Barrel timing???

[newfalguy101]

I am new at this and am wondering if any of you wonderfully helpful people have a picture, sketch or just a REALLY good explanation of how the barrel is supposed to be timed??

Also exactly what is timing?? I am thinking that it is the relationship between the gas piston hole and where the barrel threads into the receiver??

I did a search and came across a post with a "red X" where the pic is supposed to be.

Thanks

[89Saleen]

Try this site

http://www.cruffler.com/trivia-April01-background.html

[newfalguy101]

Thanks, that helps.

[blackrifle]

Here is another pic:

http://www.gungrabber.com/FAL.htm

[dandor]

deadeye,

I have used the "two rod" method and it works great, however, on my last two builds I used two aluminum line levels. (small levels used in construction that can hook on to a nylon cord while setting forms for pouring concrete) I timed the barrel by "eye" then check it by lying one level across the front sight ears(you can use a large rubber band wrapped around the gas block from end to end of the level to hold it in place) and another across the top of the dust cover rails of the receiver. Level the receiver in vise first with a straight up bubble in the level, then make adjustments as necessary while turning the barrel until both bubbles are straight up "level") This worked for me.

[bykerhd]

I've been using the two rod method also with mixed results. I tried a variation with two magnetic torpedo levels (what I had) last time. Barrel in the Elliott vise with level in place across the sight ears. Left the rod in place also.. Lined up the receiver using the rods and the second level on the receiver. I haven't shot them yet(put two together that way) but the levels seem to make a finer alignment possible. I was surprised at how much out ok by rod looked compared to ok by level. Front sight ear damage or out-of -spec would make this not work. I'll find out.

[gunzilla]

I timed a G1 barrel to a FAC (DC Industries) receiver today and used this simple method to ensure that I was there. I had torqued the barrel in once already and I came up a few degrees short. I used a protractor head on a machinists rule and measured the degrees of offset by setting the protractor head on the flat side of the receiver and the rule on the barrel flat. Came up with 14 degrees. This calculated out to .0024" so I put the barrel between centers on the lathe and turning it by hand removed that amount, aproximately. Back to the vice and torqued it in. Still not there when I tried the gas tube and nut. Then I noticed that the barrel has a small cutout in it that must provide clearance fo the gas tube nut. This was obviously not centered under the female threads in the receiver for the nut, but only slightly so. Unscrewed the barrel and took a stone to the shoulder. Back to the vice. Wound it on and I could see while everything was still attached that the cutout was centered just right. Took it out of the receiver wrench and vice and everything (gas tube assembly) went together just fine.
Lacking a lathe, one of those barrel shaving gizmos would do the same.

[ratas calientes]

I was going to use the two rods method, but on my first build the hole throuh the gas block was not normal (at 90 degrees) from the vertical. Very roughly machined. Even the two front-sight ears were obviously of a different thickness. BTW, this was in IMBEL kit. So, I just tightened on the barrel, and removed it from the barrel vise. I then looked down the assembly from the front, then the rear. Then I attached the lower assembly and looked at it again from all angles. Inside the garage and in the yard. It then went back into and out of the barrel vise a few times to get tweaked. When I was happy, I finished the assembly. Proof of proper timing was when I sighted in the rifle, and the rear sight was nearly centered. Good enough for me. The second build was the same way. Rear sight was pretty much centered again after a trip to the range.

Ratas

ps - I have seen a few Bushmaster AR15 uppers that required more windage to sight in than either of my first two builds. As a matter of fact, I have yet to see any Bushmaster rear sight that was centered. But I have seen them deviate to both sides, both on my rifles and others. So it isn't just my eyes.

[MK ULTRA]

Best method I've found is to get a .308 chamber laser boresighter. Alpec has them that work in .223, .308, 7mm-06 and 243 all in the same unit. It's $100. It makes it so easy. I told GP about this over a year ago and he said it was a waste of time. He just eyeballs them. Thats what he said. Guess he has a good eye. I do too but I wouldn't chance it on someone sending it back because of it.

Anyway this is what you do

You just tighten your barrel close but not too far. Put the stock on with the rear sight in the middle of it's adj. With the laser in the chamber look through the back sight and at the laser dot on a wall. You can tell if the front sight is off or not.

Lining up the rear sight and the laser on your neighbors house if the front sight is to the right it needs tightened more. If it's to the left it's too tight. Just get the rear sight and the laser lined up then tighten your barrel up till it's lined up. When all three (rear sight, front sight and laser dot on a wall) are lined up the barrel timing is perfect.

When the laser dot is right on top of the front sight it's just right. I've gotten them so close this way it needed no windage adj at the range.

The laser is good for mounting scopes and boresighting your other weapons too.

[newfalguy101]

I agree lots of very good info and ideas.

I have another question now.

How tight does the barrel have to be torqued into place or does it even need to be torqued??

I recall reading that benchrest shooters just hand tighten theirs in place, I realize they use boltguns and is that the difference??

Thanks again

[HankB]

ps - I have seen a few Bushmaster AR15 uppers that required more windage to sight in . . .

Interesting comment. My Bushmaster needed about 17 clicks to sight in. Feeling this was too much, I contacted Bushmaster. They issued a UPS call tag, the BBT picked it up the next day, and about 10 days later the upper came back. Now centering the group takes 2 clicks. Good service, good company, good rifle.

Now, if there was only some way to make an FAL trigger as good as the Jewell I put in my Bushmaster . . .

BTW, what type of thread locker (if any) do you use on the barrel/receiver coupling?

[ratas calientes]

HankB -

The first Bushmaster barrel I bought was a dissipator model that I assembled to a Colt upper. It required well more than two clicks to sight in. I really didn't think much of it. I later looked over a friends rifle (that I was storing for him at the time) and his rear sight was well off-center in the other direction. I never considered sending mine back. I figured that they just came that way. Subsequent barrels also required more than a few clicks for windage. I just sight them in and leave them alone.

I buy almost all of my AR parts through Bushmaster. I have always been pleased. I even have their AR-15 poster on the wall at work. Good conversation piece.

As for threadlocker - I don't use it - I prefer anti-sieze.

Ratas