POI change from bipod to barricade

[Baron85]

I have an AR I built using Seekins upper receiver and triangle handguard that bolts to the upper not the barrel nut. 24” lilja 223 barrel. Shooting prone off a bipod it’s sighted in. Then when I transition to shooting off barricades using a bag I’m hitting .4-.5 mils low at 100 yards. I tested moving the bipod back to where the rifle rests on the bag and it was shooting around .3 mils low from prone.

This was very repeatable between myself and another accomplished shooter so I don’t think it’s shooter error. We played with pressure and free recoil with no improvement. We were shooting bolt guns as well and did not experience this shift.

Double checked I don’t see anything loose and the barrel, gas tube, gas block are not contacting the handguard. Accuracy was excellent in all positions.

Anyone have some advice, tips, tricks ect.

 

[Hecouldgoalltheway]

A couple of things to consider.....

Is the cheek weld correct? Do you have an adjustable cheek piece on the stock that is giving you consistent sight alignment in multiple positions. If it isn't that, then something is touching your barrel somewhere and causing the poi shift, has to be. Can you show us some pics of the rifle please?

Who has a triangle handguard? Is this 1974 again and nobody told me?

 

[BurtG]

Who has a triangle handguard? Is this 1974 again and nobody told me?

The dnr it’s pretty nice

 

[357Max]

I have an AR I built using Seekins upper receiver and triangle handguard that bolts to the upper not the barrel nut. 24” lilja 223 barrel. Shooting prone off a bipod it’s sighted in. Then when I transition to shooting off barricades using a bag I’m hitting .4-.5 mils low at 100 yards. I tested moving the bipod back to where the rifle rests on the bag and it was shooting around .3 mils low from prone.

This was very repeatable between myself and another accomplished shooter so I don’t think it’s shooter error. We played with pressure and free recoil with no improvement. We were shooting bolt guns as well and did not experience this shift.

Double checked I don’t see anything loose and the barrel, gas tube, gas block are not contacting the handguard. Accuracy was excellent in all positions.

Anyone have some advice, tips, tricks ect.

Well that's disappointing to hear. Suppose to be the strong suite of the Seekins.

24" is a long stick, what profile, & what's on the muzzle?

I've got a 22" in a VLTOR F-15 Fusion monolithic & need to test it for shift.

 

[Hecouldgoalltheway]

I dont think that handguard is flexing. This is interesting. Have you tried shooting the bipod off the barricade and the barricade off the bag, in the name of science of course?

Is that a magpul prs buttstock? If so, you should have a solid cheek weld.

 

[srt-4_uk]

Who has a triangle handguard? Is this 1974 again and nobody told me?

Not Seekins. Someone doesn't know their shapes.

 

[Hecouldgoalltheway]

Not Seekins. Someone doesn't know their shapes.

It wasn't what I expected when I read "triangle handguard".

I was thinking:

 

[Baron85]

I don’t have any pictures but will get some in a bit. I’m running a seekins 10x stock. Pretty similar to the PRS. I will check again for barrel contact but pretty confident there is no contact. I had to switch gas blocks due to contact when I built it and I remember double checking everything at that time as well as my buddy and I both did a check over it today.

I’m running a KGM R30k with TBAC CB brake mount on the muzzle.

Not sure what the contour is but it’s a heavy fluted barrel from Lilja. I built this rifle a few years ago so don’t remember all the specs.

The handguard is this one with the matching upper receiver. https://seekinsprecision.com/parts-accessories/handguards/sp3rv3-mod-rail-16.html
It’s triangle ish shaped.

And I did not try the bipod off the barricade. I was using a sawhorse for kneeling and my tripod setup for standing position. Both with a sand filled shmedium game changer. POI for both kneeling and standing were the same

 

[357Max]

I don’t have any pictures but will get some in a bit. I’m running a seekins 10x stock. Pretty similar to the PRS. I will check again for barrel contact but pretty confident there is no contact. I had to switch gas blocks due to contact when I built it and I remember double checking everything at that time as well as my buddy and I both did a check over it today.

I’m running a KGM R30k with TBAC CB brake mount on the muzzle.

Not sure what the contour is but it’s a heavy fluted barrel from Lilja. I built this rifle a few years ago so don’t remember all the specs.

The handguard is this one with the matching upper receiver. https://seekinsprecision.com/parts-accessories/handguards/sp3rv3-mod-rail-16.html
It’s triangle ish shaped.

And I did not try the bipod off the barricade. I was using a sawhorse for kneeling and my tripod setup for standing position. Both with a sand filled shmedium game changer. POI for both kneeling and standing were the same

Next timeout try the same test with KGM removed & see if poi shift is reduced.

The Seekins receiver set is stiffer than std for sure, but it's still aluminum.

Heavy 24 + can may be asking a lot.

I'm surprised no one has made a steel AR upper yet. Everyone adds weight to positional comp rifles anyway & that's who would buy them. I know I'd damn sure buy a couple.

 

[Baron85]

Pictures as requested. The 2 groups on the bottom points of the diamonds are prone. I shot one group then shot off the barricades that went low then went back to prone and shot the other bottom point group. Don’t remember which was first or second but went back to the same point.

The other 2 pictures were off the saw horse with the game changer. I was aiming at the side points of the triangle and both were about the same elevation low. Like said above, after shooting these I went back prone and ended up zeroed again.

I just checked the rifle again and have good clearance all around the barrel and gas block. Nothing touching. And no real flex in the handguard. It is really solid.

 

[Baron85]

Good point on trying without the can, I will give that a try next time. Unfortunately I won’t have time before the competition dynamics match next weekend, kinda eroded the confidence I had in the rifle. Atleast I know I need to hold high off supports.

 

[357Max]

Good point on trying without the can, I will give that a try next time. Unfortunately I won’t have time before the competition dynamics match next weekend, kinda eroded the confidence I had in the rifle. Atleast I know I need to hold high off supports.

There's another potential cause that should be ruled out. If your rifle is dipping in the rear bag when shooting prone, it will shoot high.

You've zeroed for it, but that would also explain what your seeing. On the props the rifle is sitting on the balance point so no dipping in the rear.
Make sure the rear bag is firm & not angled when prone.

223 has little recoil, but there's still the secondary recoil from the BCG.

 

[Molon]

then something is touching your barrel somewhere and causing the poi shift, has to be.

No, it doesn't "have to be" that something is touching the barrel somewhere. Any time that you alter the recoil vector, there's the possibility that the point of impact will be affected.

....

 

[Baron85]

Hmmm hadn’t thought of that. Will check that out next time. It felt very solid and have not experienced that with my bolt guns but they are also much heavier guns.

Thanks for the suggestion

 

[2aBaC̶a̶]

Ever heard of Rifle Kraft? read up. sounds like what you are experiencing.

Rifle Kraft

 

[Hecouldgoalltheway]

No, it doesn't "have to be" that something is touching the barrel somewhere. Any time that you alter the recoil vector, there's the possibility that the point of impact will be affected.

....

Sure, but, and this is conjecture, you likely won't see a perfectly consistent shift time after time if it's a recoil management issue.

 

[JustSendit]

I’ve had gas guns specifically have a poi shift from bipod supported to bag just ahead of the mag on a barricade.

I’ve seen it so often, it’s definitely a thing, and is in my experience, rifle dependent.

It’s may not be eye alignment related and I’ve seen some fairly large shifts, .4-.5mil. I would run the barricade position for 20,30rds on paper if the shift is consistent, then plan it in your dope.

Or confirm it’s a thing.. while I said it may not head parallax, it could be. So build the data before you make your final conclusion.

My gas guns do this but my bolt guns do not.

 

[aslrookie]

24” barrel with a suppressor is your problem. I had a 224 Valkyrie that had the same issues and same POI shift you noted. On prone with bipod, no issues. Shooting off objects, about .4mil low every time and was consistent regardless of distance.

It’s a lot of weight far away from the connection point and asking a lot for the receiver extension to handle. I bet if you took the suppressor off the issue would likely be eliminated.

 

[Baron85]

So assuming it’s not me and it’s the gun. It’s the leverage hanging off the front of the reciever causing deflection. Hence why when I moved the bipod back to where the bag rested I got similar offset down?

That does make sense but sucks. Atleast it seems to
Be consistent. I will have to do more testing to verify.

 

[gthirteen]

If the foreend is connected at the barrel nut, and it’s free floating, why would the contact point on the free floated foreend changing, affect POI?

 

[2aBaC̶a̶]

So assuming it’s not me and it’s the gun. It’s the leverage hanging off the front of the reciever causing deflection. Hence why when I moved the bipod back to where the bag rested I got similar offset down?

That does make sense but sucks. Atleast it seems to
Be consistent. I will have to do more testing to verify.

Why would you assume its not you? maybe just for shits and giggles or because knowledge is power consider reading over that link I provided above.

they have a test to analyze poi shift that goes

• Standing 1, 5, 9

• Kneeling 2, 6, 10

• Sitting 3, 7, 11

• Prone 4, 8, 12

and gas guns just shoot different than bolt guns.

 

[Baron85]

Sorry, didn’t come off the right way. I was trying to understand the idea/theory of the down shift assuming if it’s not me. I am absolutely open to the idea that it is me. I’m going to make time tomorrow after church to go test it out more thoroughly with suggestions provided.

I greatly appreciate all the suggestions so far. And yes I have heard of the Kraft drill and actually have shot with Chris Way at a few of the local matches. I will re read the info you posted and dig back into the Kraft drill. I have been doing something similar but haven’t done it exactly his way in quite some time.

 

[357Max]

If it's not you, the below pic explains better than words.

The whole point of the Seekins, Mega Monolithic, VLTOR fusion, LMT Mars etc is to minimize this.
Unlike std mil spec, these receivers take the rail off the barrel nut in an attempt to stiffen the upper receiver-rail assembly.

On std mil spec the pivot point occurs right at the barrel extension to receiver face. Likely unnecessary for a floated 16" barrel & 12" rail.
Make everything longer and heavier it becomes more pronounced.

 

[BuildingConceptsllc]

If you have a smaller can you could try that too. You could cut the barrel down to 22" also, IF, you determine that's what is going on.

 

[357Max]

If you have a smaller can you could try that too. You could cut the barrel down to 22" also, IF, you determine that's what is going on.

Yeah I looked up the can. The R30K is only 9oz & like 5.8"
I am curious to see if it gets better with the can removed.

I would also make sure all the rail - receiver screws are fully torqued & might consider upping the barrel nut torque to see if it helps. This is assuming Baron is using good recoil management with a firm rear bag.

@Baron85 - I'm not picking on you.
I took a Frank & Mark class in Sept & realized my fundamentals were suffering from bad competition habits.
Shooting a well balanced 20lb 6mm, with a 1lb trigger, & rarely shooting prone doesn't exactly promote the best fundamentals.

For the class I brought my 6.5 Creedmoor with some spicy 130's going 2950. The first thing Mark did at the initial evaluation was tune me up on recoil management. I was also using Mark Taylor's rear bag as was pretty much everyone in the class. There was emphasis placed on proper rear bag use combined with good recoil management. All to prevent dipping in the rear when prone & shooting over the targets.

 

[Baron85]

No offense taken. I’m sure I have bad habits and have never had any classes or professional training. I’m open to any tips, tricks and advice.

I just finished checking all the screws and bolt on the rifle and did a thorough cleaning so tomorrow will be a fresh start. Didn’t find anything loose.

I will be testing with and without the suppressor tomorrow as suggested above. I will also try to shoot off the barricade with the bag up toward the front and a tripod rear support to see if that replicates the prone POI. I will play more with light/heavy pressure as well as try my sand bunny ear rear bag that I have the best success with shooting prone. I was using my game changer as a rear bag which usually works as good but will test for the sake of it.

I started shooting local prs matches relatively serious this year so pretty new to the positional stuff. My normal rifles are a 20 ish pound bighorn 6br, and 16-18# tikka 223 and just finished a Falkor 6 dasher in the low 20’s so this AR is a different beast. I usually only use it to blast prarie dogs but used it for the team safari match a couple months ago and wanted to try it again and see if I could improve on my last performance.

 

[JustSendit]

If it's not you, the below pic explains better than words.

The whole point of the Seekins, Mega Monolithic, VLTOR fusion, LMT Mars etc is to minimize this.
Unlike std mil spec, these receivers take the rail off the barrel nut in an attempt to stiffen the upper receiver-rail assembly.

On std mil spec the pivot point occurs right at the barrel extension to receiver face. Likely unnecessary for a floated 16" barrel & 12" rail.
Make everything longer and heavier it becomes more pronounced.
View attachment 8013407

This is my observation. I’m the first to throw the it’s fundamentals flag. But sometimes it’s the system.

 

[Huskydriver]

This is my observation.

I would be willing to bet there are some guys who doubt this. I would advocate, to test it yourself.

I think people can be very consistent in their fundamentals. Ultimately ruling out that factor, so what’s left? If the shift is observed and is repeated, the phenomenon is due to the system’s construction.

I think the mating of the barrel and the upper is not as rigid as a bolt gun. I have not seen a consistent poi shift from a bolt gun vs a gasser.

I was fortunate enough to do some testing with knights m110s and dozens of shooters a while back and that kind of solidified what I had seen with a few AR10s I owned. Including one with a carbon barrel.

I also had a gasser that had no shift whatsoever. I also saw less or more likely no shift in several ar15s. But I don’t have any that are as heavy as my AR10s where even the carbon barreled rifle had a heavier hand guard and larger brake.

Again just my testing. Maybe it’s sample size is too small but I think there’s something there. Typically groupings we’re 1-2MOA low and sometimes favored left or right (and low). With the m110s if only a handful had a shift, then sure, fundamentals. But it was pretty overwhelming and all trending the same direction and was about 30 different people.

You got me curious to try and see if I can observe this on paper. I am in the shim and glue my ar barrels into the uppers crowd but don't shoot my gas guns enough off barricades to say I have seen this when just smacking steel inside 700.

Do you usually drop your barrels in and just ugga bugga the barrel nut on your gas guns or do you shim extensions or other voodoo?
Etc?

 

[JustSendit]

You got me curious to try and see if I can observe this on paper. I am in the shim and glue my ar barrels into the uppers crowd but don't shoot my gas guns enough off barricades to say I have seen this when just smacking steel inside 700.

Do you usually drop your barrels in and just ugga bugga the barrel nut on your gas guns or do you shim extensions or other voodoo?
Etc?

Lol I wish you wouldn’t have seen that post - I thought about it and revised it because I have a feeling there’s a lot who will disagree.

That being said: I don’t do anything dramatic, I run JPs and have a seekins and an OBR. I have shoot them off a lot of barricades preparing for PRS and I have only used what the factory did or in the case of the OBR what the specs say to do as far as torque.

With the knights that’s all done at knights.

 

[bfoosh006]

For the OP, you might find this article interesting, but an extreme test.
https://www.gunsamerica.com/digest/...r-rails-to-find-zero-retention-for-ir-lasers/

How is your scope mounted ?
I ask, because if you use a riser mount, it might help with rigidity . ( pure conjecture )
https://www.precisionreflex.com/rail-risers/242-pri-308-flat-top-rail-riser-with-20moa.html

 

[Baron85]

I am using a warne 0 moa cantilever 1 piece scope mount mounted only on the upper reciever, it is not bridged to the handguard.

My barrel was installed using loctite green bearing retaining compound and was a tight fit in the upper, I remember putting the barrel in the freezer to get it to fit in the upper. I don’t remember what I torqued the nut too but I’m sure it was the 45-50 recommended by seekins.

Interesting article listed above, seems to not have any real data or conclusion on actually bullet accuracy using the scope vs laser but interesting none the less.

 

[Molon]

Sure, but, and this is conjecture, you likely won't see a perfectly consistent shift time after time if it's a recoil management issue.

I never said anything about "recoil management." I said recoil vector.

...

 

[Baron85]

I played around a bunch on another target and seems when I gripped over the top of the handguard and pinched the bag on the barricade it was throwing them low as well as I was putting quite a bit of pressure into the bipod yesterday.

I lowered the pressure on the bipod and stopped gripping over the handguard and the results look pretty consistent, much better than yesterday. The only weird one is the bipod slid back close to the magwell was still low and was really unstable.

Top row was with the can on bottom was can off minus the group circled, that one I just wanted to double check the results from the top row.

Looks like it was shooter error and just need to learn how to shoot this rifle different than my bolt guns, or the bolt guns just do a better job masking my poor form.

 

[357Max]

I played around a bunch on another target and seems when I gripped over the top of the handguard and pinched the bag on the barricade it was throwing them low as well as I was putting quite a bit of pressure into the bipod yesterday.

I lowered the pressure on the bipod and stopped gripping over the handguard and the results look pretty consistent, much better than yesterday. The only weird one is the bipod slid back close to the magwell was still low and was really unstable.

Top row was with the can on bottom was can off minus the group circled, that one I just wanted to double check the results from the top row.

Looks like it was shooter error and just need to learn how to shoot this rifle different than my bolt guns, or the bolt guns just do a better job masking my poor form.

Looks like poi was better with the can off. Your zero would need to adjust down, but 3 of 4 were close on elevation without can.

Still the trend is when gun is supported front and rear = high. Center support = low

I rarely shoot the positions #2 & #4.

For #2 about the only time I pull the bi pod back is for movers to reduce how far I have to arc the back end around to chase them. The closer the mover the farther back it comes.
#4 I typically have it on a bag in front of magwell + rear tri pod support.

For the most common positions #'s 1 & 3, Your target shows advantage going to can removed.

 

[Baron85]

I have never shot with the bipod that far back. I used to slide the bipod about 1/2 way back to shoot off barrel tops but now use a bag. And position 4 was simply to test the theory of flexing. I don’t see any use shooting like that in reality.

Without the can certainly seemed more consistent but the rifle typically shoots better with the can on and I know I perform better suppressed, I hate muzzle blast. This has certainly opened my eyes and will be doing more testing in the future to confirm these findings.

 

[de5115]

Hey brother. I had a similar issue with a wandering zero as I changed shooting positions. I found it was because my eye relief from the scope was changing whenever I changed shooting positions. I ended up placing a piece of tape across my buttstock where my cheek rested on the stock from my prone shooting position. Now whenever I change positions I ensure my eye relief is positioned in the same spot.

+100 for training using the Kraft drill. That’s how I realized I had a problem.

 

[Denver_AR]

@Baron85, wanted to check-in and see how your AR is doing. I've built essentially the same rifle although with different components and am seeing the same .4 mrad POI drop when shooting from a bag off barricade positions. Has this turned out to be a technique issue or an inherent problem with long, heavy ARs?

 

[Baron85]

I have learned to control it better. I think it’s a combination of inherent issue and technique to overcome it.

I just practice on being as consistent as possible with the pressure I put on the forend or pushing into a barricade. Different technique than I use for my bolt guns. I feel im pretty heavy on my bolt guns.

I’m for sure no expert so not sure what’s right or wrong but the rifle has been working very well for me.

 

[FredHammer]

Did anything come of the Kraft Drill in 4yrs of data gathering?

Considering nothing changes with the gun, it's all about body position with differences in recoil movement of the butt pad in the shoulder, and also with changes in eye relief.

There was a reason we had a data book in bootcamp to record our zeros per position.

 

[Rio Precision Gunworks]

It's not always easy narrowing this down with a gas gun. There's multiple recoil impulses and the hand guards can flex depending on the model.

Once you rule out the hand guard (or something else like heavy suppressor flexing things), then it's just a game of consistency. Through training and practice you can achieve pretty much the same POI across all positions.

You can also go through multiple positions shooting and use the center of the collective group as your zero. That helps keep the deviations to a minimum unless one positions is way off from the other.