Sizing reamer

[Rich S]

Looking for recommendations for specs for sizing reamers. Is there a general rule for how much under the chamber reamer at the shoulder and 200 line? Looking at making dies for 6 BR, 308 and 7 SAUM. Is any allowance made for polishing the die after reaming it?

 

[Sniperhandle]

Talk to my buddy Lance at JGS, Or Dave Tooley.

 

[DaveTooley]

Looking for recommendations for specs for sizing reamers. Is there a general rule for how much under the chamber reamer at the shoulder and 200 line? Looking at making dies for 6 BR, 308 and 7 SAUM. Is any allowance made for polishing the die after reaming it

First you have to stay out of trouble matching the finish reamer to the brass. Are you doing anything other than SAAMI specs?

 

[Bill Rodolph]

Contact Ray at Manson, he can fix you up!

 

[gunsandgunsmithing]

I use about .003 smaller than the chamber reamer, on the smaller ppc/br cases..at both top and bottom. This yields a case that measures about .0015 smaller at the shoulder and about .0005 or so at the .200 line, after springback. It has worked well for me.

 

[Rich S]

First you have to stay out of trouble matching the finish reamer to the brass. Are you doing anything other than SAAMI specs?

None are SAAMI. All are for benchrest and Fclass chambers for which I have the reamers. All are JGS reamers. My chambers range from 6 BRA, 6 Dasher, 308 to 7 SAUM AI

 

[bugman]

I use about .003 smaller than the chamber reamer, on the smaller ppc/br cases..at both top and bottom. This yields a case that measures about .0015 smaller at the shoulder and about .0005 or so at the .200 line, after springback. It has worked well for me.

FWIW, like you I have used the .003 reduction at shoulder and web with good results on the smaller/PPC cases.
With the larger cases, I have used .004 reduction at the web for a little extra squeeze, especially when I was wanting an upper node speed. That brass thickness at the shoulder is relatively thin, and .003 reduction works well there for every caliber I have shot........but a little extra reduction at the web helps if brass is many times fired at upper charge weights. Yes, I anneal every time.

 

[gunsandgunsmithing]

First you have to stay out of trouble matching the finish reamer to the brass. Are you doing anything other than SAAMI specs?

Several years ago now, people had the idea of spec'ing chamber reamers based on virgin brass dimensions. The chambers were often too tight. It was popular at the time, especially with ppc and br brass. Popular enough that the custom die market became necessary rather than vogue. Lots of people consider custom dies a necessity still. They are not...if the die and chamber have the proper relationship with one another in regard to how much they size your FIRED brass. I'm not knocking custom dies at all but a sizing die has a very simple job to do. It's not the finish nor the bells and whistles that make that happen, though. Even a pretty ugly finish in the die doesn't matter because it and the case are tapered and the die is sliding over it longitudinally. Now way it can show up on the brass. In fact, it might hold lube, be less prone to galling and feel even better than a super smooth custom die. Yes, too smooth is a thing.

Dave, I quoted you but not so much directing these comments to you as I agreeing with you about spec'ing chamber reamers around brass.

Again though...not knocking custom dies or makers at all. Most make a very good product and service that is sometimes needed. Heck, I've got a few and I've made my own.

When I first started out wildcatting a Grendel case, I spec'd the chamber reamer around the dimensions of a Redding full length bushing die. Man...it just works and makes so much sense to go about it this way, IME. That's been almost 20 years ago now and I have no regrets for it. The one downside, if it is one at all...at some point a few years ago Redding started making that die about .0005 smaller. I assume that was to accommodate gas guns a tad better but it was such a small amount that the difference in the end result was very negligible. But, it was out of my control unless I did a new reamer over a half thou. That half thou doesn't yield a half thou more sizing. More like an extra tenth or so at the .200. As bugman said, how hot and how many firings is at least as important and probably more so than the difference of the change redding made to the die. The main thing...no loss(nor gain) in accuracy and brass life is same, as far as I can see.

 

[NZ_Fclass]

Random thought. When is a 308 - for FTR - no longer a 308?

Should an FTR 308 meet SAAMI specs? How about the 2013 FTR Team reamer with its long freebore ( and whatever other modifications) ?

The TR guys have the Bisley chamber - which does get tested - so FTR gets a pass? Just askin'.

 

[LVLAaron]

Random thought. When is a 308 - for FTR - no longer a 308?

Should an FTR 308 meet SAAMI specs? How about the 2013 FTR Team reamer with its long freebore ( and whatever other modifications) ?

The TR guys have the Bisley chamber - which does get tested - so FTR gets a pass? Just askin'.

First of all.... lower your voice.

 

[Alex Wheeler]

If a 308 sizing die works Id call it a 308.

 

[NZ_Fclass]

First of all.... lower your voice.

oh...was that out loud? Sorry. It's the age.

 

[LVLAaron]

which does get tested

How?

 

[LVLAaron]

oh...was that out loud? Sorry. It's the age.

It's a joke us kids use. Example... Someone says out loud "wow you're carrying in here" - first of all, lower your voice.



I say it here, to not give the NRA any ideas. dont let them hear you. SHHHH.

 

[Rich S]

Thanks for the responses

 

[NZ_Fclass]

How?

I believe that they have a gauge (looks like a loaded round) at maximum size for the chamber/freebore. I have only been told about it, 'cos I'm not a Flat Earther. ( ha ha - they're all good guys really)

 

[memilanuk]

Random thought. When is a 308 - for FTR - no longer a 308?

In the USA... when it physically exceeds the SAAMI dimensions. If it doesn't change the size / shape / combustion volume, it's still a .308 Win.

Should an FTR 308 meet SAAMI specs? How about the 2013 FTR Team reamer with its long freebore ( and whatever other modifications) ?

The 2013 US FTR team reamer creates a chamber that is physically smaller in almost every dimension than SAAMI. Note I said the chamber, not the throat or leade.

The TR guys have the Bisley chamber - which does get tested - so FTR gets a pass? Just askin'.

For the 2017 FCWC, the ICFRA folks had their heart set measuring the chamber, rather than just the fired brass. Previously (2009, 2013) we'd been randomly asked to submit a fired case if there was a question about a competitor's ammo. 2017, every FTR gun was required to be checked at sign-in. Further, competitors would be 'randomly' selected as they came off the line, and both gun, ammo and fired brass would be re-checked (including re-weighed) to make sure nobody tried pulling a fast one and swapped barrels after sign-in.

There was a reference chamber gauge made available to all the national teams. I don't know about other countries/teams, but there was a bit of... kerfuffle... on our end, because most of our competitors tend to have barrels chambered towards the tight/minimum end of the spec between SAAMI GO (1.630") and NO-GO (1.634") gauges. The reference gauge was closer to 1.632"-ish. I say that because the team's copy of the gauge was shipped around to each member to check their chambers. More than a few had to have barrels re-chambered to close on the test gauge. Being as I had a barrel nut, I just loosened the nut and re-set it accordingly. I also have a Forster National Match chamber gauge set for .308 Win, which goes from 1.630 to 1.638 in 0.001" increments. The stripped bolt closed the same on the test gauge as on the 1.632 gauge, so...

The previous push-back on checking chambers with a steel gauge had always been in large part due to concerns about a ham-fisted 'volunteer' stuffing a steel plug in a match chamber. I will say that the 2017 FCWC match organizers made sure that the people doing the inspection / checking were actual active known competitors, which meant they knew *exactly* how shooters feel about someone else doing potentially damaging actions to their precious gun, that all their competitive hopes are hanging on, and behave appropriately. I know I still didn't like it on principle, but it was the best way to go about it.

I don't remember if there was any actual action on minimum cartridge neck dimension ala Bisley 150 rule. I know there was some 'safety' concerns about minimum neck dimension - apparently they (ICFRA, Brits, whoever) - thought someone with an expensive match rifle would just pick up some randomly piece of ammo off the ground, and shove it in their match chamber and pull the trigger. Personally I think that is an absolute crock of... but that was the logic presented.

What the current state of things is... you'd have to ask someone still in the game.

 

[NZ_Fclass]

"I don't remember if there was any actual action on minimum cartridge neck dimension ala Bisley 150 rule. I know there was some 'safety' concerns about minimum neck dimension - apparently they (ICFRA, Brits, whoever) - thought someone with an expensive match rifle would just pick up some randomly piece of ammo off the ground, and shove it in their match chamber and pull the trigger. Personally I think that is an absolute crock of... but that was the logic presented."

Quite. Considering that they still shoot "issued" ammo - certainly at Bisley - it seems odd. Thanks for the comprehensive reply.

 

[Leeman]

Random thought. When is a 308 - for FTR - no longer a 308?

Should an FTR 308 meet SAAMI specs? How about the 2013 FTR Team reamer with its long freebore ( and whatever other modifications) ?

The TR guys have the Bisley chamber - which does get tested - so FTR gets a pass? Just askin'.

I don't shoot F/TR but was interested enough to have a look.

A 2min check on the ICFRA website revealed the following: Technical rules 2023 edition F2, technical specification page 6

An F/TR Class rifle is limited to .223 Remington or .308 Winchester calibre chambers or their commercial metrification equivalents. Chamber dimensions must conform to SAAMI or CIP dimensions. Bore, Groove and Throat dimensions may be selected to suit bullets used. Ammunition may be commercially made or hand-loaded as defined in Rule F2.20

and Match Conditions F Class shooting FC7.4 page 3

During the individual and team championships a competitor may be required to provide at least two and not more than five rounds overall (at random), for technical checks by qualified experts provided by the host nation. These checks may include firing the rounds in the competitor’s rifle.

Couldn't find a definition page of what constitutes a 'qualified expert' though, or what technical checks may comprise