Long stroke SureFire Carrier

[Diamondback]

Just for the hell of it... if we had the chance to combine the best features from everybody's innovations (like a combined Industry Working Group where we had access to everybody's patents) to develop an "Ultimate AR BCG/Buffer System", what might it look like other than starting at the back with either the A5 (or maybe Geissele S42 as an "acceptable alternate") buffer system?

[tom12.7]

If you are keeping the current RE inside diameter, then the A5ish with a little more L1 tension combined with a little less L2 tension using that with a somewhat extended free cam path way for timing events, if used with our current receiver confines. This can work better when looking at certain exhausting of the action relationship. Using those with an appropriate powder and with a combination of lesser case volume to higher bore volume, you can alter timing events further for more benefits.
If you go outside our current receiver confines, you can end up much better, as far as timing events and a few other things go, but you run into the negative of a larger non standard base to use to begin with.
Beyond the concept of firing and unlocking, we also have a magazine problem for the amount of time we have available for proper round presentation. We need to insure that there is enough time after the bolt over travels the magazine, that magazine has enough time to catch up.
There's a lot of things that we can look into for a "system", if we decide to look further into those, with some other items.

[BufordTJustice]

There is a reason the KAC E3 bolt uses a spring retained extractor pin and why LMT added that extra bit to the front of their E-Carrier.

Unless surefire has a better way of retaining the extractor pin it will fall out. The carrier is what retains the pin in the AR bolt.

100% correct. I will assume that SF has addressed this issue.

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[BufordTJustice]

If you are keeping the current RE inside diameter, then the A5ish with a little more L1 tension combined with a little less L2 tension using that with a somewhat extended free cam path way for timing events, if used with our current receiver confines. This can work better when looking at certain exhausting of the action relationship. Using those with an appropriate powder and with a combination of lesser case volume to higher bore volume, you can alter timing events further for more benefits.
If you go outside our current receiver confines, you can end up much better, as far as timing events and a few other things go, but you run into the negative of a larger non standard base to use to begin with.
Beyond the concept of firing and unlocking, we also have a magazine problem for the amount of time we have available for proper round presentation. We need to insure that there is enough time after the bolt over travels the magazine, that magazine has enough time to catch up.
There's a lot of things that we can look into for a "system", if we decide to look further into those, with some other items.

Salient points, Tom.

How much room is left inside the receiver to elongate the gas key, permitting a later depressurization event as it telescopes off of the gas tube?

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[tom12.7]

There's not really any room to elongate the key to gas tube interface without modifications in our current system.
If you basically make a longer version of our conventional key, we run into some issues. Things come up like adding items to support the gas tube since we lost it in the upper. Relocating the interface to an area with less access and exposing other areas to complications resulting from that does not help either.
If you want to extend the interface by moving that away from the muzzle end, then you will need to look into a different type of key with changes to the carrier. There are more possible positives going this direction for many other items as well that we can look into. When we have the options on the table for more than minor changes, we can do a lot.

[BufordTJustice]

There's not really any room to elongate the key to gas tube interface without modifications in our current system.
If you basically make a longer version of our conventional key, we run into some issues. Things come up like adding items to support the gas tube since we lost it in the upper. Relocating the interface to an area with less access and exposing other areas to complications resulting from that does not help either.
If you want to extend the interface by moving that away from the muzzle end, then you will need to look into a different type of key with changes to the carrier. There are more possible positives going this direction for many other items as well that we can look into. When we have the options on the table for more than minor changes, we can do a lot.

Agreed. If we don't wed ourselves to the current design envelope, many things are possible. Particularly without robbing Peter to pay Paul.

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[tom12.7]

There are a lot of things that we can do to make the receivers a better base for most anything that will accept a magazine similar to the size we have now. Most of those are easy to apply, but it is a change though, and that requires a market demand to make it feasible to do so.

[Diamondback]

If you down-chambered an AR10 to 5.56, would its larger receivers allow more room for internal-parts redesign?

[tom12.7]

The overall size can be similar to some AR-10 receivers, but you wouldn't want that as the base.

[BufordTJustice]

There are a lot of things that we can do to make the receivers a better base for most anything that will accept a magazine similar to the size we have now. Most of those are easy to apply, but it is a change though, and that requires a market demand to make it feasible to do so.

Agreed. Though, it would seem, that it would be beneficial to make as many changes as would be optimal if one is to deviate from the std receiver design in any meaningful way.

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