Gunsmithing How to determine freebore when ordering a reamer?
- Thread starter Bradu
- Start date
Well, if you start with the case and a bullet, figure out how far into the case you want to seat your bullet so it will fit into the magazine. Then get the dimensional numbers for the case and bullet and calculate the distance from the mouth of the case to the ogive of the bullet.
Easiest way is to make a dummy round with the brass and bullet you’re going to use at the seating depth you want and the jump you’re starting at. Send it all to the shop that's making your reamer and they will make what you need. If you’re turning your necks, make sure the dummy round is made with a brass representive of your process and dimensions.
Bradu,
When deciding on your reamer's FB along with the jump you desire, remember you can always lengthen your FB with a throating reamer but you can't put material back. Some shooters will opt for a minimum FB based on their bullet and seating depth (dummy round) as well as the minimum jump desired and have the gunsmith use a throating reamer to lengthen the chamber if necessary. This is not an uncommon practice as a gunsmith might have a reamer with everything a customer wants but with a freebore shorter than he desires. If he can use the reamer and throat it out to the customer's specs it saves the cost of buying multiple reamers with just a few thousandths difference of freebore.
When deciding on your reamer's FB along with the jump you desire, remember you can always lengthen your FB with a throating reamer but you can't put material back. Some shooters will opt for a minimum FB based on their bullet and seating depth (dummy round) as well as the minimum jump desired and have the gunsmith use a throating reamer to lengthen the chamber if necessary. This is not an uncommon practice as a gunsmith might have a reamer with everything a customer wants but with a freebore shorter than he desires. If he can use the reamer and throat it out to the customer's specs it saves the cost of buying multiple reamers with just a few thousandths difference of freebore.
^ this is exactly what we do now.
I order with a dummy round and if need be we set final OAL with a throater. Quick, easy and efficient. This is less of a practice with my mag feed stuff but common with my single feed match rifled. That said we have started ordering reamers with 0 freebore and throating to the bullet and desired OAL. It gives us options should the next best bullet comes out 6 months after the reamer is made.
I order with a dummy round and if need be we set final OAL with a throater. Quick, easy and efficient. This is less of a practice with my mag feed stuff but common with my single feed match rifled. That said we have started ordering reamers with 0 freebore and throating to the bullet and desired OAL. It gives us options should the next best bullet comes out 6 months after the reamer is made.
I considered getting a throating reamer for my 6 creedmoor barrel that came with my Sako I bought off here. The local gunsmith was going to do the work for me but I opted to just shoot the barrel as is. It's so short that it seats the bullet deeper on factory ammo.
