To SBR or not to SBR.

[Neomet]

Upfront I will say I love my carbine length MPX.  That said I am curious if there is any real advantage in our game to SBRing it.  Cost isn't really a factor.  I can tax stamp the one I have and once it finally arrives either get an 8" barrel from SIG (assuming they ever decide to actually make spare barrels rather than just advertise that barrels interchangeable) or cut my current one down.  I figure it will lighten up the gun a bit and move the balance point further back a bit.  I haven't found the length of the carbine to be an issue but arguably shorter would be better.  

On the down side while it can certainly be done it is kind of a PITA to take a SBR into another state and I do travel to shoot.  I also current hold my off hand further down the handguard than I could if I SBR it.  

Thoughts?  Comments?  Anyone actually done it???

 

[Posvar]

Great thread. I started with a new pistol last week and will be getting the SBR paper work done to it next week and then the long wait. I like the pistol enough that I will be getting the carbine and will leave it in that form for out of state matches if that need arises. The SBR will most likely be the go to gun for PCC at this point. I too grip farther down the guard but the pistol will be doable with a longer LOP stock. 

 

[Aircooled6racer]

Hello: I have been thinking about this as well for an AR based rifle. I have been told the paper work is not that much of a big deal when you go out of state for a match. Now is a short barrel really going to help that much in USPSA. I think it would depend on the coarse of fire and the stage setup. A really tight side to side transition stage it would really help but a field coarse I am not sure. I have been looking at barrels in the 7 1/2-10 1/2" range that could be suppressed in the future. Using a longer hand guard would help with recoil also. We have a couple of guys here shooting SBR's and they do alright but not that much better than the guys shooting longer barrels. Thanks, Eric

[bwikel]

Don't let the NFA transfer across state lines paperwork scare you, it's pretty painless. Just fill out a 5330.20 at the beginning of each year for the name and address of each range you will be shooting at and list the dates of Jan. 1st through Dec. 31st. and you are covered for the entire year.

[Sarge]

1 minute ago, bwikel said:

Don't let the NFA transfer across state lines paperwork scare you, it's pretty painless. Just fill out a 5330.20 at the beginning of each year for the name and address of each range you will be shooting at and list the dates of Jan. 1st through Dec. 31st. and you are covered for the entire year.

Compared to just packing up the truck and going to matches even that seems like a PITA. For just fun and games I prefer the KISS principle.

[IntenseImage]

I started w Carbine ... Added 10" Lancer handguard w plans to cut barrel and slap a comp on just after the handguard



It was a great idea and may still happen later but I came across an 8" upper and just went to that for now - with a thread adapter and linear comp to clear the longer handguard

I'll see if SIG will sell me a carbine barrel and will chop that as planned and then cut this to 4.5 for suppressed use

[Posvar]

I like the 10" lancer guard. Nice looking piece!

[Neomet]

1 hour ago, IntenseImage said:

I started w Carbine ... Added 10" Lancer handguard w plans to cut barrel and slap a comp on just after the handguard



It was a great idea and may still happen later but I came across an 8" upper and just went to that for now - with a thread adapter and linear comp to clear the longer handguard

 

I'll see if SIG will sell me a carbine barrel and will chop that as planned and then cut this to 4.5 for suppressed use

 

What if any differences can you tell between the carbine and SBR while shooting??  

[Posvar]

I too would like to bear Brian's comments on the above question 

[IntenseImage]

I haven't put that many rounds through the shorter upper yet. From just messing around w those coupled mags, I don't think there will be a huge difference. When I have time I am going to setup a gridded target and try the 8" w flash hider and the NERD comp I have and track dot movement. Then I'll switch to the 10" handguard and linear comp and do the same check. I know the shorter length will help for USPSA when moving around is needed

[usmc1974]

20 hours ago, bwikel said:

Don't let the NFA transfer across state lines paperwork scare you, it's pretty painless. Just fill out a 5330.20 at the beginning of each year for the name and address of each range you will be shooting at and list the dates of Jan. 1st through Dec. 31st. and you are covered for the entire year.

This will be my first SBR, I was not aware of this, Is there some kind of waiting period for this?

[Doug H.]

23 hours ago, bwikel said:

Don't let the NFA transfer across state lines paperwork scare you, it's pretty painless. Just fill out a 5330.20 at the beginning of each year for the name and address of each range you will be shooting at and list the dates of Jan. 1st through Dec. 31st. and you are covered for the entire year.

Wrong form, you mean 5320.20.

Doug

https://www.atf.gov/file/4781/download

[bwikel]

18 minutes ago, Doug H. said:

Wrong form, you mean 5320.20.

Doug

https://www.atf.gov/file/4781/download

Oops I fat fingered that one.

 

3 hours ago, usmc1974 said:

This will be my first SBR, I was not aware of this, Is there some kind of waiting period for this?

It is a notification of the ATF of your transferring the item across state lines. There is no waiting period just a confirmation they got the form.  

Edited December 28, 2016 by bwikel

[robertg5322]

How much more powder is required to make power factor with a short barrel?

Any detrimental increase in recoil associated with it?

Not that it matters for me, California being the statist he'll that it is.

[DocMedic]

probably not as much powder as it would take to make powerfactor with a pistol

 

[usmc1974]

is not PCC all scored minor?

[robertg5322]

It is. But all things being equal, more powder is usually required ro attain a given velocity in a ahorter barrel.

 

Bob

[IntenseImage]

It is. But all things being equal, more powder is usually required ro attain a given velocity in a ahorter barrel.

 

Bob

If you have rounds that make minor in a handgun you are good to go

[Tom Freeman]

The SBR process is easy.  Keep in mind you are pretty much married to that gun now that it is a Title 2 firearm.  Selling it to someone means they have to pay the $200 tax to Uncle Sam to buy it form you.

Just because it is a SBR does not mean you have to run a short barrel on it.  If you make a permanent change you must notify the ATF, other than that pick the barrel length that suits you.

Short guns swing easier/faster.

The CDI factor is off the charts on SBRs.

[robertg5322]

54 minutes ago, IntenseImage said:

If you have rounds that make minor in a handgun you are good to go

 

Yeah, I get that.

 

But for the same reason I won't be shooting 150 power factor in my pistol (we're talking USPSA matches here), I'd rather not shoot 150 power factor in my rifle. Less recoil, less dot bounce, less time between shots. 

So, since you have a shorter barrel (hence the term Short Barreled Rifle), logically it should require more powder (than a 16" barrel) to make minor power factor. More powder equals more gas/boom, equals more bolt speed (blowback system here), more dot bounce. 

My question was whether it actually required more powder to make minor power factor in an SBR than a 16" barreled rifle, and if yes, was there also an increase in felt recoil?

[Aircooled6racer]

Hello: I will be building a AR 9mm pistol with either a 7 1/2" barrel or a 10" barrel. I will chrono it and compare it to my 16" barrels. I am thinking they maybe very close. As for which one will be better a short barrel rifle or a 16" carbine, I am not sure. Thanks, Eric

[robertg5322]

Looking forward to your post.

 

Bob

 

[Posvar]

^^^It may be 8 months or so

[SpaceMan]

15 hours ago, Tom Freeman said:

The SBR process is easy.  Keep in mind you are pretty much married to that gun now that it is a Title 2 firearm.  Selling it to someone means they have to pay the $200 tax to Uncle Sam to buy it form you.

Just because it is a SBR does not mean you have to run a short barrel on it.  If you make a permanent change you must notify the ATF, other than that pick the barrel length that suits you.

Short guns swing easier/faster.

The CDI factor is off the charts on SBRs.

 

The only downside to SBR would be if you shoot matches out of state. While I am not the most versed on the laws regarding it don't you have to file paperwork while transporting a nfa item to another state?

[jcalvert86]

On 12/27/2016 at 6:43 PM, IntenseImage said:

I'll see if SIG will sell me a carbine barrel and will chop that as planned and then cut this to 4.5 for suppressed use

 

Mind sharing the stock adapter/tube details?