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Goodbye polymer, hello aluminum! My new MKA/TAC-12


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The tale of the Firebird and the logo   The firebird is the phoenix, the bird that rose from its own ashes.   I was once very into dragboat racing and would race at Firebird international raceway

Can I request a lower that has an additional engraving around the safety... that looks like this  

I dont believe you have any idea if firebird would even consider this, before you start speaking to the forum about starting something like this, you should find out if FB would want to do this. I rea

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I too got an e-mail...yea !!

 

1) Do you still have to buy the stock adapter or is it incorporated into the new lower, if yes, is it (millspec or commercial size) ?

 

2) Also, do you get the anti-walk pins shown in the picture from Pyro or do you have to buy those also ?

 

3) I didn't see safe/fire lasered into the lower in the original pics in this post, I assume they are there now in the final piece.

 

 

 

 

Thanks

 

1) No, you don't need a stock adapter. The TAC-12 receiver accepts commercial spec buffer tubes.

 

2) Anti-walk pins are included with the TAC-12 receiver. Reason being is that the stock pins work in a plastic receiver just fine since they somewhat press-fit into the receiver, they do not however press-fit into an aluminum receiver.

 

3) Fire/Safe was not engraved on the receiver, that will probably change shortly.

Thanks for your timely reply.

 

Can I wait and have mine engraved or can it only be done before anodiziing ?

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I thought the threads were the same with commercial and mil-spec tubes.

 

I believe they are too, but we use and suggest commercial for everything.

From what i know, The threads are the same, its the actual tube that is slightly different. So a commercial stock on a milspec tube will be loose and seem flimsy

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There are variances in the diameter of the factory safety detent set screw. If yours is the correct spec it will fit just fine, but some of them have a larger diameter than they're supposed to. All TAC-12s have started shipping with a US made ball detent.

Also, the factory bolt lock roll pin is garbage to say the least. The TAC-12 lower is designed to use a standard AR bolt lock roll pin, however, you'll need to re-drill the hole in your MKA bolt lock to .100-.104.
Lastly, the poorly-filed clearance in the factory MKA uppers for the bolt lock is hand-filed to fit for each factory lower. They're all different since tolerances on the factory lower vary so much. With the TAC-12s all being the same dimensions, in some cases this filing in the upper is insufficient for the bolt lock to function properly, so you'll have to work on that clearance.

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There are variances in the diameter of the factory safety detent set screw. If yours is the correct spec it will fit just fine, but some of them have a larger diameter than they're supposed to. All TAC-12s have started shipping with a US made ball detent.

Also, the factory bolt lock roll pin is garbage to say the least. The TAC-12 lower is designed to use a standard AR bolt lock roll pin, however, you'll need to re-drill the hole in your MKA bolt lock to .100-.104.

Lastly, the poorly-filed clearance in the factory MKA uppers for the bolt lock is hand-filed to fit for each factory lower. They're all different since tolerances on the factory lower vary so much. With the TAC-12s all being the same dimensions, in some cases this filing in the upper is insufficient for the bolt lock to function properly, so you'll have to work on that clearance.

 

Is there a possibility that the bolt lock has been filed at the factory too far to be usable? Are replacement bolt locks available through Firebird Precision?

 

Is the ball detent screw also shipping with the new receiver or should I add one of those to the parts order?

 

The same for the AR bolt lock roll pin? Can you supply those? Any lower parts for an AR are next to impossible to find.

 

Thanks.

 

Bill

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Is there a possibility that the bolt lock has been filed at the factory too far to be usable? Are replacement bolt locks available through Firebird Precision?

 

Is the ball detent screw also shipping with the new receiver or should I add one of those to the parts order?

 

The same for the AR bolt lock roll pin? Can you supply those? Any lower parts for an AR are next to impossible to find.

 

Thanks.

 

Bill

 

The upper was filed by the factory, not the bolt locks themselves, so there shouldn't be any issue with the lock. But no we currently don't offer a replacement bolt lock for the guns.

The ball detent for the safety and the roll pin for the lock will ship with the lower, as well as a set of our anti-walk pins.

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Wait, the firebird FCG is separate? Hrmm. Are they available to order? My lower is already on the way. Saw the new mag release too. Damn slow down folks, I need that now as well.


The day I get this all put together you guys are going to release the TAC-12A1A or whatever it is.... belt felt, drum fed, caseless ammunition shotty...

 

Then I will have order that shit to.

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Your old FCG parts will work. With the exception of the items we include with the lower which are anti-walk pins, safety detent, bolt lock roll pin, and assembly screw everything is backwards compatible with any of the FCG parts made by us, Tromix, and T&N, as well as the factory parts.

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We don't sell our FCG as a stand-alone item, but we do sell a lower parts kit for the TAC-12, it runs $150. It includes our hammer, trigger, disconnector, springs, and ambi safety. If you have one of our lower conversions in your polymer gun it's the same parts. Our earlier lower conversions didn't have an ambi safety so you may have one of those earlier ones.

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Thanks Anubis -

 

Other than Ambi, and 922 is there an advantage to the FB FCG in the TAC-12?

 

I need to order a FB Handguard and New Mag Release anyway now that I have the lower in hand and I am sufficiently motivated to actually start doing something with my MKA. Before I put in another order, want to get all things lined up.

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Thanks Anubis -

 

Other than Ambi, and 922 is there an advantage to the FB FCG in the TAC-12?

 

I need to order a FB Handguard and New Mag Release anyway now that I have the lower in hand and I am sufficiently motivated to actually start doing something with my MKA. Before I put in another order, want to get all things lined up.

 

What do you think of the lower thus far?

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It's damn cool. Glad to see so much investment in a mag fed shotty platform other than S-12 based systems. The AK is an amazing system. I hate the safety for one, though. I enjoy what comes with the fine machined receivers and other goodies on a AR. The TAC-12 brings that to a mag fed shotgun. Just glad to see another flavor.

 

My only real concern now is it could be out-cooled by the TAC12A1 or what-not and I will want to switch gears to that.

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well after calling I'm probably not on the list at all, started one in December I guess, and when I saw the list forming then I was thinking, oh I've talked in length and had her put me on the list before. I guess not, no big deal, I'm patient :)

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My lower has a few issues, one not mentioned yet.

1. Yes it needs the bolt lock drilled to accept the AR roll pin. I did not get a pin in my box (first few shipped out) but have one now.

2, my detent will not fully thread even after chasing the threads with a 10-32 tap. (new detent is on the way, If I can find my 10-32 die I will chase the detent also)

and one not mentioned.

 

The rear assembly bolt has a slot on the lower it fits through. Some guns need to have the slot lowered so the upper moves all the way rearward then the upper will contact the lower at the rear section. (this per Jim)

Mine does this but when tightening the bolt, the lower to upper longitudinal mating surface becomes gapped.

(the upper still contacts the lower at the important rear section)

I hav decided I want full contact so have lowered the bolt slot so the upper contacts at both sides.

 

It's a really nice lower and the custom fitting is no problem IMO

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We've found a number of consistency issues from upper to upper. I've come to the conclusion that the assembly bolt hole is drilled and tapped by hand, and I've seen that hole at the very top of the lug all the way to the very bottom. This issue has become more pronounced with the XN version of the gun, with the very worst being the run of guns that have XN at the end of the serial number. This produces problems for current buttstock adapters on the market, as well as our lower. We did our best during design to accommodate the vast majority of uppers out there, but some of them are just so far out of tolerance it's ridiculous. Some will need hand fit our lower to fit their specific upper.
Another issue we've found, again worst in that same run of XN guns, is that the barrel interface into the upper has been overbored, allowing the barrel to insert too far back into the upper and bear upon the feed ramp before fully seating into the upper. To compensate for this, the factory only partially machined the forward upper/lower mating feature, which pulls the entire upper forward and pulls the barrel off the ramp. But this produces a gap between the upper and lower at the rear, and moves all the load bearing during firing to that forward mating feature. We've had to re-machine uppers in shop to fit, and machine one-off ramps that don't contact the barrel in these cases. Luckily this problem seems to have been short lived as the later run of XN guns seem to all mostly be in spec.

Our upper is only a few months from production and all these minor differences will be a thing of the past. smile.png

As far as the detent goes, they are some metric thread, but virtually identical to 10-32. Unfortunately there are some variances in the factory detents, some threads have been cut deeper than others, resulting in differences in minor diameter. The difference is only about 2 thousandths, but if the threads are cut shallow, they'll not fit in our lower due to the minor diameter being too large. We never saw this issue in the polymer lowers simply because polymer is far less rigid than aluminum and will deform around such a small difference. Anyway, we've decided to ship all lowers with a US made 10-32 detent to resolve any tolerance issue there.

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