is this headspacing

[vano]

mod 12 benchrest installing new 6br barrel bolt snug to unfired lapua case then added 002 shim as a no go which it was
is this headspacing
thanks vano

[bigedp51]

The average commercial case is .002 shorter than minimum headspace, if you add a .002 shim your headspace will be at the minimum or GO.

Below is a RCBS Precision Mic for the .308/7.62

http://i122.photobucket.com/albums/o254/bigedp51/IMGP5130-1.jpg

The zero pictured below is minimum headspace or GO

http://i122.photobucket.com/albums/o254/bigedp51/IMGP5157-1.jpg

Below the Precision Mic has a new unfired Wincheater .308 case in the gauge, the gauge shows the case to be .002 shorter than minimum headspace.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP5254.jpg

Below is a military 7.62 NATO case in the Precision Mic, military cases are .0015 longer than civilian commercial cases and approximately .0005 shorter than minimum SAAMI headspace. Military headspace is longer than commercial SAAMI headspace and the cases are slightly longer and thicker in the base web area

http://i122.photobucket.com/albums/o254/bigedp51/IMGP5256.jpg

To answer your question if you use a cartridge case to headspace your rifle you will be .002 UNDER minimum headspace (too tight) if you use a .002 shim you will be at minimum headspace or go.

NOTE: The act of dry firing a fired case will shorten the case approximately .001 each time you dry fire the case (drive the shoulder back) You are also warned to never use cases that were used for reduced loads again for normal pressure loads because the case will be much shorter than normal and case head separations can and will occur.

You do not need to set your headspace as tight as many of you are, the act of fire forming your cases will blow out the shoulder and make your cases a custom fit to your chamber.

I shoot and reload for the .303 British Enfield rifle, the military headspace settings are so "loose" (up to .020 head gap clearance) I put a rubber o-ring around the base of the case to hold the case against the bolt face to fire form my cases.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP5096.jpg

http://i122.photobucket.com/albums/o254/bigedp51/IMGP6290.jpg

Now here is some "headspace" information to think about. (about a half inch too much)

http://i122.photobucket.com/albums/o254/bigedp51/image006e.jpg

http://i122.photobucket.com/albums/o254/bigedp51/762natoin3006.jpg

[gotcha]

BIGEDP51, Excellent presentation! This is the "good stuff" you don't get from r/l manuals or, for the most part "gun writers". Particularly, the caveat of judging cartridge headspace from under powered loads. Thus the advice from posters cautioning to use headspace gauges(at the very least a go-gauge plus tape) on 1st builds. Don't know if it's Big ed p51 as in mustang or big edp as in electronic data processing or what? But Enjoyed the post, Dale

[claysshotgunner]

Vano, everything I have read said to use a fired case, not virgin brass.

[bsekf]

Please keep in mind that headspace is a subjective thing. SAAMI headspace measurement is used as a industry standard, so that the Win 308 ammo you buy is PA is the same size as the Federal 308 you buy in Montana. If you reload and just neck size, after fire-forming, headspace becomes mute. Headspace way too long (>.002) and you may get case separation, headspace too short and you can't close the bolt.

BIGEDP51, Excellent presentation!

Bill

[bigedp51]

A fired case can be ANY length depending on the head gap clearance or the length of the chamber. A re-sized case can be a crap shoot also depending on the dies and how the press is set up.

You can check your head gap clearance or the "air gap" between the rear of the case and the bolt face with a new unfired case and a spent used primer.

First measure your unfired case with a vernier caliper and write the measurement down.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP0710.jpg

Next seat the spent primer just starting it in the primer pocket.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP0704.jpg

http://i122.photobucket.com/albums/o254/bigedp51/IMGP0706.jpg

Now chamber your test round and slowly seat the primer as you close the bolt. Remove the test cartridge and remeasure the case again. Now subtract your first case measurement from your second case measurement and this will give you the "airspace or gap" between the rear of the case and the bolt face.

I myself would want .002 to .003 as this would give you minimum headspace (GO) to .001 more than minimum headspace.

Remember when you re-size your cases in a full length resizing die the brass has only one direction to move and that is forward. If you set your headspace too tight the re-sized case may be extremely tight fitting or the bolt might even refuse to close.

They make headspacing shims for reloading dies and shell holders to help you resize your cases to your proper length.

http://i122.photobucket.com/albums/o254/bigedp51/7-17-201054719PM.jpg

http://i122.photobucket.com/albums/o254/bigedp51/7-17-201054345PM.jpg

http://i122.photobucket.com/albums/o254/bigedp51/7-17-201055522PM.jpg

If you set your headspace to short or "below" GO you run the chance of the case not fitting in the chamber. The average new case is .002 smaller to ensure chambering and to make allowances for manufacturing tolerances.

I set one of my Enfields headspace to below GO (.002 under) and in very cold weather firing the rifle caused condensation droplets to freeze inside the chamber and my reloads refused to chamber. "Headspace" serves a purpose and that is to allow any newly manufactured cartridge case to chamber in your rifle. Proper fire forming will take the "slop" out of your cases, set your headspace at minimum headspace (GO) or .002 to .003 over minimum.

Below as an example is SAAMI headspace settings for the .308 Winchester.

308 Winchester (SAAMI) Gauges

GO - 1.6300"
NOGO - 1.6340"
FIELD - 1.6380"

U.S. Military 7.62 NATO Gauges

GO - 1.6350"
NOGO - 1.6405"
FIELD - 1.6455"

If you use a new .308 case to set your headspace your headspace will be 1.61 and .002 under minimum, on any commercial factory rifle your headspace is set between 1.630 and 1.634. That is anywhere between .002 and .006 thousandths larger than a new cartridge case.

+ .003 over a new case would be about perfect.

Note: On my British Enfields at the maximum headspace setting of .074 and a American SAAMI case I can have as much as .020 (twenty thousandths) head gap clearance for my cases to stretch. And you people are worried about .001 or .002 thousandths, I wish I was that lucky on a British Enfield rifle.

http://i122.photobucket.com/albums/o254/bigedp51/headspacestretch-1.gif

The rubber o-ring around the .303 rim makes the word "headspace" meaningless.

http://i122.photobucket.com/albums/o254/bigedp51/headspacestretch_frame_0001.jpg

Once fire formed the case headspaces on the shoulder

http://i122.photobucket.com/albums/o254/bigedp51/fireformed-zeroheadspace.jpg

[Ray Gunter]

bigedp51........ a great post...... lost of good stuff there

[Eric in NC]

"The rubber o-ring around the .303 rim makes the word "headspace" meaningless."

Until it is so excessive that you get a case head separation because your o-ring doesn't provide any support past the web area of the cases.

Why not just seat your bullets long and fire form that way? Better yet why not get a #2, 3 etc. bolt head (assuming you aren't using a No.1 Enfield)?

And there is a big difference between loading for the 303 Brit and loading for more modern cartridges. Yes I use the "fireform to chamber dimensions" type of headspacing on many old low pressure cartridges, but I wouldn't want to do that with some of the loads folks are running in 6mmBR rifles.

[bigedp51]

You can use a new empty case to set your headspace and it would work, "BUT" several things could go wrong.

1. You take your rifle hunting and forget and leave "your" special ammunition at home and find out normal store bought ammo wont fit in your rifle.

2. You find over time your cases are getting hard to chamber and your decide to use a full length resizing die to bump the shoulder back only to find out your cases are now longer than when you started. You would need to lap your shell holder and remove a few thousandths to get the cases to chamber.

3. You sell the rifle to someone and he gets home and finds out his Remchester cartridges wont fit the rifle and he looks you up again and beats you to death with your old rifle.

Trust me, the shell holder below had .002 removed on a lathe and .001 removed by hand lapping in order to get a custom .270 to chamber a fully FL resized case to fit in the chamber. Just because yours truly wanted a tight chambered .270 rifle.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP6943.jpg

[pdog06]

mod 12 benchrest installing new 6br barrel bolt snug to unfired lapua case then added 002 shim as a no go which it was
is this headspacing
thanks vano




Vano, to answer your question I would use a FL sized new case instead of an unsized case. That will be your "GO".

Then use .003"- .004" worth of shims(1or2 pcs of scotch tape) to make your "NO-GO.

If this is a barrel that has been shot before then using a fire-formed case as your "GO" would be good to use.

Or, you could buy or borrow a set of headspace gauges too, which should probably be best recommended for a first build.

Saami spec for the 6br case is 1.560". New Lapua brass measures 1.556-1.558" usually, so as you can see using a pc of unsized brass is gonna put you under spec like mentioned above.


Theres alot of great info being given here, but you're doing a 6br, not a 308 or a 303 Enfield.


Just as a test since you already have it heaspaced the way you mentioned, you should FL size your case then see if it chambers. I'd bet it either wont chamber or will be pretty tight. Then I'd re-set the headspace to the sized case.

If you want to read up some more on the 6br, here's a very good article with alot of info:

http://www.6mmbr.com/6mmbr.html#26585

[bigedp51]

"The rubber o-ring around the .303 rim makes the word "headspace" meaningless."

Until it is so excessive that you get a case head separation because your o-ring doesn't provide any support past the web area of the cases.

Why not just seat your bullets long and fire form that way? Better yet why not get a #2, 3 etc. bolt head (assuming you aren't using a No.1 Enfield)?

And there is a big difference between loading for the 303 Brit and loading for more modern cartridges. Yes I use the "fireform to chamber dimensions" type of headspacing on many old low pressure cartridges, but I wouldn't want to do that with some of the loads folks are running in 6mmBR rifles.



My Enfields are headspaced at .067 or less,(.074 is max) my Remington and Winchester cases have a rim thickness of .058.
When fired without the rubber o-ring the cases will stretch .009 in the web area.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP4521-1.jpg

http://i122.photobucket.com/albums/o254/bigedp51/IMGP4523.jpg

http://i122.photobucket.com/albums/o254/bigedp51/IMGP4513.jpg

Seating the bullet long does not work, the Enfield is long throated and also cordite ammo was used making the throat even longer. Creating a false shoulder on the neck to hold the case against the bolt face causes split necks because of the large military chamber.

Even a 174 grain round nose bullet will not touch the rifling.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP6291.jpg

The American made .303 British cases have small base diameters and the o-ring has the added benefit of centering the case in the chamber and helps prevent "banana" shaped cases.

Headspace is governed by the cases you shoot and NOT the rifle.

Military cases have a larger base diameter.

http://i122.photobucket.com/albums/o254/bigedp51/thicker-2.jpg

Military cases have thicker rims.

http://i122.photobucket.com/albums/o254/bigedp51/thicker-3.jpg

And Military cases have thicker case walls.

http://i122.photobucket.com/albums/o254/bigedp51/thicker-1.jpg

I fire form my modern rifle cases at mid level loadings, and for my .303 I use .312 pistol bullets using reduced loads and the o-ring method to blow the shoulder out.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP4691.jpg

Our American ammunition companies can't seem to figure how to make British military cases, the Remington case below has the shoulder of the .303 case a 1/4 of an inch too short.

http://i122.photobucket.com/albums/o254/bigedp51/twocases.jpg

The reason I use the rubber o-ring is because some brilliant people tell everyone to oil or grease their cases to fire form them which doubles the bolt thrust on your pet rifles.

http://i122.photobucket.com/albums/o254/bigedp51/TBOSA-1.jpg

http://i122.photobucket.com/albums/o254/bigedp51/TBOSA-2.jpg

http://i122.photobucket.com/albums/o254/bigedp51/oilcover.jpg

http://i122.photobucket.com/albums/o254/bigedp51/oilinchamber.jpg

Eric in NC

I'm 60 years old and have been reloading since I was 18 years old, I'm not stupid, retarded or brain dead.
If you want to teach me something about reloading then teach me how to reload these..................

http://i122.photobucket.com/albums/o254/bigedp51/IMGP6286.jpg

http://i122.photobucket.com/albums/o254/bigedp51/IMGP2800-1.jpg

[drybean]

wow












wow i like to come to your house an taste your reloading










111

[DGD6MM]

pdog06 is spot on, do what he said and there will not be a problem. All the scotch tape that I have measured has been .002.

[possum1]

YES SIR !! From the very first post about head space from biged, which was a while back, I knew there was something about biged I liked and now he post a image of it. ;D

[pdog06]

biged,No real need to make this a personal "who knows more" thread. There is more than one person on here that knows what they are doing, and the original poster asked a pretty simple question.

Great choice of beer ...Mmmmmmm!

[bigedp51]

biged, No real need to make this a personal "who knows more" thread. There is more than one person on here that knows what they are doing, and the original poster asked a pretty simple question.

Great choice of beer ...Mmmmmmm!



Eric in NC wrote

And there is a big difference between loading for the 303 Brit and loading for more modern cartridges.

bigedp51 in P.A. answers about his "old" decrepit 67 year old Enfield rifle in a ancient out of date caliber.

"In a pigs a$$ there is" (the actual difference between the .303 and 6mmbr is 7,000 CUP and 300 fps and I didn't have a scope) ESAD!

http://i122.photobucket.com/albums/o254/bigedp51/range-day-2-1.jpg

Here is 10 shots before I moved the front sight.

http://i122.photobucket.com/albums/o254/bigedp51/range-day-target.jpg

Now who wants to talk about headspace and hand loads, and stay away from MY beer you drunks.

[fatdaddy]

"IN A PIGS A$$"... "ESAD"... Really???

[pdog06]

"In a pigs a$$ there is" ........................ ESAD!



Why do you have to act like that. We're all friends here and try to help one another, not show up one another. If you wanna pump your chest out like youre better than everyone else then I suggest you try it elsewhere...

[lostart]

I have noticed that when there is "friction" in a thread that most people avoid said thread because they do not want to become involved. This turns an otherwise informational and useful thread into a dead thread or a **** measuring contest. We can disagree, but lets do it respectively.

[possum1]

I posted a wisecrack about the beer because odd brand's of beer intrigue me, don't drink alcohol;long story. Don't understand what happened to this thread, I've PM'd biged several time's and he has always been professional and always helped me all he could. I think he is a stand-up guy.