How come we never see

[Oh Mr. Wilson]

How come we never see anyone say you should or must lap the lugs of Carbine bolts?

I'm fitting a different (flat) bolt to my Carbine, one of the last things I did just for giggles was to coat the lugs with a magic marker, install it and run ten dummy rounds through the rifle by hand, I did this twice and then checked the bolt. I found the left (small) lug is showing very little contact, in fact hardly any at all. I had checked the round bolt I have been using since I built the rifle and that has good contact on both lugs. So now I'm wondering, is there any benefit to lapping a bolt for the little .30 Carbine cartridge? Is there a reason why bolts are not or shouldn't be lapped on a Carbine?

I was going to ask Larry..... seeing how he knows everything. I bet he has a PDF instruction sheet on how to do it. :) Ha!!

[canes7]

Carbines have no reputation for accuracy, so why try to improve on it.

[Oh Mr. Wilson]

Carbines have no reputation for accuracy, so why try to improve on it.

That was one of the reasons I was thinking about.

I'm not worried about MOA, my concern is more of stress on just the right lug showing full contact and almost none on the left. Will that put undue stress on the bolt and receiver? I realize the .30 Carbine doesn't come anywhere near the pressure of the 30-06 cartridge. So after looking at the bolt contact I'm getting I was wondering, should I lap this bolt? And is there a reason why you shouldn't lap Carbine bolts?

I know a young fellow who lives in my town, he and his Dad collect a lot of Milsurp's. He had a Carbine that sheared the left lug off a bolt and broke the locking lug area off the receiver. Now there is more to that story, it was a rifle he built on a BR he bought from the CMP and the bolt he used was an AM part. It didn't take long for it to fail either, within a month or so after he had it built. I forget now where he got it from but it was from one of the on line companies we have seen guys mentioned before on the "other" forum. :)

Maybe I should put a few rounds through this and re-check the bolt lugs, I may find I'm getting much more contact during live fire that's just not going to show up while hand cycling.

Checking this bolt just got me wondering why I have never heard of lapping Carbine bolts, they look so much like the Garand lugs. So I figured I'd throw it out there for some feedback from those who know more then I. :)

[timshufflin]

Carbines have no reputation for accuracy, so why try to improve on it.


This has nothing to do with why some lapp bolts. I have had horror stories told to me of shops scarring the beguzus out of people if they don't lapp their bolt lugs. The story goes like this;
"Sir, I found you had no contact on your right bolt lug and now you have 50,000 PSI right next to your face, itching to explode and cause death all around you." Okay, so I added the "itching" part but the rest is true. There are places that claim Garands had the bolts lapped when they were sent off the assembly line.

It is one thing to prefer that a bolt be lapped, it is quite another to tell people they must spend the $ to lapp their bolt or they're going to die. This argument is specifically true with some M14/M1A builders. I've even called one in particular up and had him savage me on the phone because I did not lapp a bolt on an M1A. He then told me the rifle would be unsafe to fire and he'd never fire it without lapping the bolt. I said "goodbye" and "have a great day". The bolt swapping that went on, particularly with the M14, was rampant. I do not understand why some folks feel the need to scare the hell out of people with this stuff.

Anyhow, back to your carbine bolt. Mr. Wilson, it is my opinion that you don't need to worry about this. If it makes you feel better though you could lap the bolt a smidge just to get "some" contact with the other side. When the gun goes "boom" I'm sure that contact will however be made.

[Orlando]

Not that I know squat but these are my thoughts
I dont see it as a real safety issue. I see it as a accuracy tweak, lapping makes equal friction for the bolt lugs/ receiver, and in theory makes a smoother function of parts that could increase accuracy. How much? probably not enough to notice unless building a full blown match rifle .
I had Tim lapp a NOS bolt on a Garand that I had a NOS barrel installed on , would I do it again? On a standard Garand probably not
Heck if the lugs arent making equal contact eventually they will wear even anyway , right?

[Oh Mr. Wilson]

I put a few rounds through the rifle today and as you said Tim, I'm getting full contact on both lugs.

I remember the deal with the guy telling folks their Garand's wasn't safe to fire unless the lugs were lapped.

Thanks for the feedback everyone!