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Posted: 2/15/2013 6:25:00 PM EDT
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I just brought home a 30 cal 8” twist chrome moly barrel blank with which I plan on building a 300 BLK upper. I’ll be chambering and profiling the barrel myself. I’ve only done bolt guns up till now but with the help of arfcom I feel confident I can do it right. I plan on a standard length of 16” and will use a carbine length low profile gas block under full length rifle hand guards and locate a standard A2 front sight in the rifle position. You younger guys might not understand why someone would want to do it this way but just wait a few years and you too might see the need to get all the sight radius you can.
The profile I have in mind is .950” over the breach stepping down to .700” between the breech and the gas block. Between the gas block and the front sight I plan on .625” dia. The dia. under the front sight will be .750” on out to the 5/8 x 24 threaded end. My first question is are these diameters workable and safe for a 300 BLK chrome moly barrel? Should I go larger or can I go even smaller? Second question is where can I find the dimensions for fitting the barrel extension to the barrel? I really don't want to take apart another upper to get them, though I guess I could. Last question is regarding the necessity of annealing cases made from 5.56 brass. Any suggestions? Thanks in advance. gk |
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Here's a lightweight with some numbers for you.
Lightweight barrel 
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wagonwheel1,
I appreciate the link, that helps get me started. I guess I'm not too far off with my numbers. Chrome moly being stronger than SS I'll bet I'm my profile diameters are fine. I wouldn't mind some more input though. Can anybody out there give me some help on my questions re/ breech and barrel extension dimensions? gk |
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Here's a link to the dimensions used by Wilson Combat. They have other barrels on their site (lightweight, tactical, etc.) that may be closer to what you're looking for.
Wilson Combat 300 |
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Thanks for the reply Roland, any help would be appreciated.
The barrel ext was no problem, I got an M4 extension from Brownells. All I need are the proper dimensions to thread the breech for the ext and if possible the most common dimensions for the breech's feed cone. Proper clearance between the bolt lugs and breech face would also be helpful. I could assume for a field gun that might be 5 - 10 thousandths but I'd like some input from experience. Thanks. gk |
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