Bipod affecting point of aim on a non free float ar15

[Travis Bickle]

I was at the range sighting in my new bcm lightweight 16" upper. I have a fixed a2 front sight and a knights armament rear. The rails are 2 piece non-Free float knights armament ras rails.
When sighting in the rifle I put a bipod on the rails. After getting the sights on at 50 yards I removed the bipod, put on a forward grip and started shooting offhand at 50 yards and noticed that my groups were wider than I expected. I shrugged it off as it was my first time using a forward grip and my first time with my new upper. I then decided to take 2 shots on my friends pistol target. I dont remeber what distance it was at, but it was close in at under 10 yards. Both shots were a good 3 inches under my point of aim. I was a little confused, it wasnt until I got home that I got the idea that the bipod putting pressure on my non-free floating rail (and by contact my barrel) messed with my accuracy.

Was the bipod on the non-free float rail most likely the source of my problem? If I put this some bipod on a different upper with a very solid hbar barrel and same rails can I expect the same problems?

 

[Yoshi]

The bipod isn't the issue and if you have a 50yd zero, you'll be shooting low at shorter distances. Could be the ammo with your wider groups at 50yds. Maybe getting used to the new gun?

 

[RoKKboXXer]

What's your height over bore?

 

[mopar92]

AR-15 standard height over bore is 1.5 inches so a 50 yard zero is going to be high. Remember that if you have to take a precision shot at short distance. Second unless you are very very good your offhand shooting will have some wild groups. Torso sized groups at 100 yards is a good milestone. Also does your fixed A2 front post have an "F" on it (stamped) if not your sights are never gonna zero properly.

 

[Half-cocked]

I think AR-15 standard HOB is 2.6".

 

[Russ D]

The bipod isn't the issue and if you have a 50yd zero, you'll be shooting low at shorter distances. Could be the ammo with your wider groups at 50yds. Maybe getting used to the new gun?

This

 

[Travis Bickle]

Its an f marked front sight base, the correct height for the rear. I guess because ar15 sights sit so high above the barrel they are "pointed downward" in order to line up with the bullet trajectory at 50 yards, so at a closer distance it would be expected to always shoot low?

 

[Caeb75]

It is normal for your groups to open up a bit if you're going from the bench to offhand. How do you shoot? There are some things you can do to help out. Making sure you use a consistent cheek weld is one of those things. I personally shoot nose to charging handle as do a number of people here that I know that shoot ar's well.

 

[Biggfoot44]

Yes , in theory there can be POI issues with bipod , likewise w/ tight sling.

But It don't think that is issue here. I'm not sure there is a problem.

 

[hvymax]

It is normal for your groups to open up a bit if you're going from the bench to offhand. How do you shoot? There are some things you can do to help out. Making sure you use a consistent cheek weld is one of those things. I personally shoot nose to charging handle as do a number of people here that I know that shoot ar's well.

Unless you are steadier than your bench yes.shooting off a bench the biggest variable is trigger pull. Offhand you throw in your whole body teetering around and flinching.

 

[sailskidrive]

You should zero at 33 meters using 62gr bullets; at least that's what we did in the USAF. You can then dial for elevation if you have an A2 style upper.

Of course we generally flew desks most of the time, so take my advice in stride.

 

[Travis Bickle]

It is normal for your groups to open up a bit if you're going from the bench to offhand. How do you shoot? There are some things you can do to help out. Making sure you use a consistent cheek weld is one of those things. I personally shoot nose to charging handle as do a number of people here that I know that shoot ar's well.

I worded that in a misleading way. I didnt expect to shoot offhand anywhere near as well as with a bipod but my groups were wider than when using my firends ar or my other upper at the same distance in the past. Im fairly sure now that it was just the vertical foregrip that felt all wrong in my hands.

I want to eventually scope my other hbar upper that has the same knights armament non-free float rails and I need to be sure that having a bipod an a non-free float system wont ruin the accuracy of the rifle before I spend money on a scope. because I have no other appropriate scope or sights me putting a bipod on the upper I talked about in the OP was my way of testing the effects of a bipod on a non-free float rail system

 

[RoKKboXXer]

AR-15 standard height over bore is 1.5 inches so a 50 yard zero is going to be high. Remember that if you have to take a precision shot at short distance. Second unless you are very very good your offhand shooting will have some wild groups. Torso sized groups at 100 yards is a good milestone. Also does your fixed A2 front post have an "F" on it (stamped) if not your sights are never gonna zero properly.

So are you saying that if his rifle is zeroed at 50 yards and takes a shot at less than 30 feet its going to be high?

 

[Half-cocked]

So are you saying that if his rifle is zeroed at 50 yards and takes a shot at less than 30 feet its going to be high?

Here's a ballistic chart that shows bullet trajectory with standard M193-type ammo, from an AR-15 zeroed at 50 yards:

 

[RoKKboXXer]

Here's a ballistic chart that shows bullet trajectory with standard M193-type ammo, from an AR-15 zeroed at 50 yards:

Thanks for that chart, it confirms my grasp of trajectories. Thats why i asked what his HOB was when he was shhoting so close. OP states he was about 3 inches low at under 10 yds. Standard height for AR is 2.6. Pretty close if he was zeroed at 50 yds. I just was asking for clarification of mopars statement about precision shooting at close range and what he meant about shooting high.

 

[Forest]

I think AR-15 standard HOB is 2.6".

That is correct.

The groups opening when going from bipod to foregrip of normal and to be expected. Offhand you are not close to being as stable as shooting from prone or a bench.

The group being lower is expected and normal. Its the result of the bullets trajectory in relation to the height over bore.