Author Topic: lapping bolt lugs (Read 782 times)

anthonyg · « **on:** January 02, 2006, 05:51:45 PM »

Can someone tell me please... when a gunsmith installs a new barrel on a rem 700 action should he lap the bolt lugs to the action. Can the lugs be lapped with the barrel installed
the rifle shot good with the original barrel (308 win varmit contour) the new premiun barrel in 260rem silhouette contor 8 twist is not a shooter. the barrel was carefully broken in and all weight match bullets used 400 rounds have been bench tested and a scope change was also tryed. the crown is perfect, 3/4 inch groups are the best i could get and they are not consistent.
the action is glass bedded and the barrel is free
only a small percentage of lug shows contact... can that be the problem thankyou and happy new year anthony g
rambuster40

cntryboy1289 · « **Reply #1 on:** January 02, 2006, 06:35:57 PM »

To do the job right and be able to clean out the grit, the job should be done with the barrel off. I maintain pressure on the front of the bolt to help with the lapping process. It would also be nigh on impossible to replace the compound in where it needs to be with the barrel on.

If you paid for the gun to be rebarreled, you should have asked for the lugs to be lapped, but it isn't mandatory that the smith do this for you. You get what you pay and most of the time, the smith will ask about it. A rebarrel job just doens't mean blueprint an action, unless you ask for it.

Now, did you buy a match barrel? If you didn't 3/4" groups may be the best you are going to get. I would double check the chamber and see if it is done correctly. Lugs might make a small difference, but you should be able to get better groups than what you are getting if the barrel is of good quality and the chamber is doen correctly.

gunnut69 · « **Reply #2 on:** January 02, 2006, 06:48:31 PM »

If you didn't buy a match barrel, 3/4 inch is pretty good. If you did it should do better. Have you been loading your ammo to match standards? What's the runnout on thenewly loaded rounds? Also and NO OFFENSE MEANT, have you shot groups smaller than 3/4 inch before? If rebarreling a hunting rifle it's fairly common for the barrel to just be screwed on and headspace adjusted. If you want match accuracy the action should be trued and the lugs lapped. But if anything is left out??

anthonyg · « **Reply #3 on:** January 03, 2006, 03:10:28 AM »

the barrel that was installed is a match grade air gauged barrel. I have had good luck with this brand barrel before I use bushing type dies and competition seater I use a rcbs case master to check for run out .I get about .002 inch of run out.I have been reloading and shooting for 42 years. Some of my rifles will shoot in the .250 range.The barrel was just screwed on and head spaced however the rifle shot very good (less than 1/2 groups) before the new match barrel was installed thankyou
anthony g
rambuster40

gunnut69 · « **Reply #4 on:** January 03, 2006, 08:17:18 AM »

Sounds as if there IS a problem in paradise.. You seem to have covered all the bases and the barrel should do better than you've indicated. What does the snith say about the situation, the barrel maker? The 3/4 inch groups are pretty good but a match grade barrel should do better.. The inconsistant statement bothers me the most. Usually inconsistancy indicates stresses somewhere and a action ring not square to the locking lugs/boltface can give those stresses. As a note, when lapping lugs you are 'hard fitting' them to their seats. That means the pressure aainst the bolt ashould be applied in a straight line and should not be spring loaded. A solid pressure on the bolt face will lap the high spots the most and the low spots the least. A spring will tend to make the lugss follow the contours and lap low and high evenly. We want the high spots lapped the most so--use a solid slug to load the bolt. I would consider having the smith pull the barrel and lap the lugs and square up the action. If I were installing a match grade barrel I would certainly ask if the customer wanted a match grade install. May be the guy'll give you a break..

oinkmaster · « **Reply #5 on:** January 08, 2006, 12:41:57 PM »

Anthony; did you try accuracy testing at a longer distance. Sometimes our rifles don't shoot small groups at 100 yds. VLD's sometimes take a little while to settle down.