Rear sight base fit to barrel

Potshot · June 06, 2012, 00:25

Guys,

How important is it to have a press fit on the rear sight base to barrel?

I am building a Polish underfolder using a Romanian barrel. Fit in the rear trunnion is good, but the rear sight base ID to barrel rear sight base land OD feels like it has ~0.002" clearance.

Will the cross pin be sufficient to retain this or do I need to peen the rear sight base, get a new one, etc.?

yemff · June 07, 2012, 15:50

This is weird, I have exactly what you do and my barrel and sight have plenty of overlap for a good press fit. Did you get the barrel and kit from apex?

4duece · June 08, 2012, 00:19

Are the barrell parts you are useing,from a stamped kit or a milled kit there is a differance in dimensions.

**gunplumber** · June 08, 2012, 07:29

rear sight base should be .001-.002 smaller than the barrel. You can knurl the barrel journal to squeeze (literally) a little more diameter out of it. I'd do a ghetto spot weld at 6 o'clock before relying on just the pin.

Potshot · June 09, 2012, 12:53

Yeah, damn. 0.001-0.002 interference is about what I thought it should be.

Polish sight base on Romy virgin barrel. Mark, do you have any rear sight bases for sale?

Had a Bulgy 74 kit I had to demill this week.... damn thing must have had 0.010" interference on it! Bored the barrel to ~0.080" wall left and still had to use a hydraulic press to get it out.

**gunplumber** · June 09, 2012, 13:48

I have one Romy takeoff that does not slide over the barrel journal of the virgin romy barrel I just tested it on, so it should be tight.

$38.50 shipped

Potshot · June 13, 2012, 14:33

Mark, sorry for a slow reply.

I'll take it, thanks!

I assume a USPS money order would be easiest?

**gunplumber** · June 13, 2012, 14:35

yes, as would be a personal check made out to me.

Potshot · August 02, 2012, 23:59

Shit! Sorry Mark, been stupid busy at work and lost track of this. Do you still have the rear sight base? I also have an oversized Polish rear 47 sight base if you want it.

**gunplumber** · August 03, 2012, 09:01

I have one - I think it is Romy.
\
Also have all the parts for a Bulgy 5.45 but only sold as a set. $150 - includes the barrel, but it wouldn't shoot straight so I replaced the whole thing. Maybe cut to a pistol?

June 06, 2012, 00:25	#1
Potshot Registered FALaholic #: 6398 Join Date: May 2002 Location: xxx Posts: 1,104	Rear sight base fit to barrel Guys, How important is it to have a press fit on the rear sight base to barrel? I am building a Polish underfolder using a Romanian barrel. Fit in the rear trunnion is good, but the rear sight base ID to barrel rear sight base land OD feels like it has ~0.002" clearance. Will the cross pin be sufficient to retain this or do I need to peen the rear sight base, get a new one, etc.? __________________ "The most foolish mistake we could possibly make would be to permit the conquered Eastern peoples to have arms. History teaches that all conquerors who have allowed their subject races to carry arms have prepared their own downfall by doing so." --- Adolf Hitler "If it was up to me, no one but law enforcement officers would own hand guns..." Chicago Mayor Richard Daley "Armas para que?" ("Guns, for what?") -- Fidel Castro

June 08, 2012, 07:29	#4
gunplumber Arrogant Bastard Gold Contributor FALaholic #: 96 Join Date: Jul 2000 Location: Surprise, AZ Posts: 15,765	rear sight base should be .001-.002 smaller than the barrel. You can knurl the barrel journal to squeeze (literally) a little more diameter out of it. I'd do a ghetto spot weld at 6 o'clock before relying on just the pin. __________________ T. Mark Graham Master Gunsmith Arizona Response Systems, LLC

June 09, 2012, 12:53	#5
Potshot Registered FALaholic #: 6398 Join Date: May 2002 Location: xxx Posts: 1,104	Yeah, damn. 0.001-0.002 interference is about what I thought it should be. Polish sight base on Romy virgin barrel. Mark, do you have any rear sight bases for sale? Had a Bulgy 74 kit I had to demill this week.... damn thing must have had 0.010" interference on it! Bored the barrel to ~0.080" wall left and still had to use a hydraulic press to get it out. __________________ "The most foolish mistake we could possibly make would be to permit the conquered Eastern peoples to have arms. History teaches that all conquerors who have allowed their subject races to carry arms have prepared their own downfall by doing so." --- Adolf Hitler "If it was up to me, no one but law enforcement officers would own hand guns..." Chicago Mayor Richard Daley "Armas para que?" ("Guns, for what?") -- Fidel Castro

June 09, 2012, 13:48	#6
gunplumber Arrogant Bastard Gold Contributor FALaholic #: 96 Join Date: Jul 2000 Location: Surprise, AZ Posts: 15,765	I have one Romy takeoff that does not slide over the barrel journal of the virgin romy barrel I just tested it on, so it should be tight. $38.50 shipped __________________ T. Mark Graham Master Gunsmith Arizona Response Systems, LLC

June 13, 2012, 14:33	#7
Potshot Registered FALaholic #: 6398 Join Date: May 2002 Location: xxx Posts: 1,104	Mark, sorry for a slow reply. I'll take it, thanks! I assume a USPS money order would be easiest? __________________ "The most foolish mistake we could possibly make would be to permit the conquered Eastern peoples to have arms. History teaches that all conquerors who have allowed their subject races to carry arms have prepared their own downfall by doing so." --- Adolf Hitler "If it was up to me, no one but law enforcement officers would own hand guns..." Chicago Mayor Richard Daley "Armas para que?" ("Guns, for what?") -- Fidel Castro

June 07, 2012, 15:50	#2
yemff Registered FALaholic #: 66459 Join Date: Jun 2012 Location: New, New Mexico Posts: 25	This is weird, I have exactly what you do and my barrel and sight have plenty of overlap for a good press fit. Did you get the barrel and kit from apex?

June 08, 2012, 00:19	#3
4duece Registered FALaholic #: 19759 Join Date: Apr 2006 Location: Eastern Pa. Posts: 488	Are the barrell parts you are useing,from a stamped kit or a milled kit there is a differance in dimensions.

June 13, 2012, 14:35	#8
gunplumber Arrogant Bastard Gold Contributor FALaholic #: 96 Join Date: Jul 2000 Location: Surprise, AZ Posts: 15,765	yes, as would be a personal check made out to me. __________________ T. Mark Graham Master Gunsmith Arizona Response Systems, LLC

August 02, 2012, 23:59	#9
Potshot Registered FALaholic #: 6398 Join Date: May 2002 Location: xxx Posts: 1,104	Shit! Sorry Mark, been stupid busy at work and lost track of this. Do you still have the rear sight base? I also have an oversized Polish rear 47 sight base if you want it. __________________ "The most foolish mistake we could possibly make would be to permit the conquered Eastern peoples to have arms. History teaches that all conquerors who have allowed their subject races to carry arms have prepared their own downfall by doing so." --- Adolf Hitler "If it was up to me, no one but law enforcement officers would own hand guns..." Chicago Mayor Richard Daley "Armas para que?" ("Guns, for what?") -- Fidel Castro

August 03, 2012, 09:01	#10
gunplumber Arrogant Bastard Gold Contributor FALaholic #: 96 Join Date: Jul 2000 Location: Surprise, AZ Posts: 15,765	I have one - I think it is Romy. \ Also have all the parts for a Bulgy 5.45 but only sold as a set. $150 - includes the barrel, but it wouldn't shoot straight so I replaced the whole thing. Maybe cut to a pistol? __________________ T. Mark Graham Master Gunsmith Arizona Response Systems, LLC

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