Will a JT 6.5 upper fit my colt government A2 lower.

[Ymf]

I think I have the small pins. My gun is stamped government, law enforcement , millitary use only and the serial # starts LGC******. I have looked and called everywhere and can't seem to get an answer other than their uppers are "mill spec ". Are the colts different than the rest? Small pins are .170 and others are .250 or so I've been told. What's the deal?

[Variable]

I think I have the small pins. My gun is stamped government, law enforcement , millitary use only and the serial # starts LGC******. I have looked and called everywhere and can't seem to get an answer other than their uppers are "mill spec ". Are the colts different than the rest? Small pins are .170 and others are .250 or so I've been told. What's the deal?

I think you are confusing takedown pins with hammer and trigger pins. Measure the diameter of your Colt lower's Front takedown pin. If it is .315" then you have a large takedown pin lower, and will need an adapter. If it is .25", then you have the standard dimension and are good to go for compatibility with other brands.

The .170" dimension you referenced is actually for large diameter Colt hammer and trigger pins (which are actually .169" IIRC, but I'm too lazy to go mic them). This will have no affect on upper/lower compatibility though. The standard diameter for hammer and trigger pins (called small pin in the Colt camp) is .154".

[Ymf]

I think you are confusing takedown pins with hammer and trigger pins. Measure the diameter of your Colt lower's Front takedown pin. If it is .315" then you have a large takedown pin lower, and will need an adapter. If it is .25", then you have the standard dimension and are good to go for compatibility with other brands.

The .170" dimension you referenced is actually for large diameter Colt hammer and trigger pins (which are actually .169" IIRC, but I'm too lazy to go mic them). This will have no affect on upper/lower compatibility though. The standard diameter for hammer and trigger pins (called small pin in the Colt camp) is .154".

Ill check that. Thanks for the info. I really want to start shooting the Grendel. I have plenty of open range to shoot some distance here in Montana. I was getting worried I would need another whole gun. I'm looking at the JT bull bbl 20" for 644$. Any experience with this set up?

[VASCAR2]

J & T use true Grendel chambers and bolts and I believe most J & T barrels are made by Shaw and are buttoned rifle. The heart of any AR style rifle is the barrel and for shear accuracy you have to pay the price. Most of the high dollar barrels tend to be cut rifled or maybe hammer forged in 5.56? I consider the J & T to be rack grade which may be very accurate depending on the ammo and shooter. If your serious about shooting tiny groups at many hundreds of yards the J & T may not be up to the task. For hunting and the more amateur shooters like me I think the J & T are great rifles. I bought a J & T 16" kit that I really like. My 16" 6.5 Grendel seems comparable to my RRA, Bushmaster, Armalite, DPMS or S&W AR's I've been around.

I had a Colt lower similar to yours and I traded it off because I didn't like the screw in the front of the receiver instead of a push type take down pin. I use my Colt 20" H Bar flat top on a RRA lower with NM trigger.