A5 w/green Sprinco binding?

[Glass04]

I have an issue with using the A5 with green Sprinco in my SBR. I noticed after a range session that after cleaning and function testing I was getting some binding in the Receiver extension when manually cycling the action.

Build Specs:
Upper - Sionics RGP 11.5”, Rugged Suppressors flash hider, geissele 10” MK3, Geissele gas block, carbine gas tube (melon its), Sionics upper receiver, Geissele airborne charging handle, BCM Ionbond BCG, Trijicon MRO/USO 1-4

Lower - DD MK18 factory lower with following part upgrades - Geissele B-GRF, Seekins safety, Geissele maritime bolt catch, BCM grip, VLTOR A5 RE, A5H3 buffer, Sprinco green, BCM Mod-0 SOPMOD stock, DD QD end plate.

After hearing/feeling the binding I went and grabbed the stock VLTOR spring and swapped it out - no binding. Pulled the buffer/spring and removed the buffer from the spring to compare to the Sprinco and I noticed the Sprinco had a slight ‘S’ curve to it. As I was preparing to head to a two class this past weekend I just swapped the stock spring and ran it with no issue for the two days ~1000 rounds or so.

Ordered a few replacement Green springs for spares and to put back in the 11.5”. None of my other rifles with this setup have this issue.

After putting a new green spring in the lower and cleaning, function checking (no binding), I put the rifle in the safe. Now after pulling it and function checking again prior to a range trip and function checking again - BINDING!!!

No rounds fired on spring/buffer combo and binding is evident. Pulled buffer/spring and sure as shit there’s a ‘S’ bend in the spring!!! Developed somehow in the safe under static spring pressure...

At a loss here as to what is causing the issue. I may pull the RE and swap in a new one. I have noticed some shiny spots in the receiver extension when looking with a flashlight indicating wear - maybe as a result of the bolt tilting and rubbing the RE?

I have only noticed this with since swapping in the A5H3. I have run the stock MK18 upper (prior to barrel replacement for gas port), 14.5 middy (no pin & weld), and the 11.5 on this lower and have just noticed the issue.

Sorry for the lengthy, rambling post but looking for feedback and possible thoughts on cause. Thanks.

[17K]

If it acts right with a normal spring, use normal springs.

I'd buy Colt rifle springs and use those.

[EzGoingKev]

Both my rifles have A5's and Sprinco green springs. I do not have any binding and they have always functioned 100%.

[SteveL]

When it binds is it restricting the rearward movement of the BCG? Or is it just rubbing against the inside of the A5 receiver extension?

You said you noticed it after a range session; did it negatively affect the function of the rifle while you were shooting?

[Glass04]

SteveL - It is noticeably increasing the ‘drag’ on the system when hand cycling the action. No noticeable decrease in function, although I was running suppressed so there would have been more force due to the increased back pressure of the system while running as such. After noticing the problem, I replaced with the factory spring and function was restored with no binding issue. Ran the rifle through a two day course with no issues during or after.

I have other lowers running the same setup (A5 w/Sprinco green) with zero issues as well. Seems to only be symptomatic in this build. One difference would be the use of the A5H3 instead of the standard A5H2 that I have in the others.

I have no problem running the stock spring or trying out Colt rifle spring, just asking the collective if there may be an issue elsewhere in the system that could be causing an issue since I have other lowers running the A5H2 and Sprinco green with no issue.

Not asking for verification of the system - I know it works. Looking to get feedback if this is an indicator of a problem or other issue in the system that should be addressed as this build was meant to be used as my primary HD setup and I would like to know that it is functioning at 100%

[MistWolf]

Is the roll pin of the buffer flush? Does the spring seat completely on the buffer? Where is the S bend forming- at the carrier end? Middle? RE end?

[Iraqgunz]

Just to be clear, since your post in confusing. It only happens when you hand cycle and not when shooting, correct?

[Glass04]

IG - I can’t say it doesn’t happen when shooting but I notice when hand cycling. Yes, There could be some binding from the pressure of the charging handle being off axis for the BCG path when firing (pulling back on the gas key).

The main issue I see is the fact that 2 Sprinco Greens have been deformed - one with a few thousand rounds and one sitting vertically in my safe with zero rounds fired. Something would have to be causing that.

I’ll pull the springs and take pics when I get a chance. I’ll also answer MistWolf’s questions at that time.

Thanks

[tehpwnag3]

Who installed the A5 RE? If done yourself, can you confirm that the nut has been tightened to about 40ft/lbs? Any chance the RE is moving off axis (even slightly)?

If everything is straight and tight, there should be none of this swapping of parts then it works fine then hours later sitting idle it's binding again. That doesn't happen unless something mechanically changes.

[GH41]

Who installed the A5 RE? If done yourself, can you confirm that the nut has been tightened to about 40ft/lbs? Any chance the RE is moving off axis (even slightly)?

If everything is straight and tight, there should be none of this swapping of parts then it works fine then hours later sitting idle it's binding again. That doesn't happen unless something mechanically changes.

What would cause his spring issue if the RE was not clocked right? I don't think he has a problem that a shot of dry lube on the spring and face of the buffer wouldn't fix.