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When the going gets weird, the weird turn pro.
Hunter S. Thompson
Just for the record (future search purposes), on DRLB systems headspace is set when the chamber is cut. It is determined by the amount of cartridge sticking out from the chamber face. This amount should be equivalent to the depth of the bolt face counterbore plus .009" (ish). This amount creates a gap between the bolt face and chamber face when a cartridge is in the chamber, keeping the brass pressed firmly in the chamber shoulder. Once headspace is set, it does not change on the HK platform.
Bolt gap is irrelevant to headspace. Bolt gap sets the placement of the bolt locking lever on the bolt head when the rollers are seated in the trunnion. The gap width tolerance (.004"~.02") controls the delay of opening (timing) after firing. Gaps too large open too soon. Every component in your rifle has a manufacturing tolerance. When made to specifications the parts typically work well in any rifle. HK is very good at making their parts right. Aftermarket vendors, not so much. As parts wear, different size rollers are used to keep the gap in spec.
However, because your rollers aren't firmly locked in the triangle (because the bolt locking lever is not on the bolt ramp) you will experience violent recoil as the pressure forces the bolt head rearward until the rollers make contact and squeeze the locking piece and carrier rearward. It's a good way to damage the bolt face windows.
On a pistol round not a rifle round.
They either have locking lugs, locking shoulder or a mechanical or gas delayed system to hold against the initial pressure of the fired cartridge.
The locking lever holds the bolt and carrier compressed together. Itís the amount of protrusion of the locking piece into the bolt that pushes the rollers out to engage the trunnion. If there is no bolt gap then the locking piece canít push the rollers out far enough to fully engage the trunnion. Which would cause the bolt to not lock up tight in the trunnion with a cartridge in the chamber.
The same as excessive headspace in any other 308 rifle.
You would most likely bulge or rupture the back of the case.
Last edited by HD Bee; 04-28-2020 at 01:06 PM.
Headspace (in this platform) is not set with the bolt locked as with those you mentioned. It's a delayed blowback rifle. You could remove the rollers completely and the headspace remains the same.
Are they safe to fire? NO
I think most gunsmithís definition of headspace is the bolts free play in a locked position with a cartridge inserted in the chamber.
With the bolt and carrier compressed the rollers are pushed out by the locking piece and the bolt is temporarily locked in the trunnion.
Any adjustment by changing the rollers or locking piece would change the free play of the bolt in the trunnion and change the bolt gap.
You guys are starting to hurt my head space. Yeesh.