hutch1510
16th January 2006, 19:13
hello 1911 tuner, i have only recently gotten into the 1911 handgun as it seems to be the one gun i can seem to hit everything i point it at,,, i have since for the past week or 2 been reading all you post on these guns, especially the stickys on the gunsmithing section.... THANKS for all these excellet posts!!!! anyway i had a few questions as i am confused a littlw with the nork report,,,, HERE IS YOUR QUOTES
((((Out of 88 Norincos...all 5-inch guns save two... 7 had unacceptable barrel fit. The problems were usually due to insufficient vertical lug engagement and only a few of the good ones had more than one lug bearing horizontally. None showed horizontal engagement on the strongest lug...the first one. Of the bad ones, only two didn't show serious lug deformation, and likely only because the guns hadn't been used very much. The ones showing deformed lugs also had excessive static headspace, varying from .925 inch to .947 inch on the extreme end. This was directly attributable to the lug setback. Oddly, horizontal lug engagement was on the #2 lug in all except three examples. Those were on #3.
On average, the #2 lug location in the slide was cut a little too far rearward...most within spec, but right on the peg...and contributed heavily to the #2 barrel lug bearing all the load. Most barrels showed a large gap between the face of the #1 lug and its mating lug abutment
in the slide...a few as much as .015 inch...but most were in the neighborhood of .005-.008 inch gauged.
Barrel lug locations varied a lot, with the #2 lug averaging the worst out of spec condition.
The #2 lug locations...slide and barrel...were the main cause of the #2 lug taking the brunt.
All had more headspace than falls within my comfort zone, averaging .915 inch...or just .005 inch shy of ordnance reject. In fairness, even though headspace was rather loose, the range of variation was closely held to the average. The excess seemed to be pretty evenly divided
between lug specs and chamber depth. The former tends to be dangerous, while the latter is more of a nuisance which leads mainly to erratic ingition and/or degraded accuracy.
All barrels showed excessive end-play, averaging .012 inch, also closely held to average...
which causes the barrel and slide lug abutments to slap-seat on firing...which accelerates
lug deformation due to the lugs having a running start at one another before engaging.
Slap-seating tends to occur earlier with insufficient vertical and/or unequal horizontal engagement. The deeper they engage, the longer it's delayed. Likewise, one lug in the horizontal plane accelerates it. More than one delays it. Most of the pistols examined didn;'t show signs of slap-seated lugs despite hard use reported by many owners. Some, however,
gave early indications of the problem with much less use, even with good vertical depth.
This tends to make me believe that the steel under the chrome plating was softer than it should have been, because other similar examples showed no warning signs.))))
MY QUESTION: you mention all had serious end play, as well as most only locking on one lug, etc etc..... basically what i am curious about is,,, do these condition you mention above ONLY refer to the 7 pistols with unacceptable barrel fit? or are they to all the 88 norinco's? i have a norinco i won on GB and will recieve it when i get home... am currently TDY with air force,,, anyway, really appreciate the informative post, and would like to know if all the referances above apply to all the guns or just the seven....reference to barrl lugs, and headspace,,, thanks a million....
((((Out of 88 Norincos...all 5-inch guns save two... 7 had unacceptable barrel fit. The problems were usually due to insufficient vertical lug engagement and only a few of the good ones had more than one lug bearing horizontally. None showed horizontal engagement on the strongest lug...the first one. Of the bad ones, only two didn't show serious lug deformation, and likely only because the guns hadn't been used very much. The ones showing deformed lugs also had excessive static headspace, varying from .925 inch to .947 inch on the extreme end. This was directly attributable to the lug setback. Oddly, horizontal lug engagement was on the #2 lug in all except three examples. Those were on #3.
On average, the #2 lug location in the slide was cut a little too far rearward...most within spec, but right on the peg...and contributed heavily to the #2 barrel lug bearing all the load. Most barrels showed a large gap between the face of the #1 lug and its mating lug abutment
in the slide...a few as much as .015 inch...but most were in the neighborhood of .005-.008 inch gauged.
Barrel lug locations varied a lot, with the #2 lug averaging the worst out of spec condition.
The #2 lug locations...slide and barrel...were the main cause of the #2 lug taking the brunt.
All had more headspace than falls within my comfort zone, averaging .915 inch...or just .005 inch shy of ordnance reject. In fairness, even though headspace was rather loose, the range of variation was closely held to the average. The excess seemed to be pretty evenly divided
between lug specs and chamber depth. The former tends to be dangerous, while the latter is more of a nuisance which leads mainly to erratic ingition and/or degraded accuracy.
All barrels showed excessive end-play, averaging .012 inch, also closely held to average...
which causes the barrel and slide lug abutments to slap-seat on firing...which accelerates
lug deformation due to the lugs having a running start at one another before engaging.
Slap-seating tends to occur earlier with insufficient vertical and/or unequal horizontal engagement. The deeper they engage, the longer it's delayed. Likewise, one lug in the horizontal plane accelerates it. More than one delays it. Most of the pistols examined didn;'t show signs of slap-seated lugs despite hard use reported by many owners. Some, however,
gave early indications of the problem with much less use, even with good vertical depth.
This tends to make me believe that the steel under the chrome plating was softer than it should have been, because other similar examples showed no warning signs.))))
MY QUESTION: you mention all had serious end play, as well as most only locking on one lug, etc etc..... basically what i am curious about is,,, do these condition you mention above ONLY refer to the 7 pistols with unacceptable barrel fit? or are they to all the 88 norinco's? i have a norinco i won on GB and will recieve it when i get home... am currently TDY with air force,,, anyway, really appreciate the informative post, and would like to know if all the referances above apply to all the guns or just the seven....reference to barrl lugs, and headspace,,, thanks a million....