Barrel Clocking

[wtfooptimax200]

I was reading a recent Marlin post and it was mentioned that the barrel was correctly 'clocked'. Can someone please explain this to me?

Thanks!

[MtGun44]

Rotated to the correct position, you probably would object to a front sight off by 10 deg, or
even 2 degrees, and for many guns, they won't function if the barrel isn't clocked right, like
to get a gas port or gas system mount to be in the right place.

Bill

[Bret4207]

Indexed is the correct word I believe.

[Gtek]

On the Garand/M14 family of weapons the correct timing / indexing is 90 degrees +/- 0.20' horizontal centerline. This can be very critical in alignment of things that attach to barrel forward of receiver, mag tubes, forearm attachment points, etc. The most important is the sight alignment, the higher the sights the more critical it becomes. Hold your arm out and put your thumb straight up, your thumb nail being front sight and your pinky being bore centerline. Rotate your wrist, that error increases with range. Barn door to barn at a 100. Gtek

[W.R.Buchanan]

Barrels are supposed to be screwed into the receiver until the sights are strait up and down.

All of the cuts for the sights are done before the barrel is assembled in the receiver so if they screw the barrel in too far or not far enough the sights aren't "Clocked" right.

"Indexed" would (and I am splitting hairs here) would be the more appropriate term for this relationship in something like a Garand where many things have to line up.

Clocking really only referres to Radial alignment.IE with reference to the positions of a clock.

Indexing can refer to clocking, but also can address positioning a part in any plane with reference to a stop point or indexing point.

You index parts in a mill vise with a stop. You clock parts in a rotary fixture, however you are also indexing that part as well.

There is another term which enters in when two pieces have a radial relationship,,, "timing". You could also say the barrel and receiver was not "timed" right.

The problem with the Marlin Rifles is that with Octagon barrels the top flat of the barrel lines up with the top of the receiver, and this is easy to see. You don't see Octagon barreled Marlins with the sights clocked off center.

With round barrels there is no readily available reference point, and since the sights aren't put on til last, they dont' have a easy way to check alignment. I think they use a torque wrench of some type to screw the barrel in to a specific torque, however this is not a foolproof way of doing this operation. (Obviously) Because the step on the barrel behind the threads can vary in it's position by a small amount thru out a run of parts.

Obviously the farther forward that step is, the farther the barrel will turn in past it's intended position before the torque value is met.

I don't understand for the life of me why they don't engrave a timing mark on the barrel when they cut the sight dovetails, then they could just use that and everyone could be checked at assembly, and thus would be right before it was passed on to the next operation ???? As long as the barrel is past a certain minimum torque then the alignment would control the operation, not a specific torque. The threads on the barrel must be timed to the dovetails, so there is no reason the relationship couldn't be marked when this operation was being done.

Hope this clarifies. This is a simple problem to fix and would cost exactly nothing to implement.

Randy

[wtfooptimax200]

Thanks for the explanation, I just wanted to know what I should be watching out for when looking at Marlin's.

[Gtek]

Hold it out as far as you can and find something long and flat to line up flat top of receiver on. Look over top at front sight, if it is more than a little - you will pick it up. Gtek

[popper]

W.R. wouldn't be free, takes NASA engineer, computer, 3 accountants, 2 checkers, 15 QC geeks to make sure it's right. The way they do things now, customer learns to put up with it or pays to get it fixed, just like GM.

[Bret4207]

Well, indexed is the word they use when the really, really high dollar gun makers, furniture makers, etc. make sure all the screw slots line up the correct way. Last I knew "clocking" was what you did when you timed a horse race or drag car.

[btroj]

I have always referred to having screws line up as "clocking".

[gunplumber]

i was in town monday looking at 22 lever guns and found a nice looking winchester 9422 i would of liked to buy untill i looked down the barrel and saw the front sight, it was mounted several degrees off to the right, it was a big let down so i guess the search continues

[John Taylor]

Clocking/indexing, may be what side of the country you are from determines which phrase you use. I have a few indexing heads for the mill so this is the term I use for the barrel/ frame alinement. I use a couple of 12" long pieces of 3/16" key stock to determine if things are lined up. One will be in the sight dovetail and the other on a flat spot of the frame. Sometimes I use the side of the frame with octagon barrels and the bottom on bolt actions. If you look from the rear or front you can tell real quick if things are lined up.
When I make up barrels for mod. 70 Win. I put a witness mark on the bottom. There is no mark on the action. This mark is so I have a reference when I am machining the sight ramp , dovetails and extractor cut.

[W.R.Buchanan]

John that is a good way to be able to see any misalignment. The longer the keys are the more it will show.

Randy

[W.R.Buchanan]

Also with referrence to the clocking, indexing, timing, term's appropriateness, please read the part of my earlier explaination where I state "and I am splitting hairs here"

This point is splitting hairs. Call it what you will, we will understand. You now have all information pertanent to this issue.

Randy

[bearcove]

I have a Rossi 92 that has this issue. Haven't got around to fixing it yet.

It is about 5 degrees out of alinement. If the barrel has right hand threads I need to tighten it a hair.

Does anyone know for sure if its rt or left thread. I haven't taken one of these apart. Can't imagine why it would be left hand thread.

[Jailer]

rbertalotto should be able to tell you. He just got done with an awesome takedown project on a Rossi.

http://castboolits.gunloads.com/showthread.php?t=130059

[W.R.Buchanan]

It's right hand.

Randy

[bearcove]

Thanks Randy

Rod

[roysha]

Clocking is potentially what the recoil shoulder in an FAL would do if it did not have the anti-clocking tab.

Also, although I haven't heard the term used in years in this way, it can mean you got decked!