Brass/Headspace Question?

[HeathSexton]

Guys, I got the big idea I was going to lap the lugs on my 77 MKII 30/06, lapped it down, groups didn't improve but they didn't get worse. According to my calipers I removed .002 off one lug, my brass after the lap is .001 longer in the shoulder area using my Hornady Comparator .37 comparator. The weird thing is with a piece of fired brass in the chamber there is no resistance closing the bolt. Have I screwed up the headspace? The brass is not bulged, split, or strange looking.


The reason I lapped the /06 is my 7mm 77 MKII shot a 6" group at 50yds with 175gr Corelokts, I lapped the lugs and it went to .339" at 50yds, I only had 1/32" of one lug touching. The 30/06 wasn't much different so I figured I would try it too.


Guess I should leave the gunsmithing to gunsmiths.


Thanks

 

[old #7]

Just because you chambered a piece of "fire formed" brass doesn't mean the bolt should close stiffly.
After firing the brass springs back a .001 or so.
When you FL resize your brass the die will "push" the shoulder forward while it is squeezing the diameter back to spec's. If you don't set your die to bump the shoulder back you will have a crush fit.
I neck size all of my brass and 97% of the time my bolt closes easily.

You stated you removed .002 off one lug. What about the other one.
I am not a gunsmith and did not stay at a Holiday inn express last night but I don't think .002 is too much. Compare your fired brass to the spec's in the manual.

 

[HeathSexton]

Well, I colored both lugs, chambered fired brass, and worked the bolt to see if I had contact, I had almost full contact on one lug and zero contact on the other, so I lapped the long lug to get contact on both lugs.

http://www.castbulletassoc.org/forum/vi ... mp_to=7201

 

[rick smith]

Once the brass is fired, set your dies to the new headspace and continue as normal. New brass, especially belted mags, normally stretches more than that.Rick.

 

[chucksniper]

bump the shoulder back till it chambers