Quote:
Originally Posted by clu2415
According to HT, the M4A1 has ACC 4 while the M16A1 has 5. I guess this is due to the shorter sight radius? More accurate barrels are about how carefully the barrel is machined. You can have an 8-10" barrel made with the same mechanical accuracy as a sniper rifle. Barrel length affects velocity, so at long range you will deliver less energy and have a longer bullet flight time (harder to hit moving targets).
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GURPS Acc is not just mechanical accuracy, but is meant to reflect adventuring utility, so I've always imagined that reduced velocity
was a factor in lower Acc for carbines over rifles.
Quote:
Originally Posted by clu2415
A 16" barrelled AR-15 can use a 14-15" long railed hanguard and have the same sight radius as a 20" barrel M16A1, and using a scope makes the sight radius superfluous anyway. Without knowing exactly why the M4 got docked a point of accuracy, I don't know what you can do to or if you can get that back.
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I've never much liked the fact that GURPS makes full-sized M16/AR-15 rifles so much more effective than carbines in combat, even combat at short ranges like 20-100 yds, due to the Acc 5 over Acc 4.
At typical combat ranges, mechanical accuracy is pretty much irrelevant, but ergonomics matter. Pretty much any longarm is accurate enough for torso, chest, vitals or even head shots at up to 100 yds and having sub-MOA accuracy won't help much in a firefight at 25 yards.
In GURPS, though, center mass shots at 25 yards after a second of Aim are easier with an M16 than with an M4 and
much easier with an M16 rifle than with a wartime M1928A1 Thompson. A normal skill 12 user will hit around 50% of the time with the rifle, 37% of the time with an M4 and 25% of the time with a Thompson.
It gets worse if you put a 10x scope on the weapons and allow three seconds of Aim for a head shot at 70 yds. An experienced operator with skill 16 will hit 83% of the time with the M16, 63% of the time with an M4 and 37% of the time with the Thompson.
The undeniable differences in mechanical accuracy between these weapons probably
won't make that much difference at such short ranges. And in the case of the M4, the mechanical accuracy is barely any worse.
I'll grant that flat-shooting trajectories make it much easier to shoot accurately and velocity therefore makes quite a bit of difference. On the other hand, from what I can tell,
both the M16 and M4 are shooting pretty flat at such short ranges anyway.
Quote:
Originally Posted by clu2415
However, high quality barrels for AR-15s are all over the place and replacement trigger groups are everywhere. A high grade trigger like a Jewell or Geisselle talong with a high quality barrel from someone like White Oak Armament, Wilson Combat, or Krieger would definitely get you +1 ACC. That's basically what the US's SDM-R is. $1600 is reasonable for a complete rifle with an adjustable stock, comfy grip, etc, but just a barrel and trigger group would cost way less than that and provide the majority of the improvement. $6-700 is definitely doable for an upgrade to an AR-15, but for any other gun you're looking at a lot more.
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+1 Acc is a fairly significant improvement, as it results in doubling effective range when you account for the fact that Acc also limits any extra bonuses for Aim. I guess I'm wondering whether improvements to mechanical accuracy are enough to justify it if you're also losing some velocity through a barrel shorter than 20".
I'm concerned that I haven't seen any firearm written up in GURPS receive stats like this. None of the FN-SCAR, HK416, Rock River LAR-15 or Barrett REC7 carbines are given higher than Acc 4 in GURPS. I have
never seen a carbine written up as Fine (Accurate) in an official GURPS product.
It seems that the GURPS rules, at least, assume that making carbines equally accurate for practical purposes as rifles at typical combat ranges is either difficult, expensive or otherwise impractical, as it seems that none of the end-users who are buying fancy tactical rifles are doing it.