New Pistol: Opinion (Hans/Doug et al]?

[Ze'Manel Cunha]

Originally Posted by DouglasCole

I'd look at it this way, instead: it's an 85mm barrel. It will do the same damage as any other pistol with an 85mm barrel.

The Glock 26 has an 88mm barrel. I suspect the two pistols' performance will be basically identical.

My sheet has it losing about 0.8pts of damage compared to a 5" barrel: 91% of full damage.

The Unofficial Glock User's Manual has a full length pistol at 360m/s, and the G26 at 347m/s: 96% of full damage.

The worst it will do is 2d+1, I'd say.

Um, I think you're significantly overestimating it.
The stat given by the manufacturer is 932fps, that is 284m/s, though I suppose it'll depend on the round being fired...

Would that be 2d-1?

[DouglasCole]

Originally Posted by Ze'Manel Cunha

Um, I think you're significantly overestimating it.
The stat given by the manufacturer is 932fps, that is 284m/s, though I suppose it'll depend on the round being fired...

Would that be 2d-1?

I didnt estimate anything. I found a source which lists both velocities and compared it with my model. They are in substantial agreement.

The NATO std round is 8g at 380 m/s, so I dont find the numbers I quote unreasonable.

I found another source or two. Here's the results:

Glock 17L with 153mm (6.02") barrel: 1350 fps (104%)
Glock 17 with 114mm (4.49") barrel: 1297fps (100%)
Glock 26 with 88mm barrel (3.46"): 1180 fps. (91%)

Since all things being equal, the GURPS damage is proportional to velocity, at least with the 115gr and 124gr loads for which I now have empirical data, I stand by the original estimation: No worse than a 10% penetration loss for the shorter barreled pistol.

Last calculation: in the range between a standard "full-size) Glock 17 (114mm) and the short Glock 26 (88mm), the velocity loss is 115 fps per inch of barrel. The gains moving from the 4.5" to the 6" barrel were only 35fps/inch. I suspect that the 9mm uses a sharp-burning powder that gives most of the impulse early on. A 6" barrel might well be verging to "too long" category. By this extrapolatin, a 12" SMG barrel would get 1560 fps, which I suspect is too fast, meaning the gains fall off more with extended barrel length. I'll look for results from longer barrels.

[Ze'Manel Cunha]

Originally Posted by DouglasCole

I didnt estimate anything. I found a source which lists both velocities and compared it with my model. They are in substantial agreement.

You're confusing the point, we're not talking about the Glock numbers, we're talking about the numbers on this specific gun, the Boberg XR9, which clearly lists its velocity firing 147gr at 284 m/s.

Ignoring the listed velocity of the pocket pistol given, and substituting in numbers from the much larger 10+1 shot 21.5oz Glock 26 is overestimating the smaller 7+1 shot 17.5oz Boberg XR9.

Originally Posted by DouglasCole

The NATO std round is 8g at 380 m/s, so I dont find the numbers I quote unreasonable.

I found another source or two. Here's the results:

Glock 17L with 153mm (6.02") barrel: 1350 fps (104%)
Glock 17 with 114mm (4.49") barrel: 1297fps (100%)
Glock 26 with 88mm barrel (3.46"): 1180 fps. (91%)

Which if you compare with the listed info on the Boberg XR9 you get:
Boberg XR9 with 85mm barrel (3.35"): 932 fps. (with 147gr 9.5oz)

The listed round is 9.5g, not 8g, the Glock 17 does fires the 147gr/9.5g federal load at much lower velocities than the 8g NATO rounds.

Of course the NATO std 8g round is much, much more accurate than the 9.5g round, max spread 19 ft/sec vs 52 ft/sec, but we're talking about close range firing, these pocket pistols aren't any accurate after 10 yards anyway.

Apparently the gun also must be snaked every 100 rounds or so, or it'll pretty much be guaranteed to jam...

[Sam Cade]

Originally Posted by Ze'Manel Cunha

Of course the NATO std 8g round is much, much more accurate than the 9.5g round

Depends on the weapon.

Originally Posted by Ze'Manel Cunha

close range firing, these pocket pistols aren't any accurate after 10 yards anyway.

Barrel length has no effect on handgun accuracy. It's all about the shooter, though little'uns are harder to shoot well due to the lack of sight radius.


It's all about the shooter.
Skip forward to about the 4 min mark.
http://www.youtube.com/watch?v=7TlUO7flMCk&feature=sub



I think the Boberg numbers are skewed in favor of the XR9 (I think the "other" pistol is a Rorbaugh) by using hotter +p ammunition.

They only specify the same bullet, not identical loads.

* Similar-sized gun is not +P rated

http://www.rohrbaughfirearms.com/products
2.9" Barrel vs 3.35" for the Boberg.

119 fps from .36" worth of barrel? I don't think so.

[Sam Cade]

Originally Posted by DouglasCole

a 12" SMG barrel would get 1560 fps, which I suspect is too fast, meaning the gains fall off more with extended barrel length. I'll look for results from longer barrels.

It depends on the pressure curve, but in 9mm 12-13" gets the most out of the cartridge and any length after that gives you a loss.

http://www.ballisticsbytheinch.com/9mmluger.html

[DouglasCole]

Originally Posted by Ze'Manel Cunha

You're confusing the point, we're not talking about the Glock numbers, we're talking about the numbers on this specific gun, the Boberg XR9, which clearly lists its velocity firing 147gr at 284 m/s.

No, I was not confusing the point, and the Glock numbers based on barrel length will be essentially the same as any other pistol of the same barrel length . . . certainly within the GURPS resolution they will. I did use the more speedy 115gr because I found it instantly to hand, but Sam's reference still supports my point: less than a 10% velocity loss, and therefore a 10% loss in damage, for the short-barreled pistol.

Ignoring the listed velocity of the pocket pistol given, and substituting in numbers from the much larger 10+1 shot 21.5oz Glock 26 is overestimating the smaller 7+1 shot 17.5oz Boberg XR9.

All of this is not germane to how quickly a bullet exits the closed tube that's a barrel. Red herrings, every one of these. The only thing that matters is velocity loss for GURPS damage.

Looking at the KE for the two rounds, it looks like the 147gr is a bit underpowered relative to the standard. The baseline for the 147 is a bit low, and since you get no credit for extra mass in vanilla GURPS, it will not do gamers any good to use the heavier round.

The ratio of the KE for the 124gr 9mm from a 5" barrel (584J) vs. the 9.5gr at 284m/s (383J) is 81%. The velocity loss from a 5" barrel (306.7m/s) to the velocity listed on the website (284m/s) is 7.4%, and the damage loss from the 9mm standard bullet is 20%.

Sorry, I've got a pounding headache right now, so let me sum up:

The velocity loss in percentage terms from a 5" standard barrel is dependent only on barrel length to a large extent.

The velocity loss for 115gr, 124gr, and 147gr ammo is 5-10% in the range we're discussing: going from a 127mm down to an 85-88mm barrel. In fact, for every bullet in Sam's web link, the velocity loss per inch is 4-6%.

The 147gr bullets tend to be a bit underpowered energetically. 475J (ish) insted of the more standard 584J. That's a 10% damage hit in GURPS right there: if the standard 9mm bullet is 9.0 to 9.4 points (depending on your reference), a generic 147gr will be 8.1 to 8.5 points.

This puts our pocket pistol at 7.3 to 7.6 points using 147gr ammo.

Of course, no GURPS gamer would voluntarily take the energy loss, which means that you're really looking at 8.3 to 8.6 points for a 124gr (or 115gr) bullet.

In REAL short terms:

88mm barrel, 147gr: 2d or even 3d-3 (avg 7.5 points), but 3d-3 isn't a standard number.

88mm barrel, 124 or 115gr: 2d+1

[Ze'Manel Cunha]

Originally Posted by DouglasCole

In REAL short terms:

88mm barrel, 147gr: 2d or even 3d-3 (avg 7.5 points), but 3d-3 isn't a standard number.

88mm barrel, 124 or 115gr: 2d+1

Oh come on, can't we say it's so borderline that it loses another -1 for being an 85mm barrel instead of the 88mm?

There's something to be said for having a little variability in damage for these pocket pistols...

[DouglasCole]

Originally Posted by Ze'Manel Cunha

Oh come on, can't we say it's so borderline that it loses another -1 for being an 85mm barrel instead of the 88mm?

There's something to be said for having a little variability in damage for these pocket pistols...

The most likely thing is that each gun (maybe each SPECIFIC gun, rather than each model) will "take" or "hate" particular ammo loads. I don't think the 3mm of barrel length will make the difference, so much as how each gun's manufacturing particulars influence the result. Given we're talking a base damge of 8-9 points for the full 5" barrel, saying it loses another full point is a pretty big statement, relatively speaking.

I find it likely that the G26 and this Boberg will put bullets downrange pretty much identically.. (Edit: I found the direct comparison right there on the product website when I poked around wondering if - see below - they made or were planning on a .40. Looks like the energy is basically identical for all manner of rounds.) I also find it likely that the Boberg, being single-stack and tiny, will nestle in the hand much better than the Glock in real life, but that it won't make a real difference in GURPS due to low resolution.

In fact, up-chambered to a .40S&W instead of the 9mm, I'd expect a VERY comfortable pocket pistol, as easy to carry and conceal as the Kahr K40, one of my favorite tiny guns, but with the benefit within that size of an extra inch-ish of barrel. That would make it low on ammo capacity, but as powerful a pistol of something between the G22 and G23, but much nicer to carry.

Anyway, without very specific data (rather than the 2d+2 = 9 pts = 127mm 124gr at 1250fps reference assumption I make) on the real-world penetration of our various bullets at the muzzle, I'd probably say whatever damage code the G26 gets (flip flip flip, checking High Tech . . . p. 101), which is 2d+1, is what I'd go with. The 2d+1 is solid for a generic GURPS 9mm round. I would have no issues with the 147gr bullet we've been discussing getting only 2d . . . . but I don't think any GURPS gamer would take it without some advantage to balance it out.

[HANS]

Originally Posted by DouglasCole

I would have no issues with the 147gr bullet we've been discussing getting only 2d . . . . but I don't think any GURPS gamer would take it without some advantage to balance it out.

The 147-grain load is Subsonic (High-Tech, p. 165). That is its game-mechanical advantage. In RL, it also shoots a bit less snappy, meaning less felt recoil. No, that doesn't affect ST or Rcl.

Cheers

HANS

[fredtheobviouspseudonym]

Originally Posted by RyanW

. . . To get better than that, you would probably have to come up with something like a single shot tube with no grip to speak of.

Let's hear it for the SOE Sleeve Gun. Mark II. http://www.nationalarchives.gov.uk/e...urces/docs/4a/