Bipod Pressure / Binding?

[Perkules]

One interesting note here: Sometimes I´ve been shooting with the bipod (Harris) resting on ice. Generally it gives me the least horizontal dispersion compared to other surfaces. I have lightly pulled the rifle against my shoulder with my right hand then, left hand supporting the sock.

Is this an indicator of my bad hold somehow, is it possible that the bipod is sometimes bent or binding when shooting on harder surfaces, thus throwing the rifle off-center during the recoil? Random vibrations? My only problem is horizontal and this light TRG-S 338 LM jumps quite high, sometimes off-center and then I know right away that I hit bad. That doesn´t happen on an icy car top,for example. It recoils straight up then.

I use a sock supporting the buttstock. Replaced with a sandbag, the POI rises almost 1 MOA. (I´m not sure why I mention this now) Is it possible that I should try holding the rifle with a little more shoulder pressure against the bipod to keep it consistant, and / or push the buttstock a bit more firmly downwards? Or pull the rifle with the right hand? Hmm...

There´s no shortcuts I know, just some thoughts here. Nothing moves when dry firing, no flinch and my follow through is fine,stance is natural and comfortable. If I get this fixed I´ll be in consistant 1,5 MOA / five shots club and ... hmm, that would be a good start.

Ideas,please? This rifle is so doggone sensitive to any mistakes,it´s a real challenge. Dropping the bipod is not an option.

 

[Brent]

Petander,

I wouldn't suggest dropping the bipod, not an option for me either. However, I would suggest dropping the carhood shooting altogether. If you're willing to deal with the POI shift, that I think you're body position is likely causing, go for it. I'd shoot the thing the way you will in the field, prone on the ice, dirt, whatever.

I'll have to post a pic of the testing I was doing yesterday off the bench rest verses the backpack layed on the bench, no bipod on this one. POI dropped with the backpack on the table, it did not using it prone though.

I pull the stock up snug with the trigger hand, no more really, support under it with the other, no pressure left or right in my natural body position and squeeze.

I don't think the bipod makes squat for difference if it's on a freefloated rifle, compressed/stressed or what have you.

Like STL said, you might control vertical more putting some downpressure on the butt, especially if you shoulder it low, I'd think. I don't think I hold as firm as you guys might.

 

[Len Backus]

Like STL, I hold very firm back-pressure of the butt into my shoulder.

[ 03-19-2004: Message edited by: Len Backus ]

 

[Guest]

There are a lot of myths with bi-pods... for a long time guys said you couldn't shoot good groups off a hard surface or that they cause inconsistency. In my short time experimenting with them I havn't found any of these to be true . What I have found is that my technique needs to be more consistent. When you apply rear pressure with your right hand use ONLY your 2 middle fingers to apply this pressure! If you use your pinky and your thumb the pressure they apply tend to touque the rifle. Also, you really need to concentrate on pulling firmly straight back into your shoulder. The next thing is the tough one... the same amount of pressure applied...
I have heard some crazy things while guys have shot off their vehicles... I feel that the metal is "springy" and cause wierd groups....

[ 03-19-2004: Message edited by: Ric Horst ]

 

[Jake in NC]

.. A lot of my shooting is done with bipods off of truck hoods and on the ground.. I have done tests with a couple of really accurate rifles (both sub .5MOA with regularity)to see what effects tension in the bipod legs, surface stability and rigidity has on POI..
..At 100 yards "pull-back" tension in the bipods resulted in an average 1" higher POI than when tension was released (align the rifle, pick up the front end and set it down so the bipod legs aren't twisted or otherwise tensioned).. I also got better results on very rigid surfaces when something was put under the legs for shock absorbtion.. The most dramatic results being with a Sako .17 MachIV that regularly shoots sub .5MOA shooting 1" or bigger off a rigid surface..!!
.. Flimsy surfaces (like some truck hoods) resulted in poor accuracy as well..
.. I've never has very good luck with light, heavy recoiling rifles and bipods..
.. Heavy rifles with muzzle brakes seem to do OK as long as the surface is reasonably stable.. The braked 7Mag Sendero seemed to maintain POI no matter what it was set on..
.. As far as hold goes my best results are usually with a semi-free recoil hold.. I hold my shoulder with just enough contact to keep the rifle from coming back and dotting my eye and squeeze the bag for fine elevation adjustments.. The type of bag varies with the situation.. One key thing is watching that rear swivel stud.. It can wreak havoc on accuracy if it's contacting something stable enough to alter the path of the recoiling rifle..
.. One thing to keep in mind tho' is that most of my experience is based on groundhog hunting that is still only out to around the 500 yard mark, so far.. So my points may not be valid for longer or more precision shooting.. d:^) JiNC

 

[Ian M]

Jake,
Nice info, that is very much like we find also. We have a .257 Weatherby that shoots reasonably well off bags and a pedastal, around 3/4" with factory loads, sometimes an inch. Put the Harris on it and it becomes a solid 3 inch rifle, might get into the 4's (4.0"!). I think that flimsy composite factory stock is the culprit.

For much of our bench shooting (benches are concrete) we put a piece of closed cell foam under the Harris or just lay a soft guncase across the bench so the Harris sits on it. Pretty much all of our long range practice is from prone, in the dirt and we never have any stringing problems with the Harris's.

I believe that kicking rifles have to be held tight, but consistent. Shoot them with a loose hold and my accuracy goes to hell.

ps I still feel bad about zapping your Savage topic

 

[Brent]

Like Ian said, my buddy Brian had a 338 that began shooting groups in the "feet" range when the Harris was clamped on. Freefloating the barrel brought it back to what it shot from the rest, that's all it was.

Ian,
Was that .257 already freefloated and doing that?

My 300 Ultra 700 BDLSS is the only one I have real experience at LR with the bipod, some with my sons M70 308. The Ultra shoots phenomenal, and I can't see zip for difference between it and a bench rest. I'm confident enough I can do load development easily with that combo. Half the shooting I've done with it was off of a hard plywood top I fitted to the box on my Polaris 6x6.

I stopped shooting off the truck hoods when I "spidered webed" the windshield on my buddies Nissan PU with the Ultra...

 

[Len Backus]

John said: <BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR> "load" the bipod in the same direction and with the same amount of force. <HR></BLOCKQUOTE>

Jake said: <BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR> "pull-back" tension in the bipods resulted in an average 1" higher POI than when tension was released <HR></BLOCKQUOTE>

John and Jake, can you guys expand on those thoughts, please?

Also, as to Brent's comments on free-floated barrels...I agree and S1 feels in addition, that the stock must be designed to achieve a very high degree of stiffness forward of the action.

 

[John Burns]

Len,

Hope I can explain this so it makes sense. I suspect most guys do this already in one form or another but here is what I have found.

When the legs of the bipod are on the ground you either are pushing forward against the legs, pulling back against the legs or are neutral. I have always had the best luck with Harris Bipods by slightly pulling back against the legs. In other words I would position the legs away from me so the finale movement would actually slightly drag the rifle back into my shoulder and preload the bipod with slight rearward pressure. With the Harris, the legs don't swivel forward and backwards so it is hard for me to shoot from a neutral position because I can't detect if I am in fact slightly preloading one direction or another from shot to shot.

The solution was to always preload by dragging the rifle rearward. I have not had good results preloading forward.

I have switched to the Versa Pod because it is so swively (My new word for the day). I can feel if I am muscling the gun and seem to be able to be more neutral in my shooting. I still drag the gun rearward but the finale movement is to push it forward about 3/8".

As to POI shifts this is an area that need more work than developing the "magic" ¼" MOA load for your rifle.

 

[Jake in NC]

".. ps I still feel bad about zapping your Savage topic .."

Hehehe.. I put that little SNAFU in my back pocket.. It may become useful one-of-these-days..

..More later.. I'm at work, still..

 

[CAM]

has anyone tried moving the tripod back to maybe the balance point of the gun? (just wild thinking!)

Seems like the further apart the rests (front and back) the better from a mechanical view.

CAM

 

[Perkules]

Gentlemen,

thanks for sharing all the great info, I never thought I´d get THIS MUCH feedback !

Working on it, working on it...

 

[John Burns]

One thing to remember is to "load" the bipod in the same direction and with the same amount of force.

 

[speedbump]

I've found just the opposite of John Burns. I preload forward. For me, preloading rearward gives the bipod legs flex in the springs, which I've found to give big vertical dispersion.

Try benching your rifle up with bipod & rear bag. Stand to the side of it & pull it to the rear about 2" while keeping the bipod feet in the same position. Note how the springs allow a vertical 'mushiness' like a '72 Olds with bad shocks? That allows the rifle to move alot under recoil & prior to the bullet exiting the muzzle. The effect is compounded in winter with heavy clothing unless firm rearward pressure is applied to compress the clothing since the buttpad moves about 2X farther under recoil.

My technique evolved over time to utilize a clump of grass or other object to 'seat' the pipod feet against while maintaining firm rearward pressure with body position & less rearward tension with the shooting hand. This allows less movement under recoil & tighter groups...for me at least. Your mileage may vary!