Gunsmithing New custom. Extractor mark on brass rim???!

[Raufoss]

Hi

I am just starting to make reload for my new custom and i have a little thing that bug me.

When i feed a prep brass(no bullet , no primer) by dropping it in the chamber i can feel a definitive ''stop'' around the first 1/4 of the bolt travel. Then need to apply some force to close the bolt and the brass exhibit marks on the rim leaved by the extractor.
If i put the brass directly on the bolt face(with the extractor in the groove) every thing is fine and the bolt close butter smooth.
If i feed by the magazine it is okay and i don't feel the resistance or barely

Is that normal because it is an unfired new custom rifle? or something is wrong?

thx
kevin

 

[selfbowhunter]

What type of extractor?

 

[buffybuster]

What action?
What type of extractor?

 

[Raufoss]

defiance deviant action

Extractors are M-16 type

 

[colchester]

Some M 16 style extractors require a slightly larger bolt nose counter-bore than a sako or rem style extractor. If your rifles tenon was set up for a rem or sako style extractor this might be why you can place the case in the boltface and run it home but when you drop the case in the chamber the bolt resists closing. The extractor will bind against the bolt nose counter-bore on the tenon as it tries to slip over the case head

 

[STR]

Some M 16 style extractors require a slightly larger bolt nose counter-bore than a sako or rem style extractor. If your rifles tenon was set up for a rem or sako style extractor this might be why you can place the case in the boltface and run it home but when you drop the case in the chamber the bolt resists closing. The extractor will bind against the bolt nose counter-bore on the tenon as it tries to slip over the case head

I also agree that this may be your problem. If it is, the barrel will have to come off in oder to enlarge the bolt nose recess diameter. The smith that built the rifle should have done all of this before final assembly. All of this is of course if this is indeed your problem. Kind of hard to give an accurate diagnosis without having the rifle in front of someone that knows what to look for.

 

[Raufoss]

 

[Raufoss]

I am thinking out loud.

Could it be that i resize to much and that is why the extractor
Leave this mark.
I say this because if i install the brass on the extractor and drive the bolt holding the brass everything goes well.

 

[STR]

That's because the extractor doesn't have to get over the rim of the brass while clearing the edge of the counterbore in the barrel.

 

[buffybuster]

Looks like the counterbore is undersized, not allowing the M16 extractor the clearance to snap over the rim. The correct method to fix this is to enlarge the counterbore. If the interference is minimal, the quick & dirty way is to remove a bit of material off the top of the extractor.

 

[Rthur]

On a rem extractor the counterbore is .705-.708. With the mini m16 it calls for .785. I'll bet it needs to be opened up.

R

 

[Raufoss]

My smith answer:

I think the problem could be because of headspacing, seems like your cases are not going in the chamber deep enough and as the bolt cams forward, its not giving the extractor enough clearance causing the diagonal marks on the rim.

 

[cruizer]

Put the brass in the bolt and feed it in with extractor over the brass. I'd bet money it's counterbore,

 

[Raufoss]

You mean i hook the brass on the extractor and then i drive the say bolt in the action and close it?

 

[MikeeBooshay]

Your smith is not doing you right brother man.

First - He should not have sent you a rifle not function tested.

Second - When asked about a problem, that was not found in Step 1 above, because it wasn't done, his answer should be " bring it by let's have a look, I'll fix it, no charge".

Third - He's feeding you a flavor, closely related to bovine excrement. Don't swallow. Headspace? Really? I thought you set that when you chambered it? It changed? Pray tell, how?

I would also agree with the the assessment by the rest of the crew here - likely an interference from the extractor into the counterbore. Simple fix, removing the barrel is the best way, second best is trimming a bit of the extractor, but would rather not recommend you do that unless you have done a few previously. Otherwise you'll get to learn how to change an extractor, when it breaks a few weeks from now, maybe in the middle of a match, a hunt or some other important function.

 

[Raufoss]

Mayde the test. Goes in without resistance and the bolt close with a light stickiness mostly due to brass not sized enought.

 

[cruizer]

Counter bore is too tight, not enough room for the extractor to lift over the case rim.

Magnum bolt face?

 

[Raufoss]

Yes mag boltface

 

[cruizer]

Make sure your smith pulls the barrel and recurs counter bore and doesn't try to just take material of of the extractor

 

[Raufoss]

Is they'r a way i can measure it myself before sending it?

So it should be around .785

 

[STR]

Not really. Can be done with special tools, however most people don't have them. Just send it back, or pay a small amount to one of the good guys here to do you right, and let it be water under the bridge. The builder already sounds like he's in denial that he failed somewhere.

 

[colchester]

Is they'r a way i can measure it myself before sending it?

So it should be around .785

You could attemp to get in there with a telescoping bore gauge if you had one it would be cumbersome but possible to get a n accurate measurement. I might try to just blacken the bolt nose counterbore with a sharpie or dykem from 12 to 3 o clock. Try closing the bolt on a PC of brass that is in the chamber and see if the extractor scratches off the sharpie if it hits you have your answer You might use a small mirror to help you see it

 

[Raufoss]

Gun is at another smith to have second tought.

 

[Raufoss]

Rifle have been check

Every thing was good espected from a stainless metal chip that was stuck under the extractor. It was not giving him he's full freedom to move.

Also the main issue was the brass. Actually headspace was not good and since they'r new they need to be fireformed.

In all i'm happy and alot less stess out.