Swiss Arms POI shift with Bi-Pod

[Ar180shooter]

Ok, so due to a little bit of a debate in this thread about what sort of POI shift one can expect to see when firing the Swiss Arms rifles with a bi-pod versus a magwell rest, I promised to try both, take pictures, and report the results.

Left: Magwell rest
Right: Bi-pod rest

As you can see (by my less than impressive 100 yard groups ), there is a definite POI shift when using the bi-pod. This doesn't come as a surprise, as since you are putting pressure on the barrel, it will be pushed up slightly. As you can see, there is approximately a 3 MOA shift created by simply resting the rifle on the bi-pod.

I will also note that the amount of shift can vary greatly, depending on how "aggressively" you're holding the rifle. I managed to push the rounds off the paper if I was pulling the pistol grip towards my body hard enough. You will also decrease the shift if you're resting the rifle closer to the mag well. I found no discernible POI shift when resting the rifle on the first 6 inches of hand guard.

So basically, there is a definite POI shift when resting a non-free floated barrel on something. The farther up the hand guard the point of rest is, the greater the POI shift will be. If you're engaging steel plates at 250-300yds, you likely won't notice a 2-3 MOA shift; however, under controlled conditions, there is no doubt that the bi-pod creates a POI shift.

 

[ESQ]

Yeah. that's why i ditched my bipod the second time out with this rifle.
Really hoping that NEA builds those free float rails for this beast.

Out of curiosity, does anyone have a rifle length (~20in barrel) non-free floated AR that could do a comparison POI test?

 

[rdgietz]

Thanks a bunch AR180shooter.. wanted to do this experiment myself now i dont have to. Thanks again..

RDG

 

[AlexF]

Ok, so due to a little bit of a debate in this thread about what sort of POI shift one can expect to see when firing the Swiss Arms rifles with a bi-pod versus a magwell rest, I promised to try both, take pictures, and report the results.

Left: Magwell rest
Right: Bi-pod rest

As you can see (by my less than impressive 100 yard groups ), there is a definite POI shift when using the bi-pod. This doesn't come as a surprise, as since you are putting pressure on the barrel, it will be pushed up slightly. As you can see, there is approximately a 3 MOA shift created by simply resting the rifle on the bi-pod.

I will also note that the amount of shift can vary greatly, depending on how "aggressively" you're holding the rifle. I managed to push the rounds off the paper if I was pulling the pistol grip towards my body hard enough. You will also decrease the shift if you're resting the rifle closer to the mag well. I found no discernible POI shift when resting the rifle on the first 6 inches of hand guard.

So basically, there is a definite POI shift when resting a non-free floated barrel on something. The farther up the hand guard the point of rest is, the greater the POI shift will be. If you're engaging steel plates at 250-300yds, you likely won't notice a 2-3 MOA shift; however, under controlled conditions, there is no doubt that the bi-pod creates a POI shift.

Was this on a hard or soft surface?
AR shooters get a similar but lesser effect when using an Harris bipod on hard surface (like concrete).
On grass, it's much less of an issue...

Alex

 

[Miltiades]

Yeah. that's why i ditched my bipod the second time out with this rifle.
Really hoping that NEA builds those free float rails for this beast.

Out of curiosity, does anyone have a rifle length (~20in barrel) non-free floated AR that could do a comparison POI test?

I have an old Colt A2 upper with 20" barrel and non free-floated. I haven't used it in years and I now plan to take it out and see what happens. However, I vaguely recall that it didn't change POI whether I supported the rifle at the hand guard, somewhere mid- location, or from the mag. At least there was not a memorable POI...

I also wish NEA will finally come out with the free-floating handguard for the SAN that they're showing on the web page.

 

[gofaster775]

I have had the same issue with a 16" AR when switching to a bench rest, non free float and the MPI shift was also 3" @ 100.

When firing with a bipod, (especially on a hard surface liike a bench) throw some sand bags under the legs, this will allow for "bedding" your bi-pod into a much more stable and repeatable position. The shift of your position round to round will decrease, because the bipod won't jump or shift as badly. ( not disappear though) I use this method and my group size decreased by .75" on average. If you can go dig that thing into some grass in the prone and try again.