Q Answered Ammo for Thompson Subgun


Mi Recruit
MI.Net Member
Dec 12, 2018
Hi, my name is John & the original reason for joining this group of you folks was to enlighten myself on how fast the 230GR ball ammo starts out from a Thompson. I had an idea that there might different spec stuff especially loaded for this weapon. Now, I have my doubts, so I welcome input from anyone who can straighten me out on the matter. Thanx in advance, & BTW I now see that there's a whole LOT more to this site than I expected & I'm glad of it. johnj1020
The standard USGI 230gr Ball was spec at 820fps and modern commercial 230gr ball can vary to as much as 850fps. There won't be much gain coming from a longer barrel Thompson, 45acp military ball or any basic std ball isn't a real high velocity . Older ammo might run slower depending on the powder used and it's age of course. Now there is much modern 45acp out there now in different bullet weights usually centered around 185gr weight for defensive use in pistols and there are several 45acp loads in both 230gr HP and 185gr HP that are +P, which means +Pressure, or higher pressure, thus faster and a bit more puff at the muzzle. (+P would be great to run in a Thompson btw it'll handle it, I've done it alot) The +P will only be perhaps 25-50 fps faster is all so not much really.
Thanx for the quick reply, uktabber, & you hit on something that I can put to use regarding SD pistols & efficient ammo. I'm saving up for a Springfield Armory Range Officer Compact in .45auto as a second option CC weapon, (my 1st is a Walther PPS M2 LE in 9mm). I've pretty much stuck with the 230s in the past, never reloading with the 185s, but they may be just what the doc ordered, so thanx for steering me in the right direction. jd
No problem. 185's are hotter due to light wght and thus are pretty snappy in the smaller frame 45acp's. In Commander and Govt models they're fine. Good old slow loping along 230 HP will be the best bet for CC for a small 45acp. The only exception I've found is the 185gr Winchester Silver Tip, they are great in the smaller 45's.
This reminds me of an old saying with 45acp's: "They all fall to hard-ball" meaning 230gr ball or HP. Cheers