My SPR Build Thread

[fyroc]

I've been trying to decide what I want this rifle to be. The lower is built, except for the Geissele 2 stage trigger that's in the mail and a temporary magpul MOE stock.

I know I'm going to be using the Mega 18" SPR barrel and a RRA upper.

I just can't seem to decide if I should do a MK12 Mod 0 type SPR or do a complete "custom" job.

EDIT: As you can see I decided to do the MK12 Mod 0... but using parts I like and/or already have.

Parts List

 

[boss_hawg]

I vote for a nice clone...but that's just me

 

[Cudruln]

That is a hard decision.




So make it easy and do both. Seems legit to me

 

[fyroc]

That is a hard decision.




So make it easy and do both. Seems legit to me

I keep going back and forth because of the cost of the MK12 Mod 0. $350 for the handgaurd, $200 for the swan sleeve, $200 for the gas block/sight, $200 or so for the muzzle device and collar... but damn dont they look sexy?

 

[becausefu]

I'm not a fan of clones. I build for form and function, not looks.

 

[Cudruln]

I keep going back and forth because of the cost of the MK12 Mod 0. $350 for the handgaurd, $200 for the swan sleeve, $200 for the gas block/sight, $200 or so for the muzzle device and collar... but damn dont they look sexy?

They are very nice and I will have me one some day.

 

[fyroc]

So I have decided to do both. I'm going to use MK12 Mod 0 furniture with my own custom parts.

Upper: BCM (Inside Diameter for barrel extension slightly undersized)
Lower: Anderson (because I have a shit load of them)
Barrel: Mega Arms 18" SPR Match Barrel
Gas Block: PRI flip up sights
Rail: PRI GenIII Round Free Float Forearm Rifle Black w/swan sleeve
Stock: Colt A1
Grip: Magpul MOE
BCG: I havent decided yet. Maybe PSA Full Auto?
Muzzle Device: Ops Inc 12th w/collar

 

[becausefu]

Why would you want the barrel extension undersized?

 

[fyroc]

Why would you want the barrel extension undersized?

It fits the barrel nice and snug in the receiver. Meaning less wiggle, and more accurate of a rifle.

 

[Wallace]

Why would you want the barrel extension undersized?

They made the inside diameter of the receiver slightly smaller so as @fyroc said, to fit their barrel more snug.

As for going clone or not, I would go with what you want. If you want the clone, just do it. If you think you would feel more comfortable with a different setup, just go with that. I personally like the MK18 Mod 0 the best, but you need to form 1 the lower.

 

[Cudruln]

Ready to see this build get started.

 

[becausefu]

If the extension is UNDERSIZED doesn't that mean it's smaller than what it's supposed to be? If it was slightly OVERsized I could see it fitting tighter but not an undersized part fitting tight

 

[fyroc]

If the extension is UNDERSIZED doesn't that mean it's smaller than what it's supposed to be? If it was slightly OVERsized I could see it fitting tighter but not an undersized part fitting tight

If a hole is undersized and you put a pole in it then it would be tighter. Same concept.

The threaded part on the barrel is the for the extension... where the barrel goes into the upper.

 

[becausefu]

If a hole is undersized and you put a pole in it then it would be tighter. Same concept.

The threaded part on the barrel is the extension... where the barrel goes into the upper.

A barrel extension is on the barrel ....that's why it's called a BARREL extension. Go look it up on brownells. ...you can buy a barrel extension.

The threaded part of an upper is just part of the upper ... it doesn't have a name

 

[fyroc]

A barrel extension is on the barrel ....that's why it's called a BARREL extension. Go look it up on brownells. ...you can buy a barrel extension.

The threaded part of an upper is just part of the upper ... it doesn't have a name

You are correct. I may have said that wrong.

The inside Diameter for barrel extension is slightly undersized for a tighter fit to the barrel. I may have worded what I was saying confusing.

 

[becausefu]

Basically you could have just said that your upper is out of spec

 

[Wallace]

Basically you could have just said that your upper is out of spec

It's in spec for BCM. They made it that way.

If you assemble one, you will notice the difference and see it as an improvement. It doesn't feel as sloppy like some of the other manufacturers machine theirs too. I mean, I had a RedX receiver you could noticeable rock the barrel extension in the receiver with. A BCM will have very very little to no-play. They even recommend using a heat gun or hair dryer on the receiver threads if it's a tad too tight for your barrel extension to fit. I would rather have that snug fit than a hot dog down a hall way, slutty receiver fit.

 

[becausefu]

I never said it was a bad thing, I'm just saying that it's not built to mil specs.

 

[Jake]

I see some things never change. SMH.

 

[fyroc]

Lower is now completed. The barrel and upper is on the way.