Could someone clear up for me "headspaceing"

slushee

slushee

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I own an M14 that went through a Hungry Clinic. It had its OP ROD GUIDE tightened, its gas cylinder lock tightened, been put into a USGI Synth stock, the barrel was already "relatively" indexed (only slightly off center, not enough to ruin the sights out of the box). The gun is also awaiting (when funds are available) a new spring guide and spring. I was also thinking about checking and 'lapping the lugs' when time wasn't an issue.

With that said, I can remember Hungry saying at the time my headspace was .. something too much. It wasn't so bad as to stop shooting but I personally can't seem to get my head around what headspacing is. Could someone try to simplify what headspacing is so I can try to understand it, and possibily correct it to improve accuracy?
 
For rimless cartridges, headspace is the clearance between the bolt face and some datum point on the shoulder of the chamber. In the case of .308/7.62, this would be where the shoulder has a diameter of .400". If you reload, it is possible to work around this by neck sizing your brass and using it only in that rifle. Otherwise, to tighten up the headspace, you need to find a GI bolt and have it fitted to the rifle.
 
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emerson said:
Can someone explain; perhaps with diagrams or pictures, how headspace is adjusted please.
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Depends on the situation. If the chamber is not deep enough, a reamer is used.
If headspace is excessive, the barrel can be turned in further. This is impractical with a M-14.
Another bolt can be retrofitted which brings the cartridge base further foreward, to reduce the cartridge end play.
This is why USGI bolts are sought after. The bolt must be fitted properly, though.
"Lapping the lugs" would be a bad idea if the rifle already has excess headspace.
 
Holy spit, do people know how to make a simple answer difficult.

slushee said:
Could someone try to simplify what headspacing is so I can try to understand it
Click to expand...

Sure I can. Headspace is the length of the chamber.

There are some technicalities such as where you measure from and where you measure to, but in essence you are measuring the length of the chamber. Too short and the cartridge won't fit, too long and the case has room to rattle around, which affects safety, reliability and possibly accuracy.
 
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