Stiffest upper receiver for long heavy barrel

[Baron85]

I don’t remember the exact shifts but I want to say it was around 1/4 ish moa and my other at was 1/2moa roughly.

That was with firm shoulder pressure vs light shoulder pressure.

Also firm grip over the hand guard onto a bag slightly influenced it as well.

Here is a picture of the finished product.

 

[RSKYBSNS]

I don’t remember the exact shifts but I want to say it was around 1/4 ish moa and my other at was 1/2moa roughly.

That was with firm shoulder pressure vs light shoulder pressure.

Also firm grip over the hand guard onto a bag slightly influenced it as well.

Here is a picture of the finished product.

Man that is some serious eye candy! Has me reconsidering wanting to go with a longer barrel!
That was one thing I had on my mind I'm glad you mentioned it, hand placement on the handguard and its effect.
What is the grip you have on the lower?

 

[Brym427]

Kac

 

[Ledzep]

My experience with the Seekins IRMT3 and my 24" 6mm ARC barrel was .2-.3 mil total shift between shooting off a bag on a prop/barricade to a loaded bipod. Moving the bipod along the ARCA rail under the handguard also caused a slight elevation shift. Resting the bipod on grossly uneven surfaces induced horizontal shift. The last two 2-day PRS matches I've shot with a bolt gun I've finished top 10. Last year when I ran gas gun I think 57th was the best I finished... You can make AR's shoot very well (Sub-MOA is realistic with enough tinkering) but the POI shift costs impacts.

As far as I'm aware, that's still the best case situation for an AR. Until someone makes a stainless steel beefy upper. The other approach that is probably viable would be to attach the ARCA to the lower and mount the bipod completely separately from the upper. If an MDT Chassis and AR-15 lower had a baby, basically.

 

[6.5SH]

My experience with the Seekins IRMT3 and my 24" 6mm ARC barrel was .2-.3 mil total shift between shooting off a bag on a prop/barricade to a loaded bipod. Moving the bipod along the ARCA rail under the handguard also caused a slight elevation shift. Resting the bipod on grossly uneven surfaces induced horizontal shift. The last two 2-day PRS matches I've shot with a bolt gun I've finished top 10. Last year when I ran gas gun I think 57th was the best I finished... You can make AR's shoot very well (Sub-MOA is realistic with enough tinkering) but the POI shift costs impacts.

As far as I'm aware, that's still the best case situation for an AR. Until someone makes a stainless steel beefy upper. The other approach that is probably viable would be to attach the ARCA to the lower and mount the bipod completely separately from the upper. If an MDT Chassis and AR-15 lower had a baby, basically.

It is too bad that the Springfield Armory SAINT Edge ATC was a flawed execution of the idea.

 

[Baron85]

Man that is some serious eye candy! Has me reconsidering wanting to go with a longer barrel!
That was one thing I had on my mind I'm glad you mentioned it, hand placement on the handguard and its effect.
What is the grip you have on the lower?

It is the mdt elite I love it since I have xxl hands.

 

[DeadFox]

My experience with the Seekins IRMT3 and my 24" 6mm ARC barrel was .2-.3 mil total shift between shooting off a bag on a prop/barricade to a loaded bipod. Moving the bipod along the ARCA rail under the handguard also caused a slight elevation shift. Resting the bipod on grossly uneven surfaces induced horizontal shift. The last two 2-day PRS matches I've shot with a bolt gun I've finished top 10. Last year when I ran gas gun I think 57th was the best I finished... You can make AR's shoot very well (Sub-MOA is realistic with enough tinkering) but the POI shift costs impacts.

As far as I'm aware, that's still the best case situation for an AR. Until someone makes a stainless steel beefy upper. The other approach that is probably viable would be to attach the ARCA to the lower and mount the bipod completely separately from the upper. If an MDT Chassis and AR-15 lower had a baby, basically.

Did you ever experiment with “bridging the gap” - locking the receiver and handguard together at the pic rail via riser or something similar? As a way to stiffen the whole assembly. Makes sense to me, but never really see it done

 

[PappyM3]

Did you ever experiment with “bridging the gap” - locking the receiver and handguard together at the pic rail via riser or something similar? As a way to stiffen the whole assembly. Makes sense to me, but never really see it done

I’ve thought about that with the PRI rail for use on other handguards. Unfortunately, the front attaches to the handguard with screws. A version that was just picatinny attachments up front would be interesting to test. It may require barrel nut shims to get the picatinny to line up, depending on handguard.

But I do think we need to bully some companies into making a steel upper.

 

[Ledzep]

Did you ever experiment with “bridging the gap” - locking the receiver and handguard together at the pic rail via riser or something similar? As a way to stiffen the whole assembly. Makes sense to me, but never really see it done

No I didn't, but IMO that's slapping another bandaid on the wound. Better than nothing but maybe a guy should use stitches.

Swapping to any flavor of CM or stainless steel immediately increases the rigidity 3x. If you had a stainless Seekins style upper I think you'd be in business. If you did that AND isolated the bipod mounting from the upper by putting a rail on the lower, you'd really be rocking and rolling.

 

[6.5SH]

Went and re-read the old thread on the ATC. Drake's Patent drawing is what should have been made:

Springfield Saint ATC Elite Review

Here is a quick review of the Saint ATC Elite from Springfield Armory. Why This Gun? I was always fascinated by the Drake Athena Chassis...and also horrified. Would this be the biggest waste of time ever or what? The claim to fame was that nothing touched the barrel nut at all...which is...

www.snipershide.com

 

[232593]

Kac
View attachment 8387109

What barrel length & caliber do you have there?

 

[Forgetful Coyote]

I’ve thought about that with the PRI rail for use on other handguards. Unfortunately, the front attaches to the handguard with screws. A version that was just picatinny attachments up front would be interesting to test. It may require barrel nut shims to get the picatinny to line up, depending on handguard.

But I do think we need to bully some companies into making a steel upper.

What about just going with a LMT or Mega monolith?

 

[PappyM3]

What about just going with a LMT or Mega monolith?

One reason is for CMP High Power/Service Rifle. Can't have one-piece receivers/handguards, and the receiver itself needs to look like a mil spec upper. But also, getting barrels modified to work with LMT is just a pain in the ass.

 

[Baron85]

Someone bumped my old thread I made about POI shifts with my AR, figured it may be helpful or interesting to others here.

POI change from bipod to barricade

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...

www.snipershide.com