Carbon or firecracking?

[AckleymanII]

That is fire cracking in the picture, take that to the bank. Check your muzzle dia with REamer pilots/Grizzley rod, find the spot in the barrel what it is that exact same measurement, start the new throat there. You do not want to go by the way the barrel looks, you want to go by the measured dia...graduated set of reamer pilot bushings used on a grizzley rod.

If you were to just cut off 2" and re chamber, it would make you sick to look at the flutes on your cherished reamer, you would see nicks under 20X magnification.

Chances are, the barrel would have to be cut off 7-9" to have same dia at the new throat and muzzle.

 

[LVLAaron]

That is fire cracking in the picture, take that to the bank. Check your muzzle dia with REamer pilots/Grizzley rod, find the spot in the barrel what it is that exact same measurement, start the new throat there. You do not want to go by the way the barrel looks, you want to go by the measured dia...graduated set of reamer pilot bushings used on a grizzley rod.

If you were to just cut off 2" and re chamber, it would make you sick to look at the flutes on your cherished reamer, you would see nicks under 20X magnification.

Chances are, the barrel would have to be cut off 7-9" to have same dia at the new throat and muzzle.

I just set back a junk barrel for the fun of it. I should post a small video of the throat area in the new chamber. One side didn't even cut and the start of the lead looks totally uneven, but the muzzle end of the leads are straight and aligned. Definitely should have cut another inch if it was a barrel I was going to use.

 

[AckleymanII]

Often, pics are worth a thousand words, 6 BRA, H4895, 105's, 1400 rounds

Muzzle dia



Throat Dia vs muzzle dia


Note the Dia 5" from Breach end


Note the dia where the barrel looked new, .2370 and the muzzle is .2360.


The big picture of bore wear

 

[tobnpr]

Edit

 

[Dusty Stevens]

I just set back a junk barrel for the fun of it. I should post a small video of the throat area in the new chamber. One side didn't even cut and the start of the lead looks totally uneven, but the muzzle end of the leads are straight and aligned. Definitely should have cut another inch if it was a barrel I was going to use.

One day when youre shooting, pull the bolt and look down the barrel. Youll see all kinds of junk on the bottom of the barrel. This is the carbon flakes that you iron in every shot. Since carbon is one step shy of a diamond in hardness the bullets wear the bottom of the barrel more- this is what you witnessed. Next time mark the top and bottom of the barrel with the old chamber and see if im right. Also take a good magnified look at your reamer leade area now.

 

[LVLAaron]

One day when youre shooting, pull the bolt and look down the barrel. Youll see all kinds of junk on the bottom of the barrel. This is the carbon flakes that you iron in every shot. Since carbon is one step shy of a diamond in hardness the bullets wear the bottom of the barrel more- this is what you witnessed. Next time mark the top and bottom of the barrel with the old chamber and see if im right. Also take a good magnified look at your reamer leade area now.

I just looked at it again. The old barrel stamp is still there so I know how it was oriented. Definitely egged out in the old bottom of the barrel.

 

[Dusty Stevens]

I just looked at it again. The old barrel stamp is still there so I know how it was oriented. Definitely egged out in the old bottom of the barrel.

Funny how gravity works even on something like that!

 

[jelenko]

Ah. That's why there's more hard carbon at the bottom of the throat. I've been wondering.

 

[Dusty Stevens]

Ah. That's why there's more hard carbon at the bottom of the throat. I've been wondering.

Pull the bolt during a group and look down the barrel. Itll look like a fog settling in the mountains

 

[Janson]

I've done a bunch, never an issue. Carbon might be hard but it flakes off instantly and is typically way less than paper thin. HSS eats it out like it wasn't there at all.

What is hss

I've done a bunch, never an issue. Carbon might be hard but it flakes off instantly and is typically way less than paper thin. HSS eats it out like it wasn't there at all.

what is HSS

 

[GenePoole]

High Speed Steel. Tool steel like what drill bits are made of.

 

[Dimner]

If anyone has a hardness tester I would be really interested in seeing what the throat area on a well used barrel measures at compared to the exterior muzzle end. Steel certainly work hardens...

Try and cut some train rail if you can get a piece. It's hard as glass.

We have an 24 inch section of train rail. We use it for an anvil with the scouts when showing backyard blacksmithing. Your point is spot on. We use the bottom part of the rail, because the top (where the train wheels ride) is insane hard and doesn't work as well when banging a hammer against heated metal. The project usually is a fire striker for flint(or chert in MI) or the more ambitious kids try and make a knife out of a railroad spike.

 

[DaveTooley]

416R steel will only get to about HRc 40. Much different than for the 4140 class of barrel steels. Railroad track is made of 1084 a medium grade carbon steel.