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M Bellm makes it sound like most rechambering jobs are hack jobs http://www.bellmtcs.com/store/index.php?cid=468 anyone recommend a So CA precision rechamber artist.
from Bellm's site ..."
from Bellm's site ..."
How I Go About My Work And What Sets It Apart.
First off, my two hands do all of the rechamber work, muzzle brake work, and other critical machine work.
Second, I DO NOT USE SAAMI SPEC. REAMERS!
I craft chambers to fit ammo, including the bullet. I do not use oversize, ill-conceived, SAAMI type reamers that are typically too large in one or more important dimension or very poorly designed, especially in the throat area.
I dial in the bore concentric with the axis of the lathe, more correctly I am dialing in off the groove area, at the point where the throat will be cut. All bores have some degree of curvature to them. None are perfectly straight. Welding the lug on the barrel also induces warpage and distortion of the bore. Dialing in off the bore at the point where the throat will be cut gives the most precise throating possible, FAR more precise than can ever be accomplished consistently with piloted reamers, even with tightly fitted pilot bushings at the risk of damage to the tops of the rifling.
I cut NO chambers where the throat is cut at the same time as the body of the chamber. ALL throating is done separately, aligned with the bore and of minimum diameter, meaning just large enough to allow a bullet to enter it. Typical SAAMI throat diameters are from .001” to .005” or more larger than standard bullet/groove diameter, which is not only absurd but is basically the same condition as a barrel that is "shot out".
Shooting enlarges the throat diameter. As the throat is enlarged, accuracy deteriorates. So when the throat diameter is cut larger to start with, you have a barrel that is to some degree "shot out" before you even fire the first round through it! Trying to "make" a barrel with a large factory throat shoot is often an impossibility. On the other hand, a barrel with the throat well aligned and of minimum diameter will shoot well with little effort or "load development" expense required. This assumes of course that the gun as a whole is assembled right and correct headspace maintained.
Where possible, the initial "roughing" of the chamber is lathe bored with a boring bar, concentric with the bore. All rim counterbores are lathe bored, not cut with a reamer. Referenced off the bore, this assures the web area of the chamber is concentric with the bore and the rim counterbore is truely centered and square to the bore.
Any fool can buy a reamer and whack out a chamber, but that is not how I go about it! If you want it quicker and cheaper, there are plenty of shops who will oblige you.
Be sure to read this page regarding chambers and what a throat is.
Click on the link above to go to the Chamber Cast Library. Use your Back button to return here.
No one I know of gives this degree of attention to the all too critical throat area. Throats are the least understood, most ignored, and most taken for granted aspect of barrels in both the production world AND the world of custom gunsmithing.
To date, in the area of TC barrels, David White is the only one I am aware of who dials in the bores and throats separately following my regimen. Most everyone else in the trade relies on the reamer companies to supply a reamer and use "floating reamer holders" that let the reamer wallow around. My system keeps the reamers in line with the bore.
The object is to build everything around a straight line with everything square and concentric. There is no way a reamer wallowing around in a floating reamer holder will keep the chamber in line with the bore, yet letting the reamer wallow around is "common wisdom" elsewhere in the trade. I'm sorry, it is an impossibilty, born out by the runout found in most chambers cut this way.
First off, my two hands do all of the rechamber work, muzzle brake work, and other critical machine work.
Second, I DO NOT USE SAAMI SPEC. REAMERS!
I craft chambers to fit ammo, including the bullet. I do not use oversize, ill-conceived, SAAMI type reamers that are typically too large in one or more important dimension or very poorly designed, especially in the throat area.
I dial in the bore concentric with the axis of the lathe, more correctly I am dialing in off the groove area, at the point where the throat will be cut. All bores have some degree of curvature to them. None are perfectly straight. Welding the lug on the barrel also induces warpage and distortion of the bore. Dialing in off the bore at the point where the throat will be cut gives the most precise throating possible, FAR more precise than can ever be accomplished consistently with piloted reamers, even with tightly fitted pilot bushings at the risk of damage to the tops of the rifling.
I cut NO chambers where the throat is cut at the same time as the body of the chamber. ALL throating is done separately, aligned with the bore and of minimum diameter, meaning just large enough to allow a bullet to enter it. Typical SAAMI throat diameters are from .001” to .005” or more larger than standard bullet/groove diameter, which is not only absurd but is basically the same condition as a barrel that is "shot out".
Shooting enlarges the throat diameter. As the throat is enlarged, accuracy deteriorates. So when the throat diameter is cut larger to start with, you have a barrel that is to some degree "shot out" before you even fire the first round through it! Trying to "make" a barrel with a large factory throat shoot is often an impossibility. On the other hand, a barrel with the throat well aligned and of minimum diameter will shoot well with little effort or "load development" expense required. This assumes of course that the gun as a whole is assembled right and correct headspace maintained.
Where possible, the initial "roughing" of the chamber is lathe bored with a boring bar, concentric with the bore. All rim counterbores are lathe bored, not cut with a reamer. Referenced off the bore, this assures the web area of the chamber is concentric with the bore and the rim counterbore is truely centered and square to the bore.
Any fool can buy a reamer and whack out a chamber, but that is not how I go about it! If you want it quicker and cheaper, there are plenty of shops who will oblige you.
Be sure to read this page regarding chambers and what a throat is.
Click on the link above to go to the Chamber Cast Library. Use your Back button to return here.
No one I know of gives this degree of attention to the all too critical throat area. Throats are the least understood, most ignored, and most taken for granted aspect of barrels in both the production world AND the world of custom gunsmithing.
To date, in the area of TC barrels, David White is the only one I am aware of who dials in the bores and throats separately following my regimen. Most everyone else in the trade relies on the reamer companies to supply a reamer and use "floating reamer holders" that let the reamer wallow around. My system keeps the reamers in line with the bore.
The object is to build everything around a straight line with everything square and concentric. There is no way a reamer wallowing around in a floating reamer holder will keep the chamber in line with the bore, yet letting the reamer wallow around is "common wisdom" elsewhere in the trade. I'm sorry, it is an impossibilty, born out by the runout found in most chambers cut this way.
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