• Winner! Quick Shot Challenge: What’s the dumbest shooting myth you’ve heard?

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KAC 6.5cm rifles and uppers

I just wish I could get KAC barrel extensions. That would solve 90% of the issue of re-barreling.

KAC extensions on the SR25 platform are pretty close to DPMS standard. Do you have an SR25 you want to put a barrel on? I know nothing about KAC SR15. I know they have some proprietary gas lengths (go figure).
 
The issue is the bolts. KAC makes the best bolts on the planet but you need the propper extension for them to take advantage of the benefits. KAC offers a rebareling service but it's over a grand and you are suck with their contours and blanks. If they sold the extension ala cart we could do some really cool shit like .260/6.5/ect sr25s. No one wants to pay almost 4k for an upper.
 
The issue is the bolts. KAC makes the best bolts on the planet but you need the propper extension for them to take advantage of the benefits.

Uhh. Are you talking about on the SR25 platform, or the 5.56 ? I make barrels on the SR25 platform. There are some nuances, but nothing that cannot be done once you know the machining that needs to be done. It is not an out of the box fit, but you can start with a DPMS pattern extension. We use the best extensions made, and then machine them to extremely tight tolerances. It is not something you want to do for one barrel, but when you get the pattern right, and do it for 300 barrels, it is rock and roll time. I have also spent alot of time, effort, research and design to get to the point that we can do this.

The LMT bolt and KAC bolt both fit. One of the shop guys said he got an Armalite bolt fit fine as well. I would not be surprised, as all firms have some legacy in common. LaRue uppers also fit on KAC lowers, and visa versa. Not sure on their bolts, but the OBR is based upon an SR25 platform.

I am running some final headspacing tests next week on a Mk11 barrel, then an M110 barrel. We do separate headspacing for LMT and KAC bolts, so people can use either with a KAC-spec barrel. The LMT bolts and carriers are not as expensive as Knight's. There is no doubt that it will work, just a matter of getting the specs and tolerances recorded for each, then we build chambers for each bolt.

If you wanted an SR25 with a 6.5 CM barrel, the first step would be to find the right bolt, and mate it to your carrier, or another carrier. I don't see why we would need to use a KAC or LMT carrier. I do that for historical correctness in clone building, but if you are going off the reservation anyway, you can start from scratch, and headspace to the bolt of your choice. Maybe a LaRue .260 bolt?
 
Yes all of KAC's rifles use a proprietary barrel extension however you need both the bolt and correctly speced extension to get the full benefit of the system. A Mil spec bolt will work for a while in them, but it is only recommended in an emergency. I don't see the need however I have never seen a documented E3 Bolt breakage.

I don't see the point of running a KAC if I am going to remove features that make the KAC. Otherwise I would just build from parts or use something much cheaper. If you have the E3 chambers figured out, you could make alot of money making KAC prefits.

Sorry if I am a little fuzzy on the specifics. Actually taking machining classes at night at the local college so by the time I get home I am drained.
 
The SR25 does not have all the proprietary nuances, believe or not, that the SR15 has. It is not a proprietary barrel extension, nor a proprietary bolt on the big frame KAC platform.

The question started as, "I wish I could re-barrel my SR25 for 6.5 CM in a cost effective manner. I am here to tell you that it can be done. No argument that the KAC bolt is great. I think the LMT bolt is just a great, and since they both make stuff for each other on the big-frame platform, it works out well.
 
I built my own with Mega receivers and Bartlien barrel. Still came in much cheaper than the KAC.

If I were to do it again, I’d use the new JP receivers since mega is now gone.
 
I am looking to pick up a 6.5 is it worth 5K to get KAC or could I build one better cheaper, and if so who would you use?
Better is relative.
Is a homebuilt going to be as reliable and well tested as KACs flagship line of guns? No.
Will the 6.5 guns shoot incredibly well? Yes.
Will a JP or GAP10 or similar quality build be more accurate? i'm not sure, but even if so the difference will most likely be minor unless your skills can outshoot the mechanical ability of the guns.
If you did buy it and didn't like it could you sell it for almost no loss or for no loss at all because its a KAC? Yes
Could you buy a 6.5 upper alone and put it on an LMT lower to lower and spread out the cost a bit? Yes, lots of people have done that.

Also, shooting large frame ARs is slightly more difficult game than a precision bolt gun if you are not familiar with it, they are much less forgiving imo. I've seen quite a few people not be able to shoot a semi as well as they can with a bolt gun then try and blame the semi.

Shot show most likely will come with the public announcement of the additional 6.5 offerings from Knights as well.