11-18-2014, 09:23 PM
The chronograph is about the closest thing the working man can have access to that will give a loose indication of what pressures you are into, working from a baseline.
As long as your chamber is concentric to the bore, and the bore is concentric to the OD, and your threads are concentric, shoulders square, bolt engagement squared up, then you can have a very accurate barrel/rifle.
2400fps with an 18" barrel is very easy to do. Since your barrel likely has 5R rifling, it won't build pressure as fast, so the speeds will generally be slower for the same charge weights in a conventional rifling pattern. That also gives you a little wiggle room on the top end to gain back velocity. Just don't jam into the lands. An 18" barrel usually will allow 2500fps with 123gr pills.
I would be careful with the 140gr, making sure to study your engagement surface length, and compare it with other projectile data in the 140gr that is available, look at those start loads, and work from there.
As long as your chamber is concentric to the bore, and the bore is concentric to the OD, and your threads are concentric, shoulders square, bolt engagement squared up, then you can have a very accurate barrel/rifle.
2400fps with an 18" barrel is very easy to do. Since your barrel likely has 5R rifling, it won't build pressure as fast, so the speeds will generally be slower for the same charge weights in a conventional rifling pattern. That also gives you a little wiggle room on the top end to gain back velocity. Just don't jam into the lands. An 18" barrel usually will allow 2500fps with 123gr pills.
I would be careful with the 140gr, making sure to study your engagement surface length, and compare it with other projectile data in the 140gr that is available, look at those start loads, and work from there.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com