Best way to ream a throat??

P

pinzmann

Guest
I need to extend the throat on a new barrel that I just got and installed on a 700 receiver. Its a long chambered and pre-threaded Shilen in 260 Rem. I fitted it to the receiver but didn't mess with the chamber. Everything is in spec but the longest rounds I can chamber is 2.775. I've got 2 other 260's that get loaded with 2.810 rounds. I know I could just make the ammo shorter but then I'd have load 2 different lengths. What would be the best route? Don't really want to send it to Shilen as they had it back once because the threads wern't right and that took over 2 months to get back. Any suggestions?
 
I don't like long throats if you don't really need them... it shortens effective barrel life... the best accuracy is usually with the least bullet jump... when the barrel wears you can only chase the rifling so far...

As your rifles get shot and the barrels wear differently, best accuracy will be with bullets seated to match each rifle... personally I would load to match the rifle and forget about trying to make the rifles the same...
 
A word of caution..

Cutting a chamber throat is not difficult if you have the right tools.

A throating reamer cuts the rifling out of a barrel like a knife in hot butter.

You need to have a stop on the PT&G Unit throater. I suggest the Lambeth/Kiff Micrometer Adjustable Reamer Stop an a action bushing.

The cost of these tools is prohibitive for one job. So I recomend you hire a gunsmith who has the right tools.

Most gunsmiths who specialize in chambering have short throated reamers and throating reamers for every caliber.

There are three ways to correctly do this job. One with the barrel on the action and the other two require the barrel be removed.

Rustystud
 
The reamer manufacturers believe the best way to ream a throat is with the chamber reamer manufactured with appropriate throat length. This ensures accurate alignment with the chamber.

I've never put a different reamer in a chamber, but I do not see why it would not work by hand?

Comments from others?
 
Explain..

Then why does PT&G, Manson Precision, JGS, Clymer, et al., all make piloted throating reamers.

Why do the europeans make three different reamers for every chamber, ie: body reamer, necking reamer, and throating reamer?

The set up is the same for a complete chambering reamer vs the specialty reamers.

I buy all my reamers with a .020 throat and ream the throats to suit the customers needs.

Rustystud
 
Agreed to all the above.. Best way is with a correctly throated chamber reamer. Next best is in the lathe with a depth stop and third would be by hand. On the one job I did with my uni throater, I took a barrel stub and made a neck and throat with the chamber reamer, then extended the throat using the uni throater (all in the lathe.) Once the throat was set to the customer's cartridge using the depth adjustment, I was able to hand ream the throat in the barrel to the same dimension. he says he can get groups well under 1/2" with the right ammo (we're still working on that.) Surfaces, etc. all looked fine through the borescope.
The uni throater takes interchangeable reamer pilots and there is a support for the rear which guides on the chamber and positively stops the reamer at selected depth. So imho, IF one is going to ream by hand, this tool offers the best support and alignment of any that I know of.
 
Rusty: As to why the Europeans do what they do.... They are usually masterful at doing things the hard way, and often their gun spec's and techniques are mired in the past. Have you ever tried to suggest to a German, for example, that they ought to modify something about one of their rifles? Or WHY do the Euro's still use .223" and tighter and a 16 twist for their .22 Hornet barrels? And why do they think that a 3 lb trigger only belongs on a "cheap" rifle? I've touched these bases in the past (and don't want to talk about it :)) Suffice to say when it comes to rifles and rifle building technology, I'm American all the way....
 
Rustystud said:
Then why does PT&G, Manson Precision, JGS, Clymer, et al., all make piloted throating reamers.

Why do the europeans make three different reamers for every chamber, ie: body reamer, necking reamer, and throating reamer?

The set up is the same for a complete chambering reamer vs the specialty reamers.

I buy all my reamers with a .020 throat and ream the throats to suit the customers needs.

Rustystud
Click to expand...

because the question was best way, not only way. Below, Dave Kiff addresses neck reaming, but I'd think the same applies to the throat.

As far as europe is concerned, I wont even go into their manufacturing processes, as I am writing this response from a hotel in Kristiansand Norway, when I have spent all afternoon yesterday in a manufacturing facility. Anyway, I'm digressing, but I do see the logic in having all three separate reamers, as you can choose your neck and freebore and be very flexible. Does it give you the best alignment? I don't see how it could.



"Q: What about neck-only reamers--do you recommend doing the neck with a separate neck reamer?

No. We always recommend using a full neck+body reamer for a high-grade custom rifle, particularly if you plan to have more than one barrel. Yes, a very talented smith can finish a chamber with a separate neck reamer (which we sell), but to get absolute 100% consistency from barrel to barrel it is best to cut the chamber with our live pilot reamer that does the neck and body at the same time. When the barrel is shot out, you can take that reamer, give it to any good smith, and get an identical chamber."


http://www.6mmbr.com/Kiffreamer.html
 
Bingo....

Ben:

There always is a better way of doing something.

How many different $138.00 reamers($152.00 to the door) is it going to take to replace, ONE $69.00 throating reamer. To get you all the seating depths you may need?

I have a bushing that fits over the PT&G Uni throater to act as a rear alignment guide. This bushing is held in place by an action screw or scope base screw. The back end is faced off 90 degrees to the bolt race.

I use a Lambeth/Kiff Micrometer Adustable Reamer stop mounted to the Uni Reamer to set the cutting depth of the piloted throating reamer.

I can cut the throat without removing the barrel from the action or remove the barrel and put it in a barrel vice then cut the throat using the Micrometer Adjustable Reamer Stop and a Hand driver. This all can be done by the gunsmith without a lathe.

I have a customer seat a bullet to the desired seating depth and cut the chamber for the desired bullet seating depth either engaged or the jump.

Why don't you ask Dave Kiff about this also. I think he will say this is the second best way to custom throat a chamber.

Rustystud
 
Rustystud can you post a picture of your reamer stop I would like to see what it looks like, sounds like a nice tool.
 
If your setup is so poor that the chamber is misaligned, the throat which is cut with an integral throater will be aligned and concentric with the chamber but not with the bore. If your setup is good (as it should be) and you are able to cut a chamber which is co-axial with the bore, you will have no problem cutting a throat which is likewise. If the chamber is well aligned with the bore and the throat is well aligned with the bore, the two will be well aligned with each other.
I like to keep the base of the bullet ahead of the juncture of neck and shoulder on a match rifle. Using some bullets in some cases (140 A-Max in a 260 Rem, for instance), a longer throat is required to accomplish this. When my throat erodes significantly, I don't chase it. I change the barrel.
On a magazine rifle, the ammunition has to fit in the magazine so the magazine dictates seating depth and consequently, throat length. Regards Bill.
 
Rustystud said:
Ben:

There always is a better way of doing something.

How many different $138.00 reamers($152.00 to the door) is it going to take to replace, ONE $69.00 throating reamer. To get you all the seating depths you may need?

I have a bushing that fits over the PT&G Uni throater to act as a rear alignment guide. This bushing is held in place by an action screw or scope base screw. The back end is faced off 90 degrees to the bolt race.

I use a Lambeth/Kiff Micrometer Adustable Reamer stop mounted to the Uni Reamer to set the cutting depth of the piloted throating reamer.

I can cut the throat without removing the barrel from the action or remove the barrel and put it in a barrel vice then cut the throat using the Micrometer Adjustable Reamer Stop and a Hand driver. This all can be done by the gunsmith without a lathe.

I have a customer seat a bullet to the desired seating depth and cut the chamber for the desired bullet seating depth either engaged or the jump.

Why don't you ask Dave Kiff about this also. I think he will say this is the second best way to custom throat a chamber.

Rustystud
Click to expand...


I agree, you have a good system, for you. I'd probably do the same if I were building many rifles, as it sounds like you do. Very flexible.

For me, I'm spending a lot of time researching and planning for a rifle to build for myself (or close friends). I have a reamer built, or buy a reamer that is ground to the size I desire, and I work out from there.

As far as a repeater, I then buy an action, that has a magazine that will fit the cartridge length I desire.

here is my process, developed from lots of conversations with gunsmiths and competetive shooters.

I start with a specific bullet, designed to hit a target at some specific maximum distance with a specific energy level. I then order a barrel, twisted for this bullet and then reamer for the cartridge, freebore, necked and throated for this barrel/bullet. Then I order a die set for the reamer, Then I buy an action/trigger group. then a stock and scope.

As far as the other issues.. Misaligned chambers, throats, magazine lengths etc. If a machinist doesn't get this right, their customer should have shopped at Wal-Mart, not that they get it right, but the price is.
 
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