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Page AR-15 » Build It Yourself
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Posted: 8/31/2011 1:51:10 PM EDT
I am reading about lowers that are High shelf or low shelf.  What does this mean and what are the advantages of one over the other?  Which is better?  And it seems as if most of the lowers I see are called Mil Spec.  Does the military use both High and Low shelf lowers??

And yes I tried to search, but the search function is useless on this site.

Thanks for any insight on this.
Link Posted: 8/31/2011 2:00:10 PM EDT
[#1]

Quoted:






I am reading about lowers that are High shelf or low shelf.  What does this mean and what are the advantages of one over the other?  Which is better?  And it seems as if most of the lowers I see are called Mil Spec.  Does the military use both High and Low shelf lowers??
And yes I tried to search, but the search function is useless on this site.
Thanks for any insight on this.






You can only search for the last 30 days.
This has been discussed ad nauseum.
If you look in inside the bottom of a lower just below the rear takedown pin the floor or shelf will intersect about midway at the selector hole on a low shelf. A high shelf will be about even with the top of the selector hole.
It does not mean very much unless you have a RDIAS.
LOW SHELF






HIGH SHELF






 
 
 
 
Link Posted: 8/31/2011 2:07:30 PM EDT
[#2]
I see.  Thanks.

Is one better than the other?  What is RDIAS?
Link Posted: 8/31/2011 2:10:54 PM EDT
[#3]



Quoted:




Is one better than the other?


No






Quoted:





What is RDIAS?


Registered Drop In Auto Sear.



 
Link Posted: 8/31/2011 2:13:19 PM EDT
[#4]
Ok, Thanks.  Since I don't think I will be getting A RDIAS anytime soon, nothing for me to worry about.

So are they both considered mil spec?  It seems as if the high shelf might be a little stronger.  Might come in handy for those that want to drop a .50 upper onto it.
Link Posted: 8/31/2011 2:56:51 PM EDT
[#5]



Quoted:




So are they both considered mil spec?  It seems as if the high shelf might be a little stronger.  Might come in handy for those that want to drop a .50 upper onto it.


No they are not. The military does not use high shelf lowers.  The strength of both are the same, as the difference in material can be measured in grams, not ounces.



If it is not accepted by the .mil, it is not mil spec. Now, a piece can be made in the same manner, using the same materials., as the ones the US Armed Forces use. These can be high, or low, shelf.



 
Link Posted: 9/15/2011 7:32:12 AM EDT
[#6]
Quoted:

Quoted:

So are they both considered mil spec?  It seems as if the high shelf might be a little stronger.  Might come in handy for those that want to drop a .50 upper onto it.

No they are not. The military does not use high shelf lowers.  The strength of both are the same, as the difference in material can be measured in grams, not ounces.

If it is not accepted by the .mil, it is not mil spec. Now, a piece can be made in the same manner, using the same materials., as the ones the US Armed Forces use. These can be high, or low, shelf.
 


Well, I received my Palmetto State Lowers yesterday.  They are all high shelf.  So now my thought is, how can they call them Mil-Spec if they are not Mil-Spec?  If they don't build lowers like the ones the .mil uses?  I am thinking it has to be money, but it cannot be that much more expensive to mill the low shelf over the high shelf.  And wouldn't this be a form of false advertising?  Thoughts?

Link Posted: 9/15/2011 9:03:31 AM EDT
[#7]



Quoted:



Quoted:




Quoted:



So are they both considered mil spec?  It seems as if the high shelf might be a little stronger.  Might come in handy for those that want to drop a .50 upper onto it.


No they are not. The military does not use high shelf lowers.  The strength of both are the same, as the difference in material can be measured in grams, not ounces.



If it is not accepted by the .mil, it is not mil spec. Now, a piece can be made in the same manner, using the same materials., as the ones the US Armed Forces use. These can be high, or low, shelf.

 




Well, I received my Palmetto State Lowers yesterday.  They are all high shelf.  So now my thought is, how can they call them Mil-Spec if they are not Mil-Spec?  If they don't build lowers like the ones the .mil uses?  I am thinking it has to be money, but it cannot be that much more expensive to mill the low shelf over the high shelf.  And wouldn't this be a form of false advertising?  Thoughts?





mil-spec refers to construction material, finishing, and quality control done on the lower. At least with CMMG, all of their lowers start off as high shelf, and are only converted to low shelf upon special order from a qualifying agency.



 
Link Posted: 9/15/2011 9:23:11 AM EDT
[#8]
Quoted:
Quoted:

Quoted:

So are they both considered mil spec?  It seems as if the high shelf might be a little stronger.  Might come in handy for those that want to drop a .50 upper onto it.

No they are not. The military does not use high shelf lowers.  The strength of both are the same, as the difference in material can be measured in grams, not ounces.

If it is not accepted by the .mil, it is not mil spec. Now, a piece can be made in the same manner, using the same materials., as the ones the US Armed Forces use. These can be high, or low, shelf.
 


Well, I received my Palmetto State Lowers yesterday.  They are all high shelf.  So now my thought is, how can they call them Mil-Spec if they are not Mil-Spec?  If they don't build lowers like the ones the .mil uses?  I am thinking it has to be money, but it cannot be that much more expensive to mill the low shelf over the high shelf.  And wouldn't this be a form of false advertising?  Thoughts?




In a sense they are and are not mil spec. We'll look at Colt, they are a manufacture that build civilian and military rifles. Essentially they are identical as far as materials and manufacturing goes. Mil spec is a grading standard based off of specifications given to the manufacture. So technically a PSA lower is mil spec. It is machined from a forged lower that is considered to be mil spec. The forging meets or exceeds the minimum quality standards acceptable by the mil spec standard.

To some folks, their interpretation of mil spec is " must be currently used or in the hands of the military to be mil spec " as an example a Colt 6920 would not be a mil spec configured carbine, but it's construction and materials are made using mil spec standards and tolerances.

Link Posted: 9/15/2011 9:30:45 AM EDT
[#9]
"Mil-Spec" as used in the civilian world is nothing more than a catch phrase, there is no legally binding definition of it when it comes
to something ANY OEM makes UNLESS, it is to meet Military Specifications as outlined in a contract to manufacture, for the United States Army,
Marine Corps, Air Farce et al, ad nausea.

Buyer beware for anything sold, traded, bartered or otherwise moving from one persons hand to yours, Mil-Spec doesn't mean shit that can be quantified.

Now that that is out of the way, Mil-Spec usually means that it conforms to generally what the people above me said. But if you're
looking for a legally binding definition, you're SOL.

Link Posted: 9/15/2011 10:29:49 AM EDT
[#10]



Quoted:



Quoted:




Quoted:



So are they both considered mil spec?  It seems as if the high shelf might be a little stronger.  Might come in handy for those that want to drop a .50 upper onto it.


No they are not. The military does not use high shelf lowers.  The strength of both are the same, as the difference in material can be measured in grams, not ounces.



If it is not accepted by the .mil, it is not mil spec. Now, a piece can be made in the same manner, using the same materials., as the ones the US Armed Forces use. These can be high, or low, shelf.

 




Well, I received my Palmetto State Lowers yesterday.  They are all high shelf.  So now my thought is, how can they call them Mil-Spec if they are not Mil-Spec?  If they don't build lowers like the ones the .mil uses?  I am thinking it has to be money, but it cannot be that much more expensive to mill the low shelf over the high shelf.  And wouldn't this be a form of false advertising?  Thoughts?





False advertising? No, not at all.



About money? No, not at all.



The PSA lowers are forged, not billet or cast, as per Mil-Spec.



The PSA lowers are made of 7075-T6 Aluminum, as per Mil-spec.



The PSA lowers are Type III anodized, as per Mil-spec.



This means, to my mind, that the company that is making these for PSA is using the same materials, created in the same manner, and finished with the same process, as the FNH and Colt lowers.



You are over thinking this. If you do not like your lowers, I'll buy them from you.



 
Link Posted: 9/15/2011 12:29:37 PM EDT
[#11]



Quoted:


"Mil-Spec" as used in the civilian world is nothing more than a catch phrase, there is no legally binding definition of it when it comes

to something ANY OEM makes UNLESS, it is to meet Military Specifications as outlined in a contract to manufacture, for the United States Army,

Marine Corps, Air Farce et al, ad nausea.



Buyer beware for anything sold, traded, bartered or otherwise moving from one persons hand to yours, Mil-Spec doesn't mean shit that can be quantified.



Now that that is out of the way, Mil-Spec usually means that it conforms to generally what the people above me said. But if you're

looking for a legally binding definition, you're SOL.



i think mil-spec implies that whatever is being made, is made to the MIL specs.  For example, I worked at a glass place for a while.  They had MIL-(some random numbers and letters etc) glass.  customers could specify that the MIL spec glass was used, even if they weren't making pieces for military hardware.



if people say something is mil-spec, such as in this case, a lower reciever, then there should be a set of specs somewhere out there that describes what they are making.  If not, then i would say it is fraud, whether anyone will do anything about it, or if there is any legal recourse, i don't know.  They can say they are made from mil-spec material, same thing applies.





 
Link Posted: 9/15/2011 3:48:41 PM EDT
[#12]
There is no military specification for a semi auto AR-15 lower. Therefore there is no true Mil-Spec AR-15 lower.

What the term implies with an AR-15 lower is that it was make with materials, finish ,most importantly, machining and tolerances as outlined in the military's TDP (Technical Data Package) which insures any standard part is interchangeable regardless of manufacturer. (as long as they are also TDP compliant.)






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