Headspace II

I hope this is OK to do this. I posted this to the headspace sticky, did not get much response and I'm guessing it's because most people ignore the sticky posts after they've read through them.

So here's my post to that thread:

Dang. Now this thread has me wondering...

I measured the head gap clearance by adding layer of tape to a F.L. sized case until bolt refused to close. Then measuring the OAL length of the case with and without the tape. I got 0.030" of gap between case head and bolt face. I'm a bit puzzled though because I could feel the bolt closing harder much earlier, but didn't get "refusal" until 0.030". And even at that I think I might have been able to force it to close without much effort.

Is that too much for a .35 Whelen?

I then measured my .357 leverguns on got 0.007" gap on one and 0.020" gap on the other.

The levergun with a 0.020" gap has given me case head separation problems, although the Whelen has not yet separated a case. Now that could be entirely because the Whelen doesn't get shot anywhere near as often as the .357 does. In fact of my Whelen brass I doubt I've even reloaded one brass more than 10 times yet.

I did however have a failure to fire on my Whelen this year. I pulled the trigger and "click" but no "boom". I chambered a new shell and got the deer. The failed shell had no primer dent whatsoever.

Any thoughts?

Too much.

AFAIK headspace should be .004" - .005"

If you apply 2 layers of frosted scotch tape to a go gage that will make a makeshift no-go gage

How do you calibrate tape, how much does tape compress and how many companies sell headspace tape for checking headspace?

Use a spent primer and a new cartridge case to measure your head gap clearance. Measure the length of the case without the primer and write it down.

Seat the fired primer in the primer pocket just using your fingers just starting the primer into the primer pocket.

Chamber this test cartridge slowly closing the bolt, extract the case and remeasure the case and write it down.

Subtract the first case measurement from the second case measurement and the difference will be head gap clearance or the air space between the bolt face and the rear of the case.

Masking tape can be anywhere between .003 and .007 in thickness and 3M scotch tape has a .0015 acrylic backing with a total thickness of .0023 to .00246 with the adhesive added to the backing included. Please note if you buy "other brands" like Chinese scotch tape you can forget the measurements or thicknesses above so "WHY" guess with scotch tape when you can use a set of vernier calipers and get the exact measurement.

[img width=564 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP0704.jpg[/img]

[img width=600 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP0706.jpg[/img]

[img width=600 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP0710.jpg[/img]

Quote:

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Originally Posted by say what

If your chamber is to deep, the cartridge will slide in to far. the bolt will hit the barrel before your cartridge contacts the bolt. you could try marker on the bolt head to see if it is being rubbed off. or remove the barrel and check the case head protrusion.

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Actually the extractor and the shape of the chamber will control how far forward the case will move in the chamber. And sometimes you can have a 1/2 inch of excess headspace. :o

http://i122.photobucket.com/albums/o.../image006e.jpg

http://i122.photobucket.com/albums/o...natoin3006.jpg

Using a spent primer is a simple and fast way of checking head gap clearance, and doesn't require "removing" the barrel. :o

Watch the primer below and you will see "head gap clearance" in motion below.

http://i122.photobucket.com/albums/o...p51/deform.gif

Black Jaque

A military British .303 with a cartridge with minimum SAAMI rim thickness of .054 and a maximum military headspace of .074 has .020 head gap clearance. The problem with .020 head gap clearance only occurs if you "reload" and the case stretched in the web area on the first firing. This head gap clearance leads to case head separations after "X" amount of reloadings and firings.

[img width=600 height=352]http://i122.photobucket.com/albums/o254/bigedp51/308fail.jpg[/img]

[img width=600 height=239]http://i122.photobucket.com/albums/o254/bigedp51/308fail-2.jpg[/img]

If you fireform your 35 Whelen cases with a false shoulder or your bullets seated hard into the rifing you will no longer have any head gap clearance and your cases will be a perfect form fit to "your" chamber. Normally a fired case has .001 springback so you are able to reload your case quite a few times before needing to bump the shoulder back to keep the cartridges from chambering hard.

Please take notice to what I have below, a GO gauge for a .243 Winchester that is 1.630 long, a RCBS Precision Mic and a .243 case fired in my Stevens 200 .243.

[img width=337 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP7241.jpg[/img]

The world is made up of plus and minus manufacturing tolerances, the 1973 dated RCBS full length resizing die on the left will only push the shoulder of of my new .243 back to 1.630. The new Redding die on the right will push the shoulder back to 1.627 or .003 more than the RCBS die. This is my third .243 rifle and because the rifles headspace is .001 over minimum my RCBS resizing die is only resizing the case into the "gray area" of minimum headspace of 1.630. These cases rub the bolt face ever so slightly and some would say this is perfect. I myself prefer a little more clearance when hunting a Tyrannosaurus Rex or bigger game. ::)

[img width=393 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP7243.jpg[/img]

Your "click" and fail to fire was caused by any of the following inside your bolt, dirt, dried oil, brass shavings or chips, ice, or all of the above. Clean your bolt, rub Viagra on the firing pin ;D and fire form your cases and head gap clearance will not be a problem. ;)

Quote:

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Originally Posted by say what

Will your prime tell you if the bolt head is rubbing on the barrel and there is no more adjustment?

you guarantee all extractors to hold a case so it will fire?

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say what

Please do not put words in my mouth or make assumptions. I collect British Enfield rifles and "NOTHING" supports the case rim but the forward edge of the chamber and the bolt face.

[img width=600 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP1355-1.jpg[/img]

I also have headspace gauges for my Enfield rifles.

[img width=600 height=433]http://i122.photobucket.com/albums/o254/bigedp51/IMGP5264.jpg[/img]

I can also measure headspace on my Enfield rifles using a set of feeler gauges placed between the reciever and right locking lug, or I can use a spent primer. ;)

[img width=600 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP6598b.jpg[/img]

The feeler gauge is actually measuring head gap clearance and when added to the rim thickness gives you actual headspace.

[img width=600 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP6600.jpg[/img]

I think I can say I understand the words headspace and head gap clearance.

http://i122.photobucket.com/albums/o...estretch-1.gif

And at times "excess headspace" is a pain in the backside and causes a foamy lip. ;D

http://i122.photobucket.com/albums/o...ambeer_lgl.jpg

BigEd,

I tried that technique of putting a spent primer in the pocket and closing the bolt. The result looked more like a fully seated primer. It did not visibly protrude beyond the case head so i did not bother to take measurements and instead moved to the masking tape trick.

I didn't figure it was necessary to know the exact thickness of each masking tape layer. I merely kept adding layers until the bolt refused to close, then measured the overall length of the empty case just the same as the primer seating trick you described.

Any reason why the primer seating method would be more or less reliable than the masking tape method?

Quote:

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Originally Posted by Black Jaque Janaviac

BigEd,

I tried that technique of putting a spent primer in the pocket and closing the bolt. The result looked more like a fully seated primer. It did not visibly protrude beyond the case head so i did not bother to take measurements and instead moved to the masking tape trick.

I didn't figure it was necessary to know the exact thickness of each masking tape layer. I merely kept adding layers until the bolt refused to close, then measured the overall length of the empty case just the same as the primer seating trick you described.

Any reason why the primer seating method would be more or less reliable than the masking tape method?

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"YES" the primer method is more reliable!

You can't compress a metal primer but you CAN compress the "stickem" on the tape that is "half" the thickness of the tape.

Tape is a "VERY" unreliable method for checking and setting headspace.

Example: What is your headspace on a "hot" day vs a cold day and where is your headspace if you use Chinese scotch tape. :o I'm saying this because I'm retired from a military overhaul depot and I spent the last 25 years in Quality Control as an Inspector. So I can tell you with 100% certainty that tape is "NOT" calibrated and it is "NOT" a precision measuring device.

If the primer was only protruding a small amount then you probably don't have a headspace problem you have a "resizing" problem from over resizing your cases and not fireforming them properly.

Minimum headspace for the 35 Whelen is 1.9835 and maximum is 1.9935, if your primer wasn't protruding ten thousandths (.010) from the rear of the case then you do not have a headspace problem. The cheap SOB used spent primer method of checking headspace is far more accurate than anything else. ;)

A NO-GO headspace gauge for the 35 Whelen is $27.99 at Midway and is "FAR" more accurate than scotch tape.

http://www.midwayusa.com/viewproduct...tnumber=543326

And the Emergency Wartime headspace on the British Enfield rifle was .084 or it could have as much as .030 head gap clearance.

You see sometimes tight headspace can get you killed in combat.

http://i122.photobucket.com/albums/o254/bigedp51/39.jpg

http://i122.photobucket.com/albums/o...edp51/170a.jpg

The jungles of New Guinea 1942, Australians reservists stopped the Japanese advancement on Port Moresby in the worst terrain and conditions imaginable. (MacArthur was still fighting at Bataan)

[img width=314 height=450]http://i122.photobucket.com/albums/o254/bigedp51/kokoda.jpg[/img]

As usual biged51, a stellar explaination.

say what

The difference between a rimmed case and a rimless case is the distance between the datum points for headspace measurements. Once my rimmed .303 cases are fireformed they are headspacing on the shoulder and not the rim, the same applies to all rifle cartridges no matter where the datum line is located.

http://i122.photobucket.com/albums/o...oheadspace.jpg

The problem here isn't bananas and apples, the problem here is someone sucking on too many lemons. If you can put on a better "Power Point demonstration" please do so and dazzle us with your book learnin'.

I do not consider collecting the Enfield rifle that has adjustable headspace and collecting Enfield books and manuals to be a fault or handicap. I also do not consider it to be a fault when I scan these old books and manuals and give them away free to my fellow Enfield collectors. ;)

All the information in the world is written in books and all you have to do is read. ;) And I have 12 DVDs full of British books and manuals and the majority of them are for the care and feeding of the Enfield rifle. ::)

[img width=600 height=424]http://i122.photobucket.com/albums/o254/bigedp51/gauge_file_Page_01.jpg[/img]

[img width=504 height=450]http://i122.photobucket.com/albums/o254/bigedp51/caseforming.jpg[/img]


Say what, I don't have case head separations because I can accurately measure case stretching in the web area and this gauge "ain't" a book. :o

http://i122.photobucket.com/albums/o...1/IMGP7193.jpg

The above message was powerful but it wasn't power point. ;D

The MOST reliable way to check headspace clearance is to use plasti-gage. It will give you an actual clearance without the subjective "feel". Plasti-gage is available at most automotive stores, and is used primarily for gauging clearance on crankshaft bearings.

Quote:

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Originally Posted by sharpshooter

The MOST reliable way to check headspace clearance is to use plasti-gage. It will give you an actual clearance without the subjective "feel". Plasti-gage is available at most automotive stores, and is used primarily for gauging clearance on crankshaft bearings.

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sharpshooter

How many main bearings and connecting rod bearings have Remington and Winchester impressed on the bearing surface. Meaning plastigage is meant for "perfectly flat" surfaces to get an accurate reading. You also have three different types of plastigage, .001 to .003, .002 to .006 and .004 to .009.

Used primers are free. ;)

http://www.plastigaugeusa.com/how.html

http://i122.photobucket.com/albums/o...tigagehelp.jpg

Ok, i really like the learn' lesson i'm getting here since i'm about to do my first barrel swap. However i do need to say that plastigage has more than one use and isn't confined to just flat surfaces, i have used it for many automotive racing applications over the years. It's ability to form around whatever surface it was used to gage is one of the reasons it's still in use after so many years.

Now, ... may i sneak back out of this while i still have all my limbs. blue

You simply can't do it any better or cheaper than the spent primer route.........Have been using this method for years. Nothing works as well for the $$