Re: Rucksack as a rifle rest
When I put the hood on, the sandbag in the top pocket goes in it's place. With the compresion strap tied down, nothing seems to move. At least, if it moves, I can't tell the differance. If I have the full ghillie top packed, the BDU top I'm wearing and the sandbag replace it. However that may be changing the system, I don't seem to notice, the change is not big enough.
Given the wide variation in field shooting positions (upslope, downslope, sideslope), whatever variance there may be in the ruck would seem to be lost in the other variables. The same thing seems to apply to shooting off a pod. The differance in the surface the pod is on would appear to be at least as big an issue as the shift in the ruck.
I don't have a strong preferance for either, though I shoot mostly from a ruck. Just this morning I had to test an M1A match rifle for a client. No cheekpiece installed, so I've got more of a chin weld than a cheek weld, but I still got a 1.3 inch group at 200 and a 1.8 inch group at 300. 4 of the 5 at 300 were inside 1.25, I called the last shot a bit high right and it was on call. I don't think I shoot any much better than that, so if shooting off the ruck is hurting me, I'm damned if I can tell.
I will say I've noticed that students seem to have more trouble getting into a position and staying there for 5 shots with a bipod than with a pack. The feet dig into the pea gravel, so they constantly alter the leags. Then the decide to shift onto the mat. Now they slide around a bit to get positioned and the feet stick on the mat and they reach up to adjust, and so it goes on and on and on.....
The guys with a pack struggle to find the right packing to get the right height, but once that's done, they seem to settle down and stay there.
I don't seem much of a differance one way or the other. Clearly, some people have a strong bias for one system. If what you've got works, I'm sure not going to try to get you to switch. On the other hand, if I find you struggling to shoot over your pack because it's so loose packed, I'm handing you a bipod. If you are taking 10 minutes to setup over your pod because you keep diddiling with the legs, I'll put you on my ruck and see if that's not easier for you.
This is one of the areas where I don't think there is a purely right/wrong answer. I certainly have some suggestions as to how each system should be used. Lowlight has made some good points. Certainly filling your ruck with things like a balloon or precut foam or some such is nonsense, it's not a real world workable system. Noone is wasting space and weight on crap like that. What I carry in the ruck is all mission essential equipment. If that turns out to make it unusable as a rest, well, that's why the bipod and sandbags are in there.
Given the discussion, I might just experiment with shooting groups with the same rifle and ammo each day for a week over the ruck and with a bipod and see if there is any measurable differance. The results of such a test would not hold very much signifigance, being only one data point, but it may still be interesting, beside, it would give me some excuse to shoot
CT