dial in TOP OF THE LANDS OR BOTTOM OF THE BORE
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mwezell
Mike Ezell
Lots of barrels don't have uniform land to groove heights and widths. JMHO, but I think this is where the barrel magic happens.
If the bore and groove are right
on the money then I will use a pilot. If they aren't then just split the difference on runout and don't use the pilot. This is assuming you drill and true with a boring bar. If somebody else has a better idea I would love the hear it.
Richard
on the money then I will use a pilot. If they aren't then just split the difference on runout and don't use the pilot. This is assuming you drill and true with a boring bar. If somebody else has a better idea I would love the hear it.
Richard
Pete Wass
Well-known member
Just a question
If one assumes it is the bulk of the barrel ahead of the throat that is going to have the most influence on what happens to the bullet once the cap is busted then why are we worried about the metal we are going to ream out of for the chamber? It seems to me it's likely the last two or 4" of the barrel that does the most to influence where the bullet goes. Just something to think about.
Pete
If one assumes it is the bulk of the barrel ahead of the throat that is going to have the most influence on what happens to the bullet once the cap is busted then why are we worried about the metal we are going to ream out of for the chamber? It seems to me it's likely the last two or 4" of the barrel that does the most to influence where the bullet goes. Just something to think about.
Pete
Pete,
I guess it depends on how you chamber a bbl. My two places to indicate are the throat and the crown. When indicating the throat I always check ahead of the throat the length of the bearing surface of the bullet. If that's good I'm ready to drill and bore. Why indicate what your going to be drilling out? You can indicate in three places depending on your method of chambering.
The rear of the chamber, the throat, and the crown. But you can only use two. If you do all three then your bending the bbl.
Richard
I guess it depends on how you chamber a bbl. My two places to indicate are the throat and the crown. When indicating the throat I always check ahead of the throat the length of the bearing surface of the bullet. If that's good I'm ready to drill and bore. Why indicate what your going to be drilling out? You can indicate in three places depending on your method of chambering.
The rear of the chamber, the throat, and the crown. But you can only use two. If you do all three then your bending the bbl.
Richard
yes i indicate at the throat where the bullet enters the bore/bbl.
i want he entry to be as square to the bore as possible.
i want he entry to be as square to the bore as possible.
Pete Wass
Well-known member
How much do you think
that matters when there is 18 or more inches that will influence what the bullet does once it leaves the throat? I'm not arguing but want to hear why you thing it's that important?
Thanks,
Pete
that matters when there is 18 or more inches that will influence what the bullet does once it leaves the throat? I'm not arguing but want to hear why you thing it's that important?
Thanks,
Pete
Pete Wass
Well-known member
I also indicate this way
but a lot of people only indicate the chamber end to the Gnat's butt and they seem to get the same results we do. This is what brings the question to my mind about the whole business of throat. Mos barrels are bananas, to some degree.
Pete
but a lot of people only indicate the chamber end to the Gnat's butt and they seem to get the same results we do. This is what brings the question to my mind about the whole business of throat. Mos barrels are bananas, to some degree.
Pete
get the bullet to enter the lands square so it travels evenly, no tilt for the bore to try and straighten.
do not attempt to use the bore to straighten the bullet to the bore.
start straight finish straight
do not attempt to use the bore to straighten the bullet to the bore.
start straight finish straight
if you indicate the butt of the chamber and also the crown you can still have a good throat, but can also cut an oversize chamber. The gun will still shoot but the chamber can be different from one bbl to another. I have multiple guns and several bbl.'s for each. The same piece of brass will fit all of them perfectly.
Richard
Butch Lambert
Active member
Pete, I guess you heard on the internet that barrels had a curved "banana shaped" bore. I never seen that. Bores can take off, but I've never seen one with a banana curve. If you have seen and paid attention to a barrel being bored, you will see what I'm speaking of. There is no way to indicate a bore to make it straight all the way through. If you do as Richard posted I don't think you can do better than that.
Yes, I've tried running an indicator rod down the barrel and all it did was make the muzzle look like a piece of spaghetti.
Sure didn't make it a shooter.
Think about it, if you indicate the throat, how much will the bore move in a half inch or so?
I don't need a bushing as I do not want the chance of a bore running off and making the back of the chamber oversize.
Yes, I've tried running an indicator rod down the barrel and all it did was make the muzzle look like a piece of spaghetti.
Sure didn't make it a shooter.
Think about it, if you indicate the throat, how much will the bore move in a half inch or so?
I don't need a bushing as I do not want the chance of a bore running off and making the back of the chamber oversize.
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Pete Wass
Well-known member
I bought range rods years ago
but don't use em because of the slop between the bushings and the rod itself. I went to using gauge pins in each end and call it good when I get both ends running true. So far, it has worked out fine. I had an indicator I could reach a 30 BR throat with but never used it so sold it to a friend. SO far, all the CF barrels I have chambered have shot small ones. I just question the whole throat thing I guess..I have around 500 pieces of 30 BR brass that will all chamber in the barrels I have reamed because I use a piece if of it as a Go gauge. Chamber until the bolt closes with a bit of feel and we're home. I have had chabers done by others in the past that I could see were not cut perfectly concentric and the rifles still shot excellently, only one or two but nevertheless - - -.
A Smith of some note told me he once chambered a barrel using a 3 jaw chuck and the barrel shot just fine. So, one has to wonder a bit.
Pete
but don't use em because of the slop between the bushings and the rod itself. I went to using gauge pins in each end and call it good when I get both ends running true. So far, it has worked out fine. I had an indicator I could reach a 30 BR throat with but never used it so sold it to a friend. SO far, all the CF barrels I have chambered have shot small ones. I just question the whole throat thing I guess..I have around 500 pieces of 30 BR brass that will all chamber in the barrels I have reamed because I use a piece if of it as a Go gauge. Chamber until the bolt closes with a bit of feel and we're home. I have had chabers done by others in the past that I could see were not cut perfectly concentric and the rifles still shot excellently, only one or two but nevertheless - - -.
A Smith of some note told me he once chambered a barrel using a 3 jaw chuck and the barrel shot just fine. So, one has to wonder a bit.
Pete
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Butch Lambert
Active member
Pete, I know of a similar situation where the bore was way off and put between centers for a clean up cut, turn the tenon, and threaded. It was then put in the steady and chambered without indicating it. Reamer was a floating one. Took for ever to get it on paper, but shot very very well. It was just a fun exercise, but made me wonder.
Pete..... to some of us we don't REAM all that excess out of the chamber because the result will always be different-sized chambers. Instead we carefully scoop it out using tooling so that when the reamer finally goes in it's not "wallering" (wallowing) about following the crooked bored hole.
MY reason is..... I've currently got 7 different 6X47L barrels IN USE between 3 different platforms and I want to be able to mix and match my brass and only have one resizing setup. AND I want these mixed/matched cases to last until these 7 barrels (and several more) are burnt out and hammered into plowshares.
20yrs ago we useta' discuss "egg-shaped chambers" and eccentric setups and I thought "WTH??? HOW can one get an out-of-round chamber??"
Then I got one......
And later figgered out WHY.....
And now I just avoid the whole issue AND point my barrel where I want to.
jackie schmidt
New member
I won’t get into the discussion of the actual chambering except that I just treat it like any other machine job. You figure out what you want to run true with what, and work from there within the parameters of the equipment on hand.
As for the OP’s question, I indicate the lands, then check the grooves.
As for the OP’s question, I indicate the lands, then check the grooves.
Im currently in the midst of chambering 5 Fclass barrels, all the same 284 reamer, 3 Brux and two Bartlein Barrels. All to be used interchangeably on three Borden Actions. Brux are the standard 4 groove, Bartlein 5R. Im through 4 of them and have one Brux left. Its been quite educational as even just dialing in the barrels (initially I dial in the end before drilling out a core, then dial in the throat with a bushing on a rod held in tailstock) there are differences in the same brand. This one has a bit more cant in the groove, that one has a slightly deeper groove, this one is 4 thou different from the first dial-in at the end of the barrel, that one didnt require more than a half thou correction, etc.... ultimately Im dialing in the throat on top of the lands somewhere between the pilot and the throat, I kind of split the difference. I step bore so the reamer pilot is in the bore and the rear of the single point bored hole contacts the reamer flutes. If I spin the chuck with the reamer pushed in at that point, runout is nil as itll be a straight, supported path when starting to ream the chamber.
Ideally I would like to be dialed into the bottom of the grooved as I feel thats the surface the bullet will center on, but am unable to with most larger chambers due to depth. That said, if using a snug piloted reamer, youll be centered on the tops of the land so you should probably dial into that surface...
Ideally I would like to be dialed into the bottom of the grooved as I feel thats the surface the bullet will center on, but am unable to with most larger chambers due to depth. That said, if using a snug piloted reamer, youll be centered on the tops of the land so you should probably dial into that surface...
I had a carbon wrapped barrel from a local manufacturer on a good hunting rifle, it would do the 2 touching then one at least 1-1.25 moa away trick...
The throat & chamber looked drunk, you could clearly see the remnants of two of the six lands in the freebore/throat & the chamber dialed up poorly
I had it straightened significantly by another smith as a favour & knowledge building experience for both of us
I'm not a smith & didn't chamber it, my regular smith did, he builds a lot of rifles for me including my bench guns that shoot great
It still wouldn't shoot & the throat still looked drunk.....
I gave up, cut the barrel up & had it measured by another smith with good enough gear, once again for a knowledge building exercise.
Groove Diameter was 0.2849
Bore Diameter was 0.2772
The land heights were
1. 37.79 thou
2. 36.61 thou
3. 38.58 thou
4. 21.25 thou
5. 37.40 thou
6. 39.76 thou
It became blatantly obvious why the throat always looked drunk, the chamber wasn't as straight as it could have been & the remnants of two lands in the throat.
It was chambered off the lands, who knows if it would have shot if it had been dialed up & chambered different, pretty hard to do now its in 4 bits
Cost me a huge amount of money but it will never happen again from that manufacturer & no I wasn't the only on with a "special" barrel from them
It was a button barrel, I guess this sort of thing just happens from time to time....
The throat & chamber looked drunk, you could clearly see the remnants of two of the six lands in the freebore/throat & the chamber dialed up poorly
I had it straightened significantly by another smith as a favour & knowledge building experience for both of us
I'm not a smith & didn't chamber it, my regular smith did, he builds a lot of rifles for me including my bench guns that shoot great
It still wouldn't shoot & the throat still looked drunk.....
I gave up, cut the barrel up & had it measured by another smith with good enough gear, once again for a knowledge building exercise.
Groove Diameter was 0.2849
Bore Diameter was 0.2772
The land heights were
1. 37.79 thou
2. 36.61 thou
3. 38.58 thou
4. 21.25 thou
5. 37.40 thou
6. 39.76 thou
It became blatantly obvious why the throat always looked drunk, the chamber wasn't as straight as it could have been & the remnants of two lands in the throat.
It was chambered off the lands, who knows if it would have shot if it had been dialed up & chambered different, pretty hard to do now its in 4 bits
Cost me a huge amount of money but it will never happen again from that manufacturer & no I wasn't the only on with a "special" barrel from them
It was a button barrel, I guess this sort of thing just happens from time to time....
jackie schmidt
New member
I had a carbon wrapped barrel from a local manufacturer on a good hunting rifle, it would do the 2 touching then one at least 1-1.25 moa away trick...
The throat & chamber looked drunk, you could clearly see the remnants of two of the six lands in the freebore/throat & the chamber dialed up poorly
I had it straightened significantly by another smith as a favour & knowledge building experience for both of us
I'm not a smith & didn't chamber it, my regular smith did, he builds a lot of rifles for me including my bench guns that shoot great
It still wouldn't shoot & the throat still looked drunk.....
I gave up, cut the barrel up & had it measured by another smith with good enough gear, once again for a knowledge building exercise.
Groove Diameter was 0.2849
Bore Diameter was 0.2772
The land heights were
1. 37.79 thou
2. 36.61 thou
3. 38.58 thou
4. 21.25 thou
5. 37.40 thou
6. 39.76 thou
It became blatantly obvious why the throat always looked drunk, the chamber wasn't as straight as it could have been & the remnants of two lands in the throat.
It was chambered off the lands, who knows if it would have shot if it had been dialed up & chambered different, pretty hard to do now its in 4 bits
Cost me a huge amount of money but it will never happen again from that manufacturer & no I wasn't the only on with a "special" barrel from them
It was a button barrel, I guess this sort of thing just happens from time to time....
It's a shame they wasted that expensive carbon wrap on a junk barrel.