Experience with 10mm so far has been limited to a 1911.  I've used Unique for some low power loads and blue dot for mid to upper end loads (10.9 max).

Typically use new Starline brass for the hotter loads and fired brass for everything else.  Heavy plated Xtreme 180's have been fine for plinking.

Thinking about moving over to a G20 Gen 4 and wanted to see what what's proven.

Now I see lots of chatter about KKM/Lone Wolf barrels, different RSA's, and plenty who run things stock and stick to Underwood.  The discussions I've followed have generally been out of the scope of reloading (i.e. no comments towards bulged brass, etc.)

Wondering how far I can get on a stock Gen 4 G20.  Would consider changing springs if necessary (trial and error) but would like to avoid replacing the barrel (cost).  Any help appreciated.

Get a glock 20 shoot the heck out of it, leave it stock unless you have a problem or special need...

If it ain't broke, don't fix it.

TightLines, Some of the Gen-4 have been great with the factory setup even with Underwood Ammo and other higher impulse rounds. 
I shoot a G-20SF using the stock barrel and test some potent stuff with it using factory RSA and the Wolff non captive 22 lbs RSA on their steel guide rod.  Both setups work but I like the non captive setup best in mine.

As you test collect you brass looking for flattened or popped primers, smiled or damaged cases.  Just beware most Glock 10mm factory barrels allow cases to bulge to 0.4340" before they smile.

Shadow, very helpful as always. I'm hoping a stock Gen 4 can handle some 10+ grain blue dot rounds with the stock barrel. Sounds like I'll need to debulge this brass before reloading (assuming they work with the stock setup.)

What projectiles are you using with your G20 reloads?

I using many different types including my cast bullets Lyman Devastator 156gr HP, RCBS & Lyman 175 TC and Rcbs 200gr TC.
Have run some FMJ, JHP like Hornady XTP in various weights, Gold Dots, Rainier Hex plated, Federal HST's, Nosler & Sierra of various weights.

Not to mention the 9x25Dillon loadings from the LWD conversion.  Soon to be testing some 9mm Luger from the LWD conversion as well.

Quote from: TightLines on August 06 2015 04:33:50 PM MDT
Shadow, very helpful as always. I'm hoping a stock Gen 4 can handle some 10+ grain blue dot rounds with the stock barrel. Sounds like I'll need to debulge this brass before reloading (assuming they work with the stock setup.)
What projectiles are you using with your G20 reloads?

My favorite loads are 10.4gr of BD with 180 XTPs and 180 Xtreme plated... It's a mid/upper warm load. All in a stock glock20.
Yes, the glock chamber is loose, but 95%+ of the cases don't need any more than running thru the Lee classic turret. After the LCT, they will fit the 10mm case gauge. The few that don't I just throw in a bin for later when I do a full length resize when I get e few hundred or so.
If your just using in the glock, prob all will do fine with a normal sizer and not even need a full resize with the above load.

Glock 20 Gen4.  I use the stock barrel for light loads and a KKM 6" for heavy loads. 

6" barrel:  180 gr XTP, 9.1 Longshot average FPS of 1,357.

I believe the Underwood loads eventually end up as max G20/G29 loads.  Just because of the numbers of Glocks involved, that is where the "too hot" complaints rise from and the loads are adjusted to not show signs in those pistols.

I normally hand load to slightly under the Underwood pressures, and I'm happy with all my 10mm firearms.  A little lower pressure only amounts to 25-35 fps difference without the stress to the brass and hardware.  Its still in the levels that S&W 40 cannot go.

All that said, Underwood is ok for my Gen4 Glock 20 safety wise, but some loadings will smile cases and I wouldn't reload those smiled cases.  I'm just glad I reload so I can shoot exactly what I like.


Greg

I'm using 10.3gr Bluedot under a 180 XTP for hunting. Been using 6.0gr of win 231 for plinking.

Just remember EVERY gun, barrel, batch of powder or primers can be different... Its up to you, your gun with your materials to determine whats safe. Manuals give acceptable guidelines. KNOW the signs and remain diligent if venturing astray form manuals recommendations.
Don't immediately trust ANY data. People make mistakes, some down right post unsafe loadings. (Not at all suggesting malicious postings here. Speaking in general.)

Now having said that, For powders, I like 800X & Blue dot but neither meters very well. Another that I love is AA#7 when you can find it. (I lucked into a dealer yesterday with some, I bought one. ) This powder meters beautifully.

I cast my own 175 & 200 TC bullets. I want a 200 WFNGC. Right now I buy them. I also like the Winchester 175 Silvertips. But again they are very very hard to find. I use the 200 XTP as well.

Good luck,
CW

Thanks all for the info.

I've got a Gen 4 G20 on order and will report back with how it handles a few of my already on the shelf reloads.

My existing 10mm reloads were used in a 1911 so I loaded them to 1.250 so we'll see how a stock G20 feeds and headspace at that length.

Thanks agin.

I don't know how  warm those reloads are, but be careful.  I'm a "start low and work up" believer.  There are loads my Witness would handle fine that would blow a case in my Gen4.

If there is a question, load a few step-up loads that run up to your existing reloads.

Greg

Thanks everyone for the input.

G20 Gen 4 finally made it in and I was able to test some loads at 9.3 and 10.5 gr of Blue Dot at 1.255 OAL.  Everything functioned well.

Did get some case bulging on new Starline brass out to .433 - .434 on the 10.5 gr loads.  These were not smiles but bulges that seem to resize fine through the Lee resizer die (no bulge buster, etc.). 

Thoughts on reloading these, especially to another 10.5gr load?

FWIW - the resized brass is now at .423 towards the base (where it had bulged to .433).

Quote from: TightLines on November 09 2015 10:34:03 AM MST
Thanks everyone for the input.

G20 Gen 4 finally made it in and I was able to test some loads at 9.3 and 10.5 gr of Blue Dot at 1.255 OAL.  Everything functioned well.

Did get some case bulging on new Starline brass out to .433 - .434 on the 10.5 gr loads.  These were not smiles but bulges that seem to resize fine through the Lee resizer die (no bulge buster, etc.). 

Thoughts on reloading these, especially to another 10.5gr load?

That's a modest-heavy load. I routinely load and shoot 180 gr. XTP and heavier BD loads at 1.260" in the OEM barrel. No problems after a few thousand rounds and several years, with R-P and Starline brass.

9.3 gr. is in the range of full .40SW. 10.4-10.6 gr. is strong, but not "heavy".