Muzzle constriction -- help!

303smle · March 11, 2003, 19:54

Any one else have this problem?

I just silver-soldered a FH sleeved by Sledgehammer on to my Autralian L1A1 barrel. Hand pressure only needed to make it index correctly. Pushed an oiled patch through the bore afterwards and there was a definite resistance at the last 1/8 to 1/4 inch of the bore that was not there before I soldered it.

I slugged the bore from the chamber to about mid-point of the barrel and also through the muzzle. Mid-point mic'ed to an average of .2997 across the lands and .3076 across the grooves. The slug through the muzzle mic'd at .2993 and .3073.

What happened? How could soldering the FH have constricted the bore like this?

I'm heading to the range Friday and I'll see how it groups. If it looks good, I'll leave it as is. If it doesn't, what are my options? Remove the FH and see if the muzzle is still restricted? Counterbore the muzzle? Or what?

gunsmith_tony · March 11, 2003, 20:46

Flux?

olephart · March 11, 2003, 20:59

Like Tony sez - flux or maybe scale. Soak it in hot water then go at it with oil on a wire brush. Report back in the morning.

**W.E.G.** · March 11, 2003, 21:15

This question comes up fairly often.

No satisfactory analysis has ever been proven here.

However, my "theory" is that the heat cooks the fouling out of the metal. The fouling oxidizes from the heat, and a spludge-spot appears in the bore.

Not to worry. Clean it with a few strokes of bronze bore brush. Oil it. Shoot it. The spludge-spot usually goes away.

Pa. Patriot · March 11, 2003, 23:20

Did you perhaps use a hand crowning or facing tool on that barrel???

If used improperly (not cleaned of chips every couple turns) it will scratch the inside of your bore in a circular horizontal to bore axis direction. This will provide a similar resistence, although no "constriction, to your patch.

Polish with JB and/or shoot a bunch

303smle · March 12, 2003, 20:36

Thanks, all, for the suggestions. I had considered flux or even a spot of solder getting in the bore, but the slug I drove through the barrel did not have any obvious gouges or other uneveness to indicate that. I had not attempted to crown or otherwise futz with the muzzle.

However, I never considered a spludge-spot! Soaked it in Kroil for a bit and then ran a brush through a couple of dozen times. Still somewhat constricted, but it doesn't seem as tight as before. Hopefully the spludge-spot theory is the cause. Guess I'll just have to fire a bunch of rounds through it and see what happens. Again, thanks for the help.

gunhead · March 13, 2003, 11:20

I would'nt think that you could feel a few "Tenths" difference by just cleaning the bore?
.3076 to .3073 at the bore is mighty close to being the same.

Am I missing something here or would .0003 really make a difference

Rich

March 11, 2003, 19:54	#1
303smle Registered FALaholic #: 2247 Join Date: Jan 2001 Location: Northern Virginia, USA Posts: 22	Muzzle constriction -- help! Any one else have this problem? I just silver-soldered a FH sleeved by Sledgehammer on to my Autralian L1A1 barrel. Hand pressure only needed to make it index correctly. Pushed an oiled patch through the bore afterwards and there was a definite resistance at the last 1/8 to 1/4 inch of the bore that was not there before I soldered it. I slugged the bore from the chamber to about mid-point of the barrel and also through the muzzle. Mid-point mic'ed to an average of .2997 across the lands and .3076 across the grooves. The slug through the muzzle mic'd at .2993 and .3073. What happened? How could soldering the FH have constricted the bore like this? I'm heading to the range Friday and I'll see how it groups. If it looks good, I'll leave it as is. If it doesn't, what are my options? Remove the FH and see if the muzzle is still restricted? Counterbore the muzzle? Or what?

March 11, 2003, 21:15	#4
W.E.G. Administrator Silver Contributor FALaholic #: 1211 Join Date: Oct 2000 Location: Virginia Posts: 31,056	This question comes up fairly often. No satisfactory analysis has ever been proven here. However, my "theory" is that the heat cooks the fouling out of the metal. The fouling oxidizes from the heat, and a spludge-spot appears in the bore. Not to worry. Clean it with a few strokes of bronze bore brush. Oil it. Shoot it. The spludge-spot usually goes away. __________________ . . . Ask me about the Mason-Dixon FAL Collectors Association.

March 11, 2003, 23:20	#5
Pa. Patriot Registered FALaholic #: 6224 Join Date: Apr 2002 Location: NEPA Posts: 1,018	Did you perhaps use a hand crowning or facing tool on that barrel??? If used improperly (not cleaned of chips every couple turns) it will scratch the inside of your bore in a circular horizontal to bore axis direction. This will provide a similar resistence, although no "constriction, to your patch. Polish with JB and/or shoot a bunch __________________ Regards, Pa.Patriot Homepage and link to pricing deleted to comply with new 'rules'

March 12, 2003, 20:36	#6
303smle Registered FALaholic #: 2247 Join Date: Jan 2001 Location: Northern Virginia, USA Posts: 22	Thanks, all, for the suggestions. I had considered flux or even a spot of solder getting in the bore, but the slug I drove through the barrel did not have any obvious gouges or other uneveness to indicate that. I had not attempted to crown or otherwise futz with the muzzle. However, I never considered a spludge-spot! Soaked it in Kroil for a bit and then ran a brush through a couple of dozen times. Still somewhat constricted, but it doesn't seem as tight as before. Hopefully the spludge-spot theory is the cause. Guess I'll just have to fire a bunch of rounds through it and see what happens. Again, thanks for the help. __________________ Never try to teach a pig to sing. It wastes you time and annoys the pig.

March 13, 2003, 11:20	#7
gunhead Registered FALaholic #: 2820 Join Date: Mar 2001 Location: Port Charlotte, Florida Posts: 2,395	I would'nt think that you could feel a few "Tenths" difference by just cleaning the bore? .3076 to .3073 at the bore is mighty close to being the same. Am I missing something here or would .0003 really make a difference Rich __________________ Gun-Head "Who ever said that Common Sense was so Common?"

March 11, 2003, 20:46	#2
gunsmith_tony Registered FALaholic #: 6564 Join Date: May 2002 Location: Atlanta, GA Posts: 2,521	Flux?

March 11, 2003, 20:59	#3
olephart Registered FALaholic #: 8163 Join Date: Nov 2002 Posts: 294	Like Tony sez - flux or maybe scale. Soak it in hot water then go at it with oil on a wire brush. Report back in the morning.

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