Colt AR-15 SP-1

A

Adventurer_96

New member
Will the lower receiver on an SP-1 accept other upper receivers other than the standard SP-1 without modification? I may buy an SP-1, and then get another upper, but I want to make sure the pivot and takedown pin holes are not drilled to a different size.
 
Just make sure it's a Colt 'large hole' upper. You'll be able to tell the difference - the SP1's takedown pin hole and the pivot pin are different sizes. The pivot pin hole is larger.

I just dropped a sweeeet 20" preban HBAR on top of my SP1 in trade for the original 16" lightweight upper that was on it. Dropped right in place without a wimper.
 
I have used an old SP1 lower in so many different variations that I couldn't even count them. The advice that yankytrash gave you is correct. It also is no big deal to use non-Colt uppers on your SP1 lower. You just need a simple adapter pivot screw that only costs a few dollars. Best. Watch-Six
 
The only thing that would keep me from getting an AR is:

1. Another AK.

2. An RPK.

3. My paycheck.

We shall see who wins this battle.
 
If this helps your decision any, I'd dump the RPK idea.

I had a Valmet M78 (RPK knock-off in 308). Heavy doesn't even begin to describe the gun.

Then add in the general inaccuracy and inadequate range of the 7.62x39, and you've got a gun that'll see more time in the safe than on the range.

Owning that Valmet was like owning a boat - the happiest days of my life were the days I got it, and the day I got rid of it.
 
Just bought a Bushmaster 16" AR-15 and in the catalog it came with are some pins for adapting a Colt Large Hole to the Small Hole Uppers or Lowers (Have pins to go both ways).

Don't know if their website has them but if you need to mate Colt and Bushmaster Uppers/Lowers this would help.
 
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