Any opinions on whether or not it would be legal to build and hunt deer in Illinois with the following configuration?

New AR lower receiver registered as "other firearm" on the 4473 (never registered as a rifle and stock never installed)
Bullet button installed
Bob sled "magazine" installed
SB Tactical adjustable arm brace installed on pistol buffer tube
16" upper chambered in 300 Blackout
Magpul angled foregrip

If it is not a legal configuration, what would need to be changed to make it legal to own and hunt with? If it is legal to build this configuration, is it legal to shoot from the shoulder if the brace has not been modified?

I apologize if some of these questions have already been asked in previous threads. Thanks in advance for your input!

The caliber of choice ofps the stumbling block here. To legally use an AR pistol, the ammunition would need to be straight wall. Something like a .458 SOCOM, 450 Bushmaster.......

Ammunition would not be legal, “....case length not exceeding 1.4 inches.....” see the copy of the Illinois DNR regulation below

I thought the case length of 300 blackout was 1.368”. I believe others are currently using this caliber in a pistol to hunt deer in IL.

A Friend is using a 300 Blackout with no gas system and a side charger upper.   He drilled a hole in the front of the lower receiver mag well and once he inserts a mag with a bobsled he threads an allen screw into the mag so the mag can’t be removed from the lower.   He has a block of would in the mag to limit mag capacity.   He is using a Sig Pistol Brace on his with a short barrel approximately 8”-10” long IIRC.   I don’t know if he’s had his pistol checked by a Conservation Police Officer but his appears to meet the criteria.

My Friend does not keep an allen wrench or spare magazines in his possession while hunting so there isn’t any practical way for him to convert his pistol to hold more cartridges.

My loading manual list a 300 Blackout case at 1.368” and a supersonic load ought to be well over 500 foot pounds of energy.

Some prior discussion that may help

300 blk for pistol hunting

https://www.ar15.com/forums/topic.html?b=8&f=23&t=626881

Thanks for the link - there was some good information in that discussion.  From everything I've read, it appears that the configuration that I've proposed would be legal to own and hunt deer with...

Dump the bullet button.  That's an unnecessary part.  
Either a Bobsled or a magazine (any capacity) with a single-shot follower installed is legal.  
No need for anything other than a factory gas block and tube either.

I've built a 300 bo ar pistol for hunting and have taken deer with it. The only thing i did was modify the mag well so no magazine could be inserted. This year i bought a barrel for the contender i already have.

Attached File


After using a 300 bo i am thinking about buying an encore so i can use the .460 s&w. I haven't been impressed with the consistancy of bullet expansion of the 300 bo. Another idea would be an ar build in .450 bushmaster.

Yes, I had a brain fart. I updated my comment in the other thread

As leonitus posted above:

"To legally use an AR pistol, the ammunition would need to be straight wall"

You are only partially correct.

From DNR website:
"For handguns, a bottleneck centerfire cartridge of .30 caliber or larger with a case length not exceeding 1.4 inches, or a straight-walled centerfire cartridge of .30 caliber or larger, both of which must be available as a factory load with the published ballistic tables of the manufacturer showing a capability of at least 500 foot pounds of energy at the muzzle. Note: There is no case length limit for straight-walled cartridges."

https://www.dnr.illinois.gov/hunting/pages/huntingdevicesandammunition.aspx

No case length restrictions on straight walled....here comes the 458 Win Mags!!!

458 win mag in a pistol?

I would use a .45-70 before a .458 myself.  
Actually I'll just stick with .300BO the  Barnes 110gr TSX seems to be killing big IL whitetails just fine with very little recoil or blast.

If you really wanted to be masochistic you could put an AR pistol together in 450 Bushmaster.

If you wanted an upgrade from 300 Blackout, there is the 338 Spectre.