oversize chamber

S

skeetlee

Active member
What would case an oversize chamber? My tail stock is about .005 to high but i am using a floating reamer pusher. The last two chamberes i cut were just a shade to big in the back end." .0015" Any ideas? i did check my left to right and it was out .003. thanks Lee
 
Left and right should be dead nuts, sweep it around with a .0005" or better indicator and adjust accordingly for left and right. For the tail stock height you can try by tightening down the tail stock more. This will generally pull it down closer.

When adjusting for left and right (if yours has the set screws on each side) make sure the tail stock is not locked down. If it's locked down this will impede correct adjusting.

Mine sits .003" high unlocked, when I crank it down good and tight, it's only .001" high, which I can live with using a floating pusher. Left and right is dead on.

Are you drilling and then pre-boring, proper fitting bushing?, chambering all the way with the finish reamer??

Are you cutting the tennon and threading before or after chambering? My take is, the easiest place to knock your set-up off is when cutting the tennon and threading because of tool pressure. Are you dial checking your work as you go??

In order to better help you find out "why"? We need to know exactly how you went about chambering said barrel from beginning to end.

It's all about rigidity and checking your work as you go.

If you can chamber by the numbers and are not indexing the muzzle high or low, I would cut the tennon to final dimension and thread last.
 
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An oversize chamber based on what? The reamer drawing, another drawing for that cartridge??
If it is a new reamer and you are sho' nuff using a floating pusher, your reamer is probably oversize/

Take the reamer by itself and remove the guide bushing, then stick it in your chamber up to the shoulder and see if there is any feel of looseness.
 
Let me do a little more investigating and i will report back. The .0015 oversize is coming from another piece of brass chambered by someone else with my reamer. I felt the FL size die feel a little tight this afternoon and it got me to checking on a few things.
I use my reamer for the hole chamber, reaming about .050 at a time. I have had some really fantastic barrels chambered this way, and mine shoot very well themselves. I do however want to do all this the best i can, and i am open to change. thanks Lee
 
So the barrels shoot very well, and you're worried? Sounds to me the sizing die will do it's job and you won't have any problems with click.
 
You can do everything right and still wind up with one chamber that is a little smaller in diameter than another one chambered at the same time. Which one will shoot better? That just depends upon the barrel. The one with the tighter chamber will cause more problems especially if you try to use the same brass in both chambers. If you want the smallest chamber, I'd suggest drilling out most of the chamber and boring it to about .010" under shoulder diameter, then finish the last .100" of the chamber with a pusher substituted for a dead center. If I push the reamer in with a dead center, I'll have no shake that you can feel in the reamer. But, if I switch over and ream the last .100" of the chamber with a floating pusher, I'll cut a chamber slightly smaller in diameter than finishing all the way with the dead center. I prefer reaming most of the chamber pushing with the dead center after drilling and boring as it gives the reamer more support when reaming. As always, there is more than one way to skin a cat when it comes to chambering a barrel. Just because someone does it differently doesn't mean they are right or wrong, just different.
 
Thanks Mike
This barrel that i finished up yesterday turned out really good. I paid closer attention to how i handled the floating pusher this go around. On my Lathe, or should i say, with my floating reamer pusher. I have to unlock the tail stock, and slide it back every time i want to clean the chips off my reamer. My holder is to long for me to just crank the tail stock out. What i did a little different yesterday, was to allow my machine to come to a complete stop before i cranked the tail stock back. I crank the tail stock back a couple turns, then i unlock the tail-stock from the bed. Then I slide it rearward. I think maybe i was putting some side pressure on the reamer, before going to this method? Anyway the barrel turned out really good. I had about .0003 run out on the chamber after it was finished, and i am most pleased with that. Heck, the barrel even shoots pretty good! thanks again fellas! Lee
 
Are you cutting the tennon and threading before or after chambering?
Click to expand...

Pardon my newbyness but just how does one set the headspace properly without screwing the action onto the barrel?
 
Suputin said:
Pardon my newbyness but just how does one set the headspace properly without screwing the action onto the barrel?
Click to expand...

By measuring the parts. I've got several rifles from several Bench Rest Gunsmiths where I can order new barrels with a simple phone call and screw the new barrel on myownself and go shoot.

I've ordered barrels years later AND IN DIFFERENT CHAMBERINGS from several of the vendors who advertise on this site. They've gone back in their records, taken the measurements from their notes and sent me a perfectly fitted barrel.

I don't recommend you try this with your local gunschmidt ;)

al
 
Suputin said:
Pardon my newbyness but just how does one set the headspace properly without screwing the action onto the barrel?
Click to expand...

You can use something like the setup below and transfer your measurements from an existing barrel or from a tenon drawing....or measure from the action face to the bolt.
The sleeve shown must be as long as the headspace dimension plus a little. For example if the headspace dimension,(for a Stolle Panda 1.115"), then make the sleeve, say, 0.250" longer, or 1.365". Then the depth micrometer reading would be 0.250".


adult upload image
 
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The ones I've made I've made flat, or made a plug gage (in Jerry's example my plug would measure .250) because I suck with a depth mic.

But then I gener'ly mistrust measures, instead relying mostly on gages and interference.

al
 
Pictured below is a few of my chambering tools. I thread first and then double check my bore indication. Put the headspace gauge in the old barrel and screw the tool on and take a measurement. Do the same on the cone. The radial lines tell me where I will engrave the lettering on the new barrel. Write this in your book and you can always go back to it for the next barrel.
Your tools will be a little different for some receivers, but it works the same.

zsok5x.jpg
 
I get the idea of measuring the distance a headspace gauge protrudes from an existing barrel for that rifle but how would I get measurements for an action for which I don't have an existing barrel or which has been modified by lapping the mugs and facing the action or going from an OEM recoil lug to a thick match grade recoil lug?

I can work out how to make a gauge to measure the action and another to measure the barrel itself but how to relate those two measurements to each other? That seems to be the trick.
 
More than likely if you are going to thicker recoil lug, you have the action in your hand and it's not glued into the stock. An action in the hand is the best way to test barrel thread fit, headspace and other clearances. If you do have a glued in action where you don't have an existing barrel that has already been fit, you can thread it between centers and test for thread fit. Use a depth gage to get your headspace readings, tenon lengths and other clearances or one of the tools that people have made to get headspace readings and cone fits. Below is a photo of the tool that I made to get headspace and cone dimensions when going from one barrel to the other.

Cone_measuring_device1.jpg

Cone_measuring_device2.jpg
 
No. The question is how do I headspace without threading the barrel tenon as some have suggested is the best way to do it.
 
Suputin said:
No. The question is how do I headspace without threading the barrel tenon as some have suggested is the best way to do it.
Click to expand...

Look at the picture I posted on #12 above. That sleeve will work on a threaded or non threaded barrel,

Why do you not want to thread the barrel?
 
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