new build - SLR sentry 7 adj GB issue

[jerrysimons]

What would they be? I mean just a couple. I'm not married to this thing.

Well barrel porting or gas-block inserts, but being as a 11.5" mid is so unconventional I wouldn't know where to start with insert sizing and would think you might like the flexibility of an adjustable gas-block.

Interesting discovery taking it apart. It seems one of the parts is out of spec. Since you seem to have it handled mechanically I would have SLR send you a new leaf spring and detent. They will be happy to do so. Swap those in and if any issue like what you found with the included parts appears then you will know it is likely the gas-block housing that is out of spec and you will need a replacement gas-block.

[MistWolf]

Simple? Possibly so, not as simple as other possible options overall.

Yes, simple. A standard gas block is simpler mechanically, but more difficult to tune and almost impossible to fine tune. With a standard gas block, the tuner can change spring rate and reciprocating mass, but can only make gross changes and can only hope the changes will put the carrier speed in that sweet spot between ejecting but not locking back and locking back but buffer slams into the rear of the receiver extension. The SLR also makes it easier to tune the AR to run reliably suppressed while minimizing gas-to-face.

Reciprocating mass, spring rate and gas flow are the three legs of the tuning triangle. Using a standard gas block limits tuning to spring rate and reciprocating mass and if gas flow (port diameter) is wrong, then mass and/or spring rate will by necessity be less than ideal to compensate, a situation which complicates matters. Not simple. Using an adjustable gas block makes it simple to set gas flow correctly.

tb-av, the factors that will make the gas block mushy are spring tension, detent length being short and detent radius not matching the grooves in the adjustment screw. From your description, I think the likely culprit is the leaf spring.

I'm using an SLR 7 on my AR pistol and now that I think about it, it feels a bit mushy too and I have to pay close attention to feel the "clicks". Also, the set screw needs to be turned one third of a turn to go from one "click" to the next. It helps to watch how far you turn the Allen key.

If the adjustment is too mushy, contact SLR and explain your problem and see if you can get them to send you a new leaf spring, detent and set screw.

You other options are to try a standard gas block and hope the gas port in the barrel is the right size, or try the gas block inserts Jerry has been experimenting with. Gas block inserts will work well, but you have to remove the gas block from the barrel to change the insert during tuning

[Hero]

I'm using an SLR 7 on my AR pistol and now that I think about it, it feels a bit mushy too and I have to pay close attention to feel the "clicks". Also, the set screw needs to be turned one third of a turn to go from one "click" to the next. It helps to watch how far you turn the Allen key.

I've got an SLR Sentry 7 on a 10.5" upper of mine. Your description of the feel of its clicks and the amount of turn between clicks is identical to my experience. Upper runs perfectly. Still waiting on my can to get jailbroken, but I have its unsuppressed setting currently at the most closed position that still locks open on empty mags (which happens to be 6 clicks open from the fully closed position).

[tb-av]

I put everything back together with the spring flipped. I feel pretty confident with it right now. It feels/sounds just about like what everyone else is describing. It drops in every 1/3 rotation. I have it open about 10 clicks now unsuppressed. That's 2/3 open on a large gas port. So I at least know I've got 5 more clicks to wide open.

Now if I take this back out to fire and no ammo cycles it at any setting or the spring and detent gets stuck and turns to mush again, then I'll go to plan B and probably get SLR involved.

Hopefully the stuck detent and spring was just a fluke and that is now cured.

[Rayrevolver]

Contact SLR. I had a few questions when I first bought my SLR and the owner responded on a weekend. So far mine clicks both in and out, no issues.

Here is some info from my 11.5mid build:

Getting BHO with Wolf Gold 223, these are clicks from fully closed:

Normal carrier+A5H2
Setting 7 - Unsuppressed
Setting 6 - Suppressed

LMT E-carrier+A5H2
Setting 5 - Suppressed

LMT E-carrier+A5H4
Setting 5 - Suppressed

[BufordTJustice]

The SLR is a simple device and simple to fix

Agreed. A simpler gun is a bolt action 1903, but I'm not selling my AR15 for one of those.

This is one issue out of many thousands of gas blocks produced and sold last year alone by SLR. They'll make it right. It's not even close to invalidating the concept.

[tom12.7]

Adjustable gas blocks can help you identify what a base barrel port may need to be in a range, but unless something better comes out, I really do not feel they are a long time solution.
I have spec'd barrel gas port reamers to .0005" increments, but I would hesitate to think that many could notice a .0025" change.
There's a lot more going on than reciprocating mass, spring rate, and gas flow. That view is over simplistic.

[MistWolf]

Adjustable gas blocks can help you identify what a base barrel port may need to be in a range, but unless something better comes out, I really do not feel they are a long time solution.

But is a simple solution for tuning an AR that is to run both suppressed and unsuppressed

I have spec'd barrel gas port reamers to .0005" increments, but I would hesitate to think that many could notice a .0025" change.

What matters is getting the AR to function correctly. On a 10.5" barrel with a .083" gas port and carbine length gas system, suppressed or unsuppressed, the SLR can be set so the AR will eject and feed a fresh round, but not lock back on an empty mag. One more click open and the AR will eject and lock back. One more click open and the recoil feels sharper from the buffer hitting the RE harder

There's a lot more going on than reciprocating mass, spring rate, and gas flow. That view is over simplistic.

What else is there? Gas pressure, volume, temperature, velocity and mass? All affect gas flow. Velocity of carrier as it closes? Spring rate. Carrier momentum as it closes? Reciprocating mass and spring rate.

When using a fixed gas port, an AR can only be tuned by changing the reciprocating mass and spring rate. If the gas port is the wrong diameter, reciprocating mass or spring rate or both, will need to be skewed to compensate

[tom12.7]

Maybe our views of simplicity do not align with each other.
I would tend to think that a simpler solution would be a proper gas port size for a particular combination over an adjustable gas block that has many potential negatives associated with that.
Adding in a variable like a possible can, simulates an additional barrel length for that port size when observing the action's characteristics. Depending on the particular combinations with a proper port for the selected span of operation you may fall into a place that is only non suppressed, suppressed only, or in some circumstances either suppressed or not with change in available action mass. Changing a buffer and possibly a spring does include those additional components, but it does not increase the complexity of the operating system.
I would tend to hesitate to think that most can users take their cans on and off during a role for end use. You either have it on or you don't for most. If the circumstance occurs that could make that switch a requirement, then the few seconds to swap that buffer during that lull is really no detriment compared than using a tool to adjust the gas that has no guarantee that the proper gas selection was performed. How can someone be convinced that an item adjustable as this did not go over or under or get lost in the adjustment?
Given, that I'm talking about proper porting as a baseline for use that suits the range in function as a baseline, either purchased or made. Not using a baseline that is over or under gassed as a baseline, then attempting to add band aids to that.

[tom12.7]

Maybe our views of simplicity do not align with each other.
I would tend to think that a simpler solution would be a proper gas port size for a particular combination over an adjustable gas block that has many potential negatives associated with that.
Adding in a variable like a possible can, simulates an additional barrel length for that port size when observing the action's characteristics. Depending on the particular combinations with a proper port for the selected span of operation you may fall into a place that is only non suppressed, suppressed only, or in some circumstances either suppressed or not with change in available action mass. Changing a buffer and possibly a spring does include those additional components, but it does not increase the complexity of the operating system.
I would tend to hesitate to think that most can users take their cans on and off during a role for end use. You either have it on or you don't for most. If the circumstance occurs that could make that switch a requirement, then the few seconds to swap that buffer during that lull is really no detriment compared than using a tool to adjust the gas that has no guarantee that the proper gas selection was performed. How can someone be convinced that an item adjustable as this did not go over or under or get lost in the adjustment?
Given, that I'm talking about proper porting as a baseline for use that suits the range in function as a baseline, either purchased or made. Not using a baseline that is over or under gassed as a baseline, then attempting to add band aids to that.