View Full Version : Questions about converting Colt Sporter Match HBAR to .300AAC/.308

July 2, 2012, 05:21 PM
Hey Guys, a question about a specific AR, the Colt .223 Sporter Match HBAR. 20" barrel and Iron sights. I have a chance to buy a virtually new one from a friend but have a couple questions.

This rifle just feels great to hold and dry-fire although I have not actually shot any live fire with it. I do notice the handle and rear sight seem to be one piece with the upper and not mounted to a rail or detachable. I cannot find any clear information if I could drop a different upper in, possibly with a rail so I could mount a different sight or even mount a .300AAC/.308 barrel/upper. I have seen/heard that you only need to replace either the barrel or barrel/upper to convert the AR15 to a .308 for hunting.

If anyone has this Sporter model and/or can help me with these questions it would be much appreciated.

Here is a link for comparison to what I think is pretty close to the exact rifle.


Thank you guys so much for the great information I have received, I hope I can contribute to the forum in the future.

Happy weekend and Independence Day, thank God and our Founding Fathers for our Liberty, God bless us to keep what we have.


July 2, 2012, 06:29 PM
You can convert to 300blk with a simple barrel swap.

You cannot turn a 223 AR into a 308....the 308's are larger all the way round.....receivers, mags, and BCG's.

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July 2, 2012, 06:45 PM
Sounds like you might be confusing the fact that the 300BLK shoots a 0.308" diameter bullet with it being a 308 Winchester caliber rifle. They are very different.

As for changing it, the simplest way to make your AR into a 300BLK will be to swap a complete upper assembly with the 300BLK barrel. That will allow you to go back and forth between 5.56 NATO and 300BLK just by swapping the uppers.

FYI, the 300BLK is ballistically very similar to the 7.62x39 ... a tad bit slower, but it uses the much stronger 5.56 bolt in the AR-15 platform than a 7.62x39 would in an AR-15. The BLK also has the ability to shoot heavy (~220gr) 308 bullets at subsonic speeds and still function well.

Hope this helps,


July 2, 2012, 06:58 PM
Great, yes it may be the .300 blackout I was thinking. I had seen where some had converted and also was using a .308, I was just unsure if the specific Colt target version was 100% NATO. I guess it would be stupid of Colt to use a different lower for any AR15 version so I suspect then yes any NATO compliment upper could fit?

July 2, 2012, 07:05 PM
AFAIK, all 223 Rem/5.56NATO Colts will accept any standard upper. Some of the Colts have larger fire control pins, but that only comes into play if you are looking to swap in a new trigger.

There are AR pattern rifles that handle the 308, but those are AR-10 type, not the AR-15 that most people refer to when they use the generic term: AR. The real limitation on the AR-15 lower is the length of the mag well ... it limits you to calibers that are no longer than a 223 round. There are a LOT of options, however, ranging from 204 Ruger to 300 WSSM to 300BLK to 6.5 Grendel to 458 SOCOM. It all depends on what you want it to do and where you will source your ammo ... keep in mind that some of these calibers are expensive to feed ... even if you hand load :eek:


July 2, 2012, 07:26 PM
got it guys; thanks alot, I wanted to be sure as far as a AR-15 goes the Colt Match was compliant with changing other AR-15 uppers, this forum is so good on info that sometimes is so contradictory by just searching the net. More opinions are welcome also.

I like the Colt Match HBAR because of the long heavy barrel. I like to shoot off hand with a sling but also looking for something I can change the uppers on for tactile or hunting.

July 3, 2012, 02:28 PM
If the HBAR in question is like mine, the Colt upper has a non-standard large diameter screw front pivot. And, the lower has a blocked fire-control well and non-standard sized trigger and hammer pins. Supposedly, this was to prevent it from being converted to full-auto with M-16 parts.

July 4, 2012, 10:10 AM
Thanks Zippy, I was looking at a used one at a recent gun show, not the one a friend has for sale, but did notice the front pivot pin looked different, like it went all the way through and had a pin or nut or something, forgive me I am going out of memory. So that would also be a modification that Colt had done to the receiver?

Thanks, I was hoping someone that had owned the actual HBAR model would chime in.

I'll check the one my friend has for sale, I think I know what to look for. If its not a compatible NATO AR-15 platform I think I'm going to pass on it.

July 4, 2012, 02:45 PM
If the price is good, don't pass on it if you can part it out and make a profit.