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Posted: 1/21/2022 10:03:29 PM EDT
I've done some searching on this topic and can't find a definitive answer. Are the major components (fire control group mostly) in a standard Anderson lower parts kit metal injection molded?

I bought a couple of these on sale a while back for cheap just to have around. The parts are very nicely finished, seemingly polished, the hammer is a little different than what generally seen in a standard parts kit. I know the topic of MIM parts in a lower parts kit comes up from time to time and it's suggested to stay away from them for obvious reliability reasons. I'm going to assume these are MIM parts, some of what I see would lend that they are, and some wouldn't, but I'm not very knowledgeable in the subject of MIM parts. They will likely suit my needs just fine for a good while. I was just curious if anyone had a little more knowledge on them. If nothing else, the stuff was cheap enough it will be nice to have spare pins, springs, and ect.

I should also mention I'm referencing a standard kit and not the kit with a stainless hammer/trigger.

Thanks!
Link Posted: 1/21/2022 10:11:51 PM EDT
[#1]
Attachment Attached File


Look like this?
If so, I'd say investment cast.

Link Posted: 1/21/2022 10:25:27 PM EDT
[#2]
When done properly they are fine.  They make engine connecting rods out of it.  MIM does not equal pot metal.
Link Posted: 1/21/2022 10:27:53 PM EDT
[#3]
Barrett went to MIM on a lot of small, light stress parts in the 82A1 family of rifles. Work just fine.
Link Posted: 1/21/2022 10:30:04 PM EDT
[#4]
No thanks
Link Posted: 1/21/2022 10:40:25 PM EDT
[#5]
Pretty sure they’re MIM. I’d spend the extra for Schmid parts.


Link Posted: 1/21/2022 10:46:12 PM EDT
[#6]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Pretty sure they’re MIM. I’d spend the extra for Schmid parts.

https://i.imgur.com/pdIamaf.jpg
https://i.imgur.com/vW98Ypx.jpg
View Quote

I'd have to agree.
Link Posted: 1/21/2022 11:38:54 PM EDT
[#7]
Very interesting... There are apparently 2 types (at least?) of "mil-spec" lower parts from Anderson. The hammers that Tigwelder1971 and MJ11B4P posted were the style I expected to get in the kits, just the plain old parts everyone is familiar with. In detail those two even look a bit different from each other though. The one MJ11B4P shared looks like what I would expect from a MIM part, slightly rough finish and the little round witness marks to fill/eject the part. The one Tigwelder1971 posted is more what I would expect from a forged part with an identifying dimple, but it's hard to say.



This picture depicts the kits I got. They are from the last several months, so I would assume this is a new style? You can see the unique recessed area on the sides of the hammer, this is what I was referring to as the hammer being a little different style than traditional. It's a bit hard to make out, but you can also see the surface finish is very smooth/polished.

I'm really not afraid of MIM parts, widely used in all sorts of applications and very widely used in firearms. I was just curious if these were MIM or something else, seems there's been some changes made to them at least somewhat recently. Guess I'll just have to run one for a while and monitor, if it gives issue I'll track down some Schmid tool stuff.
Link Posted: 1/22/2022 12:12:05 AM EDT
[#8]
CDNN blew some out similar to those, labeled a "lightened hammer":

Attachment Attached File


I've seen your style before, thinking it was the S&W recall awhile back,  but not positive.

ETA: Yeah, BTI made kits for S&W.

LINK
Link Posted: 1/22/2022 12:32:23 AM EDT
[#9]
Midway has a lot of the parts in their kit that have a mim appearance just looking at them. Seen what appears to be mim in other kits some places also. I wound up with one mim hammer once and the width was off on it at the pin arms giving a lot of side to side movement.
Have seem mim extractors, hammers, disconnectors, triggers, mag catches one piece whole catch, mag catch buttons, bolt catches, ejectors, selectors, and just the mag catch main piece not the threaded arm portion.
Link Posted: 1/22/2022 1:02:05 AM EDT
[#10]
MIM is fine when done properly, problem is allot of time it isn’t, corners cut, lesser grade metals, etc. over the years I have seen good, bad and ugly. For what it’s worth if this is the same Anderson manufacturing that used to make parts for Chevrolet before they lost their contracts I would be hard pressed to use anything of theirs.
Link Posted: 1/22/2022 11:11:19 AM EDT
[#11]
I bought some similar Anderson LPK recently.    

The parts on the left are USGI and the parts on the right are MIM.   You can see the injection point on one hammer.  Click and make the pic fullsize.

MIM is fine, the LPK's will not be sent back.



.

upload photo
Link Posted: 1/22/2022 11:16:03 AM EDT
[#12]
Magazine catch is what gives it away. No rivet.

I'll stick with CMMG.
Link Posted: 1/22/2022 12:09:36 PM EDT
[#13]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I bought some similar Anderson LPK recently.    

The parts on the left are USGI and the parts on the right are MIM.   You can see the injection point on one hammer.  Click and make the pic fullsize.

MIM is fine, the LPK's will not be sent back.


.
https://i.ibb.co/qxGGhkD/IMG-0460.jpg
upload photo
View Quote


MIM may be "fine" for some,  and to each their own....

LMT and KAC selectors along with LMT gas keys haven't fared too well though.




Link Posted: 1/22/2022 12:17:31 PM EDT
[#14]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I bought some similar Anderson LPK recently.    

The parts on the left are USGI and the parts on the right are MIM.  

MIM is fine, the LPK's will not be sent back.
View Quote


It might be these days, I am sure the tech has advanced.  
I still have those images in my head of the snapped in half Kimber MIM parts they tried to use in 1911s.

I can't shake it, it's not for me when there are readily available tool steel, etc. parts available.  Currently, there is just no reason for me to to go with MIM
Link Posted: 1/22/2022 3:07:19 PM EDT
[#15]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I bought some similar Anderson LPK recently.    

The parts on the left are USGI and the parts on the right are MIM.   You can see the injection point on one hammer.  Click and make the pic fullsize.

MIM is fine, the LPK's will not be sent back.



.
https://i.ibb.co/qxGGhkD/IMG-0460.jpg
upload photo
View Quote



Excellent photo, thanks for sharing that. Those are Anderson's stainless versions I take it? It is very clear the injection point on the one. I will go dig out my kits and try to get some detailed pictures of the parts in my standard mil-spec kits. I bought them assuming MIM, but the surface finish on my parts is unlike what I've seen from other MIM parts so I'm not sure they?

I'm also of the opinion that MIM parts is suitable for some parts and in some rifles. Is it the best, no, everything is made to a price point, but that it's still okay for somethings. If I bought from KAC or LMT I would not be happy with MIM parts, but I have a much different expectation from their stuff. I bought these for extras and I want to put together a budget rifle from cheap but okay parts to bang around with me on the ranch, not something that's life dependent just one I don't have to care much about.
Link Posted: 1/22/2022 3:25:08 PM EDT
[#16]
Here some of the parts I put aside because they had the appearance to me of being MIM. The mag catch button is steel not the normal aluminum.

Link Posted: 1/22/2022 8:49:01 PM EDT
[#17]
Not for me on bolt catches, or fire control parts.
Link Posted: 1/22/2022 11:32:06 PM EDT
[#18]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
The one MJ11B4P shared looks like what I would expect from a MIM part, slightly rough finish and the little round witness marks to fill/eject the part. The one Tigwelder1971 posted is more what I would expect from a forged part with an identifying dimple, but it's hard to say.
View Quote
Since it seems there's a little confusion on your part, mil-spec isn't forged.

Mil-spec (like the Schmid parts) are investment cast.

As far as your parts, I think you're eighth that you got mom parts. If it isn't a self defense rifle, I wouldn't worry about it.

Hope this helps.
Link Posted: 1/23/2022 3:03:44 AM EDT
[#19]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Since it seems there's a little confusion on your part, mil-spec isn't forged.

Mil-spec (like the Schmid parts) are investment cast.

As far as your parts, I think you're eighth that you got mom parts. If it isn't a self defense rifle, I wouldn't worry about it.

Hope this helps.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:
The one MJ11B4P shared looks like what I would expect from a MIM part, slightly rough finish and the little round witness marks to fill/eject the part. The one Tigwelder1971 posted is more what I would expect from a forged part with an identifying dimple, but it's hard to say.
Since it seems there's a little confusion on your part, mil-spec isn't forged.

Mil-spec (like the Schmid parts) are investment cast.

As far as your parts, I think you're eighth that you got mom parts. If it isn't a self defense rifle, I wouldn't worry about it.

Hope this helps.

Well here’s my opinion, every rifle should be built as if your life depends on it, as it just might. I’m also hoping that eighth is right and mom parts is MIM parts?
Link Posted: 1/23/2022 3:18:55 AM EDT
[#20]
Took an Anderson LPK and a trigger jig w/ me for 9 months.  Constantly dryfired it.  Wore the sear surfaces so badly I could get the hammer to release when taking off the Elftmann speed safety.

Anderson replaced the LPK, no questions asked.

How is MIM different from traditional casting?
Link Posted: 1/23/2022 10:01:09 AM EDT
[#21]
Best I could tell it is supposed to be possible to make a MIM part equal to a casting. I saw your post I think and it was with what looked like the stainless style parts. I did the test after seeing your post with the trigger, hammer, and a selector like the one in the above picture including rotating the selector. I got no unusual wear on those parts. But I mentioned earlier the hammer width is out of spec compared to the drawing I saw.

Supposedly it is possible to make MIM parts equal to castings. Might have been a onetime thing but I have cold blued a cast hardened selector once and it barely would take the bluing or color. I cold blued the end of a MIM selector I had smoothed with a file once and it easily took on a dark bluing. Not saying it was but to me it almost seemed like it was porous or something.
Link Posted: 1/23/2022 11:14:17 AM EDT
[#22]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


How is MIM different from traditional casting?
View Quote


One process does not utilize powdered alloys essentially "glued" (diffusion bonded) together nor parts that leave the mold with an average 40% air content, relying on additional processing steps in order to attempt to produce a viable component.  

I do not believe that a 100% density can be achieved with MIM.
Link Posted: 1/23/2022 12:45:53 PM EDT
[#23]
Discussion ForumsJump to Quoted PostQuote History
Quoted:  One process does not utilize powdered alloys essentially "glued" (diffusion bonded) together nor parts that leave the mold with an average 40% air content, relying on additional processing steps in order to attempt to produce a viable component.  

I do not believe that a 100% density can be achieved with MIM.
View Quote


Don't most cast parts require finish machining?  Does MIM produce a lighter part for a given volume?  Is the process less expensive simply b/c there is less steel?
Link Posted: 1/23/2022 1:31:00 PM EDT
[#24]
6 of my 8 ARs that I have are equipped with Schimd lower parts. All of them have those small circular spots on them.
Link Posted: 1/23/2022 1:35:23 PM EDT
[#25]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
6 of my 8 ARs that I have are equipped with Schimd lower parts. All of them have those small circular spots on them.
View Quote


Interesting, I thought the Schmidt kits avoided the MIMz.  I guess it is more common than I thought.
Link Posted: 1/23/2022 1:46:26 PM EDT
[#26]
How do you tell a an injection site from a pour site on the finished piece?  The AR lower I cast has a pour site.
Link Posted: 1/23/2022 1:48:31 PM EDT
[#27]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Don't most cast parts require finish machining?  Does MIM produce a lighter part for a given volume?  Is the process less expensive simply b/c there is less steel?
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:  One process does not utilize powdered alloys essentially "glued" (diffusion bonded) together nor parts that leave the mold with an average 40% air content, relying on additional processing steps in order to attempt to produce a viable component.  

I do not believe that a 100% density can be achieved with MIM.


Don't most cast parts require finish machining?  Does MIM produce a lighter part for a given volume?  Is the process less expensive simply b/c there is less steel?

MIM molding process  yields a net/near net dimension part greatly reducing the need for second operations to obtain a finished part.

The largest issue with MIM parts is it's near impossible to identify an issue until part failure.
Link Posted: 1/23/2022 1:52:06 PM EDT
[#28]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I bought some similar Anderson LPK recently.    

The parts on the left are USGI and the parts on the right are MIM.   You can see the injection point on one hammer.  Click and make the pic fullsize.

MIM is fine, the LPK's will not be sent back.



.
https://i.ibb.co/qxGGhkD/IMG-0460.jpg
upload photo
View Quote



I have the silver trigger. Its horrible imo.
Link Posted: 1/23/2022 2:00:08 PM EDT
[#29]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
6 of my 8 ARs that I have are equipped with Schimd lower parts. All of them have those small circular spots on them.
View Quote

Remnants from the gating and runner system.
Link Posted: 1/23/2022 2:19:22 PM EDT
[#30]
The circular spots don't necessarily mean the part is MIM. The ejectors leave circular marks on the wax part used to build the casting mold. Circles on a part like a disconnector that is normally stamp or cut from flat metal might indicate it as MIM. Fine lined letters and numbers also might be an indication. Things like circles on the arm of the mag catch is not something you would see on a part made by the material shown on the drawings. Threads on the mag catch arm that are flat on two side inside of a normal threading appears to be a MIM part. Finding the part listed on the MIM manufacturers web site is kind of a giveaway too.
Link Posted: 1/23/2022 2:55:03 PM EDT
[#31]
Don't know about Anderson.

I will say this about MIM.

The answer most often received, and most useless when asking about MIM or investment cast firearm parts is,
"When done properly, there just fine".

So heres my take since no one knows what is done "properly" or what "properly" is.

There is no "Mil-Spec" anything for AR15 semi auto parts.

The best investment cast parts in the world is Pine tree technologies, which Ruger owns.


The best manufacture of MIM parts is Pratt and Whitney who among other firearms manufactures, is currently a OEM supplier to Colt firearms for parts used in thier current Anaconda and Python revolvers.

Parts can and do fail.

Forged, cast or MIM.

That said it's all about the process and material used and after process conditioning.

Proper heat/annealing treatment, milling sequence, raw material, finish coatings/polishing, etc.. all have a effect.

Mil-Spec has call outs and specifications of tolerances with testing for each and every step of the process.
You typically can not purchace a Mil-Spec part, it goes through Government approved procurement procedure, which in and of its self is part of the Military Specification.

Go forged if your concerned.
Link Posted: 1/23/2022 5:23:29 PM EDT
[#32]
This is a pretty interesting technical paper.
Metal Injection Molding Process for Aircraft Engine Part Production
Link Posted: 1/23/2022 8:48:58 PM EDT
[#33]
Hasn’t Ruger been a Pioneer/Leader in mim parts in firearms And Aerospace ?????   Not really heard of their shit failing …..???????

H
Link Posted: 1/23/2022 9:07:46 PM EDT
[#34]
Attachment Attached File


Attachment Attached File


Attachment Attached File


Attachment Attached File


All MIM failures.

Not a risk that I'm willing to gamble on personally.
Link Posted: 1/23/2022 9:19:30 PM EDT
[#35]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Since it seems there's a little confusion on your part, mil-spec isn't forged.

Mil-spec (like the Schmid parts) are investment cast.

As far as your parts, I think you're eighth that you got mom parts. If it isn't a self defense rifle, I wouldn't worry about it.

Hope this helps.
View Quote


Very interesting, I had always assumed the spec would call for forged, I did not realize it was investment casting. Thank you for that clarification. Lots of good information has been shared here!

I took a real close look at the Anderson kits I have, I have come to the conclusion they are indeed MIM on the fire control group, bolt catch, mag catch, and safety. All have the tell tale "injection port." I took some pictures, my phone is old though so they aren't the best but I think you can see what I'm talking about.

The parts in question


This is the mag catch, I think this was the best picture I got of the injection site.


Here's the hammer with the same sort of site.


All of them have a similar spot on them that would be where the powdered metal is injected into the mold as I understand.
Link Posted: 1/23/2022 11:36:27 PM EDT
[#36]
Discussion ForumsJump to Quoted PostQuote History
Quoted:  Very interesting, I had always assumed the spec would call for forged, I did not realize it was investment casting. Thank you for that clarification. Lots of good information has been shared here!

I took a real close look at the Anderson kits I have, I have come to the conclusion they are indeed MIM on the fire control group, bolt catch, mag catch, and safety. All have the tell tale "injection port." I took some pictures, my phone is old though so they aren't the best but I think you can see what I'm talking about.

The parts in question
https://imgur.com/1lLFB0s.jpg

This is the mag catch, I think this was the best picture I got of the injection site.
https://imgur.com/ubtdgFy.jpg

Here's the hammer with the same sort of site.
https://imgur.com/HS3RJ8Q.jpg

All of them have a similar spot on them that would be where the powdered metal is injected into the mold as I understand.
View Quote


Again, how can you tell the difference btwn a cast part and a MIM part by looking at it?  Molded parts will have very similar injection sites where the liquid metal is poured into the mold.

As far as 1911 safeties, as pictured above, I snapped one in half in the early 90's while working as a docent at the National Firearms Museum when we were reassembling spare donated 1911s - that would have been a cast safety, I presume, and it snapped right in half as I was fumbling trying to force it into the frame.  (I did not yet own a Dremel at the time nor had I been to WECSoG yet.)
Link Posted: 1/24/2022 12:55:56 AM EDT
[#37]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Again, how can you tell the difference btwn a cast part and a MIM part by looking at it?  Molded parts will have very similar injection sites where the liquid metal is poured into the mold.

As far as 1911 safeties, as pictured above, I snapped one in half in the early 90's while working as a docent at the National Firearms Museum when we were reassembling spare donated 1911s - that would have been a cast safety, I presume, and it snapped right in half as I was fumbling trying to force it into the frame.  (I did not yet own a Dremel at the time nor had I been to WECSoG yet.)
View Quote


I could be way off track, but it is my understanding the MIM parts will have a VERY finite spot that the material was injected into a mold. MIM parts are very dimensionally accurate right from the mold and take basically no machining to finish (I think that's largely the appeal in industry and why they're cheaper). Cast parts are not like that, they shrink a great deal after being poured, so they will have to be overfilled to a larger degree, leaving a sprue that will need removed by machining along with other areas needing better/precise finishing.
Link Posted: 1/24/2022 7:41:13 AM EDT
[#38]
On average cast steels shrink by ~2.5% during the cooling period and molds are built with this in mind.


MIM components during the diffusion bonding proces typically shrink by 15% in each dimension.
Link Posted: 1/24/2022 7:44:32 AM EDT
[#39]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Again, how can you tell the difference btwn a cast part and a MIM part by looking at it?  Molded parts will have very similar injection sites where the liquid metal is poured into the mold.

View Quote


Correct, and much of the time it can be visually near impossible to tell one from another.

With some MIM components there will be a visible sink depression left that is an immediate tell, but not always.

Buying from a trusted vendor that is open about specs is one's best bet.
Link Posted: 1/24/2022 9:02:51 AM EDT
[#40]
Discussion ForumsJump to Quoted PostQuote History
Quoted:  I could be way off track, but it is my understanding the MIM parts will have a VERY finite spot that the material was injected into a mold.
View Quote


Umm, how do you think casting works?  I bet you cast items every day, think through that process and how it works for gun parts.
Link Posted: 1/24/2022 9:38:24 AM EDT
[#41]
Investment casting are stuck to a center core piece of metal. They are cut from the tree and ground down usually flush with the surface. Not uncommon to see the grinding marks on the end of selectors and or even raised faces on some hammers where they were not ground flush.
Link Posted: 1/24/2022 9:41:56 AM EDT
[#42]
MIM process:

Attachment Attached File


Investment casting process:

Attachment Attached File
Link Posted: 1/24/2022 9:48:02 AM EDT
[#43]
Quoted:
Investment casting are stuck to a center core piece of metal. They are cut from the tree and ground down usually flush with the surface. Not uncommon to see the grinding marks on the end of selectors and or even raised faces on some hammers where they were not ground flush.
View Quote

MIM?


ETA, Tigwelder wanswered
Link Posted: 1/24/2022 9:49:21 AM EDT
[#44]
Casting you can see where the parts were attached. https://youtu.be/In1-sU7yw6k
Metal injection molding you can watch the selector get the dents from being ejected at around 2:30 and 3:20 https://youtu.be/ncWu31iMkk8
You can see at around 2:05 the tie between the two appears to be removed before it was heated and shrinks. The U shaped places on the pics in the post above look like a blade sliced them of the metal in the channel it attached to and the powder was injected.
Link Posted: 1/24/2022 11:27:20 AM EDT
[#45]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


One process does not utilize powdered alloys essentially "glued" (diffusion bonded) together nor parts that leave the mold with an average 40% air content, relying on additional processing steps in order to attempt to produce a viable component.  

I do not believe that a 100% density can be achieved with MIM.
View Quote
I was under the impression that MIM could reach 90-95% density, but you are on point about them not reaching 100%.

40% would be enough that you could fee the weight differences in like parts.
Link Posted: 1/24/2022 11:33:50 AM EDT
[#46]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I was under the impression that MIM could reach 90-95% density, but you are on point about them not reaching 100%.

View Quote


Courtesy of Indo-MIM:

Typical MIM densities achieved are = 96% of theoretical. Properties vary depending upon the alloy chosen however they will be similar to wrought material.


95-98% seems to be the normal claim. If it's done correctly.
Link Posted: 1/24/2022 9:16:50 PM EDT
[#47]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Umm, how do you think casting works?  I bet you cast items every day, think through that process and how it works for gun parts.
View Quote


You're right, I do not know what I'm talking about. Just sharing my observations, take it with a grain of salt.
Link Posted: 1/24/2022 10:02:19 PM EDT
[#48]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
You're right, I do not know what I'm talking about. Just sharing my observations, take it with a grain of salt.
View Quote


I don't either, I just don't understand how someone can look at a part and tell if it was cast or injection molded.
Link Posted: 1/25/2022 5:54:22 AM EDT
[#49]
Attachment Attached File


It's the gates that are the giveaway
Link Posted: 1/25/2022 8:12:37 AM EDT
[#50]
You won't always see a gate mark on some parts that have secondary machining because it is placed where it gets removed during machining.

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