Increased dwell time

All 5 of my carbines are like this..too early for the later increased dwell time..
I imagine overhauls would have received the updated change
https://www.milsurps.com/images/impo...95571387-1.jpg

Garandrew, I do not understand your question... Are you asking if you can update your shooters to increase the dwell time? Yes, just change to a type V or VI slide. I have also changed to later round bolts in my shooters - mainly to save the wear on the collectable flat bolts.

No, as an original carbine, I want it as it is, but if they were overhauled, they would have received new slides?

I don't think that from a function standpoint it makes much difference. It was just an upgrade like many they did. I suspect anticipation of the full auto feature may have been part of it? My Win has a type 4 slide and functions flawlessly always has.

Keeping the bolt locked after firing for an extra 0.25 msec apparently helped enough to eliminate breech flash and improve extraction for the design to stick as "7160091". I've never seen breech flash from my guns (semiautos w/ mostly early slides) though, even at night.

If you're asking if a depot would have made changes to the slide itself the answer is probably not. Older slides without the increased dwell were used along with ones that did have the increased dwell during rebuild. From a functionality standpoint the increased dwell does make a difference, that's why they increased the dwell in the first place. Not all type V slide have the increased dwell so simply changing to a type V slide won't change the timing unless it is one of the slides with the increased dwell. As pointed out in the article there are earlier type slides that also have the increased dwell.

Thankyou...

The TM9-1276 (1953), page 80-81 states (paraphase) that when inspecting shows that a slide needs replacing, use the Type V (7160091 - preferred) or the Type VI (5337151 - useable) until exhausted. The Type VI (7161843) was authorized, but was supposed to be reserved for M2's until the type VI's and V's were exhausted in the supply system. The tech manual itself neither identifies nor talks about the differences which create the increase dwell time.

The dwell time was creased by changing the deminsion on two cuts on a slide - one increased the size of the cam cutout and the other decreased the width of the area the piston strikes. The easiest way to detect it is measure. On the bottom of the slide, measure the distance between the hole where the bottom of the slide stop comes out and the rear of the cam cut-out. The slide without the cut has a distance of about .100". Slides cut to have the increased dwell time have much smaller distance of about .050". As far as the Type V's which do have the cuts, GENERALLY it was the ones with the 7160091 part number stamped on them - BUT - as Brian said, not all Type V's have the cuts.

(Thanks Brian for keeping me honest....)

I am guessing, the January 2011 Carbine Club newsletter #363 that just came out two weeks ago, prompted this thread. There is a three page article on Changes in Late Operating Slides. Didn't say who wrote it, but whoever, did a great job.

To those scratching their head and not understanding the meaning of Garandrew's picture and statement. This issue of the newsletter has detailed pictures and explanations. The newsletters are such a vast wealth of information. Just another reason to think about joining, and maybe not scrach your hair out. Heck, at our age most can't afford to lose anymore hair.

Newscotlander wrote the article.

Nice job, NS. I enjoy measuring things within an inch of their lives and you gave me fresh fodder. Do you think the change in the profile of the inertia block was to keep the weight the same after reducing the rear wall thickness? Confusingly, J.B. Powers in CCNL #172 shows an M2 slide that weighs considerably less than the increased dwell L379. If this weight is representative of M2's, maybe a change in mass didn't matter to the M1 so much after all?

TR, Figure 58 in the 1953 TM 9-1276 shows the old slide as usable - again with no mention of dwell or internal dimensions.

Quote:

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Originally Posted by BrianQ

Newscotlander wrote the article.

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Thanks Brian.

And thanks to Newscotlander.

Quote:

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Figure 58 in the 1953 TM 9-1276 shows the old slide as usable - again with no mention of dwell or internal dimensions.

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I'm sure that the reason why the earlier slide was usable is that there were not enough of the 7160091 or 7161843 slides to put in all the 6+ million carbines. It does say that the 7160091 slide is preferred.