Gunsmithing .30-06 chamber reamer help

[SPAK]

Hey guys,

I'd like to have Pacific Tool and Gauge build me a custom .30-06 chamber reamer, but I'm not exactly sure what specs to have it made to.

My goal is basically to minimize working of the brass and preserve throat life if I can.

Info:

Lapua brass turned to .014"
208 gr Hornady Amax

Loaded round measures .336" OD of the neck
Sized base measures .469-.470" (using forster sizing die)

I trim my brass every firing to 2.485"

Here's what I "think" I want in my reamer so far:
.339" neck
.470" base
2.495" chamber length


What I don't know is what to specify for the throat length, leade angle and I'm sure I'm missing some other things.

Any input would be great. I've never done this before and I'd like to order a reamer that I can use for the next few rebarrels.

Thanks again!

 

[bohem]

Re: .30-06 chamber reamer help

I would give the round a full 0.004" of diametral clearance on the neck dimension (0.340")

The other question is your leade/throat details.

A 1* 30' leade with a Freebore that's setup to keep the bullets in your magazine would be the best idea IMO.

For example:

If you're running a 30-06 in a Rem 700 LA with factory blind magazines you'll have 3.65" OAL to work with. So:

Load a 208 Amax into the case where the base of the bullet bearing surface is at the shoulder/neck junction and measure the OAL, it will probably be around 3.41" long. This is a good starting point and leaves you plenty of "burn" time on the throat to work with. You aren't cramping the powder capacity much and the leade angle will be nice to those bullets. You'll have plenty of room to burn up the throat and still keep the Amax about 0.020" off the lands for the whole life of the barrel.

Take that dummy round you're looking at using, make 2 more just like it, then mail them in to Dave Kiff and ask for a reamer setup to be a tight match version using that dummy round.

Once you do that, would you mind sharing the print with me please

 

[SPAK]

Re: .30-06 chamber reamer help

Thanks for the input Bohem, once I get the print made up I'll let you know!

Should the dummy round be set up to be touching the lands??

question about the case capacity and the freebore:

which has the greater effect on chamber pressure; bullets taking up space in the case or adding more powder to the case?

Basically, keeping magazine length in mind, will maximizing case capacity with powder net a higher velocity without excessive pressure vs having to seat a bullet deeper in the case because of a short throat?? Does that make sense??

 

[DAVETOOLEY]

Re: .30-06 chamber reamer help

On the neck I would go +.004" as too tight, .003" or less doesn't work well on large calibers and on the body you need again +.004" over virgin brass to allow for expansion and spring back to get it out of the chamber and then it's sized and springs back again. You have room for a range of motion both directions or you'll be beating on the bolt handle.

 

[SPAK]

Re: .30-06 chamber reamer help

Dave,

My virgin lapua brass at the base meausres about .465". Should I go with .469" base then?? I don't know if my forster sizing die would size smaller than that.

 

[DAVETOOLEY]

Re: .30-06 chamber reamer help

That's small brass. You still have to have room for the brass to expand then spring back regardless of the size it started out life. I would go +.003" on your sized brass. It will move a lot on the first firing but from then on you're not working it much. Just don't get too tight or you'll be polishing out your chamber to get a little more room.

 

[Falar]

Re: .30-06 chamber reamer help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">I would give the round a full 0.004" of diametral clearance on the neck dimension (0.340")

The other question is your leade/throat details.

A 1* 30' leade with a Freebore that's setup to keep the bullets in your magazine would be the best idea IMO.

For example:

If you're running a 30-06 in a Rem 700 LA with factory blind magazines you'll have 3.65" OAL to work with. So:

Load a 208 Amax into the case where the base of the bullet bearing surface is at the shoulder/neck junction and measure the OAL, it will probably be around 3.41" long. This is a good starting point and leaves you plenty of "burn" time on the throat to work with. You aren't cramping the powder capacity much and the leade angle will be nice to those bullets. You'll have plenty of room to burn up the throat and still keep the Amax about 0.020" off the lands for the whole life of the barrel.

Take that dummy round you're looking at using, make 2 more just like it, then mail them in to Dave Kiff and ask for a reamer setup to be a tight match version using that dummy round.

Once you do that, would you mind sharing the print with me please

</div></div>

I already had PTG do this for my '06 build and I'm pretty sure the print does say it is 1* 30'. I seated the bullet a little bit above the neck/shoulder junction though and COAL is in the 3.51" range.

 

[SPAK]

Re: .30-06 chamber reamer help

Is there any negative or positive to going with a 1deg leade angle?? Dave from PTG said that he normally puts a 1 deg leade angle on the 30.-06?

Falar, would you mind sharing your specs on what your reamer was made to? Have you chambered your build with it yet?

 

[Falar]

Re: .30-06 chamber reamer help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Falar</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">I would give the round a full 0.004" of diametral clearance on the neck dimension (0.340")

The other question is your leade/throat details.

A 1* 30' leade with a Freebore that's setup to keep the bullets in your magazine would be the best idea IMO.

For example:

If you're running a 30-06 in a Rem 700 LA with factory blind magazines you'll have 3.65" OAL to work with. So:

Load a 208 Amax into the case where the base of the bullet bearing surface is at the shoulder/neck junction and measure the OAL, it will probably be around 3.41" long. This is a good starting point and leaves you plenty of "burn" time on the throat to work with. You aren't cramping the powder capacity much and the leade angle will be nice to those bullets. You'll have plenty of room to burn up the throat and still keep the Amax about 0.020" off the lands for the whole life of the barrel.

Take that dummy round you're looking at using, make 2 more just like it, then mail them in to Dave Kiff and ask for a reamer setup to be a tight match version using that dummy round.

Once you do that, would you mind sharing the print with me please

</div></div>

I already had PTG do this for my '06 build and I'm pretty sure the print does say it is 1* 30'. I seated the bullet a little bit above the neck/shoulder junction though and COAL is in the 3.51" range. </div></div>

I mean to say that I seated a 208gr Amax to where the ogive/BT transition was about 1/16" above the neck/shoulder junction of the case. My rifle is already basically done; I picked it up from getting painted and now am waiting on an extractor and need to work on a few fitment issues that the paint has caused.

I have the print sitting in front of me and it is 1* 30. It lists freebore as being .197" and the neck as .340".

 

[longshooter]

Re: .30-06 chamber reamer help

You might want to consider what you would like for the freebore diameter.

 

[SPAK]

Re: .30-06 chamber reamer help

Longshooter, do you have a reccommendation on free bore diameter?? I've never considered it before.

 

[SPAK]

Re: .30-06 chamber reamer help

Another question on base diameter. I know that brass typically springs back about .001" If the base diameter is .469", will the fired case ever stay at .469" or will it always spring back about .001" to .468" or so after firing for the life of the brass??

 

[DAVETOOLEY]

Re: .30-06 chamber reamer help

From experience don't get too tight with the freebore diameter. I spent the last week getting carbon out of a barrel that restricted the freebore to the point of causing pressure problems. At one time I went .0005" over nominal bullet diameter but that gets you in trouble as not all bullets are dead on size wise. I go .001" to .002" over depending caliber. The more volume the case has the larger I go.

Under normal circumstances brass takes on the dimensions of the chamber -.001" Large diameter cases and over pressured loads can eliminate that bit of clearence and cause an interference fit and extraction issues. The barrel tenon expands past the yield point of the brass. The barrel returns to it's original diameter and the brass doesn't. That's when you start beating on bolt handles.

The problem is not just the size of the chamber but the relationship between the sizing die and the chamber. When I order a set of reamers, finish and resize, the finish reamer is +.004" over the brass and the resize reamer is -.003" under the finish reamer. That's a very fine line in the sizing department. That's usually for just one brand of brass. Smaller diameter brass will work but larger diameter brass doesn't work because you can't size it down smaller than what it was new.

 

[longshooter]

Re: .30-06 chamber reamer help

When I rebarrel my .300WM, and 8X57, I am going for 0.0008". For bullet alignment.

But like Dave has said, it depends on usage.

 

[SPAK]

Re: .30-06 chamber reamer help

Hey guys, got the reamer in the making. Question on your preffered barrel length:

was planning on cutting the tube to 24" shooting it with a suppressor. Any thoughts on a longer regarding accuracy?? Was toying with the idea of matybe a 26" barrel for the addedd velocity, but wasn't sure if the suppressor would add too much weight on the front end and degrade accuracy.

any thoughts??

 

[DAVETOOLEY]

Re: .30-06 chamber reamer help

The longer the barrel the greater the POI shift when you have the suppressor on. I shot two rifles side by side a couple of weeks ago. One a 20 fluted heavy barrel 308 and the other a 23" <span style="font-weight: bold">heavily</span> fluted 308. I stood about 15 feet behind them and was comparing noise levels and noticed the amount of barrel whip on the 23". I could see none on the 20" barrel and the 23" barrel moved so much I could see it whip around after firing. Shorter is stiffer and that's a good thing. Then's there's the question of balance.

 

[SPAK]

Re: .30-06 chamber reamer help

Dave any thoughts on whether or not a non fluted heavy round barrel would have less barrel whip??

 

[DAVETOOLEY]

Re: .30-06 chamber reamer help

Same contour-same length the nonfluted barrel will be stiffer. That's not to say flutes are bad. The cooling thing is a red herring. A hot barrel is a hot barrel and it takes time to cool off. The fluted barrel takes a little less time but non the less it still takes time. At the range I run ice water down the barrel, clean and go back to shooting so flutes don't help there. Flutes change the weight some, the balance of the rifle and they look cool.
You could go with a larger diameter and then flute it and end with the same stiffness as a smaller nonfluted barrel. Lija has a program you can down load from his website that calculates the muzzle deflection (sag) for any barrel contour, fluted or nonfluted. I need to see what the deflection is on this whippy barrel.

There's a balance to everything, the extremes are problematic and everything is a compromise.

 

[SPAK]

Re: .30-06 chamber reamer help

Thanks for the input dave. Barrel will be an AMU contour, non fluted. I think I'll go with the 26". It'd be nice to get a little velocity boost without the pressure and I don't mind the extra length. Bottom line, I just don't want to degrade the accuracy any.

 

[bohem]

Re: .30-06 chamber reamer help

RUnning a26" heavy barrel won't hurt the accuracy. The "short stiff" idea is heavily followed by the point blank BR guys but look what the F class and 1k BR guys are doing. They're running the long, heavy contour barrels for a multitude of reasons.

IIRC, Tom Sarver's 2 world records were set with a 30" Krieger.

I think that there are 2 huge considerations to worry about:

What barrel maker (just get a barrel from one of the premium makers, you'll be set)

What tube fitter? Get it installed by a top level 'smith

After that, the difference in accuracy afforded by 24, 26, 28" barrels will be more limited by the shooter than the barrel length or contour.

If you're going to run it suppressed make sure you have enough meat at the muzzle to thread it, other than that, just run it.

A lighter contour will tend to give more vertical shift when the suppressor is attached by I really consider this a non-issue as long as the shift is consistent.

I screw the can on, add X.x MOA to the dope and run it.

For my AR15 with a 20" tube I know that my 300 WM suppressor (with a thread adapter) pulls the 75 BTHP's down 3 MOA @ 100yd. I dial 3 MOA into the turrets and go about my usual business. That rifle is shot a lot with just holdovers, once I make the change in the dope on the turret I don't even think about it any more.

 

[SPAK]

Re: .30-06 chamber reamer help

Thanks Bohem, I appreciate the input. 26" it is...

 

[SPAK]

Re: .30-06 chamber reamer help

I've got my reamer print in if anyone is interested. Bohem, send me your email and I can send it to you.

 

[customshooter]

Re: .30-06 chamber reamer help

go with a .338 neck...

 

[SPAK]

Re: .30-06 chamber reamer help

I already had the reamer made to a .340 neck. My loaded rounds at the neck measure .336-.3365" OD. I diddn't want anything less than .003" neck clearance since I will be using this rifle out in the field. I didn't want any dirt to possibly cause a problem for me under less than ideal conditions.

 

[SPAK]

Re: .30-06 chamber reamer help

Another question: if I wanted to lengthen the FB after the chamber has been reamed can I simply order a throating reamer and have the throat lengthened??

Are there any negatives to doing this on a match chamber??

 

[Bugholes]

Re: .30-06 chamber reamer help

You can get a 30 cal uni-throater from PTG, keep the 1 degree-30 angle and you can push the throat forward as you see fit. This is done by hand and you don't even need to take the barrel off the action. Better to do this on a chambering aid (if you have one) before you move onto cutting the barrels chamber...

 

[SPAK]

Re: .30-06 chamber reamer help

Greg, if the chamber is already cut can you still use the uni throater?? I'd more than likely have a smith do the work for sure. Not something I want to screw up unless it really is that easy to do by hand.

sorry for my ignorance but, what's the difference between the uni throater and the standard throat reamer?

 

[Bugholes]

Re: .30-06 chamber reamer help


It is really easy to do by hand, but you need some unit of measure (comparison) for the length of the new throat, best if you can cut the throat of a chambering aid/barrel stub before you move into the rifles chamber. The unithroater has a sleeve that stops on the shoulder of the chamber you're cutting and two jamb nuts that allow you to adjust the cutting depth in small increments. Set the tool up on a "practice chamber"(Chambering aid) then set the stop where it should be and move on to the rifles chamber. The stop will cause the second throat to be cut the same as the first