forcing cone question

nedfig · January 15, 2001, 02:59 PM

I got my barrel back this weekend after having the forcing cone lengthened. It is definately longer, but there is an abrupt hump where the new transition is. Instead of having an angled transition, it is squared. Sorry for my bad verbal illustration, but I think you get the idea.

**4V50 Gary** · January 15, 2001, 10:29 PM

Let me see if I have this right, your forcing cone begins with a gradual taper, has a sharp 90 degree step, and then tapers again? I have but one word: shoddy workmanship. If the forcing cone can't be reconfigured by cutting more away (and you can only cut so much), the barrel will have to be replaced.

nedfig · January 15, 2001, 10:37 PM

No. Take the barrel off your SG and run a small wood dowel along the inside against the chamber wall. You will be able to push the dowel and just feel a small hump where the forcing cone is. That's how mine WAS. Now if you slide the dowel down the bore's wall, when it hits the new forcing cone, it stops.

PJR · January 16, 2001, 12:29 AM

That doesn't sound right at all. I just checked 12 barrels in this manner and there was a faint hump in one of them and the rest were smooth from chamber to forcing cone to barrel. If the dowel stops there must solid lip at the end of the forcing cone which would do all manner of damage to the shot.

BBBBill · January 16, 2001, 01:09 AM

Hey dude! Long time no talky. Your forcing cone should have NO step. The reamer should cut a smooth transition from chamber to bore. Some guns have thin barrels which limit how much you can ream. Is this your 870 or another gun? How old? After reaming, it should be honed to remove any chatter marks from the reamer.

George Stringer · January 16, 2001, 08:09 AM

Nedfig, I would think the only way this would be possible is if the wrong gage reamer was used. A 20 ga reamer in a 12 gage bbl. If the correct reamer was used then at worst there might be a slight hump like PJR mentioned where the two different angles met. George

nedfig · January 16, 2001, 10:31 AM

Hey BBBill, it's my new Mossy 500. I took the barrel off last night and the dowel does continue forward but there is some resistance. It's not nearly as smooth as the factory cone. I'll take it back to the smith and get him to smooth it out. Shouldn't he have run a bore polisher in there to smooth it out after the cut?

ned

**4V50 Gary** · January 16, 2001, 01:24 PM

Opps. I was thinking revolver.

January 15, 2001, 10:29 PM	#2
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 22,306	Let me see if I have this right, your forcing cone begins with a gradual taper, has a sharp 90 degree step, and then tapers again? I have but one word: shoddy workmanship. If the forcing cone can't be reconfigured by cutting more away (and you can only cut so much), the barrel will have to be replaced. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

January 15, 2001, 02:59 PM	#1
nedfig Senior Member Join Date: March 2, 2000 Location: Houston, Texas Posts: 263	I got my barrel back this weekend after having the forcing cone lengthened. It is definately longer, but there is an abrupt hump where the new transition is. Instead of having an angled transition, it is squared. Sorry for my bad verbal illustration, but I think you get the idea.

January 15, 2001, 10:37 PM	#3
nedfig Senior Member Join Date: March 2, 2000 Location: Houston, Texas Posts: 263	No. Take the barrel off your SG and run a small wood dowel along the inside against the chamber wall. You will be able to push the dowel and just feel a small hump where the forcing cone is. That's how mine WAS. Now if you slide the dowel down the bore's wall, when it hits the new forcing cone, it stops.

January 16, 2001, 12:29 AM	#4
PJR Senior Member Join Date: June 1, 2000 Posts: 1,127	That doesn't sound right at all. I just checked 12 barrels in this manner and there was a faint hump in one of them and the rest were smooth from chamber to forcing cone to barrel. If the dowel stops there must solid lip at the end of the forcing cone which would do all manner of damage to the shot.

January 16, 2001, 01:09 AM	#5
BBBBill Senior Member Join Date: January 5, 2000 Location: Alabama Posts: 197	Hey dude! Long time no talky. Your forcing cone should have NO step. The reamer should cut a smooth transition from chamber to bore. Some guns have thin barrels which limit how much you can ream. Is this your 870 or another gun? How old? After reaming, it should be honed to remove any chatter marks from the reamer.

January 16, 2001, 08:09 AM	#6
George Stringer Staff Alumnus Join Date: October 12, 1998 Location: Earlington KY Posts: 2,299	Nedfig, I would think the only way this would be possible is if the wrong gage reamer was used. A 20 ga reamer in a 12 gage bbl. If the correct reamer was used then at worst there might be a slight hump like PJR mentioned where the two different angles met. George

January 16, 2001, 10:31 AM	#7
nedfig Senior Member Join Date: March 2, 2000 Location: Houston, Texas Posts: 263	Hey BBBill, it's my new Mossy 500. I took the barrel off last night and the dowel does continue forward but there is some resistance. It's not nearly as smooth as the factory cone. I'll take it back to the smith and get him to smooth it out. Shouldn't he have run a bore polisher in there to smooth it out after the cut? ned

January 16, 2001, 01:24 PM	#8
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 22,306	Opps. I was thinking revolver.