Increasing freebore

M

model14

Guest
I want to increase the amount of freebore on my newly chambered .260 Rem 700. With the Sierra 142 MK's seated right on the rifling, the bullet extends more than I want into the case (quite a bit more than I want!). The reamer used was a stock SAMI spec Pacific Tool and Gauge. Have any of you had experience with a throat reamer? I understand that can be used to increase freebore? Were you happy with the results?
 
Using a throating reamer..

Caution....Caution...Caution

If you use a throating reamer make sure you know where it engages into the rifling before you begin reaming. Because once you start you can't go by feel anymore. I suggest you use a tailstock dial, or a ram stop with an indicator. Even better a Micrometer Adjustable Reamer Stop.

A throating reamer is only taking a few (.001") off the tops of the rifling and there is very little resistance. A throating reamer will cut like a hot knife in butter.

Good Luck
Nat Lambeth
 
model14 said:
I want to increase the amount of freebore on my newly chambered .260 Rem 700. With the Sierra 142 MK's seated right on the rifling, the bullet extends more than I want into the case (quite a bit more than I want!). The reamer used was a stock SAMI spec Pacific Tool and Gauge. Have any of you had experience with a throat reamer? I understand that can be used to increase freebore? Were you happy with the results?
Click to expand...
You will need to rig up a way to control the depth of the freebore reamer, elstwise ou can easily screw up the whole chamber job.

Nat, we hit it the same minute didn't we. I'll bet your patented reamer gage would work wonders here??
 
Pacific makes a throater they call the uni-throater that can be run by hand with an extension if necessary. It has a shouldered bushing on the throater with a couple of lock rings that allow you to cut the amount of freebore length that you want. The lock rings are calibrated and you can dial in the amount of freebore that you want once you know where you are on the lands. Their regular throaters can be used fairly easily in a lathe and the uni-throater would be best used in a lathe.
 
Thanks for the inputs. I can now talk intelligently with my gunsmith about precautions to be taken if I choose the throat reamer route.
 
MARS and UNI Throater.

Jerry and Mike:

If you make a 701 OD and .4375 ID bushing to fit the back of an action. Then run the MARS on the UNI Throater and into the bolt race bushing. Insert the bolt race bushing into the bolt race. Lock the bushing with a action screw or scope base screw. now run the piloted throating reamer in very carefully until it bottoms out in the chamber throat. Then slide the MARS down until it bottoms out on the bolt race bushing. Lock the set screw on the MARS onto the UNI Throater. You now have a refrence point to start from. Unlock the MARS Micrometer dial and dial the number of .001" you want to open up the throat. Lock it back with the locking collar. Turn the handle on the UNI Throater and bottom out the MARS onto the bolt race bushing. This will open up the throat keeping the reamer in alignment with the bolt race. This can all be acomplished without removing the barrel from the action.

Nat Lambeth
 
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