Throat ream

The uni-throater Pacific sells comes with a depth stop and t-handle that allows just what you're looking for.
 
Since you will probably be doing this by hand proceed very carefully if you want a smooth finish..

Remember. the leade is where most coppering starts


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These "throater" reamers are very sharp and the material you're cutting is mostly lands. It takes very little pressure and only a few turns to cut much more than you might imagine if you haven't done this before.

In other words, measure very carefully and cut with caution. You can't go back. I recommend setting the throater to about half your target distance, make the preliminary cut, and then measure. Then you'll have an idea of how quickly the cut proceeds. Said another way, if this is your first time then "sneak" up on the amount of cut you want. If you go too far, you ain't gonna' fix it with J.B. Weld, that's for sure. ;)

It's actually rather easy, but use caution.
 
I do a lot of it trying different things and it is better done with the barrel out and straight down if you do it by hand. You need some tools to measure with.... jim
 
I'm not sure I'd attempt it myself, atleast not yet anyway. What's a ballpark figure for having a smith do this work with the bbl still on the action? Would it be common for a smith to own a throat reamer, or would they more than likely have to rent a reamer too?
 
I'm not a gunsmith...and Holiday Inn is too expensive...but Wayne Shaw says that Pacific thing has a stop to control the cut. Although I would never be guilty of such, it sounds fairly easy to me.
 
It is a Uni-Throater and I have two for 6mm a .2435 and a .2438 both are 1.5 degree. They are very easy to use and very accurate. They are lined up on both ends, ..... jim
 
Measuring throat depth

Gents:

What is the recommended method for getting an accurate throat measurement?

Thanks in advance,
Ben H
 
Ben H said:
Gents:

What is the recommended method for getting an accurate throat measurement?

Thanks in advance,
Ben H
Click to expand...

Be glad you're asking on this forum, this shouldn't turn into a fight! ;)

WHAT I DO is....

I use a nicely fitting fireformed case.

I pop the primer out manually using a hammer.

I "soft seat" a bullet "long" which means I adjust my neck tension to light enough that I can basically move the bullet around with my fingers and set the bullet out very long.... And I measure it with a Sinclair "nut". I measure it a couple times and write it down.

Now I gently insert it into the chamber and pull it out. Measure it. Write it down.

Do this at least 5 times to make sure the bullet isn't sticking in the leade and screwing your reading.

And that's IT :)

Some tips and tricks;
only do this with fireformed and well fitted brass
of course different bullets, different ogives seat differently..... even different lots of the same bullets seat differently.
if you want a visual representation try coloring the bullet with a silver sharpie
different neck tensions also give sometimes valuable information.


hth


al
 
Ben H said:
Gents:

What is the recommended method for getting an accurate throat measurement?

Thanks in advance,
Ben H
Click to expand...

Seat a bullet long in an unpowdered case. Chamber it and let the chambering push the bullet to the throat depth. The difference between the jammed bullet and what you want is jump.

On a hunting chamber you want the throat deep enough for your longest load. For precision shooting the bullet jam is part of the tuning formula.


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Or make a chamber casting using Cerrosafe and measure it.

While Cerrosafe first shrinks (so you can remove the casting), and then slowly enlarges (by well known amounts) the actual movement is very well documented.
It passes through zero 'error' but then is very slightly oversize forever.

Most of those reamers have a removable pilot on their tip.
The pilot must be made to the EXACT size on every job.

If you do enough of these jobs you might accumulate a pilot you can use more than once.
They are typically measured to 0.0001 so it can take a decent number.

They occasionally get scratched and can only be reduced in size though.

While it may not look that way the cutting edges of reamers like this are razor sharp.
Not razor angle, but razor sharp.

You will not even feel them initially cutting into your skin.
Be VERY careful handling them.

Leave their wax cover on as long as you can and be sure to put it back on carefully.
 
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