HD AR Build

[Charlie Foxtrot]

I was thinking 5.56 or 6.8. Never really considered 300.

One thing you might consider - it is (somewhat) possible to chamber a 300 round into a 5.56 chamber. The 300 uses the 5.56 as the mother brass. Too many documented cases of experienced people blowing up their 5.56s with a 300 round. http://notonemoregunlaw.blogspot.com...blk-irish.html Other than that, it is a VERY interesting round.

I also have a DD 6.8 SPC II, which I'm desperately in lust with. However, I use it for longer ranges - not close in SD/HD situations. So, I'll agree with several others with the suitability of the 5.56 for HD.

[rob_s]

Is there a standard diameter for cans ?

Generally 1.5" OD for most 5.56 and 7.62 cans, sometimes <1.5" for 9mm.

All of that said, a handguard with a >1.5" ID tends to be pretty fat, and I wouldn't run the handguard past the mounting point for a variety of other reasons, unless I was 100% certain I wouldn't be removing the can.

this might help

[SamuelBLong]

Just ordered a DD 11.5" 5.56 Gov profile 1:7. Now to search for a 13 or 15 inch handguard that will go over a standard diameter can.

What is your reasoning for wanting to have the rail + can setup like this ?

I don't see how it has any real benefit, and only see negatives...Especially for your stated purpose of HD 100m and in.

And if you are insistent on having it setup this way... Look at Seekins Precision. They make long hand guards that have 1.8" internal diameters, but still relatively trim outsides.

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[23JAZ]

What is your reasoning for wanting to have the rail + can setup like this ?

I don't see how it has any real benefit, and only see negatives...Especially for your stated purpose of HD 100m and in.

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Excuse my ignorance, but can you elaborate on those negatives? The only canned AR I've fired was set up like that and I really liked it. Honestly that's my only reasoning behind wanting one.

[SamuelBLong]

- Heat build up is the big one. Any rail that covers the back area of the suppressor is going to be taking lots of heat. Makes it pretty uncomfortable and sometimes even unbearable to grip the rail at all.

-Not being able to effectively either access your QD mount to remove a QD can or clean your threads ( if you're getting a thread mount).




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[HCM]

Rob, thanks. I have a spare 12 DD MFR - I'll save it for a longer build.

Other than heat what is the downside to perm mount cans like the DD ISR ?