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Posted: 6/1/2008 5:24:46 PM EST
I have done the 6.8 and now want to do a 6.5 my question is what is the ideal barrel length and twist? I read the 6.5 FAQ but this wasnt answered.
Thanks
Link Posted: 6/1/2008 5:54:41 PM EST

Originally Posted By mstennes:
I have done the 6.8 and now want to do a 6.5 my question is what is the ideal barrel length and twist? I read the 6.5 FAQ but this wasnt answered.
Thanks


What do you want to do with your Grendel?
Link Posted: 6/1/2008 7:23:56 PM EST
I'm looking at something to replace my 16" middy. I want a do all. I built a DMR but at 20 its kinda bigger than I want, so I'm thinking a 16" middy but I have not ruled out 18-20" Since we have to 16" anyway no need to go any shorter. I was just looking for the best balance
Link Posted: 6/2/2008 5:11:30 AM EST
Alexander Arms uses a 1:7.5 in their 14.5 and 16" models, and a generally a 1:9 in their 20" and longer models. There are exceptions, and a Satern cut-rifled barrel in 16" gets a 1:8 twist.

Without having done the scientific testing, it's my gut feeling that the 1:7.5 is a bit overkill in the shorter barrels, particularly if you're not going to be shooting the heavy 130 and 140 6.5mm bullets.

But, at any rate, that's how AA specs their barrels.

John

| 6.5 Grendel: The State-of-the-Art Combat Cartridge. |

www.65grendel.com
Link Posted: 6/2/2008 12:29:14 PM EST
[Last Edit: 6/4/2008 6:13:55 AM EST by RedFalconBill]
[sucking up]I'd listen to John[/sucking up]

Seriously, consider an 18" barrel.

If you are never going to shoot anything heavier than a 120 SBT, or 125gr Nosler Partition, use a 1/9" twist barrel.

If you want to shoot everything lighter than a 130 gr HPBT, you want a 1/8.5" twist barrel.

If you want to shoot everything from the 90gr TNT through the 140gr HPBT, you want a 1/8" or the Sabre Factory 1/7.5" twist barrel.
Link Posted: 6/2/2008 7:47:10 PM EST
Good to know as I want to the ability to shoot all ammo grains. I run 1in7's on all my 5.56's as I like to run the 75's and 77's, but still be able to use the 55's. Is a 18 better than a 16? I mean how much more do you gain on the 6.5 with 2"
Link Posted: 6/2/2008 7:52:05 PM EST
Thanks to whoever made this:

Link Posted: 6/2/2008 9:33:42 PM EST

Originally Posted By mstennes:
Good to know as I want to the ability to shoot all ammo grains. I run 1in7's on all my 5.56's as I like to run the 75's and 77's, but still be able to use the 55's. Is a 18 better than a 16? I mean how much more do you gain on the 6.5 with 2"


Depends upon your application. An 18" barrel splits the difference between 16" and 20". Oh, did I mention that I have an 18" barrel?

As to HOW much better than a 16", it varies, but an 18" barreled Grendel will run anywhere from 40-80 fps faster than a 16".
Link Posted: 6/3/2008 4:19:00 AM EST
good to know looks like I might end up building 2 6.5's, it is looking like its better than the 6.8
Link Posted: 6/4/2008 1:23:41 AM EST
i just ordered my barrel from alex arms its a 16inch with the 1in8.5 twist
i dont see a 1in7 like you guys are talking about
Link Posted: 6/4/2008 6:12:16 AM EST
[Last Edit: 6/4/2008 6:31:58 AM EST by RedFalconBill]

Originally Posted By gunslingshortmag:
i just ordered my barrel from alex arms its a 16inch with the 1in8.5 twist
i dont see a 1in7 like you guys are talking about


The factory Sabre Defence AR barrels come with either 1/7.5" or 1/9" twist.

The AA Factory 1/8.5" is good for the 140gr Flat Base Spitzer bullets and the 130 gr Match BTHP bullets.

FWIW, I do not think that a 16" barrel is at its best firing the heavier bullets.

Bill Alexander has done some good load work up for reloaders and have found that his suggestions make for good, workable, safe, loads.
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