New AR Build Question -- Uppers & BCGs

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As stated, any M16/M4/AR15 BCG will work.
This is the "Mouse Gun", the small frame that you are building.
There are standard specifications for these.

Now the large frame AR10/308AR/SR25, is a very different story.
There are no standard specifications for these.

This is a good time to build.....prices are low.
Here's a Toolcraft BCG (top shelf part) for what I've paid for a much lesser BCG...
Toolcraft BCG - Toolcraft Bolt Carrier Group - Monmouth Reloading
 
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Mouse gun? That's a new one on me
The only mil spec / commercial differences I know of are with the buffer tubes. If you have all that together from when you did your lower then you got past any match up problems.
Mouse guno_O
 
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Mouse gun? That's a new one on me
The only mil spec / commercial differences I know of are with the buffer tubes. If you have all that together from when you did your lower then you got past any match up problems.
Mouse guno_O
I can't be 100% sure of where that came from but here are some possibilities :

When the military was moving from M14 to M16, the new plastic rifle seemed like a toy compared to the man's gun (M14) with a wood stock and big bullets (ie. Mickey Mouse).

A friend who was in the Army said that his buttstock said "Mattel" on it which reinforced the above sentiment. If you dig into it, I think you'll find that the Mattel Toy Co. contracted to provide some of the M16 buttstocks.

To a lesser degree (in regards to the above), in Chevrolet racing nomenclature the small block is affectionately known as the "Mouse" motor.
The big block is known as the "Rat" motor.
 
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I can't be 100% sure of where that came from but here are some possibilities :

When the military was moving from M14 to M16, the new plastic rifle seemed like a toy compared to the man's gun (M14) with a wood stock and big bullets (ie. Mickey Mouse).

A friend who was in the Army said that his buttstock said "Mattel" on it which reinforced the above sentiment. If you dig into it, I think you'll find that the Mattel Toy Co. contracted to provide some of the M16 buttstocks.

To a lesser degree (in regards to the above), in Chevrolet racing nomenclature the small block is affectionately known as the "Mouse" motor.
The big block is known as the "Rat" motor.
Just never heard it in relationship to ARs
 
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Dont forget... theres also the Colt trigger pin diameter being larger than everyone else's... as far as I am aware. That is why most if not all the AR kits have the statement of " some Colt lowers use a larger diameter pin for trigger, if your lower needs the larger pin, order it *linky* here". There is also the possible issue of receiver pivot pin size but I think the vast majority of Civilian AR15s all use the same 0.250" receiver pin diameter.. some of the Colt Sporters, mostly those from the 60s til the 96 models had larger receiver pivot pins. Only of interest if you come across a vintage "prepan Colt" sporter upper or lower assemblies and want to upgrade or replace parts.

Edit. Any AR15 BCG will work with the PSA upper.
 
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Dont forget... theres also the Colt trigger pin diameter being larger than everyone else's... as far as I am aware. That is why most if not all the AR kits have the statement of " some Colt lowers use a larger diameter pin for trigger, if your lower needs the larger pin, order it *linky* here". There is also the possible issue of receiver pivot pin size but I think the vast majority of Civilian AR15s all use the same 0.250" receiver pin diameter.. some of the Colt Sporters, mostly those from the 60s til the 96 models had larger receiver pivot pins. Only of interest if you come across a vintage "prepan Colt" sporter upper or lower assemblies and want to upgrade or replace parts.

Edit. Any AR15 BCG will work with the PSA upper.
I believe Colt has stopped with the oddball large pins.
The cut-off date was mid-2009 and coincided with the release of the 6940.
 
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PSA and Sarco are great budget sources for parts. Not sure of JSE Surplus but they sometimes have just what one needs if theyre after a particular style/look..... bit more money though. Model 1 sales and Del-Ton are also pretty good. And someone here says Curts Discount shooters in Milwaukie tends to have a bargain bin with take-offs for AR15s?
 
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I am looking for a BCG that will work with the upper to my 1st AR I've pieced together. I've heard there can be some compatibility issues with Mil spec pieces.

This is the upper I've bought. Nothing too fancy, just something for my first go at an AR.
PTAC 16" Carbine Length 5.56 NATO 1:7 Nitride M4 Upper - Without BCG or CH - 39236

Do I need to use a specific type of BCG for this? Thanks for any help.
Buy from a good company. That's about all you can do. The nice thing about an AR is the headspace is done for you thanks to the barrel extension.
 
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Bolt affects headspace which affects accuracy. More headspace means more chances of the bullet hitting the lands off center or something like that.
This is why keeping parts in spec and keeping an eye on the accuracy of a turning center and mill to make the bolts and extensions is key.

When I did, I was told to keep my tolerance on the bolts a couple tenths. Less than half a thousandths.
 

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