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Posted: 8/3/2015 10:03:13 PM EDT
Does anyone know the difference between the large dimpled 601 selectors and the small dimpled 601 selectors? My guess is that the small dimpled selectors are earlier, since I have seen fewer of them.
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Does anyone know the difference between the large dimpled 601 selectors and the small dimpled 601 selectors? My guess is that the small dimpled selectors are earlier, since I have seen fewer of them. http://i302.photobucket.com/albums/nn115/kkrad_photo/244ddb2ce964e79c9c60ef7d8800034d.jpg http://i302.photobucket.com/albums/nn115/kkrad_photo/44701c0df4f9de3abdd3ddf94d1c2a69.jpg 
WANT! |
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My guess is you are trying to sell them. LOL I was just thinking there needs to be a look what I found thread lol but as far as useful info for this thread, I have seen them with some different holes. These were all pretty much hand made in the finishing process so I would think that there would be some differences in each of them but I dont know about early vs late dimples. Beats me 
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| I have only seen the two different sized holes, not lots of different sizes. I did not start this thread to sell my items. If, and when, I decide to sell any, I will do it per the rules and put them in the equipment exchange. I truly am curios about the two vastly different sized dimples I have observed. Sine the small dimple seems to be less common, it is my conjecture that it must be of earlier manufacture. I'm just curious if anyone had any documentation or other evidence about dimple size. |
Machinist, "Hey Mac, I broke this number one center drill...got any more?" Tool Crib Attendant, "Le' me see...nope...all outta number ones, we got some new number twos though." Machinist, "Yeah, that'll work, gimme one o' them." In all seriousness, the conversation probably went something like that. I've been a machinist for over twenty years and learn new things almost everyday. A few things I have learned: some things matter, some things don't, hot is on the left, cold is on the right, and shit don't flow uphill....hmm...where was I? Oh yeah. You have to apply some common sense and knowledge of things you've learned on past jobs. Read you drawings, schematics, specifications, ETC. Break out the machinery's handbook, machinist ready reference, and/or other useful guides. As my boss would say, (jokingly...I think  ) "It ain't rocket science, it's only going on a nuclear submarine."
ETA: Life is short drink more bier. |
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We had this discussion a few months back and it all seems to boil down to how much they were ground/finished before parkerized. While that is a good theory, it is simply not true. I took them to a machinist today, and he confirmed that two different center drills were used. The amount of grinding would NOT affect the deep center of the dimple, and you can plainly see in my photo that they are different diameters. My machinist agreed with 44echo10's theory that the machine shops #2 center drill broke, so they substituted a #1 center drill (which is probably the one used on takedown pins. |
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While that is a good theory, it is simply not true. I took them to a machinist today, and he confirmed that two different center drills were used. The amount of grinding would NOT affect the deep center of the dimple, and you can plainly see in my photo that they are different diameters. My machinist agreed with 44echo10's theory that the machine shops #2 center drill broke, so they substituted a #1 center drill (which is probably the one used on takedown pins. Quoted:
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We had this discussion a few months back and it all seems to boil down to how much they were ground/finished before parkerized. While that is a good theory, it is simply not true. I took them to a machinist today, and he confirmed that two different center drills were used. The amount of grinding would NOT affect the deep center of the dimple, and you can plainly see in my photo that they are different diameters. My machinist agreed with 44echo10's theory that the machine shops #2 center drill broke, so they substituted a #1 center drill (which is probably the one used on takedown pins. That was my Initial theory as well but boywonder put up a pretty convincing argument. I will dig for the link, because like you I was wondering this same thing. |
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Question is why they are even dimpled and what purpose did it serve being that they were. Seems like a waste of time to dimple them. I have a theory there was a holding fixture for machining that located using the selector arm and clamped down on the center holes. Then later they devised a faster simpler way that did away with the center holes. Makes no difference (within reason) what diameter center drill was used because the included angle is the same. |
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That was my Initial theory as well but boywonder put up a pretty convincing argument. I will dig for the link, because like you I was wondering this same thing. Quoted:
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We had this discussion a few months back and it all seems to boil down to how much they were ground/finished before parkerized. While that is a good theory, it is simply not true. I took them to a machinist today, and he confirmed that two different center drills were used. The amount of grinding would NOT affect the deep center of the dimple, and you can plainly see in my photo that they are different diameters. My machinist agreed with 44echo10's theory that the machine shops #2 center drill broke, so they substituted a #1 center drill (which is probably the one used on takedown pins. That was my Initial theory as well but boywonder put up a pretty convincing argument. I will dig for the link, because like you I was wondering this same thing. The pilot diameters are clearly different sizes. The depth they were drilled to varies, which makes the diameter of the 60 degree countersink different from piece to piece. More than one machine/set up was used and more than one operator was involved. Clean up grinding on the face is also a factor in the appearance. I hate it but at times in the past have worked in production, running a cell of 4-6 machines making thousands of the same fucking thing every shift. I can tell you that even though each machine was making the same part, they all looked a little different from machine to machine. Each cell was making the same part, every operator had their own way they liked to set things up and adjust things. However all the parts were in spec despite the subtle variations.
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The theory that small indent = early vs large = late is not borne out by actual period photographic data.
Looking at "the Black Rifle" V-1 photos show: Small hole (indent) : Colt model 601 Sn. 011476 Colt model 601 Sn. 011776 Colt model 602 Sn. 078901 Colt M16A1 Sn. 778769 H & R M16A1 Sn. 2000022 GM (HYD) M16A1 Sn. 3000028 Large hole (indent): Colt model 601 Sn. ?? (page 93) Colt model 601 Sn. ?? (page 168) also............ Colt Model 602 Sn. 023294 (photo in TM 9-1005-249-14) From this small sampling it appears there is no pattern to the use of small vs large indent safety . A small indent safety could actually be from a much later M16A1. It may well be as was posted earlier that it was a difference in tool use that determined the size of the indent. As a FYI ....the reason for the indent was for using the firing pin as a take down tool and not a bullet tip. Jim Gilmore Jim Thorpe, PA |
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The theory that small indent = early vs large = late is not borne out by actual period photographic data. A small indent safety could actually be from a much later M16A1. It may well be as was posted earlier that it was a difference in tool use that determined the size of the indent. As a FYI ....the reason for the indent was for using the firing pin as a take down tool and not a bullet tip. Jim Gilmore Jim Thorpe, PA How could an indented selector be from a "much later M16A1"? M16A1 selectors did not have detents. The detents being part of the manufacturing process makes total sense. The detents being placed there for use with a bullet OR a firing pin for takedown does not make sense. You don't need ANYTHING to push on a safety to get it in or out of a receiver. Now, some drill instructors MAY have said that was the reason they were there, but they were probably the same instructors who claimed the notch on early dog tags was to put them in the teeth of a fallen soldier (when the REAL reason, was that the early dog tag machines had an indexing pin that the notch rotated against). |
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M16indiana wrote:
".....How could a small indent pin be from a "much later M16A1"? M16A1 selectors did not have detents....." Please read my post again. I did not refer to "indent pins" but to safety selectors that have indents ("holes") in them. I am referring to the indents in the center of the safety shafts right and left as the photos in the beginning of this thread show.. As for the M-16A1 safety ....some did indeed have indents (holes) ....look at the photos I have listed and you will see this clearly and also in the TM 9-1005-249-14. Not all had them but some did as the photos show. [b] ".....The detents being part of the manufacturing process makes total sense. The detents being placed there for use with a bullet OR a firing pin for takedown does not make sense. You don't need ANYTHING to push on a safety to get it in or out of a receiver......" Please refer to TM 9-1005-249-14. Look at chapter III, page 3-9, Figure 3-5, step # 20 and you will clearly see the proper way to use the firing pin to remove the selector lever (safety ). The following diss-assembly steps also show using the firing pin to remove the hammer/trigger/auto sear pins. Wether it makes sense or not this is how it was to be done and why these indents (not detents) were put in the components. As to whether the firing pin is needed to remove the safety depends on if the pistol grip is attached with the spring detent. If it is then the firing pin may be needed to push it out and override the detent and spring. Removing the pistol grip was not part of the standard diss-assembly of the weapon at that time. Question......if the indents were part of the MFG process then why did/do more recent M16 series weapons not have them? Jim Gilmore Jim Thorpe, PA. |
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As an additional note........ For clear photos of two M16A1 rifles with small indent selectors (safety ) look at page 286 ( GM (HYD) M16A1 Sn. 3000028 ) & page 287 ( H & R M16A1 Sn. 2000022 ) in the book "The Black Rifle" V-1. ...of course this is not to say they all did ....just examples of ones that did. Jim Gilmore Jim Thorpe, PA. |
| Jim, I WAS talking about an indented selector. Maybe a firing pin was indicated in TM's for removing a safety, but the indent/detents (or whatever you want to call them) would not be necessary for removing the safety. The FACT that early parts (such as safeties with Dimples) were often used/reused on later models is well documented. I once saw 601 hand guards on an M16A1. Does that mean M16A1's were issued with 601 handguards? What is also well documented is that ALL early AR's, in original configuration, had safety selectors with dimples. So they are obviously an early feature. |
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As an additional note . . . .
you HAVE opened my eyes to an alternate theory as to why so many early parts & pins have indents/detents/dimples. IF they were originally machined for take-down use, rather than as part of the machining process, I can see how it was quickly discontinued as a cost savings, and not necessary. Thanks Jim. |
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I'm now gonna thro out some info for you all to chew on. Good Friend and member of our living history group did 4 years in EOD. Got out maybe 3 years ago. When he went over to the sand box he was issued a relatively new if not brand new ( a quick call to him can confirm) M4 carbine. Had the bar code on the right side of the mag well. His weapon definitely HAD dimpled pins, and may have had a dimpled selector I don't remember for sure on the selector.
All depends on who the subcontractor was making the parts at the time, type of machine used, and as echo said, how the operator set up his machine. This also applies to the duel bit drill used for drilling for the tapered pins on FSBs and is why we often have trouble "swapping" FSBs from one barrel to another. |
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I believe you guys nailed it.
The center drilling had to have been done to facilitate the machining processes. I really can't imagine somebody willing to risk screwin' up the FP just to use it to remove a selector (or whatever) .... especially when it is totally not necessary. Even IF the selector could be punched out without removing the grip, detent and spring, it'd be fun to try to replace it without some disassembly. Also, you can only remove these in one direction, so why would they be center drilled on both ends? The remaining question is .... why they no longer show up? With the sophisticated machining techniques developed over the years, I'm guessing that they just found a different (better/cheaper) way to secure the workpiece. |
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Like Rob said on occasion "dimpled pins" still show up. Sometimes only on one side of the pin. I still believe these are a by product of the maufacturing process used. It's simply a non value added step. The manufacturing processes have been refined to save time and bring cost per unit down. Front and rear pins can be turned out rapidly today on a CNC turning center with live tooling and a bar feeder. I am sure there are/were multiple vendors supplying Colt with small parts, the companies may have totally different types of machines but in the end make the same component to specification. More than one way to skin a cat.
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| Just realized something not mentioned. We go from a period at Colts where we see the "dimpled" parts, then a change to non dimpled. Then in 68 when H&R and GM got their contracts, our own willp found evidence that both of those contractors had used dimpled pins. IIRC dimpled one side only. Could have been double dimpled, I'd have to try to dig up some of his old research, and that of wpnsman who was a major contributor to willps research.. Again,, multitude of subcontractors involved. |
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Just realized something not mentioned. We go from a period at Colts where we see the "dimpled" parts, then a change to non dimpled. Then in 68 when H&R and GM got their contracts, our own willp found evidence that both of those contractors had used dimpled pins. IIRC dimpled one side only. Could have been double dimpled, I'd have to try to dig up some of his old research, and that of wpnsman who was a major contributor to willps research.. Again,, multitude of subcontractors involved. a member here had a dimpled H&R selector https://www.ar15.com/archive/topic.html?b=3&f=123&t=580021 |
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OK, then is this an H&R dimpled selector lever? http://i302.photobucket.com/albums/nn115/kkrad_photo/0f255f0735da240c93dfb56edadb7ea6.jpg marking is consistent with H&R. most of the colts i've seen have the E in a C. some reported having the number in a C but i haven't seen many of those. |
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“…..The center drilling had to have been done to facilitate the machining processes. ...." No...not for machining.......the indents were there for a reason....the dissassembly of the rifle. This was carried over from the original ArmaLite AR 15 prototypes and the AR 10. "......I really can't imagine somebody willing to risk screwin' up the FP just to use it to remove a selector (or whatever) .....” The FP will not be damaged by using it as a disassembly tool. I would again refer you to TM 9-1005-249-14 to see how this is used. It was standard procedure and how the weapon was designed…… for a bullet and firing pin to be the only tools needed to disassemble the rifle. This was actually a selling point for the rifle when originally offered for sale. ”……..Even IF the selector could be punched out without removing the grip, detent and spring, it'd be fun to try to replace it without some disassembly…..” Not IF….the selector could be and was supposed to be removed for cleaning with the pistol grip still on the rifle. Again, if you will look at TM 9-1005-249-14 , chapter III, page 3-9, figure 3-5, step 20 shows removing the selector with the FP and with the pistol grip on. On the same page step 4 shows how to push down the selector spring and detent with the firing pin to allow the selector to be pushed into the receiver. ”……….Also, you can only remove these in one direction, so why would they be center drilled on both ends?…” The indent on the lever side is for using a bullet tip in conjunction with the firing pin depressing the selector detent and pushing the selector in. Please note that whether you can or cannot remove or install the selector without a bullet tip or firing pin does not matter….this was the prescribed way to disassemble the weapon according to the US Army Jim Gilmore Jim Thorpe, PA.. |
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“……We go from a period at Colts where we see the "dimpled" parts, then a change to non dimpled. Then in 68 when H&R and GM got their contracts, our own willp found evidence that both of those contractors had used dimpled pins. IIRC dimpled one side only…..” The most likely reason for the indent on the selector on these rifles is the lax attitude at Colt to keep part drawings up to date. This was a very real problem and many of the drawings Colt supplied to the Govt. under the first contracts were from the original ArmaLite part drawings and had not been updated. Colt had to request over 70+ RA’s just to change the drawings to reflect the actual parts. When the Govt. paid Colt for the manufacturing data package they got all the drawings for the weapons. These were then turned over to the possible bidders as data packages. When H&R and GM were given contracts to build rifles they were to be to the Colt drawings from these data packages. If the selector drawing was the original one and showed the indents then they would have been required to produce the part exactly to that drawing. They then could later request a RA to change the part with Govt approval. Jim Gilmore Jim Thorpe, PA. |
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“…..I still believe these are a by product of the manufacturing process used. It's simply a non value added step. The manufacturing processes have been refined to save time and bring cost per unit down…..” Well…..how were these selectors machined that the indents would be used? Does anyone have actual data or drawings to this effect? Actually….were not the selectors pressure castings? The close up photos show mold parting lines and the 1 in the square looks to be part of a mold. I can prove that the indents were designed for easy disassembly of the rifle but can anyone prove the manufacturing process theory? I would also point out here that the early ArmaLite AR 15 had an indent only on the right side of the selector. They also had indents in the trigger and hammer pins for takedown as well . Jim Gilmore Jim Thorpe, PA. |
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Jim;
THANK YOU VERY MUCH for finally providing an explanation WITH proof/references about the dimples on M16 parts. I think your explanation about GM and. H&R using early Colt drawings, hence the dimples on their parts, was spot on. You have converted me from a "machining guy" to a "take down guy". |
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