Action thread timing Question

[Gil P.]

Are the threads inside of custom actions always timed the same? I assume this varies between manufacturers.

Have any of you seen manufactures who always time their actions the same way?

I recently made a thread concerning prefits and was wondering how the smith who chambers the prefit would know where the action threads begin.

Aren't all barrels slightly bent? Would you want the muzzle on the barrel pointing upwards?

Ideally all barrels are perfect straight and drilled perfectly straight. Do perfect barrels exist?

 

[kuraki]

If the actions are thread milled, which I assume a majority of them are, then just by the nature of how that canned cycle works, the threads will be timed the same from one to another without any intent on the maker's part.

The first barrel I ever installed myself must have had a pretty good warp to it. I threaded and chambered it myself, and got it sighted in at 100 yards, did some load development and had it shooting consistent 1/2" groups. I was very proud of myself until I shot it 300 and 600 yards and found it would shoot about 1 MOA or better to the right in no wind.

Nothing perfect exists. It's all a question of relativity. I have other barrels I've since installed, that I never checked for bore straightness relative to the action, that don't display any horizontal deviation at range. Did I get lucky and time them up or down on accident? Or were they just not warped enough to matter relative to my expectations?

 

[Alex Wheeler]

Pandas time the same. Most Bats do, but there are small % that wont. I usually like to have the action one time and record the timing info just to be sure.

 

[msalm]

Howa’s are pretty much timed all the same believe it or not.

 

[tobnpr]

The timing is the rub when it comes to engraving.
You'll notice many "shouldered prefits" are not engraved. Easy enough to get the boltface to receiver ring dimension consistent on the receiver and reaming the chamber accordingly.

Getting the barrel threads timed precisely enough to engrave, without having the action in hand- different animal. There are a few high-end shops with the capability to do it.

 

[butchlambert]

Bent barrel?? I just don't understand folks that post this. Barrel makers do not put them in a press to bend them or run over them with a truck!

 

[Gil P.]

Bent barrel?? I just don't understand folks that post this. Barrel makers do not put them in a press to bend them or run over them with a truck!

I didn't mean a visual bend. I said that to acknowledge that it's not possible to have a barrel that is perfectly straight.

There must some measurable deviance in straightness from one end of the barrel to the other.

 

[Tokay444]

If point of aim was point of impact at 100, it wasn’t the barrel that caused the shift at 300 and 600.

 

[Gil P.]

If point of aim was point of impact at 100, it wasn’t the barrel that caused the shift at 300 and 600.

I would agree it likely doesn't matter.

Heres the way I see it. The accuracy of a rifle is dependent upon an accumulation of errors. Less errors = more accuracy. I am no gunsmith, but the process appeals to my meticulous nature. If I was a gunsmith, I would want the error in the straightness of the barrel timed in a way where it would cause the least amount of deviation. However small that deviation might be.

 

[Tokay444]

I would agree it likely doesn't matter.

Heres the way I see it. The accuracy of a rifle is dependent upon an accumulation of errors. Less errors = more accuracy. I am no gunsmith, but the process appeals to my meticulous nature. If I was a gunsmith, I would want the error in the straightness of the barrel timed in a way where it would cause the least amount of deviation. However small that deviation might be.

In a vacuum, with a 600 yard target behind a 300 yard target behind a 100 yard target, completely in line, and elevations lining up with trajectory, a bullseye at 100 will be a bullseye at 300 will be a bullseye at 600, regardless of a bent barrel. The only arc the bullet stays on once it leaves the muzzle is the arc of elevation vs gravity.

 

[46and2]

In a vacuum, with a 600 yard target behind a 300 yard target behind a 100 yard target, completely in line, and elevations lining up with trajectory, a bullseye at 100 will be a bullseye at 300 will be a bullseye at 600, regardless of a bent barrel. The only arc the bullet stays on once it leaves the muzzle is the arc of elevation vs gravity.

Minus spin drift and coriolis.

 

[Tokay444]

Spin drift? And cornholeiolis? At 600? Easy there Swagger.

 

[Bamban]

The first barrel I ever installed myself must have had a pretty good warp to it. I threaded and chambered it myself, and got it sighted in at 100 yards, did some load development and had it shooting consistent 1/2" groups. I was very proud of myself until I shot it 300 and 600 yards and found it would shoot about 1 MOA or better to the right in no wind.

How did it shoot when you shot at 100 on a thermometer target with the straight line set by plumb bob, and crank your 600 elevation? I assume you were shooting optics not irons.

 

[DaveTooley]

If point of aim was point of impact at 100, it wasn’t the barrel that caused the shift at 300 and 600.

It's called spin drift.

 

[DaveTooley]

Bent barrel affecting point of aim. Not the way I chamber. Dial in the muzzle and the throat. Any barrel chambered this way will pretty much point to the same spot on any given action. We are talking about the length of the bearing surface of the bullet as it leaves the muzzle. That's the only part of the bore that affects point of impact. What it does between leaving the case and prior to that last fraction of an inch doesn't matter. Where is the muzzle in relation to the barrel shoulder. I want the muzzle perfectly perpendicular to the plane of the tenon shoulder.

 

[kuraki]

How did it shoot when you shot at 100 on a thermometer target with the straight line set by plumb bob, and crank your 600 elevation? I assume you were shooting optics not irons.

I never tried, and the rifle is long gone now.

 

[Tokay444]

It's called spin drift.

And how much of it is there at 300? 600?

 

[WillyTP]

And how much of it is there at 300? 600?

This is on a 6 Dasher with all wind inputs at 0.

 

[46and2]

And my 300 wsm.

Spin drift? And cornholeiolis? At 600? Easy there Swagger.

Swagger

 

[daylate]

This is on a 6 Dasher with all wind inputs at 0.

Just having my first cup….Is this saying 11.4 inches at 600 yds with zero wind?