10-24-2010, 03:48 PM | #1 |
Join Date: Oct 2010
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Stats on unlisted calibers
Hey guys, I am relatively new to GURPS, and have started by picking up the Basic Set, High Tech, SEALs in Vietnam, Gun-Fu, and Martial Arts.
I've done a LOT of looking, and haven't been able to find any stats on firearms chambered in the Remington 6.8x43mm SPC, the 6.5mm Grendel, or the .50 Beowulf. I figured I'd have make them up, but I haven't familiarized myself enough with the rules to do it well, so I'm asking the community for help. Are weapons in those calibers statted out in other books for 4e, or has anyone made them up, and if so, what guidelines did you use to help you figure out the stats? Also, as a sidebar, what's with the wacky ranges and target distance difficulty? I figure I must be missing something when an M4 is listed with a range of 750/2900 YARDS. What the heck??? Any help would be appreciated. |
10-24-2010, 03:50 PM | #2 |
Join Date: Feb 2009
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Re: Stats on unlisted calibers
I think .50 Beowulf is in Monster Hunters
There is also the awesome Douglas Cole simple damage calculation system, all you need is the diameter of the round, weight and velocity and it gives you a damage |
10-24-2010, 04:17 PM | #3 | |||
Doctor of GURPS Ballistics
Join Date: Sep 2004
Location: Lakeville, MN
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Re: Stats on unlisted calibers
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The 6.8x43mm SPC will, IIRC, make an appearance in the forthcoming Tactical Shooting. Quote:
For the 1/2D range, it depends on how you clock it. Ballistically, the 1/2D range for the 5.56x43mm round has nothing to do with the rifle, and all to do with the round; it will lose half its velocity, and thus half its damage, based on how it decelerates from its initial velocity, and basically hits V = 50% x Vo. For the M855 I calculate this as about 405yds.
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10-24-2010, 04:39 PM | #4 | |
Join Date: Jan 2010
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Re: Stats on unlisted calibers
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[edit]: Never mind, damage is sqrt of KE. Sorry. Last edited by lexington; 10-24-2010 at 04:44 PM. |
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10-24-2010, 04:40 PM | #5 | ||||
Join Date: Oct 2010
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Re: Stats on unlisted calibers
Thanks. I'm interested in eventually running a modern SpecOps campaign...probably something with CAG/DEVGRU level players. I figured those books were a good place to start
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A stationary human-sized target at 700 yards requires a shot at -15 to skill Two equally skilled operators are prone (with bipods), and are lining up shots on said badguy. One operator is using an FN SCAR-L (SV) in 5.56x45mm with a fixed 4x scope (Acc = 5+2). The other is using an FN SCAR-H (SV) in 7.62x51mm with the same fixed 4x scope (Acc = 5+2). Both weapons are braced, and both shooters are going to take the maximum number of Aim actions before shooting. At the end of it, the difficulty of both shots is identical. In reality, making a 700 yard shot is MUCH harder with 5.56mm than with 7.62mm. Am I missing something, or, other than the 1/2 damage thing, does the round you are firing not influence the difficulty of the shot at all? So basically, given two platforms with the same ACCURACY and same quality optics, the difficulty of a 2000 yard shot will be the same, even if one platform is firing 5.56x45mm and the other is firing a .50 BMG? |
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10-24-2010, 05:05 PM | #6 | ||
Join Date: Jul 2005
Location: Jeffersonville, Ind.
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Re: Stats on unlisted calibers
Check e23, it's only "printed" as a PDF.
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10-24-2010, 06:00 PM | #8 | ||||
Doctor of GURPS Ballistics
Join Date: Sep 2004
Location: Lakeville, MN
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Re: Stats on unlisted calibers
As mentioned earlier, it's an e23 release, so always.
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My own numbers would suggest the following numbers, given: 115gr round at 2650fps (7.45g at 808m/s), assumed 55,000psi from a 16.5" barrel. Aspect ratio about 4.2 Damage: 6d Max Range: about 4000yds 1/2D range: calculated at about 550yds* For the 6.5 Grendel, I assume a 123gr 5:1 aspect ratio bullet at 2615 fps (8g at 797m/s). Delivered at 50,000psi from a 20" barrel. Damage: 6d+1 Max Range: about 4450yds 1/2D range: calculated at 640yds *These ranges are literally the range at which the round falls to 1/2 its muzzle velocity, therefore roughly half its damage (exactly half using the unpublished semi-official ruleset Hans and David use for gun stats). By this same calculations, the M855 5.56x43mm bullet is 1/2D of 406yds, and the standard 7.62x51mm NATO bullet is 578yds. Quote:
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One more point: in totally, meaning mathematically perfect, still air, the two shots probably ARE the same. Given my calculations, which are admittedly not perfect, the 5.56mm round will arrive on target after 1.38 seconds; a 7.62mm round roughly 1.28 seconds. So essentially equal time of flight, the very high initial velocity of the small caliber round canceled out by how fast it slows down. OK...so there are two things that will drive the answer here, making the shot with the bigger bullet more reliable in reality, plus a third that will appeal to gamers everywhere. 1. Time of flight at long range. This example is pretty close, but at longer ranges, the retained velocity of longer and heavier bullets will mean less chance for the target to move or random stuff to interfere with the shot 2. Wind and air density fluctuations between you and your target. The small mass bullet will be impacted by this more, and this is the missing link between reality and GURPS. 3. Oh, yeah...the 7.62 will arrive with 3.5d damage instead of 2.5d. We all like that. Quote:
Bigger, heavier bullets tend to be more accurate, though...and out of longer barreled rifles with good scopes, will deliver better...this can be properly found using the Acc ratings of various precision rifles. I don't think you'll find many Acc 6 rated .223s, though you might find them in .338 Lapua Magnum (as near as I can tell, the "Sniper Rifle" from Basic Set) and .50BMG. I did a quick search, and there are people out there hitting stuff at 700-1000yds with .223 ammo (usually 69-75grain stuff). The repeated claim I see is "yes, it can be done. No, it can't be done as reliably as .308 and higher..." This suggests that it's really my Point #2 that reinforces the conventional wisdom about long range shooting out of platforms with equal accuracy. It's that in The Real World (TM), you want a heavy and ideally long bullet to resist velocity loss (shorter time of flight, flatter trajectory) and not be as influenced by random variation in unknowables. But to make a long story...less long: within what GURPS considers, the two guns will hit the same target the same amount. Given that +1 is 50% longer range, this is correct.
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10-24-2010, 07:23 PM | #9 | |||
Join Date: Oct 2010
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Re: Stats on unlisted calibers
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This does bring up another question, however. HT lists the FN MK 17 Mod 0 [aka SCAR-H] (guessing 16" barrel, firing 150 gr 7.62x51mm ball at ~2600 fps)as doing 6d damage, same as the 6.8 SPC you specced out. Granted 35 grains of mass isn't THAT big of a difference, but it should be enough to at least warrant a +1 difference, don't you think? I would REALLY like to see that spreadsheet you put together that everyone on these forums is talking about, if it's something you are even willing to share. I did something similar for 3rd and 4th edition Shadowrun (VERY time consuming), but I know well the utility it added to the games I ran. Quote:
I suppose my expectations don't always mesh with real numbers, and GURPS, unlike most of the other games I've played (I'm looking at you, Shadowrun), has people involved in game design who actually do REAL research and understand how firearms actually work. This delights me. :-) Quote:
Thanks again for your insight and help. I'm looking forward to getting that SpecOps game going. |
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10-24-2010, 08:09 PM | #10 |
Doctor of GURPS Ballistics
Join Date: Sep 2004
Location: Lakeville, MN
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Re: Stats on unlisted calibers
If you give me a PM i will send the sheet.
The 6.8 and 6.5 are personal interests of mine. Ive had stats for them for a while so it was no sweat to copy them to you.
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caliber, firearms, guns, modern |
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