Help needed in ordering a chamber reamer

S

South_Pender

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Can you guys give me some advice on ordering a chambering reamer?

I want to have a varmint rifle built in 6 PPC. I don't want to go with the 6 PPC-USA chamber because of its large neck diameter (.272", I believe) and long leade/throat. I have that chamber in a factory Sako Vixen sporter in 6 PPC, and I have to seat the bullets very long to reach the rifling, with the bullet making contact in the case neck only about half the way down. And the 6 PPC CIP also seems large. I've been toying with the idea of a .265" neck and short throat. I'm happy to turn case necks.

First, what do I need to order? Will a "finisher" do everything--i.e., cut the chamber and leade/throat? Or do I need a separate reamer for the leade/throat?

Second, when I specify the neck diameter, how do I specify the throat length. I see "freebore" as a variable, but I'm not sure how to specify this to get what I want--which is having the light 6 mm.. bullets (68 and 62 grain) jamming the rifling while still seated well down into the case neck, with the bullet base close to the case neck/shoulder juncture.

Any advice will be greatly appreciated.

Edit: My apologies if this is the wrong forum for this thread. This is not exactly Centerfire Benchrest, but it seems close!
 
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Ok, when you say "want to have a varmint rifle built" do you mean a REAL 6PPC? Or do you mean re-barrel the Sako?

I am setting here spec'ing a 6PPC reamer as we speak..... taking parts from Boyer III, Bryant Bore Rider, Dwight Scott, Borden, JGS 1045 and others and bending it to my weird fat butt spec but I feel I must specify that there's a huge difference between 6PPP-USA and a real 6PPC both in the design of the case and in the required action strength.

Soooo, Sako? Or Custom?
 
South Pender,
Call JGS (or your preferred vendor) and have Sarah send you the 6PPC "benchrest" print.
They have multiples but their standard one I believe has a .262 nk.
Once you have the print you can change the neck dimension to what you want and can specify the
lead (or freebore) anyway you want.
If I have a customer with a specific bullet they want to use I will send them a sample round with the bullet seated where I/they want it in the case and have them set the lead off the sample.
Just tell them to "touch" off the sample.
They will send you a modified print for your approval.
Hope this helps.
Greg
 
alinwa said:
Ok, when you say "want to have a varmint rifle built" do you mean a REAL 6PPC? Or do you mean re-barrel the Sako?

I am setting here spec'ing a 6PPC reamer as we speak..... taking parts from Boyer III, Bryant Bore Rider, Dwight Scott, Borden, JGS 1045 and others and bending it to my weird fat butt spec but I feel I must specify that there's a huge difference between 6PPP-USA and a real 6PPC both in the design of the case and in the required action strength.

Soooo, Sako? Or Custom?
Click to expand...
Custom. Nesika action.
 
if not competition, then go with a thicker, turned neck.
less handling dings
270 ??
 
I would forget about the 6PPC USA and get a reamer designed to shoot the Norma 6PPC Brass. It will have a neck diameter of around .269. That gives your loadeded rounds about .003 inch overall clearance without any neck turning or other hassles. That’s just right for what you are doing.

Get the old original JGS 1045 throat, freebore, what ever you want to call it, at .060. With that, you can shoot 68 grn to 70 grn bullets.
 
Just to be a little more precise in what I'm asking, I would like to have the Bart's 68-gr. FB bullet contacting the lands when the base of the bullet is even with the neck/shoulder juncture of the case. This means that the overall length of the loaded round with the Bart's 68 FB will be about 2.043" (since the bullet is about .828" in length). How can I translate this desired state of affairs to the freebore on the reamer when I'm ordering it?
 
South_Pender said:
Just to be a little more precise in what I'm asking, I would like to have the Bart's 68-gr. FB bullet contacting the lands when the base of the bullet is even with the neck/shoulder juncture of the case. This means that the overall length of the loaded round with the Bart's 68 FB will be about 2.043" (since the bullet is about .828" in length). How can I translate this desired state of affairs to the freebore on the reamer when I'm ordering it?
Click to expand...

A .060 throat will put a Bart’s FB, ( he makes several different ogive configurations), about 1/2 way down in a PPC neck when just touching the lands.

I have a “zero” free bore reamer that puts a FB about 1/16 above the neck shoulder junction.

In all honest, you need to keep the base of the bullet away from that area. Repeated firings and sizing will cause a tight spot there, playing heck with neck tension.

Why do you want the base of the bullet there.
 
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jackie schmidt said:
A .060 throat will put a Bart’s FB, ( he makes several different ogive configurations), about 1/2 way down in a PPC neck when just touching the lands.

I have a “zero” free bore reamer that puts a FB about 1/16 above the neck shoulder junction.

In all honest, you need to keep the base of the bullet away from that area. Repeated firings and sizing will cause a tight spot there, playing heck with neck tension.

Why do you want the base of the bullet there.
Click to expand...
Jackie: I would like more bullet contact in the neck than I'm getting with my Sako sporter in 6 PPC. I get only about .125" of case-neck contact with the 68-gr. Bart's FB (touching the lands, where it shoots best) in that rifle. I don't know what the freebore was on the reamer that cut that chamber, but I'd imagine that it was very generous. Would .020" freebore get the bullet (Bart's 68-gr. FB just touching the lands) about .080" above the neck-shoulder junction?

I'm also concerned about boattail bullets. If the base of these is at a certain point, the contact surface will be that much less because of the boattail form.
 
jackie schmidt said:
A .060 throat will put a Bart’s FB, ( he makes several different ogive configurations), about 1/2 way down in a PPC neck when just touching the lands.

I have a “zero” free bore reamer that puts a FB about 1/16 above the neck shoulder junction.

In all honest, you need to keep the base of the bullet away from that area. Repeated firings and sizing will cause a tight spot there, playing heck with neck tension.

Why do you want the base of the bullet there.
Click to expand...

I definitely agree with Jackie on this. You don't want the base of your bullet to seat as far down as the neck shoulder junction. That's a myth that you want to have the base of the bullet at the neck shoulder junction. Never understood where that originated except that it has to be somewhere. To go even farther than that, if you are using a size die that uses a neck bushing, a neck bushing will not normally size the full length of the neck. You don't want the base of the bullet to seat below the portion of the neck that is sized with the bushing. I'm presently shooting barrels chambered with a JGS reamer with a .265" neck and did pretty well with it last year. The chamber length from the base of the case to the end of the neck is 1.515". I find that the 1.515" chamber length is more forgiving on keeping your brass trimmed to length than the shorter chamber lengths such as a 1.500 or 1.505". The freebore diameter is .2437" in diameter x either .060 or .070" in length with a 1 degree 30' leade angle. I'd have to look at the reamer print to make sure what the length was on the freebore. I went with .2437" on the freebore diameter to give a little clearance on fat bullets that measure over .243" in diameter. I quite often shoot bullets that measure .2435" and the .2437" gives a little clearance on the bullet shank. I shoot a boat tail bullet with a .060 or .080" long boat tail. If I shoot a Berger 65gr BT in it, I have so little bearing surface in the neck that it's a little scary, but they shoot so well. If I was going to change anything on the reamer that I'm using, it would be to use a .040 to .045" freebore length if the Berger 65 gr BT was what I planned to shoot. Other wise, the longer freebore works well.

A lot of reamer selection comes into play with just what kind of rifle you are wanting to build and what your plans are for it. I chambered a barrel a year or so ago with a .269" necked reamer for a prairie dog shooter who used unturned Norma brass with it and he said it was scary accurate for a long barreled 6 PPC. If something like that is what you are planning to do, then as Jackie said use a .269" neck, no turn Norma brass and a 0 freebore and never look back. It will work great. I've spent lots of money over the years on 6 PPC reamers. Basically what I've found is that there is not a magic reamer. The reamer that I'm using now is not that much different than the first reamer that I ever bought except that its no longer a .262" neck and freebore length is a few thousandths longer.
 
Hey South Pender,
Pay close attention to what these 2 Texans are saying.
Read the reply Mike wrote and believe what he says. He is a very accomplished shooter and an excellent gunsmith.
Neither Mike or Jackie will give you poor information and will probably save you money and frustration.
Joe Hynes
 
South_Pender said:
Custom. Nesika action.
Click to expand...


This is totally off the subject but I've got some Nesika actions and have always found them to be sticky. Especially the skinny-bolt ones.

I've tried every brand and type of lube including 2 different recommendations from the makers and had decided wax was "best" but still not great.

Then I tried 'Hobo Oil' from the guy over on Accurate Shooter on the bolt body. Awesome.

jus' passin' it along....
 
I started with a 262 neck and a 35 freebore reamer when i got started,but now i am using a 268 neck 70 freebore beacuse im a powder hog and load my ppc with about 30gr of 133. My reason for switching was Because of the bulletts that i use 68gr on 825 jackets. I could only use so much powde in my cases with a short freebore (35 and 262 neck) when i seated the bullets with a hot load i would ck the oal of my loaded rounds with a comParator and a few menutes later I would ck them again and the powder in my cases would actually push the bulletts up a few thousands. I even tried Tighter neck bushings. With my 268 neck and 70 freebore i dont have that problem anymore. The norma no turn neck idea also sounds good.
Gabe
 
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I've made some progress in specifying the chamber reamer I'd like to get. I wanted a .265" neck diameter, .030" freebore length (to be able to shoot light BT bullets), and 1.510" overall length. I obtained a standard chamber diagram from one of the reamer makers--this one for a no-turn 6PPC--and made the changes to it shown in red in the picture below. I'm planning to turn necks.

What I need your advice on is whether these changes I've made are consistent with the rest of the dimensions in the drawing (I'll have the neck diameter at the shoulder changed to .2655, I guess). Should there be other changes given the revisions I've made, or will this chamber work fine?

Your advice is much appreciated.

FVw7Z6N.jpg
 
South_Pender said:
I've made some progress in specifying the chamber reamer I'd like to get. I wanted a .265" neck diameter, .030" freebore length (to be able to shoot light BT bullets), and 1.510" overall length. I obtained a standard chamber diagram from one of the reamer makers--this one for a no-turn 6PPC--and made the changes to it shown in red in the picture below. I'm planning to turn necks.

What I need your advice on is whether these changes I've made are consistent with the rest of the dimensions in the drawing (I'll have the neck diameter at the shoulder changed to .2655, I guess). Should there be other changes given the revisions I've made, or will this chamber work fine?

Your advice is much appreciated.

FVw7Z6N.jpg
Click to expand...

When you changed the OAL from 1.525" to 1.510", you forgot to shorten the neck length to .300". If your base diameter of .442" is .200" from the bolt face, you might want to tighten that dimension to .440". Also make throat diameter .2437" as mentioned by Mike Bryant. Also remember that a .268" - .269" neck diameter (also mentioned above) allows you to still neck turn Lapua brass, or shoot Norma as is. Why not have the best of both worlds?

I also Just noticed your diameter tolerance. Should be tighter at minus .000" and plus .0004", not plus .001". This is mainly because of the throat diameter needs a tighter tolerance.

Michael
 
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Many thanks to all of you who have contributed here. Below is my final attempt at designing a 6 PPC chamber reamer for my upcoming project. I've incorporated most of the suggestions offered. The one final question I have is whether I can be completely sure that the newer Norma 6 PPC-USA brass will chamber in this design. I know that the newer Norma 6 PPC-USA brass is slightly different dimensionally from the "true" 6 PPC, and I want to be sure it will work in this chamber. Does anyone know offhand whether this brass will work in the chamber below, or where I could find some dimensions for the Norma brass?

WMQdbmg.jpg
 
The shoulder on the Norma brass is set back appx .007 further than my 6ppc chamber. Takes a couple of firings to blow them out. The necks are appx .265. If you need it, I will measure and give you the oal. I am sure it will chamber.
 
CCrider said:
The shoulder on the Norma brass is set back appx .007 further than my 6ppc chamber. Takes a couple of firings to blow them out. The necks are appx .265. If you need it, I will measure and give you the oal. I am sure it will chamber.
Click to expand...
Thanks, CCrider. That's good information. The .265 you mention must be without any turning. Would you happen to know the diameter at the base (or .200" above the base) and at the shoulder? I'm wondering how much more the chamber at those dimensions should be than the brass to ensure smooth chambering without excessive expanding on firing.
 
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