It had been a minute since I've purchased any Underwood 10mm stuff, in fact my old stash is loaded in brass cases and in 50 round boxes. So I ordered a few boxes of 180 XTP (no more Gold Dot it seems) to test a more recent offering.  I also grabbed a couple boxes of Sig V-Crown 180's locally mainly due to the positive results of a couple YouTube videos I saw.  I generally load my own, but do use factory stuff occasionally when carrying, and I do like nickel plated factory loads for long term storage in a couple mags.

Chronographed them today in my KKM factory length barreled Glock 20, and my KKM factory length Glock 29. 

New Underwood 180 XTP, Glock 29, 1196 fps.
Same load, Glock 20 1282 fps.

Sig V-Crown 180, Glock 29, 1249 fps.
Same load, Glock 20, 1304 fps.

Seems as though the Sig ammo is out Underwooding the Underwood stuff these days...It's the real deal for sure!  And YouTube gel testers have had great results as well. By comparison, my older Underwood 180 Gold Dot loads clocked 1290 and 1360 in the 29 and 20.

My usual load of the Gold Dot 180 with 9.5 Longshot runs 1275 in the short 29, and 1325-ish in the 20.

I know that this is not exactly related to 10mm stuff, but the sig short barrel 124 gr speer gold dots are better than anything I have came close to reloading my own.

Near as I can get out of my P365 with BE86 powder is 1095 fps average with the 124's.

Pretty sure the sig says they're getting about 1140 out of them.

Again, this is for the short barrel stuff.  The p365, while it has about a 3 inch barrel, 1-1/4" of that barrel is just the chamber.   So, anyone capable of critical thinking, realizes that only leaves about 1-3/4" of actual barrel length.

So, that's about as far as I have tried to push my handloads.  If sig found a powder that pushes another 50 fps than what I'm getting, more power to them. 

Is that the Speer 124 Grain Short Barrel load?  I can't imagine Sig is loading Gold Dot when they have their V-Crown competitor.

I was under the impression that it was gold dot, but after you mentioned it, caused me to go to sigs website to look and they were offering the vcrown components, so you're correct.

I also do not see the short barrel ammo even listed now.   They are showing some 365 ammunition that uses 115 gr bullets, but they are rated at 1050 fps.  My loads are heavier and a bit faster.  I cannot find their 124 loads now at all, or anything marked short barrel like what I had seen before.

Quote
Muzzle velocity for both 9mm SIG 365 115gr V-Crown and FMJ loads is 1,050 fps from the P365 3.1-inch barrel with muzzle energy of 282 ft-lbs

.

https://www.sigsauer.com/9mm-115gr-elite-v-crown-365-jhp-1.html

The BE86 loads that I'm using under the 124 GD is getting me about 1094 fps average.  It's a bit snappy though.  I'm not gonna lie.  It's a bit of a handful, but that doesn't bother me.  Slow is fast.

Interesting detour, ha.

I am curious about this in particular since the post is current/2023:
My usual load of the Gold Dot 180 with 9.5 Longshot
The current online load data I can find from Hodgdon and bullet makers shows 8.2 grains max.

Quote from: The Professor on April 11 2023 08:38:04 AM MDT
I am curious about this in particular since the post is current/2023:
My usual load of the Gold Dot 180 with 9.5 Longshot
The current online load data I can find from Hodgdon and bullet makers shows 8.2 grains max.

There has been some speculation that Longshot has gone through some reformulation. I haven't found that to be the case in the Longshot I've purchased in the last couple of years. IIRC, one of the older manuals listed 9.4 or 9.6gr as max for a 180gr bullet.

800X and Longshot are the 2 go to powders when chasing velocity from the 10mm. Unfortunately, 800X can have some scary pressure spikes when approaching the old max loads published and has been published with a lesser max charge for some years now. I haven't found that to be the case with Longshot. I have no explanation for the changes in Longshot data.

I would strongly suggest that any time you're going over book max, do a work up .2gr at a time, and check your cases for over pressure signs. Slightly flattened primers aren't too big of a deal in hot 10mm loads. A chronograph is also the best way to know what you're actually getting out of a charge.

FWIW, I've run 9.4gr of Longshot with 180gr XTPs and FMJ out of my 1911s and my gas op 10mm AR runs great with them. But I'm just some guy on the internet offering advice. So if you choose to go this route, please do your own work up using your guns. YMMV.