LOCKING LUG ENGAGEMENT

[joeb33050]

Mauser-principle bolt guns are essentially interrupted-thread designs with locking lugs engaging action ramps.
Some people lap rifle locking lugs to the action ramps.
As I understand it, the Savage bolt head has some play about the long bolt axis and is designed to self-align the locking lugs on the action ramps.
Using magic marker on the rear of the locking lugs and pulling back while operating the bolt, the Striker locking lugs engage a lot-much magic marker wipes off. The M10 locking lugs engage little, on but a small percent of the lug area.
Is this normal on the M10?
Does anyone lap locking lugs on Savages?
Thanks;
joe b.

[82boy]

Mauser principles are still regarded as gospile in many gun circles, but most part they are outdated. The Savage design is much diferent that a Mauser,Remington, Endifeld or anything else, so what may or may-not work on them, doesn't necassarly work on the Savage design. With the Savage floating bolt head design the need to lap the lugs in is not needed. In fact if you was to try and lap Savage lugs, you would have problems as the floating bolt head would move making it lap in diferent areas accomplishing nothing.

[1jonzmith]

Me. I do that.

[joeb33050]

Me. I do that.

And do the lugs lap in? Please tell about it.
Thanks;
joe b.

[1jonzmith]

Two ways:

Midway lug lapping system. It is a fake barrel end with a spring loaded plate in the center. Screw it in with the bolt in battery, tighten a smidge, smear some grinding compound on the lugs and cycle the bolt in and out of battery till you feel all the grinding compound is gone. Wipe ff the bolt head and it should show a grey dull patch that is the contact patch. repeat till you have 60 to 80% contact patch. Clean everything REALLY GOOD. You are done.

Home made. Cut the center of a brass. Insert a stiff coil spring that makes the "assembled" brass about 3/8 inch longer than un modified brass. Insert the brass in the barrel chamber, dope the lugs with compound. Cycle as mentioned. repeat till the grey patch is almost complete. Wsak everything and RE-SET the head space. Wala.....almost free. Coil spring must be pretty stiff. Sorry to go all technical on ya. ;D

I suggest that any time you have any grinding compound around a barrel you should stuff some paper towel in the bore so you can push put and debris. NEVER FORGET...first flush with a solvent finish with soap and water and a rinse thoroughly THEN OIL ALL THE PARTS. No matter what anyone tells you, if it is oily after you work it it will have some dirt in it.

John

[Eric in NC]

When you set off the 35,000-60,000 PSI "bang" in the chamber, the floating bolt head will have more contact than it shows with magic marker.

[joeb33050]

Thank you, that's very interesting.
joe b.

[1jonzmith]

When you set off the 35,000-60,000 PSI "bang" in the chamber, the floating bolt head will have more contact than it shows with magic marker.


I agree with that statement completely. Having said that, the benefit of lapping the lugs remains. More so, you want things to "not" change their relative position at the point of "bang". I won't try to tell you that eliminating a fraction of a thousandth of mismatch between your lugs or improving the contact patch to 80% will cause any benefit you might see. Many other things must be "working" also. But I do know that resolving these issues and improving the precision of your action will NOT open up your groups or generate "flyers". Won't happen. And what is your investment? I do know that the Smiths that build those multi thousand dollar rigs do it ALL to the Nth degree and that includes the lugs. I heard tell of one builder that would not let a rifle go out the door till he cast a "spell".

One part of this post is pure fiction...see if you can pick it out. ??? ::) ;D Be well and happy,

John