Bipod schooling please

[RussellC]

Few questions on bipods. I see some of them in discussions allow "cant" adjustment. I know what cant is, just wondering how this is compensated for with "certain" bipods. I have a small vortex level, And can align cross hairs with a plum bob and string, but wondering how cant adjustment is done, and of course, any bipods to be recommended with this feature?

Since I am shooting an AR, I just use a little english on the pistol grip if needed to true the bubble....probably not the best way?

Often wondered why there isnt some adjustment on the feet or legs...
Thanks,

Russellc

 

[wally]

I have an inexpensive bipod that QD clips to a rail, the legs extend from a spring loaded "pivot" that allows about +/- 20 degree cant. This is much faster than futzing with trying to perfectly level it by adjusting the legs. Works well for me, but I've not yet been able to get to targets past 300 yards, so I may need better for longer ranges -- its been too wet these past six months to get the brush cleared and dirt work done

 

[Bart B.]

As long as the cant angle is the same for every shot, it won't cause horizontal shot stringing.

Sine of cant angle (degrees) times bullet drop at target range equals horizontal shot displacement from zero cant.

Most precise way to see if scope elevation axis is parallel with bore to scope axis is to use a collimator in the muzzle. If it's reticle tracks parallel to the scope vertical wire, it's good.

Using a plumb line requires it be parallel to the bore-scope axis. How is that done? Twisting rifles to align scope reticles to plumb lines twists the bore - scope axis the same amount. All things have to be in line on the true vertical axis using plumb lines.

 

[Orcon]

Buy a Harris S-L and either a "pod-lok" kit or buy the parts from T-Nuts and install. The bi-pod swivels and the handle will allow you to lock it down, plus the legs are notched for fast and secure field adjustments.

I can tell you from experience that if you buy a cheap "Harris-style" bi-pod you will ultimately be disappointed, maybe not right away but eventually. I've bought 3 cheap-ohs, and regretted each one. The Harris, on the other hand, was worth every cent.

 

[RussellC]

As long as the cant angle is the same for every shot, it won't cause horizontal shot stringing.

Sine of cant angle (degrees) times bullet drop at target range equals horizontal shot displacement from zero cant.

Most precise way to see if scope elevation axis is parallel with bore to scope axis is to use a collimator in the muzzle. If it's reticle tracks parallel to the scope vertical wire, it's good.

Using a plumb line requires it be parallel to the bore-scope axis. How is that done? Twisting rifles to align scope reticles to plumb lines twists the bore - scope axis the same amount. All things have to be in line on the true vertical axis using plumb lines.

I see what you are saying. What I had figured is (and obviously suffering from probs you point out) with scope mounted and gun set up on tripod I used the plumb line to line up crosshairs, (well, the vertical one anyway) then set a small vortex level to where bubble is in the middle.

Walking in front of gun and looking from the front, I could see the magazine was ever so slightly not straight up and down. (AR type rifle) Going back behind the gun from firing position, I could see the bubble slightly off. By an ever slight pressure on the pistol grip it moves back to the middle "level" position.

This was what had me interested in this "cant" business. If I shoot from a bag, at 100 yards I seem to have a problem keeping the gun from moving slightly from side to side, with a scope. With a bipod this doesn't happen for me, much more steady. This is what led me to ask this cant question.

Bart, I will study a little on "collimator in the muzzle"......Have no idea!

Would it help to use a small level I have seen for similar purposes that attaches to the picatinney rail leveling gun, (well, the upper receiver anyway) then use plumb line to set vertical crosshairs? Then put the vortez level back on the scope tube and remove the picatinney rail level?

I assume this for cannons is not it! https://www.seilerinst.com/division.../collimator-assembly-muzzle-reference-sensor/

Should I just buy a bore sighter, or does this present the same problem a different way?

Russellc

 

[Nature Boy]

I can tell you from experience that if you buy a cheap "Harris-style" bi-pod you will ultimately be disappointed, maybe not right away but eventually. I've bought 3 cheap-ohs, and regretted each one. The Harris, on the other hand, was worth every cent.

Like Orcon, I have a small pile of Harris knock-offs in my closet that have shed parts, wobble, won't lock and generally frustrate. Eventually you buy a Harris or Atlas, then look at that pile of crappy bipods and tell yourself, ".....dang, didn't learn my lesson that time either....."

 

[RussellC]

Would this any of these items help? http://graflex.com/products/muzzle-boresight-systems/boresight-options

http://www.opticsplanet.com/centuri...g-kit-17-caliber-thru-12-gauge-nsaligner.html

 

[RussellC]

Like Orcon, I have a small pile of Harris knock-offs in my closet that have shed parts, wobble, won't lock and generally frustrate. Eventually you buy a Harris or Atlas, then look at that pile of crappy bipods and tell yourself, ".....dang, didn't learn my lesson that time either....."

Maybe I am looking at the wrong Harris pods, the ones I see are not that expensive, 80-99 bucks or so. Some of these things are well over 200 or more. Like this? Harris Engineering S-BRM Hinged Base 6 - 9-Inch BiPod I found on Amazon? https://www.amazon.com/Harris-Engineering-S-BRM-Hinged-Base/dp/B000JJGXAI

Thanks,

Russellc

 

[RussellC]

Cheap copy that looks suspiciously similar: https://www.amazon.com/CVLIFE-Inche...1254859&sr=1-1-spell&keywords=civ+life+bi+pod

Russellc

 

[RussellC]

Like Orcon, I have a small pile of Harris knock-offs in my closet that have shed parts, wobble, won't lock and generally frustrate. Eventually you buy a Harris or Atlas, then look at that pile of crappy bipods and tell yourself, ".....dang, didn't learn my lesson that time either....."

I have a similar pile of holsters....

Russellc

 

[stoky]

The resolution of small bubble levels is poor.
Shoot at the same POA, in the center of a 3' magic marker plumbed line, at the top and bottom of the BDC, at ±100yds. If the impacts are more than an inch or so off the line, rotate the scope and try, try again. A subtle witness mark on the scope by the ring split might help.
I just put a Shooters Ridge adapter on a 26" bbl .308.
I fear I'm going to end up buying an Atlas.

 

[FL-NC]

I have found the cant feature on Harris bipods an excellent option in the field when the ground is uneven- unlike a shooting bench or flat ground on a firing line at a range.

 

[rabid wombat]

I think Bart B is referring to a collimator like:

http://www.alleysupplyco.com/default.asp?pc=sl

 

[pintler]

"Most precise way to see if scope elevation axis is parallel with bore to scope axis is to use a collimator in the muzzle. If it's reticle tracks parallel to the scope vertical wire, it's good."

I'd love to hear more details about this. I'm not following, I'm afraid - possibly because I've never used one of the collimators.

 

[wally]

"Most precise way to see if scope elevation axis is parallel with bore to scope axis is to use a collimator in the muzzle. If it's reticle tracks parallel to the scope vertical wire, it's good."

I thought the OP was asking about bipods and their ability to compensate or not for uneven ground, not how to determine if the scope is mounted cock-eyed or not.

 

[Bart B.]

Pintier, imagine what would happen if your scope was twisted 45 degrees left in its rings when you zeroed it at 100 yards. Then you wanted to adjust it to zero at 300 yards and needed to raise bullet impact 6" by coming up 2 MOA.

What adjustment would you make on the scope with its elevation adjustment twisted 45 degrees left from a line between bore and scope centers with the rifle held upright? 2.8 MOA up on the elevation knob, 2.8 MOA right on the windage knob.

What if the scope was mounted normally so it's elevation adjustment axis was parallel to a line between bore and scope centers? 2 MOA up on the elevation knob.

 

[stoky]

The Shooters Ridge bipod allows tilt and pivot, with a threaded lever lock. It seems like it would be better if there was more range of friction control of the lock.

 

[RussellC]

I thought the OP was asking about bipods and their ability to compensate or not for uneven ground, not how to determine if the scope is mounted cock-eyed or not.

True, but this works into it, bipod for longer range accuracy, the question was more about cant and effects on sight alignment.
That brought use to scope set up in relation to cant and how they all work together. I did ask to be schooled here, its all good!

Russellc

 

[RussellC]

"Most precise way to see if scope elevation axis is parallel with bore to scope axis is to use a collimator in the muzzle. If it's reticle tracks parallel to the scope vertical wire, it's good."

I'd love to hear more details about this. I'm not following, I'm afraid - possibly because I've never used one of the collimators.

Bingo. Just about the time I think I have it clear, I learn something new which pushes me back a couple steps! Thats OK, it is what learning is...eventually I will step forward in my knowledge quest .

I have learned, Im keeping my money in my pocket until I get this, smaller piles of mistakes.

Russellc

 

[stoky]

no no no
U got it all wrong
You need to buy a collimator and a bipod (or two).

 

[RussellC]

I think Bart B is referring to a collimator like:

http://www.alleysupplyco.com/default.asp?pc=sl

I thought he may mean something lime this.
I used a similar device years ago when I worked at JCPenneys. Yup, back in the day they sold guns, hardware, etc.

I sold guns and accessories, and used a "bore sighter" to set up their scopes. It had a number of devices to go in the bore, depending on caliber, a knob on the end made it expand slightly to tighten.

Then a device clamped on the end of it. As you looked through the scope and into the device, you saw a grid. Turning the knobs on the scope, you lined your reticle up with the grid.

People came back to tell me it got them on paper to where minor tuning was all that was required. I should have bought that thing which I could have had for little or nothing when we closed out hard lines and only sold clothes. (Big mistake, James Cash Penney never intended it to be another clothes boutique, and they have struggled ever since)..but I digress...

Russellc

 

[RussellC]

no no no
U got it all wrong
You need to buy a collimator and a bipod (or two).

Oh for the love of Pete, we both know we have piles of mistakes, and dont worry, Ill have tons of useless bipods and collimators before this is done! Lol

Russellc

 

[RussellC]

Bart, lest I start another "learners pile of mistakes" is this one to have? Or are there others to look at. I like the price range this one is at, 98 bucks and the spuds you need for calibers used?

Thanks for any help in mistake pile reduction.

Russellc

 

[Bart B.]

I think the Sweany Site A Line is the best; I've had mine since 1971. Got a set of Bushnell adjustable spuds cheap at a gun show for it that work well across 22 to 45 caliber bores.

Bushnell's laser bore sighter may be darned near as good. I've thought about buying one, then clamping a barrel in a vice such as the laser spot would be 50 feet away. Then orient the bore sighter every 90 degrees in the barrel to see if its spot went around in a circle. If it does that, it's laser beam is not aligned with the plastic spud in the bore.

I know 7 people who've never made a mistake, error, boo-boo, or other ne'er do well things in life. 'Course they never did anything worthwhile in the first place.

 

[Varminterror]

The effect of a canted rifle is fairly similar to that of the middle case in this picture below, but the picture itself is meant to illustrate the importance of a colimator, rather than simply a laser boresighter to ensure the reticle is true to the bore. The Orange dot is the POA on of the target picture, with a 4MOA hold-over. The green dot on target is the resulting POI. Even though all 3 cases show the same POA, the POI shifts according to the angle of the reticle vs. truth line to the bore.