Steve Jackson Games - Site Navigation
Home General Info Follow Us Search Illuminator Store Forums What's New Other Games Ogre GURPS Munchkin Our Games: Home

Go Back   Steve Jackson Games Forums > Roleplaying > GURPS

Reply
 
Thread Tools Display Modes
Old 07-01-2009, 05:39 AM   #1
Max Schreck
 
Max Schreck's Avatar
 
Join Date: Mar 2006
Location: Copenhagen
Default [HIGH-TECH]Recoil for submachine guns and machine pistols

Recently I just skimmed some of the weapons tables in GURPS High-Tech, and I noticed something for the first time that struck me as rather odd. All submachine guns have the same recoil, namely 2.

I am no weapons expert, and I have only fired a few firearms in my life, but it seems somehow wrong to me that e.g. a M1921 .45 ACP or a MAC-10 .45 should have the same recoil as a FN P90 or a MP5 or whatever; mind you, I have never fired any of these weapons in my life, but when I've seen real life footage of these guns fired on full auto, it seemed to me that there was significantly more recoil with the Thompson than with a P90 (or many other SMGs for that matter).

Furthermore, looking at the pistols, one kan see that a M1911 .45 ACP has more recoil than a 9mm Browning Hi-Power. And yet a .45 calibre SMG has no more recoil than a 9mm SMG. There was a difference in the Basic Set, but now no more.

So, am I just wrong, and SMGs have no appreciable difference in recoil or is this legitimate errata? What gives?

Cheers,

Max
__________________
"Les préjugés sont la raison des sots."
Max Schreck is offline   Reply With Quote
Old 07-01-2009, 05:54 AM   #2
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: [HIGH-TECH]Recoil for submachine guns and machine pistols

Certainly there are differences in felt recoil between various submachine guns, but those differences are below the granularity level of GURPS. The ST stat for the weapons, however, is affected by felt recoil as well as weight.

The reason that large bore pistols have a higher Rcl stat than submachine guns of the same calibre is that the pistols are much lighter. They lack enough mass to act as a counterweight. The SMGs, however, are more than heavy enough to be stable when firing what is, after all, a pistol cartridge.
__________________
Za uspiekh nashevo beznadiozhnovo diela!
Icelander is offline   Reply With Quote
Old 07-01-2009, 06:14 AM   #3
Max Schreck
 
Max Schreck's Avatar
 
Join Date: Mar 2006
Location: Copenhagen
Default Re: [HIGH-TECH]Recoil for submachine guns and machine pistols

Quote:
Originally Posted by Icelander View Post
Certainly there are differences in felt recoil between various submachine guns, but those differences are below the granularity level of GURPS. The ST stat for the weapons, however, is affected by felt recoil as well as weight.

The reason that large bore pistols have a higher Rcl stat than submachine guns of the same calibre is that the pistols are much lighter. They lack enough mass to act as a counterweight. The SMGs, however, are more than heavy enough to be stable when firing what is, after all, a pistol cartridge.
Hm... I see your point about granularity and weapon size, but would it be completely oustide the bounds of reality to give a high-calibre compact SMG like the .45 ACP MAC-10 a Rcl of 3? I mean, there's not much there to offset recoil, unlike the heavy Thompson.

Cheers,

Max
__________________
"Les préjugés sont la raison des sots."
Max Schreck is offline   Reply With Quote
Old 07-01-2009, 06:51 AM   #4
SCAR
 
Join Date: Oct 2004
Location: Yorkshire, UK
Default Re: [HIGH-TECH]Recoil for submachine guns and machine pistols

Just to be clear: I've never fired a gun in my life, so I have no real world expectation of what 'recoil' might mean.

In GURPS terms, the Recoil (Rcl) stat for Firearms is used to calculate the number of hits for RoF2+ weapons. (See B271 and Rapid Fire - B373).
That's as much as I need to know as far as playing the game is concerned!

If you search for Recoil in this forum I think you'll find this question and the following argument more than a few times!
SCAR is offline   Reply With Quote
Old 07-01-2009, 07:03 AM   #5
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: [HIGH-TECH]Recoil for submachine guns and machine pistols

Quote:
Originally Posted by Max Schreck View Post
Hm... I see your point about granularity and weapon size, but would it be completely oustide the bounds of reality to give a high-calibre compact SMG like the .45 ACP MAC-10 a Rcl of 3? I mean, there's not much there to offset recoil, unlike the heavy Thompson.
It wouldn't be completely outside the bounds of reality, no. On the other hand, the energy of a 9mm bullet compared to the 3 lbs. of a typical pistol actually yields a higher free recoil number than the energy of a .45 ACP compared to the 8.4 lbs. weight of the Mac-10.

If you don't want all pistols being Rcl 3+, the logical conclusion is that the Mac-10 is probably large enough to absorb the kick.
__________________
Za uspiekh nashevo beznadiozhnovo diela!
Icelander is offline   Reply With Quote
Old 07-01-2009, 10:08 AM   #6
Max Schreck
 
Max Schreck's Avatar
 
Join Date: Mar 2006
Location: Copenhagen
Default Re: [HIGH-TECH]Recoil for submachine guns and machine pistols

Quote:
Originally Posted by Icelander View Post
It wouldn't be completely outside the bounds of reality, no. On the other hand, the energy of a 9mm bullet compared to the 3 lbs. of a typical pistol actually yields a higher free recoil number than the energy of a .45 ACP compared to the 8.4 lbs. weight of the Mac-10.

If you don't want all pistols being Rcl 3+, the logical conclusion is that the Mac-10 is probably large enough to absorb the kick.
Ack... I suppose you're right. Oh, well, nothing's wrong with the SMGs in High-Tech, then. Carry on.

Of course, I also noted that the MP5/10A3 had Rcl 3 as the only SMG in High-Tech, but then again, the 10×25mm Auto is one hell of a round.

Thanks for the input.

Cheers,

Max
__________________
"Les préjugés sont la raison des sots."
Max Schreck is offline   Reply With Quote
Old 07-01-2009, 11:52 AM   #7
Hannes665
 
Hannes665's Avatar
 
Join Date: Aug 2004
Location: Reykjavik, Iceland
Default Re: [HIGH-TECH]Recoil for submachine guns and machine pistols

Quote:
Originally Posted by Max Schreck View Post
Ack... I suppose you're right. Oh, well, nothing's wrong with the SMGs in High-Tech, then. Carry on.

Of course, I also noted that the MP5/10A3 had Rcl 3 as the only SMG in High-Tech, but then again, the 10×25mm Auto is one hell of a round.

Thanks for the input.

Cheers,

Max
Well what realy matters is the ST number. For example the Colt 45 has a ST 10 while a Glock 17 9mm has ST 9. ST 9 man firing the Colt would get a -1 extra for lower ST for each shot, in real life terms that could mean that he does not have enough ST for a control follow up shot. (I must admit I dont get why ST affects first or single shot in any gun since the recoil is not felt until after the round has left the barrel, with the exception of very low velocity rounds).

The MP5/10 is not a very popular gun, it had to much "kick". The 10x25 Auto (Norma) is a very powerfull round, the FBI used a reduced load for their agents called the 10x25 FBI load by gun nuts.

You will also notice that 10x25 mm pistols get ST 10 and whopping Rcl of 4.
__________________
In the Griffin World I play Agriana Trotter, here is the GURPS crunch.


Darth Vader "Luke! I am your fathers second cousins sisters best friends brother!"

Luke Skywalker "Nooo... eehh What?!"
Hannes665 is offline   Reply With Quote
Old 07-01-2009, 12:31 PM   #8
Phantasm
 
Phantasm's Avatar
 
Join Date: Jun 2006
Location: On the road again...
Default Re: [HIGH-TECH]Recoil for submachine guns and machine pistols

Quote:
Originally Posted by Hannes665 View Post
I must admit I dont get why ST affects first or single shot in any gun since the recoil is not felt until after the round has left the barrel, with the exception of very low velocity rounds
That's actually somewhat of a misconception. Recoil is actually felt as the bullet starts moving, not when the bullet leaves the barrel; the time between the two is imperceptibly short, but remember Newton's Third Law of Motion: for every action there is an equal and opposite reaction. The force of the powder exploding to move the bullet also produces the recoil.

ST matters for the first/single shot because it's accounting for not just recoil, but also holding the gun steady. A weak grip (owner's ST below the gun's ST rating) means that as soon as the powder goes off, that's enough force to "jerk" the gun away from the target the shootist is aiming at. A firmer grip is necessary to keep the gun steady as the bullet moves down the barrel.
__________________
"Life ... is an Oreo cookie." - J'onn J'onzz, 1991

"But mom, I don't wanna go back in the dungeon!"

The GURPS Marvel Universe Reboot Project A-G, H-R, and S-Z, and its not-a-wiki-really web adaptation.
Ranoc, a Muskets-and-Magery Renaissance Fantasy Setting
Phantasm is online now   Reply With Quote
Old 07-01-2009, 01:38 PM   #9
RyanW
 
RyanW's Avatar
 
Join Date: Sep 2004
Location: Southeast NC
Default Re: [HIGH-TECH]Recoil for submachine guns and machine pistols

Quote:
Originally Posted by Hannes665 View Post
The MP5/10 is not a very popular gun, it had to much "kick". The 10x25 Auto (Norma) is a very powerfull round, the FBI used a reduced load for their agents called the 10x25 FBI load by gun nuts.
Which, IIRC, often failed to cycle autoloaders. If you notice, the 10mm Auto was standard FBI issue for about 12 seconds.
__________________
RyanW
- Actually one normal sized guy in three tiny trenchcoats.
RyanW is offline   Reply With Quote
Reply

Tags
high-tech, recoil, submachine gun

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Fnords are Off
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 05:47 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.