Parts interchangability

odugrad · January 3, 2014, 09:57 AM

I'm still learning about rifles and possibly building one.

I have a question about lower receivers. Can you take a mid-length upper or a carbine-length upper and use it on the same lower receiver?

Can you also use any bolt carrier group for a carbine-length or mid-length rifle?

I'm assuming so because the only change is in the length of the gas tube, correct?

Quentin2 · January 3, 2014, 12:00 PM

The answer is yes in most cases. However there always are exceptions, especially when using light loaded ammunition. You might have to make a buffer swap for 100% reliability.

Really you would have to try it and see if it works with your equipment.

A lot of folks use multiple uppers on the same lower, most times it works fine.

odugrad · January 3, 2014, 01:11 PM

I know the H buffer is kind of the universal one. Are there better/more efficient buffers?

CTS · January 3, 2014, 01:30 PM

H buffer really is not the standard. The standard is a standard mil spec (weight) buffer. The H buffer (and H2 or H3) is a heavy buffer used for solving some problems you may have. There is really no way to know what buffer will work best till you try one and see. The standard carbine (or rifle, depending on which you are building) buffer is the cheapest and usually the best place to start. No need changing it if everything is working properly. BCM standard buffer $11, H buffer $22. If it ain't broke, don't fix it.

semi_problomatic · January 3, 2014, 02:03 PM

There are differences in bolts, as well. You have full-auto bolts, non milspec bolts, supertitaniumunobtanium bolts coated by nano technolodgy. I think the best way around all that is an adjustable gas system.

Oh, and generally not a good idea to swap bolts between rifles. Not unless the use protection...

And if your uppers had an adjustable gas system you could tune your upper to your lower...

odugrad · January 3, 2014, 02:40 PM

Would a BCM bold carrier group be compatible with a Daniel Defense rifle and vice versa?

semi_problomatic · January 3, 2014, 02:50 PM

Yeah. Just a full auto bolt with a heavy spring and buffer is bad juju unless you're running suppressed. They'd fit, just be way to heavy for that application.

My rifle is a spikes tactical lower, with a stag lpk, gieselle sd3 trigger, LMT BCG with the bolt that was headspaced to my barrel, ergo grip, magpul crt stock, rainier arms upper, superior barrels nitrided barrel, seekins precision forearm, pws enhanced buffertube, hogan sights and comp.... And some no name standard milspec buffer, spring, and charging handle... It all works fine together.

January 3, 2014, 09:57 AM	#1
odugrad Senior Member Join Date: March 13, 2013 Location: The East Coast Posts: 477	Parts interchangability I'm still learning about rifles and possibly building one. I have a question about lower receivers. Can you take a mid-length upper or a carbine-length upper and use it on the same lower receiver? Can you also use any bolt carrier group for a carbine-length or mid-length rifle? I'm assuming so because the only change is in the length of the gas tube, correct? Last edited by odugrad; January 3, 2014 at 11:21 AM.

January 3, 2014, 01:30 PM	#4
CTS Senior Member Join Date: November 6, 2011 Location: NE Georgia Posts: 1,070	H buffer really is not the standard. The standard is a standard mil spec (weight) buffer. The H buffer (and H2 or H3) is a heavy buffer used for solving some problems you may have. There is really no way to know what buffer will work best till you try one and see. The standard carbine (or rifle, depending on which you are building) buffer is the cheapest and usually the best place to start. No need changing it if everything is working properly. BCM standard buffer $11, H buffer $22. If it ain't broke, don't fix it. __________________ 01 FFL, NRA, NAGR, GOA. Last edited by CTS; January 3, 2014 at 01:36 PM.

January 3, 2014, 02:03 PM	#5
semi_problomatic Senior Member Join Date: July 27, 2009 Location: Ft. Polk Posts: 883	There are differences in bolts, as well. You have full-auto bolts, non milspec bolts, supertitaniumunobtanium bolts coated by nano technolodgy. I think the best way around all that is an adjustable gas system. Oh, and generally not a good idea to swap bolts between rifles. Not unless the use protection... And if your uppers had an adjustable gas system you could tune your upper to your lower... __________________ Freedom's just a word. If I'm gonna die for a word, my word is jello...

January 3, 2014, 02:50 PM	#7
semi_problomatic Senior Member Join Date: July 27, 2009 Location: Ft. Polk Posts: 883	Yeah. Just a full auto bolt with a heavy spring and buffer is bad juju unless you're running suppressed. They'd fit, just be way to heavy for that application. My rifle is a spikes tactical lower, with a stag lpk, gieselle sd3 trigger, LMT BCG with the bolt that was headspaced to my barrel, ergo grip, magpul crt stock, rainier arms upper, superior barrels nitrided barrel, seekins precision forearm, pws enhanced buffertube, hogan sights and comp.... And some no name standard milspec buffer, spring, and charging handle... It all works fine together. __________________ Freedom's just a word. If I'm gonna die for a word, my word is jello...

January 3, 2014, 12:00 PM	#2
Quentin2 Senior Member Join Date: June 18, 2009 Location: NorthWest USA Posts: 1,996	The answer is yes in most cases. However there always are exceptions, especially when using light loaded ammunition. You might have to make a buffer swap for 100% reliability. Really you would have to try it and see if it works with your equipment. A lot of folks use multiple uppers on the same lower, most times it works fine.

January 3, 2014, 01:11 PM	#3
odugrad Senior Member Join Date: March 13, 2013 Location: The East Coast Posts: 477	I know the H buffer is kind of the universal one. Are there better/more efficient buffers?

January 3, 2014, 02:40 PM	#6
odugrad Senior Member Join Date: March 13, 2013 Location: The East Coast Posts: 477	Would a BCM bold carrier group be compatible with a Daniel Defense rifle and vice versa?