Shortening the barrel on my FAL - how will accuracy be affected?

[goon]

I am planning to have the barrel on my Imbel shortened to something like 17" and a short flash hider installed.
As the rifle is right now, it shoots pretty well. I don't like the ugly Tapco muzzle brake on it but I have lived with it until now.
My question is this: What are the odds that I will screw up the accuracy if I have the barrel shortened? Also, it is zeroed now but I don't have a whole lot left to deal with a change in POI as far as windage goes. What are the odds that my POI will change too much for me to correct with my sights? Is there any way to answer any of this until I actually do it?

 

[rfurtkamp]

No way to really tell until you do it.

My 8.5" barrelled Vector HK-51 clone is accurate from the bench out to the 200m I've tried it with as much as my old Springfield SAR-8 was with a 19".

 

[goon]

That's what I thought. I am not so worried about the accuracy so much because I am thinking that as long as it is cut properly and with a good crown there shouldn't be any reason that it won't be accurate enough for what I want it for. The point of impact change is what has me concerned.
I am suprised that no one else has any insight on this though.
Guess it really is sort of a guess and check type of a thing.
Thank you.

 

[Rem700SD]

I don't think that your accuracy will vary with the change. Gas pressures will change, with a faster let-off in pressure. It will get louder. Windage should not change at all. Bullet velocity will decrease some, possibly shifting POI, but not more than an inch or 2 at most.
Just my theory
Dan

 

[goon]

Probably have to drill my gas port out another size as well. Thank you.

 

[Rem700SD]

You may not have to. FN FAL have gas valves, so just adjust it if need be. I doubt it will be enough to affect cycling.

 

[goon]

Cool. I would prefer not to drill it out again. I had to do it once before and although it wasn't the huge drama that I had expected and it did work out perfectly, I would rather not have to do it again.

 

[geekWithA.45]

Barrel LENGTH has little to do with accuracy, it's biggest impact is on muzzle velocity. (IIRC, the rule of thumb on .308 is 50 fps/inch)

The muzzle crown has a LOT to do with accuracy, and a poorly crowned cut down that allows gas to escape unevenly when the round exits the barrel can have a negative effect.

Also, changing the length of the barrel will necessarilly change that barrel's harmonics, which means that whatever hyper tuned handload recipe you might have used in the past will no longer be valid.

I recommend that you take no shortcuts, and completely revalidate your rifle after the shortening to re-establish its performance envelope, POI, and so on.

 

[Coronach]

Also, if you're nearly out of windage, are you sure your existing barrel is timed properly? A mistimed barrel (basically, the front end is not torqued around so that the gas block and front sight sit at 12 noon, but instead sit a little off) will result in you having to make some odd windage and elevation adjustments to reconcile POI and POA.

My DSA was mistimed, and if they can do it, ANYONE can do it. Of course, when I described the problem, they fixed the rifle and had it back to me inside of a week. Go DSA.

The point is that removing the barrel and chopping it might result in a better re-installation, thus eliminating your extreme windage issue (if that was the problem to begin with).

Mike

 

[Chuck R.]

Goon there’s also a good chance that you’re going to need a new front sight post (shorter) or an Izzy Rear. The carbine length barrels have a tendency to shoot low. It’s got something to do with the shortened bullet/barrel time and the recoil curve.

Chuck

 

[sobrbiker883]

Most folks will open their gas ports a tad, that's depend on where you are on the adjustment pre-shortening. Mine is in the middle of the range with most ammo, so if I were gonna shorten, I'd go a touch bigger. And proper re-crown is an absolute must.

Personally, I think 18" should be the minimum for 308, allowing best burn from most ammo..........(Been wondering how the SA SOCOMII's are doing with their 16" barrels. I know alot of AR10 style rifles are coming in 16" carbines now as well......maybe I'm wrong).

 

[Scottmkiv]

My guess is that your accuracy stays the same or improves depending on how well the cut and crown are done.

 

[goon]

The barrel was originally mistimed on this FAL too. I sent it back to Ohio Rapid Fire and they retimed it to where it does now shoot to point of aim but I have the feeling that it is always going to be tight one way or the other.
I also had to open the gas port on it as well to get it to work right, IIRC it is now a .0105 instead of the standard .089 (I think). I was leary of drilling it out at first but I managed to do it in an old garage with vise that I had padded with several layers of cardboard, a peice of thread stock, and a cordless drill. I can do it again if need be.
I also have an extra front sight for it because I had to add a higher one to get it to zero for elevation so I could stick the original 2-dot one back on to bring POI up if I had to.
There are a couple smiths around who can handle cutting and recrowning the barrel without too much trouble but I am on my own as far as the rest goes. AFAIK, there are no FAL smiths in my area of PA. I have thought about just sending it to DSA with a list of what I want done but I may have to try it myself and see how it goes first.