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My first 6.5 G upper was a complete upper from AA. Now I want one for my left handed wife. I got a left handed upper receiver and a left handed 7.62x39 bolt from BCA. I also purchased a new 6.5 G barrel from Saturn, and also bought a lightly used 6.5G BHW barrel from a buddy. I have a set of 264 LBC gauges and a 6.5G reamer. It is my usderstanding that the chamber needs to be deeped about .009" to use the 7.62x39 bolt. Is there any other problems that I might encounter on this build? Will the 7.62 bolt have a shorter life?
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its not that simple, you need to find out what the bolt face depth is, then get things to match
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I hate to be that guy. But I'm going to be honest you waisted a bunch of money and are in for a very bad headache with the products you bought.
Honestly I would dump the 2 barrels off and that x39 bolt. Get anouther AA barrel and a left hand grendel bolt with the .136 bolt face depth. Belive it's maxim firearms that has the left hand grendel bolts.
Sorry if my post comes off rude just felt it best to say what kind of headache is infront of you with the products you bought.
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12-13-2019, 06:38 PM
(This post was last modified: 12-13-2019, 06:52 PM by VASCAR2.)
I think your making this more difficult than it needs to be. I suggest you look at the BHW barrel and see if it is marked type I (1) or Type II (2). If the Black Whole Weaponry barrel is marked type I it is chambered to use a 7.62x39 bolt with a bolt face depth of .125 inches. If the barrel is marked type II the barrel is chambered to use a 6.5 Grendel bolt with .136 inch deep bolt face. If the chamber and bolt are in spec within .001 + or- then you should be gtg. The chamber gauges should verify the barrel and bolt are compatible.
The bolts are heat treated and I would not modify a bolt or chamber. If I had a stainless steel barrel with a short chamber I might use a finish reamer if it could not be returned to the manufacturer.
If your unable to determine which bolt the barrel is chambered to use call BHW/Columbia River Arms for assistance. If the BHW barrel uses a Type II 6.5 Grendel bolt get a Maxim left hand 6.5 Grendel bolt. Don’t try to deepen a 7.62x39 bolt, it is cheaper and safer to buy the appropriate bolt.
The reason Bill Alexander chose the .136 bolt face depth was to give more room for the extractor just like Colt had done with their 7.62x39 AR-15. A standard 5.56/223 bolt uses a .125 bolt face delth and most x39 manufacturers use a .125 inch bolt face depth. If you deepen a x39 .125 inch bolt the tail to lug face will be to short and you will need to shorten the firing pin. Most 6.5 Grendel bolts measure 2.810 inches in length from the tail to the face of the bolt lugs. (+or- .001). Standard .125 bolt face depth bolts measure 2.800 inches in length from the tail to the bolt face. Bill A. lengthened the tail .01 inches to account for the deeper bolt face depth and permit the usage of mil spec length firing pins. The spec for firing pin protrusion on the AR-15 is a minimum of .028 inch to maximum .036 inch. Brownell?s sell a firing pin protrusion gauge.
http://www.maximfirearms.com/online-stor...left-hand/
https://www.brownells.com/gunsmith-tools...26477.aspx
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Thanx for the input. The BHW barrel is marked .135 headspace. The Saturn barrel is for a Gren II, which I believe is a .136 hs also. I thought about deepening the bolt, but then thought of all the stuff that I would need to adjust to make it right. That's why I opted for deepening the chamber. Looking at it now, the LH Maxim bolt looks like the way to go. Maybe I can make another upper in 7.62x39 with the bolt, if trying to sell it fails.
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The tolerance on bolts should be +or- .001 so a left hand Maxim bolt sounds like the best most economical option.
