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  #31  
Old 03-17-2010, 11:33 AM
fafenman fafenman is offline
 
Join Date: Oct 2009
Location: SW Ohio
Posts: 434
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I have a couple of questions about the slides as they are decribed by Newscotlander and BQ97. I follow what you are saying about the extractors and ejectors. But could you guys explain a little more about the dwell modification on the slide and by increasing the weight of the inertial block are you refering to the area of the slide that is struck by the gas piston? Also what do you mean by a L379 slide? I know about the 7160091 number. Thanks
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  #32  
Old 03-17-2010, 11:44 AM
DaveHH DaveHH is offline
 
Join Date: Nov 2009
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Default Thanks Brian, I appreciate the information

So the dwell was the important part of the puzzle? I know that the original Winchester I have has a type 4 slide and except for that one range session, it performed flawlessly. The new NPM I have now as a shooter has the type V slide, a Packard made piece, and it works very well after changing the recoil spring. No FTF or ejection problems whatsoever. It has a disturbing little glitch where the slide makes a distinct feel as the slide jumps the disassembly notch, like it is hitting the receiver after crossing the notch, but that is with manual usage and it doesn't appear to have a beat up slide or receiver in that area.
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  #33  
Old 03-17-2010, 11:52 AM
Newscotlander Newscotlander is offline
 
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Location: New York
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War Baby! explains the changes made to the slide, in order to increase the dwell, on page 301. There is a pretty good picture showing the changes in Carbine Club newsletter 353, page 10. Basically, the increased dwell means that the bullet would travel farther down the barrel before the bolt begins to open. This will reduce the pressure in the chamber and allow the empty brass case to be extracted easier.

The L379 slide is the configuation that the Carbine Club uses to identify slides. If you look at the slide section of the data sheet: http://www.carbineclub.com/DataSheet_7_01_08a.pdf you will see numbers in the check boxes. Notice the "L" or "E" to identify the cam shape. There are also numbers for the arm joint, slide box rear, and internal cut. Depending on the configuration of a specific slide determines the corresponding number to be used.
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  #34  
Old 03-17-2010, 12:16 PM
fafenman fafenman is offline
 
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Location: SW Ohio
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Thanks, I actually have that data sheet saved for reference, just never put the number thing together.
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  #35  
Old 03-17-2010, 04:00 PM
BQ97 BQ97 is offline
 
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The weight change of the inertial block is shown in NL 353 comparing the more sloping outer sides of the earlier slides to the flatter sides of the later slides. Less material removed from the profile resulted in a slightly heavier slide which resisted movement longer. The slide side profiles shown in War Baby on pages 300 & 301 are of the earlier inertial block design. If you compare these to a later slide you can see how the later slide has a longer vertical straight portion on the L/R sides. Obviously it didn't fully solve the problem so the next step was to increase the dwell. It is fortunate for the engineers that the increased dwell mod worked even without the additional weight because when the M2 slide was developed all the added weight of the redesign was removed to allow the slide to trip the disconnector lever.
Once you know what to look for the dwell increase mod is very easy to spot even without a comparison. Just remember that not all angle cam surface slides have the increased dwell changes.

Keep in mind that millions of carbines with earlier design slides function reliably and a later slide won't cure all problems especially on a 60+ year old carbine.

Sometimes the root cause of a problem isn't the most obvious. What the developers initially thought was an ejection problem turned out to be an extraction problem, not caused by the extractor, but caused by the slide timing.
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  #36  
Old 03-17-2010, 05:53 PM
DaveHH DaveHH is offline
 
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Default Occam's Razor at work

Considering all the development they did on these guns and the multitude of people involved, it says a great deal about both the genius of the engineers and the quality of the product. I've often wondered about how some of these changes were implemented considering the problems that each change made for the builders. For instance, when a specific company starts having bolts break in the 6,000 round tests, were the previously shipped carbines recalled or was it just accepted and the improvements added as they became available? Some of the changes were minor in scope but major in effect.
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  #37  
Old 03-18-2010, 02:00 AM
kmad2001 kmad2001 is offline
 
Join Date: Oct 2009
Location: Nashville, TN
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Hello folks. I have quietly been following this. Much over my head but learning. I had not realized my extractor was chipped nor not seated in that pic. I have pics of the bolt from last year showing it well seated. Below are a couple pics of my Op-Slide. A fellow a while back thought it was broken and welded back together. I can get different views of it up in a day or so if this may further identify what may be going on with this system.


Last edited by kmad2001; 03-18-2010 at 02:11 AM.
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  #38  
Old 03-18-2010, 11:01 AM
fafenman fafenman is offline
 
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Location: SW Ohio
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The slide is a type II and they were replaced due to fatigue at the arm joint. It appears the there is a wear mark on the back side of that area. I don't think that part has been welded.
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