I have read of the Underwood .380 mentioned several times--- have not read of any tests anywhere. Recently I did get a 42 that is +P capable and ordered 3--20 rnd. boxes of the 90 gr. XTP and 2 boxes the +P 102gr. Golden Sabres to try. Anybody run across any gel/expansion/penetration on this ammo tests I missed??  Underwood lists the XTP at 1200 fps-- the GS 102 at 1060, both should be potent loads.

Two part question--- would you be reluctant to load this ammo in a LCP strictly for defensive purposes--- not shoot a bunch, just as a carry load. Ruger says, '' Not +P rated'', but, I don't think a little boost in H.P. when NEEDED might not be a bad thing,,,,,,,,,

I've only been able to test the Remington Ultimate Defense SB 102 and the Federal HST SB 99. If the Golden Saber 102 is the same bullet being used under a re-branded name, then it's performace is severely lacking and I only got 8 inches of penetration. The HST however, got to 12 inches and while I have yet to test 90 XTP, I'm almost at the conclusion that HST right now is the hammer of thor for .380's.

You sure about that? According to SAAMI there is no such thing as .380+P.

There are only 5 cartridges with a +P version, and the .380 is not one of them.

They are the 9mm Lugar, .45 acp, .38 auto (aka 38 super), .38 special, and 257 Robers.

Might want to talk with Glock before shooting out of spec, over pressure ammo through your new carry piece.

I carry Underwood's .380 +p XTP load in my 42. It has more recoil than all other non +p loads but it's still relatively light.

Although SAMMI does not list a .380 +p, it is still a common enough load with several manufacturers listing some type. I would not worry about shooting it in your G42. You will not be able to afford enough ammo to harm that gun.

I too am waiting on some test results for the +p loads.

It is my understanding that the Glock 42 is fine with +P ammo---- IF anybody has different info, please chime in.

It probably is, except that there is no such thing as .380 +P.

Anyone selling .380 +P is selling out of spec, over-pressure ammo.   +P has a specific defined meaning per SAAMI.  It's not just "higher pressure" it's a specific pressure per cartridge.

Very true. If it isn't SAAMI, a big nooooooope from me.

As said above, 380 +P is a wild card, theres no set definition of what it is, that said, most of the 380 +P on the market generates 9x19 pressures (just something to think about). Most modern autos should be able to handle it a few times (i have run Buffalo Bore 100gr +P through my 238) but honestly after learning theres no set definition, Ill never run it again...
And finally, with good performers in standard pressure 380, why expose your pistol to the added abuse?

To me there is no such thing as "+p .380".  You're taking chances on a non-standard round.  Maybe that will change in the future but for now I refuse to use it in my guns.

See, the argument that SAAMI doesn't annoint the appellation +P in the caliber 380 is meaningless. SAAMI also doesn't believe 9mm +P+ exists, yet it does, and is manufactured by major manufacturers.
Underwood and Buffalo Bore are not basement ammo makers churning out high power loads between beers.

My opinion is that SAAMI has done some negative things to our ammunition.
Try buying 8mm Mauser loaded to service levels...the only ones are S&B or surplus. US spec 8mm is mainly good for getting brass. 38spl gets weaker and weaker, and most 38spl +P isn't worthy of the name.
I used to get European 380 and 32acp that was noticeably more powerful than US ammo made to SAAMI spec.
I've shot Underwood +P 380 XTP in my Beretta 84F, and the pistol seemed to like them just fine.

SAAMI has set standards for 9x19+P, 45ACP+P, 38 Super +P, 38spcl+P. Rounds marked as +P other than those rounds can vary and as they have no set industry standard I would just as soon not run them.