10mm Underwood 155gr XTP @1,500 fps-HOLY COW!!!

[Don_M2]

I try to practice 2 or 3 times monthly with my S&W 2.0 10mm, 4.6" barrel. This past Saturday was no exception.

My usual is 50 rounds of 170gr ball ammo, followed by 25 rounds of Hornady Custom 155gr XTPs, rated at 1,410 fps - just to accustom myself to a hotter round that's closer to my actual carry ammo, which is the 155's from Underwood. This time however, I also added 20 rounds of Underwood's to see how my real carry rounds act...HOLY COW!!!!!

The ball ammo delivers a decent "punch" to the hand and some moderate muzzle flip, and I'm accustomed to it. The Hornady Custom has less flip and punch, but a significantly increased blast and flash - but I'm used to that as well.

The Underwoods however, while having a similar blast (minus the flash) to the Hornady's, has a SIGNIFICANTLY greater punch than the heavier 170gr FMJs. So much so that each and every round STINGS LIKE CRAZY!!

I have NEVER had a handgun sting my hands like that, not even the .44 Magnum snubby I'd fired. The ammo is very accurate and controllable out if my M&P, but DANG it smarts more than a little.

It's so vastly different from anything else, that I've decided to drop the Hornady's from my range line up and start using the Underwoods instead for acclimation.

 

[padom]

Thats weird, the lighter 10mm rounds have less felt recoil for me. I shoot and test a ton of 10mm in 2 Dan Wesson's (4.6" and 6") and a Glock 40

The Underwood 200gr HC at 1209 have the most felt recoil for me but nothing that would equate to stinging my hand. I worked up my own load to mimic this crazy expensive Underwood ammo that consists of 200gr Montana Bullet Works 200gr Hard Cast Gas Check over Longshot that chrono at 1225 ND stupid accurate.

I did a bunch of load development with 200gr Sierra HP and 140gr Lehigh Extreme Penetrators (Underwood makes factory ammo with this bullet also).

My 140gr Lehigh Xtreme Penetrators load has zero recoil, stupid accurate feels like shooting a 9mm and chrono @ 1610

My 9mm 90gr Xtreme Defender load on the left and my 10mm 140gr Xtreme Penetrator load on the right

https://imgur.com/a/YjmxbHF

 

[TonyinKY]

I’ve always been a believer of the TKOF (Taylor Knock Out Factor) when figuring bullet weight and/or caliber for hunting big game and self defense especially in handguns where trajectory means little due to the limited range. This has always pointed to a big bore with heavy bullets for me. I shoot a lot of 180s but hunt and carry 200 gr in my 10mm 1006, G40s, G29 and even my PCC. I ran the TKOF on your 155 gr Underwood load vs their 200 gr load with the same (XTP) type bullet.

https://www.vcalc.com/wiki/taylor-knock-out-factor

 

[Don_M2]

I’ve always been a believer of the TKOF (Taylor Knock Out Factor) when figuring bullet weight and/or caliber for hunting big game and self defense especially in handguns where trajectory means little due to the limited range. This has always pointed to a big bore with heavy bullets for me. I shoot a lot of 180s but hunt and carry 200 gr in my 10mm 1006, G40s, G29 and even my PCC. I ran the TKOF on your 155 gr Underwood load vs their 200 gr load with the same (XTP) type bullet.

https://www.vcalc.com/wiki/taylor-knock-out-factor

View attachment 1719990View attachment 1719991

That's cool. I noticed that the 155 has 1 less on the TKOF, but 30.48 more fp energy, so that's interesting.

My primary concern is that my experience is in densely populated urban areas, where over-penetration is a major issue. The 180gr to 200gr rounds have a good deal more penetration in ballistic gel testing, so even though in some cases they have more ft lbs, much of it is lost because of excessive penetration and unacceptably raises the danger of serious injury to someone behind the threat. So even if 12" to 16" in gel only equals 6" to 7" in the real world, I'm OK with that.

Now if I was HUNTING deer, or going for large animal defense, it would be 180gr + all day long.

 

[troupe]

A glock in 10mm is going to kick, it is a lite pistol, even an all steel 1911 will have a punch. 10mm is a stout little round is loaded warm.

 

[Don_M2]

A glock in 10mm is going to kick, it is a lite pistol, even an all steel 1911 will have a punch. 10mm is a stout little round is loaded warm.

Mine is a full-sized M&P

 

[TonyinKY]

A hot 10mm load ain’t easy on the shoulder either!

 

[troupe]

Plastic pistols are going to recoil. Simple physics.