Chamber Reamers

[Marlin Junky]

If a gunsmith tells you his reamer measures .389" on the neck (a .35 Whelen reamer) can one assume the chamber will have a .389" wide neck? What are the typical machining tolerances involved when cutting chambers? Seems to me that a .35 Whelen reamer ought to cut a .383" wide neck in order to shoot cast boolits worth a hoot especially if there's a generous throat which it appears all .35 Whelens have.

MJ

[felix]

389 reamer should give you a minimum chamber neck. Most '06 brass is 015, but I have seen it at 016, as well as 014. 358+016+016=390. So, when you stretch the brass upon expanding, let's say we end up with 014 for safety. 358+014+014=396 reamer minimum using wildass military cases. So, a 389 reamer should provide you with 003 clearance, which is fine for hunting guns. I think the implication you have is chamber dimension, not reamer dimension. ... felix

[S.R.Custom]

Ask to see the reamer and judge the throat for yourself.

When I have work done, I have my man use a throatless reamer to cut the chamber, and then he uses a couple of dummy rounds I supply for fitting when cutting the throat.

[leftiye]

When used right a reamer does cut about the same size that it measures. Minimum chamber is good, generally - so long as it doesn't pinch the cartridge in the chamber causing high pressures. You need to slug that barrel and then do felix's calculation (including the oversize for lead boolits). Try to have about .002" extra in the chamber for clearance. If your gunsmith polishes the chamber you'll get .002 with that reamer, and that brass- neck thickness, and .358 bullets. Now .360" boolits are another matter!