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<blockquote data-quote="TheGuy" data-source="post: 2173153" data-attributes="member: 97862">The BCM uppers barrel extension bore is slightly undersize, and requires heating the receiver to install the barrel.&nbsp; I have had great luck with this, and in my 12.5&quot; DD barrel have no problem hitting 10&quot; steel at 415 yards, using M193 55gr.&nbsp; The setup seems accurate, but its still new and primer availability is hindering my load development.&nbsp; Use good parts and and a good torque wrench for the barrel nut and you should be close to as accurate as any bolt gun.&nbsp; I do agree with 600 yards being a more realistic limit for reliable accuracy, over that you may start to loose accuracy with unstable bullets as they will affected by the transition from supersonic to subsonic velocities. I came from the same background, with lots of bolt gun experience, and got into the AR game later, but the process is the same to be honest.&nbsp; Biggest differences you will notice is you cant neck size, so brass life is less, and COAL is dictated by the magazine, and the ejection process can make brass more difficult to read.&nbsp; Good parts, and careful assembly of the upper is what is going to make the biggest difference, and performance is the same as bolt guns, longer barrels for more velocity.&nbsp; 1 in 7&quot; twist will be what you are looking for to reliable stabilize the 77+ gr bullets.</blockquote>

[QUOTE="TheGuy, post: 2173153, member: 97862"] The BCM uppers barrel extension bore is slightly undersize, and requires heating the receiver to install the barrel. I have had great luck with this, and in my 12.5" DD barrel have no problem hitting 10" steel at 415 yards, using M193 55gr. The setup seems accurate, but its still new and primer availability is hindering my load development. Use good parts and and a good torque wrench for the barrel nut and you should be close to as accurate as any bolt gun. I do agree with 600 yards being a more realistic limit for reliable accuracy, over that you may start to loose accuracy with unstable bullets as they will affected by the transition from supersonic to subsonic velocities. I came from the same background, with lots of bolt gun experience, and got into the AR game later, but the process is the same to be honest. Biggest differences you will notice is you cant neck size, so brass life is less, and COAL is dictated by the magazine, and the ejection process can make brass more difficult to read. Good parts, and careful assembly of the upper is what is going to make the biggest difference, and performance is the same as bolt guns, longer barrels for more velocity. 1 in 7" twist will be what you are looking for to reliable stabilize the 77+ gr bullets. [/QUOTE]

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