Reaming a chamber?
- Thread starter andym79
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rcmodel
Member in memoriam
If you have a roughed in chamber, you finish it with a finish reamer.
You cannot ream, say a .30 cal barrel to a 30-06 chamber with a finish reamer without wearing it out, or burning it up before you got done.
Otherwise they wouldn't make both types of reamers.
rc
You cannot ream, say a .30 cal barrel to a 30-06 chamber with a finish reamer without wearing it out, or burning it up before you got done.
Otherwise they wouldn't make both types of reamers.
rc
BBBBill
Member
A roughing reamer leaves the chamber........ ROUGH! 
Some very skilled folk single point the chamber on the lathe with just a boring bar before finish reaming. Not something you want to do unless you have lots of practice and thoroughly understand the process. So, yes, a roughing reamer and a finish reamer are necessary.
Some very skilled folk single point the chamber on the lathe with just a boring bar before finish reaming. Not something you want to do unless you have lots of practice and thoroughly understand the process. So, yes, a roughing reamer and a finish reamer are necessary.25cschaefer
Member
You can most certainly ream a full chamber with a finish reamer, it just takes longer and will eventually wear it out but we are talking about many, many, barrels. To cut time down and reduce wear on reamers, it is common to hog out the majority of the chamber with a common drill bit about 0.010" smaller than the shoulder. The run out will not be severe enough to worry about because your reamer has a pilot and will engage the bore. When drilling you want to stop short enough to still have engagement of the bore by your pilot.
The most common place you will find roughing reamers is in the production world, most small shops and manufacturers are going to be using a drill bit or just a finish reamer.
The most common place you will find roughing reamers is in the production world, most small shops and manufacturers are going to be using a drill bit or just a finish reamer.
243winxb
Member
http://benchrest.com/showthread.php?59097-Jackie-chambering-a-Barrel-(Pictures I see a special drill being used in photos.
Kp321
Member
Not to disagree with rc, but I have been in business almost 40 years and don't own a roughing reamer, only finish reamers. Granted I don't build hundreds of rifles per year, more like 20 in various calibers. None of my reamers have been used over 15 times, most two or three. I ream in my lathe, running in the slowest gear and use plenty of good cutting oil. I will back the reamer out and clean the chips often, usually after cutting .050 to .100". So far, I have not had to have a reamer reground.
Howard Roark
Member
I too have only used finish reamers. If I did a lot of chambering for a specific caliber I would get and use a roughing reamer to make the finish reamer last longer before it needed sharpening.
I've done as Kp321 says above. Slow gear, lots of lube and .050 per cut. My match .223 reamer has chambered 12-14 barrels so far and still cuts smooth.
I wouldn't use a drill bit to rough chamber barrel to be used for precision. Too much can go wrong with a drill bit and push it off center such as dullness on one side or another and chip loading. If the rough chamber is off center and deep (like a 30.06) the reamer won't have a chance for the pilot to center on the bore before it's too late to center the body back up. A $320 blank ain't worth it.
That said I've cut down several shot out .223 match rifle barrels and made very good shooting M4 length barrels by roughing the new chamber with a drill bit. But then again I wasn't on the way to the nationals with it either.
I've done as Kp321 says above. Slow gear, lots of lube and .050 per cut. My match .223 reamer has chambered 12-14 barrels so far and still cuts smooth.
I wouldn't use a drill bit to rough chamber barrel to be used for precision. Too much can go wrong with a drill bit and push it off center such as dullness on one side or another and chip loading. If the rough chamber is off center and deep (like a 30.06) the reamer won't have a chance for the pilot to center on the bore before it's too late to center the body back up. A $320 blank ain't worth it.
That said I've cut down several shot out .223 match rifle barrels and made very good shooting M4 length barrels by roughing the new chamber with a drill bit. But then again I wasn't on the way to the nationals with it either.
jmorris
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Yes, you can use just a finish reamer. How many barrels can you do with just one finish reamer? I don't know what round are we talking about in what barrel(s).
If you are clambering .22lr barrel liners, correctly, you can do hundreds with one. If you are hogging out Lothar Walther 50 BMG blanks you might want to invest into a roughing reamer or by "chambered blanks".
A chamber reamer is just a cutting tool, other than shape, no different than a regular reamer.
If you are clambering .22lr barrel liners, correctly, you can do hundreds with one. If you are hogging out Lothar Walther 50 BMG blanks you might want to invest into a roughing reamer or by "chambered blanks".
A chamber reamer is just a cutting tool, other than shape, no different than a regular reamer.
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barnbwt
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Lessons I learned reaming my first chamber today;
-Use sharp reamers!
-Don't use much pressure to advance the cut after initially biting into the barrel (depending on the leade cut, some force may be required to get the first chips going when you start out)
-Since flutes will try to catch on the rifling lands, pre-drilling the first bit of the bore to eliminate them (or get closer to the finish diameter) will make holding the handle/wrench steady during engagement much easier & safer (lathes are powerful, and you are basically resisting several times the torque of a twist drill for reaming, minimum; if it catches you could get hurt if you don't position your grasp on the wrench strategically)
-Clear chips frequently & inspect for flute damage when cleaning them out
-The reamer will stabilize after the first 1/4" or so of cut, and begin cutting more quickly with less force. Be aware of the change so you don't let chips build up too quickly or overshoot your mark
-In my case (HK33 barrel) it was easiest to headspace by chambering past where I needed, and facing the barrel back to proper case protrusion. Easier to dial in a lathe apron than a reamer depth (due to spring back and 'grabbing' of the walls during reaming, it can be difficult to get the depth right to the thousandth in accuracy, especially since cutting too slowly causes chatter)
-Even O1 drill rod homebrew reamers (45acp) can be run faster than you think without being damaged, and actually cut better, but remember that bit about having to control the wrench while doing so
-You will likely (almost certainly) need to polish the chamber with an abrasive flap or small stone after reaming (you can end with small burs at the neck/shoulder transitions, as well as the sucky-but-often-inevitable scoring from a chip that gets by the flutes during cutting)
Reamers are just fancy drill bits (not even that fancy, or they'd be spiraled) so they will cut what you need, and for many barrels, also. But they are also very expensive or a real chore to make, so anything you can do to reduce their workload is worth it. That's what pre-drilling and roughing reamers are for. Roughers can have tougher cutting surfaces, and leave a reduced profile that is strategically shaped to support the finish reamer nicely for the followup and prevent chatter & reduce cutting forces.
Speaking of 50BMG barrels; it pays to know if your barrel is chrome-lined or stellite-lined before ruining a reamer on it (not my lesson, but a friend's)
-Use sharp reamers!
-Don't use much pressure to advance the cut after initially biting into the barrel (depending on the leade cut, some force may be required to get the first chips going when you start out)
-Since flutes will try to catch on the rifling lands, pre-drilling the first bit of the bore to eliminate them (or get closer to the finish diameter) will make holding the handle/wrench steady during engagement much easier & safer (lathes are powerful, and you are basically resisting several times the torque of a twist drill for reaming, minimum; if it catches you could get hurt if you don't position your grasp on the wrench strategically)
-Clear chips frequently & inspect for flute damage when cleaning them out
-The reamer will stabilize after the first 1/4" or so of cut, and begin cutting more quickly with less force. Be aware of the change so you don't let chips build up too quickly or overshoot your mark
-In my case (HK33 barrel) it was easiest to headspace by chambering past where I needed, and facing the barrel back to proper case protrusion. Easier to dial in a lathe apron than a reamer depth (due to spring back and 'grabbing' of the walls during reaming, it can be difficult to get the depth right to the thousandth in accuracy, especially since cutting too slowly causes chatter)
-Even O1 drill rod homebrew reamers (45acp) can be run faster than you think without being damaged, and actually cut better, but remember that bit about having to control the wrench while doing so
-You will likely (almost certainly) need to polish the chamber with an abrasive flap or small stone after reaming (you can end with small burs at the neck/shoulder transitions, as well as the sucky-but-often-inevitable scoring from a chip that gets by the flutes during cutting)
Reamers are just fancy drill bits (not even that fancy, or they'd be spiraled
) so they will cut what you need, and for many barrels, also. But they are also very expensive or a real chore to make, so anything you can do to reduce their workload is worth it. That's what pre-drilling and roughing reamers are for. Roughers can have tougher cutting surfaces, and leave a reduced profile that is strategically shaped to support the finish reamer nicely for the followup and prevent chatter & reduce cutting forces.Speaking of 50BMG barrels; it pays to know if your barrel is chrome-lined or stellite-lined before ruining a reamer on it (not my lesson, but a friend's
)rcmodel
Member in memoriam
In my experience, all U.S. Machinegun barrels are lined with something harder then Woodpecer lips!!
The older .50 barrels you come across especially, are usually Stellite lined.
Death to reamers in one turn !!
rc
The older .50 barrels you come across especially, are usually Stellite lined.
Death to reamers in one turn !!
rc
Yes you can, I can. You can call a manufacturer of reamers. They are proud of their products, they claim it is possible to ream as many as from 25 to 30 chambers. then there is that part about advancing, the roughing reamer is used to rough in a chamber for a barrel blank, that could require advancing the reamer 2.50"+. Then there are short chambered barrels, short chambered barrels have a chamber that is roughed in, all that is necessary is 'to finish'.
I purchased a barrel from Midway, they advertised the barrel as 'short chambered'. I checked, then called, I wanted to know 'how short'. The chamber was .250" short of being finished. .250" should be enough reaming to finish 10 chambers 'minimum'.
Some smiths have no pride, when it comes to roughing they will use a drill then a core hole drill etc., etc..
F. Guffey
Clark
Member
I am an amateur gunsmith, just building my own rifles.
I started 15 years ago and I now have a couple dozen finish reamers.
The gunsmith on staff at Brownells told me I did not need a roughing reamer.
But I often go in the a drill for 1/2".
Then I finish up the 1/2" deep hole with a boring bar.
Then I go in with the finish reamer for 1/2".
It takes about 5 sets of these steps to do a 7mmRemMag.
I put a drawing and a plan on the lathe so I don't get confused.
DRO is a must.
The 22LR reamer just cuts out one match head of metal, so I don't bother.
Everything else is somewhere in between.
I started 15 years ago and I now have a couple dozen finish reamers.
The gunsmith on staff at Brownells told me I did not need a roughing reamer.
But I often go in the a drill for 1/2".
Then I finish up the 1/2" deep hole with a boring bar.
Then I go in with the finish reamer for 1/2".
It takes about 5 sets of these steps to do a 7mmRemMag.
I put a drawing and a plan on the lathe so I don't get confused.
DRO is a must.
The 22LR reamer just cuts out one match head of metal, so I don't bother.
Everything else is somewhere in between.
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