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Does Throating Reamer Affect Accuracy?

NV_Dmax

NV_Dmax

Gold $$ Contributor
I have a reamer that I will be using to chamber a 1000yd FOpen barrel. Problemis there is only .080” freebore and that puts the bullet way down inside the case.
Will using a throating reamer to extend the freebore cause accuracy/consistency issues? I’m thinking about having the reamer reground but I like the short freebore for magazine fed rifles.

thanks,
 
You can't teach technique via a keyboard. It just isn't possible.

To do it correctly, you need three things:

1: The tool stop set correctly - You need to know when to stop
2: The tool dead center and straight with the bore
3: Proper lubrication and a slow, deliberate cut

I'm a fan of buying my reamers with the desired throating included. I can have a new barrel chambered and KNOW exactly where to start.
 
Did I not answer the question correctly? I have learned by videos, asking HOW and reading the instructions. Keith gives great information. If you follow his directions you will not go wrong.

Don Dunlap
 
Thanks shortgrass and Keith. I didn’t mean to upset anyone but NV dmax asked a legitimate question and the first reply seemed a little “smart” to me. I too, am trying to learn and I know you can’t learn machining via keyboard. Hell, tubalcain ( YouTube) has taught me just about all I know about a lathe. Good resource if you don’t have a machinist friend nearby.
 
Ok now I know you have a lathe. For this job I would run the barrel in a steady rest on the threads. Always found that setup to work the best on remodeling jobs. I don't know who's throating reamer you or how long it is. I'm sure you have a way of measuring spindle travel on the tailstock. I use a Sinclair case holder on the shank and hold it with my fingers. No support. I hold the end of a long throater in a drill chuck. Shorter ones I have extensions for. With the lathe stopped insert the reamer by hand until you make contact. This may be the end of the neck or it may be the lands. You'll find out in the next step. Set your travel indicator or whatever your using to zero. Back off a bit and start the lathe. Come back to zero and see what you feel. If it's a smooth feeling your at the end of the neck. If you're at the lands it will go curchunk curchunk... Know how far you want to extend the throat. As soon as you feel the curchunk start counting. The reamer is pretty much self centering so with a reasonably good setup there's not much you can do to screw it up.
 
I prefer to buy my reamers with the appropriate throats in them. When I need to use a throating reamer, I use a reamer stop to control depth of cut but it is still a challenge to figure out when the throating reamer is at the start of the throat installed by the chambering reamer. Requires good touch and feel. --Jerry
 
I wouldnt use a throating reamer without the correct dummy case installed like i wouldnt use a 223 throating reamer on a 22-250. Definitely use the stop they come with
 
carlsbad said:
I prefer to buy my reamers with the appropriate throats in them. When I need to use a throating reamer, I use a reamer stop to control depth of cut but it is still a challenge to figure out when the throating reamer is at the start of the throat installed by the chambering reamer. Requires good touch and feel. --Jerry
Click to expand...
Totally agree, I have started putting my reamer stop on the throater loose and turning the throater backwards for the "touch" then tightening it down. It is on "0" and then dial in the added freebore with reamer stop. The bad part is repeatability. Some send more than 1 barrel for same specs and its a gamble.

Edit to add, it has no ill effect at all on accuracy if done correctly.
 
Last edited:
Dusty Stevens said:
I wouldnt use a throating reamer without the correct dummy case installed like i wouldnt use a 223 throating reamer on a 22-250. Definitely use the stop they come with
Click to expand...
Dusty am I understanding you correctly that you ream the neck with a case installed as a guide?
Case head drilled out for reamer.
 
Dusty Stevens said:
No when you buy a throating reamer for a 223 it comes with a 223 sized guide on it like a case
Click to expand...
I think you are referring to the uni throater. They also make a plain throating reamer so if its for a 22 centerfire it will pretty much work with any 22 cf chambering
 
paperpuncher said:
I think you are referring to the uni throater. They also make a plain throating reamer so if its for a 22 centerfire it will pretty much work with any 22 cf chambering
Click to expand...

Thats the ones thatll ruin a barrel real quick if you dont watch it. Ill rechamber with the correct reamer if i dont have a uni throater
 
Thanks for all the replies everyone. This is an evolving project so I was just kicking the idea around to see my options. I am just going to order a new one with the desired throat. I’m going to order the resizer reamers at the same time. This project is based on the 150 SMK, I’m really hoping I can get it to shoot.
 
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