Ballistics Question

[jeffyboy]

I have a ballistics question I hope someone on here can answer. I have a 16in 1/9 chrome-lined barrel that shoots good out to 300yrds. If I were to cut the barrel down to 14.5in and pin a brake or FH what impact might there be to the overall ballistics of the barrel.

[wildcard]

The only difference you'll see if a lower velocity which means the bullet will hit a little lower, but with the same accuracy at that distance. Because of the lower velocity, you will decrease your maximum effective range a little. No issues out to 300 yds though.

This of course assumes you're using the same load and the gunsmith does a good job. Some gunsmiths may find that cutting a chrome lined barrel is not something they are comfortable doing. So keep that in mind.

[rksimple]

Is it a carbine length gas system? If so, you'd improve how smooth it cycles. As far as ballistics inside 300, you won't notice a difference. You may even get better accuracy with a better crown.

[jeffyboy]

The only difference you'll see if a lower velocity which means the bullet will hit a little lower, but with the same accuracy at that distance. Because of the lower velocity, you will decrease your maximum effective range a little. No issues out to 300 yds though.

This of course assumes you're using the same load and the gunsmith does a good job. Some gunsmiths may find that cutting a chrome lined barrel is not something they are comfortable doing. So keep that in mind.

never thought about there might be an issue with a CL barrel...ouch

[jeffyboy]

Is it a carbine length gas system? If so, you'd improve how smooth it cycles. As far as ballistics inside 300, you won't notice a difference. You may even get better accuracy with a better crown.

yes, it is a carbine length gas system. So what you are saying is that there may be a "benefit" to cutting it down?

[wildcard]

yes, it is a carbine length gas system. So what you are saying is that there may be a "benefit" to cutting it down?

The benefit isn't because you made the barrel shorter, but a competent gunsmith MAY give you a crown cleaner than what you got at the factory.

Cutting a chrome lined barrel can be done. Just got to use the right cutting tool/material to do it.

[rksimple]

yes, it is a carbine length gas system. So what you are saying is that there may be a "benefit" to cutting it down?

In addition to the new crown like wildcard mentioned, you'll get a smoother gas system. A 16 in carbine-gas is overgassed. The bolt carrier/bolt is trying to move rearward before the case has had a chance to shrink back down to size in the chamber. There are other small issues as well. Cutting it back lessens dwell time and improves things with the carbine gas system. I think Randall did a good write up on it. Paging Randall...

[buffybuster]

The carbine length gas system was DESIGNED for a 14.5" barrel. PutTing a 16.1" barrel for ATF purposes keeps the system under pressure for too long. So by cutting the barrel back to 14.5" brings the system back into the original design configuration.... Therefore, all things being equal, smoother cycling.

[jeffyboy]

In addition to the new crown like wildcard mentioned, you'll get a smoother gas system. A 16 in carbine-gas is overgassed. The bolt carrier/bolt is trying to move rearward before the case has had a chance to shrink back down to size in the chamber. There are other small issues as well. Cutting it back lessens dwell time and improves things with the carbine gas system. I think Randall did a good write up on it. Paging Randall...

Go info to know. I'll try and search for the posting

[ar15barrels]

Is it a carbine length gas system? If so, you'd improve how smooth it cycles. As far as ballistics inside 300, you won't notice a difference. You may even get better accuracy with a better crown.

[ar15barrels]

In addition to the new crown like wildcard mentioned, you'll get a smoother gas system. A 16 in carbine-gas is overgassed. The bolt carrier/bolt is trying to move rearward before the case has had a chance to shrink back down to size in the chamber. There are other small issues as well. Cutting it back lessens dwell time and improves things with the carbine gas system. I think Randall did a good write up on it. Paging Randall...

https://www.ar15barrels.com/prod/operation.shtml

Cutting chrome lined barrels is something that many people are afraid of.
I'm glad they are afraid because I have done hundreds of them without a single complaint of accuracy loss.
I usually get reports of accuracy improvements because factory crowns suck and my crowns are good.

[jeffyboy]

Thanks for the info Randall. What's the best way to reach you (thru calguns or your website)? I have some work for you.

[ar15barrels]

Thanks for the info Randall. What's the best way to reach you (thru calguns or your website)? I have some work for you.

PM's here.