02-10-2021, 02:33 PM
So there are a lot of ways to assess this - in the end it comes to buy what makes ya smile! But if you do want to get analytical on it; here's my criteria for assessment.
1) range to 1000 ft-lb energy (for standard hunting ranges; some say 800 ft-lb is OK). This is your distance of optimal/ethical terminal effectiveness (depending on who you talk to at least)
2) range to transonic flight (~around 1250 fps or so can be when various subsonic destabilizing eddies can start to form) Also look at range to subsonic, which is around 1100 fps.
3) what is the purpose of this gun, and the appropriate balance of weight to performance? Usually I want my gear to be cross-purpose capable.
Two tools to help you with that
1) Any ballistics app (I prefer Strelok - Pro); run it to give you velocity and energy in 10 yard increments out to 1200 yards.
2) Gordons reloading tool, which will give you muzzle velocity of any particular load as a function of barrel length. i.e. it gives a travel curve down the barrel showing you the velocity of the bullet at any point. Just look up almost any reloading recipie for your particular bullet, and put it in there; then adjust the powder charge until the exit velocity matches up with whatever is published for whatever their published BBL length is, and you have it. Use the velocity at 12, 14.5, 16, 18, 20, 22 for your math in Step 1 above.
If you do comparisons based on those first 2 criteria, you see and learn quite a lot. For example, criteria 1 ( @800 ft-lbs for varmints... and such), shows that BBL length in 5.56 makes a tremendous difference in relative "terminal" range. And shows that 16" actually has almost double the terminal range of a 14.5" (depending), and 20" can be double that. In 5.56, BBL length can matter. If you read BlackHawkDown, they complain about how ineffective the 14.5" was at any distance beyond shooting across the street. The original 20" spec of a skinny light 20" M16, is a much better spec than it gets appreciation for today - I think at least.
For Grendel, the math on those two gets interesting. Even little 12" can impress; with 1000 ft-lb energy at the more typical <200 yard hunting ranges. And if you are at high altitude, even a 12" can be supersonic (i.e. still relatively accurate) out to 1,000 yards (depeneding). Kind of incredible. While Grendel was original developed with long barrels in mind (it seems), it really shines in the shorter barrel configuration as well. FWIW, I'm working on a build for a 14.5" skinny barrel with a pin and weld brake, to be that ultimate optimization of size and weight to distance and performance (without SBR/pistol reliance), for this reason. Obviously that won't be a 1000 yard gong-banger, but it can be if I point it that way, as it'll still be supersonic at that distance.
I will say, you don't HAVE to go short, to be handy. One option also that folks seem to not appreciate is that a skinny profile longer barrel can have similar weight and balance(ish) to the common thick-countour shorter BBL; but giving you the advantage of that longer ballistics. (i.e. M16A1)
Also, BBL length advantages are most profound the shorter your start from. Going from 12" to 14.5", will in general have more benefit that going from 16" to 20". That's why I tend not to mess with 22" or longer barrels much, as the length does start to get unwealdy, for only so much advantage. Depends on the roll - if you want a bench-bipod-blaster, that goes from car to bench, get a nice 26" heavy barrel. But then, why did you even bother going Grendel and not just go Creedmoor, if you want to do that? To my eye, the entire point of Grendel is optimized performance in as small a package as you can get. If I want to hit really hard really far, and am willing to put on a few extra pounds to do it, Grendel isn't the route I'm going.
Just my opinion - run what brings ya joy; and it's OK to like stuff I don't like
1) range to 1000 ft-lb energy (for standard hunting ranges; some say 800 ft-lb is OK). This is your distance of optimal/ethical terminal effectiveness (depending on who you talk to at least)
2) range to transonic flight (~around 1250 fps or so can be when various subsonic destabilizing eddies can start to form) Also look at range to subsonic, which is around 1100 fps.
3) what is the purpose of this gun, and the appropriate balance of weight to performance? Usually I want my gear to be cross-purpose capable.
Two tools to help you with that
1) Any ballistics app (I prefer Strelok - Pro); run it to give you velocity and energy in 10 yard increments out to 1200 yards.
2) Gordons reloading tool, which will give you muzzle velocity of any particular load as a function of barrel length. i.e. it gives a travel curve down the barrel showing you the velocity of the bullet at any point. Just look up almost any reloading recipie for your particular bullet, and put it in there; then adjust the powder charge until the exit velocity matches up with whatever is published for whatever their published BBL length is, and you have it. Use the velocity at 12, 14.5, 16, 18, 20, 22 for your math in Step 1 above.
If you do comparisons based on those first 2 criteria, you see and learn quite a lot. For example, criteria 1 ( @800 ft-lbs for varmints... and such), shows that BBL length in 5.56 makes a tremendous difference in relative "terminal" range. And shows that 16" actually has almost double the terminal range of a 14.5" (depending), and 20" can be double that. In 5.56, BBL length can matter. If you read BlackHawkDown, they complain about how ineffective the 14.5" was at any distance beyond shooting across the street. The original 20" spec of a skinny light 20" M16, is a much better spec than it gets appreciation for today - I think at least.
For Grendel, the math on those two gets interesting. Even little 12" can impress; with 1000 ft-lb energy at the more typical <200 yard hunting ranges. And if you are at high altitude, even a 12" can be supersonic (i.e. still relatively accurate) out to 1,000 yards (depeneding). Kind of incredible. While Grendel was original developed with long barrels in mind (it seems), it really shines in the shorter barrel configuration as well. FWIW, I'm working on a build for a 14.5" skinny barrel with a pin and weld brake, to be that ultimate optimization of size and weight to distance and performance (without SBR/pistol reliance), for this reason. Obviously that won't be a 1000 yard gong-banger, but it can be if I point it that way, as it'll still be supersonic at that distance.
I will say, you don't HAVE to go short, to be handy. One option also that folks seem to not appreciate is that a skinny profile longer barrel can have similar weight and balance(ish) to the common thick-countour shorter BBL; but giving you the advantage of that longer ballistics. (i.e. M16A1)
Also, BBL length advantages are most profound the shorter your start from. Going from 12" to 14.5", will in general have more benefit that going from 16" to 20". That's why I tend not to mess with 22" or longer barrels much, as the length does start to get unwealdy, for only so much advantage. Depends on the roll - if you want a bench-bipod-blaster, that goes from car to bench, get a nice 26" heavy barrel. But then, why did you even bother going Grendel and not just go Creedmoor, if you want to do that? To my eye, the entire point of Grendel is optimized performance in as small a package as you can get. If I want to hit really hard really far, and am willing to put on a few extra pounds to do it, Grendel isn't the route I'm going.
Just my opinion - run what brings ya joy; and it's OK to like stuff I don't like