Checking Headspace

[Hawk]

My brother has a Remington Model 760 pump in .270 Winchester.
It was my Dad's and he bought it in the 1950s, I think.
Lots of use on it.
Anyway, we are trying to reload for it and it is giving me really flattened primers at 3.0 grains below the charge of H4831SC that I am using for my .270 in my Remington 700. No sticky extraction in the Model 760, but really flattened primers.
I'm loading 60.0 Gr. of H4831SC behind a Nosler 130 Gr. Accubond. A stout load, but no pressure signs in my gun.
I think it is excessive headspace.
Question is, how can I measure the headspace of a cartridge fired in the Model 760.
I don't have go, no-go and field gauges and any type of tool of that sort of equipment is sold out anyway.
I want to try to actually measure the headspace of new cartridge, brass fired in the Model 760 and one fired in the Model 700, just to compare the three to each other. A datum point would be fine. It doesn't have to be the actual headspace. Just an apples to apples comparison.
I thought about trying to use a washer to set the neck of the brass in, just to have a datum point, but I would need something like a 19/64 washer. I have no machine tooling to make anything.
The other thing is, the pump action doesn't have the same closing feel as a bolt action.
I'm not sure I would trust closing the pump action on a piece of brass as a good indicator of a completely closed action.
Any suggestions would be appreciated. (I probably knew this at one time and have forgotten).

 

[Spindrift]

Before i got the Hornady headspace tool, I used a 9mm parabellum- case. Knocked the primer out, and reamed the inside case mouth of the pistol cartridge. Slid the pistol brass over the neck of the rifle cartridge, measured the total length. This gave reasonably reproducible readings on .30- cal brass.

 

[4060MAY]

something to try
use a Factory fired case with spent primer, push the primer half out of the case,put in chamber, close the action, remove case
if the primer is not flush, may be a Headspace problem

 

[RBHarter]

Had a 760 in 06' some factory ammo showed pressure . The chamber was tight not SB tight but if you didn't chamfer the outside sometimes it wouldn't take its own fired brass back from 1x factory for get anything over .3095 .

 

[Ian]

270 Winchester (.277) Cartridge Gauge

270 Winchester (.277) Cartridge Gauge by Hornady Bullets and Ammunition Hornady Lock-N-Load Gauges are designed to ensure that your brass cases will fit correctly in a SAAMI spec chamber. All gauges are constructed of high carbon steel to ensure long life.

www.midsouthshooterssupply.com

 

[Hawk]

Thanks, I tried to buy several, only to be told at checkout, they were out of stock.

 

[462]

A funny story:
I bought a Hornady cartridge gauge for the .223 Ruger American Rifle. Every so often a full length sized case would sit proud. Cases were range pickup and some purchased once-fired. Printed the SAAMI drawing. Made and compared measurements. There is was no apparent reason why the cases wouldn't fit. It drove me nuts. One day I noticed a burr on the extractor lip on a piece of that day's range pickup.

The range has a concrete walkway behind the shooting stations and some brass were getting burrs from hitting the concrete.

 

[Hawk]

Well, I bought the Hornady gauge.
I was hoping to find a redneck solution that wouldnt cost me money.

 

[popper]

Case or nogo? The primer trick is good - if the pocket is tight you can measure with feeler gauge (close bolt slow). The other method is masking tape on the case head but sometimes the ejector needs to get pulled. Should be able to mark the bolt so you can tell if it is locked up. brass fired in the Model 760 and one fired in the Model 700, just to compare the three to each other. Won't really tell you anything useful. Guns are set up to give proper HS, not spec datum to case head. Real HS in the 760 is good to know, worn lugs, etc. Plus you set the sizer for that rifle.

 

[CWLONGSHOT]

Excessively Flattened primers are generally not a result of a head space issue.. Byproduct possibly, but caused by not so much.

Also, Primers alone are a very poor exhibitor of a cartridges pressures. Excessive recoil/ Noise, Hard bolt lift and most importantly, case head expansion is much more accurate way to see/know your getting excessive pressure. With a primer you have no way to know if the cup was thin or soft making it flaten easily/easier.

One thing with primers that WILL suggest a HS issue is if a primer is left proud. Of coarse a loose pocket can show similar.

A chamber cast that includes the throat would be more telling.

Good luck

CW

 

[Joshua]

Before i got the Hornady headspace tool, I used a 9mm parabellum- case. Knocked the primer out, and reamed the inside case mouth of the pistol cartridge. Slid the pistol brass over the neck of the rifle cartridge, measured the total length. This gave reasonably reproducible readings on .30- cal brass.

Ok, love cheap solutions like this! Thank you! The 9mm works pretty well on empty cases. I wanted to measure some loaded rounds also, l happened to have two 357 Maximum cases in my possession. Using this longer case doesn’t give as reliable a measurement, but with a little careful fiddling it can give an approximate +.001,-.001 reading.

What I don’t love is finding out that I have been excessively full length sizing my brass! I have always just screwed my sizing die tight to the shell holder, and had faith that every thing was gonna be just fine!

I also learned that one of my shell holders is apparently taller than the other one.

It would seem that this seasons hunting ammo that I loaded last week is averaging .005” to .008” shorter at the shoulder than a case that has been fired at full pressure.
And, the brass that was sized with the shorter shell holder is a full .014” shorter.

Screwing down the die tight onto three pieces of Christmas wrapping paper (.0023” x 3 = .0069”) gave enough gap to only bump the shoulder back .002”.

Question for all you guys with the proper gauges. How much do you bump back your shoulders, in relation to your chambers?

 

[Ian]

also learned that one of my shell holders is apparently taller than the other one

Amazing what you discover when you start measuring stuff and paying attention to details. Just don't start doing things like checking your bolt faces for squareness or barrel/receiver alignment and you'll continue to have blissful sleep.

As a rule I bump shoulders back no more than .002" and no less than .0015". You get one shot at an accurate measurement due to brass springback, if you bump the case twice to get your measurement and lock the die,the next one will be long.

Having read Harold Vaughn's book which delved exhaustively into unbelievably trivial details of rifle accuracy, I got a really good concept of just exactly what headspace is and needs to be.

 

[waco]

Question for all you guys with the proper gauges. How much do you bump back your shoulders, in relation to your chambers?

.0015"-.002" is what I normally do.

 

[Brad]

I would agree with Walter.

 

[popper]

All chambers are not Saami nor the same. Check fired and factory against the gauge.

 

[Joshua]

Thank you for your input!

My brass is all over the map. I just downloaded the SAAMI Rifle .pdf. All 375 pages of it. From what I have read, a .014” difference like I have is just barely at the edge of the tolerance. Min. cartridge head space vs Max chamber headspace. So I am still “safe”, but not ideal at all.

So going forward this will be something that I will have to include into my sizing and sorting routine.

I set my die for a .002” bump. But some of this brass was shot with low pressure loads, so these ones are still

I think that that 9mm case is going to be living with that die set from now on.

 

[Joshua]

All chambers are not Saami nor the same. Check fired and factory against the gauge.

The method I’m using is comparative. So I’m using a fired full pressure piece of brass to compare to my sized brass.

 

[Ian]

Remember, SAAMI min/max are for ONE firing on virgin brass. If you stretch your brass .014" every time you fire it it will probably separate on the third firing. Little #$%& they don't tell you about.

 

[Joshua]

I’m aware that this is going to create problems for me. I’ve already got the bent paper clip out looking for separation rings.

 

[CWLONGSHOT]

When I set up a set of dies, they get their own shell holder. For just this reason, they vary quite a bit!!
Sure sometimes it doesn't matter as much, like loading 45 ACP or 40 Smith and Wesson or 9 mm 38/357 you're not gonna notice a huge difference but with rifle stuff, stuff that's going to be on wanted to be more accurate & relied relied upon to be more accurate, the key is consistency and more consistent you can make something the better reliability with consistent accuracy you'll find.
CW