In searching for possible reasons for the headspace problem with my 308, a member asked whether I shot R1 (7.62x51) milsurp in the rifle.
Yes, I did, but I don't know how many shots. It might have been a good 200 shots, on and off, over ten or fifteen years. It might also have been a little less or more.
Could that have made a difference, or caused headspace trouble?
No
Quote from: janfred on May 06, 2024, 12:00 AMNo
Any idea then what could be the cause of DsJ's headspace problem ? ???
Quote from: Ds J on May 05, 2024, 09:56 PMIn searching for possible reasons for the headspace problem with my 308,
Do you have standard to spec ( SAAMI or CIP ) GO and NOGO gauges for your rifle ?
Really only the proper way to check the headspace - ON THE RIFLE - using factory ammo
( Of course YOUR headspace is a different matter .. ;) :) )
SIZING dies also have a role to play - IF you reload
Once you have measured and know what your rifle / chamber dimensions are -you can then work out a solution
Most reliable method is to take the rifle to a gunsmith to measure the headspace.
Second place is to shoot the rifle as is and set the sizing die to bump the shoulder 0.003". Yes, target and PRS shooters bump to 0.001", but we want reliable hunting ammunition that can chamber under adverse conditions.
Lastly, measuring case growth is a good indication of headspace. Measure the case length before priming, and again after it has been fired. The difference in length is very close to how much you bumped the shoulder
From the OP I surmised that there was something not correct beyond the normal scenario of setting head-space by FL sizing die when reloading ?
Something like an incorrectly cut or oversize chamber / Bolt face problem / Problems between / with bolt and chamber
Overpressure scenario
Thus the reference to the use of military ammunition
DsJ needs to tell us what the exact problem is ?
Ds J
Please describe how you set your sizing die before sizing your cases for this specific rifle and batch of cases.
Quote from: janfred on May 07, 2024, 11:34 AMDs J
Please describe how you set your sizing die before sizing your cases for this specific rifle and batch of cases.
Good evening Folks, work keeps me from chatting here, and it will be the same for the next few weeks.
In short: I read and follow the manual to the letter. It is for a RCBS full length sizing die in a Rockchucker.
If memory serves correct, the procedure is to screw the die down untill it touches the shell holder. Then there is something about screwing it out, or back, two turns, and then to lock the nut.
Set your die up according to the following procedure.
https://www.gscustomusa.com/faqsizerdie.html
Not only will your headspace problems disappear, your cases will last longer as well and you will still have reliable hunting ammo.
Quote from: janfred on May 08, 2024, 11:34 AMSet your die up according to the following procedure.
https://www.gscustomusa.com/faqsizerdie.html
Not only will your headspace problems disappear, your cases will last longer as well and you will still have reliable hunting ammo.
Thanks, will do.
Setting up the sizing die according to the above procedure eliminated the cracked cases I got from my 7x57mm and increased accuracy.
Die set up will fix incorrect die set up issues, you not going to fix head spacing with die set up - perhaps reduce its apparent resultant showings, but not much more.
The easiest way to check head spacing is to take the rifle to a gunsmith and test the chamber with go /no-go gauges. Quick and easy, but might cost a couple of bucks for the gunsmith's time.
Quote from: Treeman on May 08, 2024, 05:02 PMDie set up will fix incorrect die set up issues, you not going to fix head spacing with die set up - perhaps reduce its apparent resultant showings, but not much more.
The GS Customs method is all good and well but there appears to be no measurements taken in the process ?
I like measuring things - One can never have enough measuring instruments ( and tools )
When you measure - you KNOW
The method described by GS Customs is in my opinion only for you to have a method of measuring without actually measuring.
Its is so to say a way of finding out if you need to or not have measurements done professionally.
If I use the GSC method I should be able to get a case sized to the actual specs of my chamber. Then, if I were to compare that to SAAMI specs, I should be able to calculate the difference in my own chamber.
Quote from: Shotofrank on May 12, 2024, 09:50 PMIts is so to say a way of finding out if you need to or not have measurements done professionally.
Purchase the right gauges and measuring instruments and learn how to use them
No need for "professionals"
Quote from: Ds J on May 12, 2024, 10:31 PMIf I use the GSC method I should be able to get a case sized to the actual specs of my chamber. Then, if I were to compare that to SAAMI specs, I should be able to calculate the difference in my own chamber.
A case sized - and or fired in your rifle chamber will always be slightly smaller than the actual chamber
It needs to spring back enough to be able to be extracted.
The ONLY real way to know what is going on in your rifle chamber is to cast it using cerrosafe or similar low melting point alloy
Making a chamber casting (https://forum.castbulletassoc.org/thread/making-a-chamber-casting/)
Cerrosafe (https://boltonmetalproducts.com/products/cerrosafe-bolton-160-190)
Unfortunately no-one has been able to tell me where to get this in SA ?
SAAMI chamber print can be found here
American National Standards Published by SAAMI (https://saami.org/technical-information/ansi-saami-standards/)
CIP chamber print can be found here
COMMISSION INTERNATIONALE PERMANENTE POUR L'EPREUVE DES ARMES A FEU PORTATIVES (https://bobp.cip-bobp.org/en/tdcc_public)
All sorts of different .308 reamers can be found here
4D Reamer rentals (https://4drentals.com/product-tag/308/)
All you have to do is learn how to read a chamber print
You can make chamber casts from flowers of sulphur. Thanks what most smiths used in the olden days. It stinks to hell but I've seen casts made using it and they look excellent.
I know an old gunsmith who told me how to make a wax chamber cast. It takes time and effort, but is accurate enough to get the necessary specs.
Here is another mehod to give a "close enough" measurement.
Size 5 cases to minimum, trim to minimum spec, load a moderate charge and shoot them in a clean chamber. Now compare case length before and after firing.
Quote from: Newton on May 13, 2024, 12:53 PMQuote from: Shotofrank on May 12, 2024, 09:50 PMIts is so to say a way of finding out if you need to or not have measurements done professionally.
Purchase the right gauges and measuring instruments and learn how to use them
No need for "professionals"
*****************************
Any idea what this would cost for 8-9 calibers, just as a once of use, to get a once off answer, even for just an answer on this one rifle once off ?
These may be part of what you need
https://safarioutdoor.co.za/catalogsearch/result/?q=Chamber+Length+Gauges
here's how to make your own way
https://bulletin.accurateshooter.com/2018/03/how-to-craft-your-own-chamber-length-gauge/
Cleverrrrrrrrrrrr ! I never thought of that myself
https://www.google.co.za/search?q=headspace+measuring+tool&sca_esv=4771c1dce5b9df5f&hl=en-ZA&sxsrf=ADLYWIJyj_JQcSmeioN5sxCRiWr5neNGhQ%3A1715629200927&ei=kGxCZpCEOICJ9u8PidSfoAI&oq=measuring+headspace&gs_lp=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-&sclient=gws-wiz-serp#fpstate=ive&vld=cid:2e4578e9,vid:riVRHOog69g,st:0
To measure the case length to the shoulder, you need some tools that actually index on the case shoulder or "datum line". These cost money.
A cheap trick to get similar results is to use a sized 9mmP case. Stick it over the 308 case mouth and measure from 308 base to 9mm base. The exact measurement on a fired case, a new case and a "bumped" case will usually tell you the story.
The "datum" shoulder diameter is .400". A.40 calibre or 10mm case might work better.
All these tools are comparators. Comparing one case to another. If you have a "zero" headspace gauge, you can then compare it to your case size.
Easiest is dtil to take the rifle to a gunsmith and ask him to measure the headspace.