Re: Bipod for trainer
i have the harris, the caldwell, the wally world winchester and a shooter's ridge.
although none of them seem to match the quality of the harris (spring tension, possibly the metal composition the knobs and hardware along with the finish), for "trainer" purposes any of them will do fine. for a heavier rifle the harris seems more solid. i think the biggest factor to select is the height.
the 6-9" harris is great for the bench as you can get lower on the bench and get a good solid stance and eye alignment.
the 9-13" winchester is a nice height for prone, as it gives you a few more inches the get a good prone position / eye alignment (at least for me) where the 6-9" comes up just a little short.
the 13-27" i have is nice for kneeling / sitting positions while hunting but tends to be too high for bench and prone shooting, as it gets the platform over the high grass. usually i'll attach this one to my field rifles and have the 9-13" along if i get into lower stuff.
swivel or non swivel? for bench and dedicated prone target shooting, i like the non swivel type, but for hunting i like the swivel (swings like a pendelum, so you can get even on uneven ground quickly). there is a tension knob on the rear of the bipod to tighten it is you should choose to when in place. there are also locking levers available to add on to make this quicker and easier. when there's time to set up even (like at a bench) the the swivel is really not so much of a needed feature as you have time to adjust the legs.
smooth or notched? for bench i like the smooth as you can get the rifle dead nuts even and for comfort, adjusting the legs in small graduations. the notched is ok for those hurry up and shoot type of shots. if you deploy the legs too high, you can almost immediately collapse the legs in around 3/4" increments. but if not paying attention the legs can cmopletely collapse and having an "oops, oh sh*t" moment.
the way the legs deploy / collapse in the different manufacturer's varies too.
the harris 6-9" smooth leg - legs are pullouts. no need to press a button to deploy. press button to collapse, or if micro adjusted, just loosen knob and leg goes back in. quick and easy on both counts, can be micro adjusted to find that sweet spot for getting the rifle even and for comfort.
the caldwell swivel 9-13" notched leg - you have to press the button, they shoot out, hard to control the where it will stop. to retract, you have to press the button, and physically push them in until you hear a click. no immediate retraction or adjusting knobs to lock in between the notches to get to the sweet spot height between the notches, but is nice for quick shots. just have to make a minor elevation change in rear support to get proper sweet spot height. again you have to physically push in the legs for retraction.
the winchester smooth leg - you have to unloosen the round adjustment knob, then pull out the legs, then tighten the round knob again to have them lock into place at whatever height. to keep them collapsed, you have to have those round knobs tightened or gravity just sucks them out. if having to deploy the legs quickly, is a bit of a hassle. they are not spring loaded in any sense - retracting or deploying. but for $40.00 serves the purpose well, and unlike the notched, can be micro adjusted.
the shooters ridge 13-27" smooth leg - all the spring loaded features of the 6-9" harris mentioned above, along with the ability to micro adjust. gets you above the ground clutter, but the base height of 13" is a bit too high for me in the prone position.
i do like the round mounting knob found on some of the models for tightening / switching in the field as you can get more leverage with that design over the sloted mounting screw. no need for a screw driver or coin to tighten.
so IMHO, for my shooting/ hunting style:
6-9" harris non swivel smooth leg for dedicated bench
9-13" non swivel smooth leg for dedicated prone.
13-27" and a 9-13" swivel smooth leg for hunting.
in a nutshell, swivel for hunting - non swivel for target.
in all of the different heights, them i'd like the pull out deployment, press a button retraction with the micro adjusting smooth leg feature, but the "less than harris" models don't incorporate all of that. the notched will suffice, but keep in mind no sweet spot height can be obtained with out adjusting the rear support, and you have to pay more attention to your adjustments in a hurry up type of shot, and i don't believe thaey are as nice for dedicated bench / prone target shooting as the smooth leg.