn't make the same warning in specs for 9mm,
10mm, or 45acp. Is there a difference in these Glocks? I'm
interested in buying a 10mm, are reloads safe in the Glock?
Sorry for the long question, Thanks for any advice,Charles.

Answer
Charles,

Let me apologize in advance for the length of this answer.  Your question can't really be answered with a simple "yes" or "no."  If you understand all the issues involved, I think it will enable you to make an informed decision.

The Small Arms and Ammunition Mfg. Institute (SAAMI)sets specifications for cartridge pressures, overall cartridge length, and chamber dimensions.

Glock has chosen to produce their chambers to the generous side of the SAAMI spec. for the purpose of making their guns as feed-reliable as possible.

The 9x19 cartridge has a tapered wall, and so does not need a generous throat to feed well, but all the 40-something cartridges you've mentioned are straight-walled.  To further enhance feed reliability in these calibers, the Glock feedramp undercuts the chamber, exposing some of the wall.  You will notice on empty casings fired from Glocks in these calibers with stock barrels that there will be a distinctive bulge just ahead of the webbing due to this feature.

You should note, too, that Glock barrels are polygonally rifled, rather than the traditional cut lands-and-grooves rifling. This increases velocity and tends to increase accuracy by swaging each bullet to the same size and shape as it travels down the bore.  However, you should NEVER shoot lead projectiles out of any stock Glock barrel. The lead will strip off and plate the polygonal rifling, actually decreasing the bore size.  There will come a point at which the constriction of the bore will cause pressures to escalate exponentially, and the gun will have a catastrophic failure (read "blow up").  THE POINT:  When reloading for the Glock with a standard barrel, use only copper jacketed, or (if loading to sedate velocities), copper plated projectiles.  NEVER use lead.

Can you load for the .40 something Glocks with factory barrels?  Sure.  I've done it for years with never a problem.  But I always make these loads sedate, and keep track of my cases, discarding them after eight uses.

There is a better solution, though.  If you are going to shoot reloads, I would recommend replacing the barrel with an aftermarket, drop-in stainless steel version.  There are a slew of good barrels out there, but in terms of value for the money, the barrels by KKM and Lone Wolf can't be beat - around $90(BarSto barrels, which historically set the pace for the industry, are no more accurate, not as nicely done, and cost 2x the amount).  The KKM and Lone Wolf barrels all have FULLY supported chambers, and are (in my experience) just as reliable as the factory Glock barrels.

They also have the advantage of having tighter chambers tolerances (note: 10mm cartridges shot out of a stock Glock barrel and resized in your loader will likely NOT fit into a KKM or Lone Wolf chamber, so shoot everything from the new barrel!), and have lands-and-groove rifling, which means you can shoot lead projectiles if you so choose (but if you use the 10mm to its potential, you will have a heavily leaded barrel to clean - best stick with copper jacketed stuff).

To sum up, "Are reloads safe in Glocks?"

"No, if you are shooting lead projectiles."

"No, if you are loading at the maximum end of the spectrum"

"Probably, if you don't push them too hard."

"Yes, if you replace the barrel with an aftermarket one with a tighter chamber that is fully supported."

Again, I apologize for the length of this, but hope it helps you to understand the issues involved.  If you need clarification on any of the points, write back.

Good luck.