.300 Blk For PA Deer Season

My friend Brian Miller sent this to me.

Making an Ar-15 legal for Pennsylvania deer season.

I have wanted to use my 16″ M4 AR in deer season. Unfortunately in my home state of Pa, in stock configuration, that is not legal.  So I decided to remove the gasblock and gas tube, and machine a ring out of aluminum to block the gas port.


I decided to use my Vortex Viper PST 2.5x10x44 in a QD Larue mount.  This is the optic I am planning on using for open class in 3-gun next year. The scope might be bordering on overkill, but it is what I had laying around.  I do not pick up the front sight post in the scope when it is mounted.



It would not matter because the front post is coming off anyhow.

I have always wondered approximately how much velocity is lost cycling the action, so I decided to chrono my shots before and after my gas system was blocked.

Now I realize this small test is not terribly scientific, but the results were interesting to me.

Cute little devils aren’t they.

I used hand loaded ammo with the charges weighed exactly the same on my digital scale. I shot the groups at 50 yards in the same environmental conditions.

5 rounds 110 grain Vmax with gas system intact:
High 2267 fps
Low 2251 fps
Average 2257 fps
ES 16
SD 6

Group size at 50 Yards


5 rounds of 110 vmax with the gas system blocked:
High 2291
Low 2255
Average 2267
ES 36
SD 13
Group size:


When cycling the action I racked the bolt and pushed on the bolt catch to lock back the bolt on each round. Then dropped the bolt by hitting the catch.  I thought it would be the most consistent method.  I am not really sure what is going on here relative to the group size.  Both groups felt the same when the shots broke, I called no flyers in either group. I have heard rounds fired out of an AR where the bolt was dropped manually was not as accurate, but I had always dismissed it. Maybe I should reevaluate that thought.  Shooting the rifle with and without the gas system did feel different to me.  Shooting it semi, the shot would break and the crosshairs would rise then drop back on target.  Without a gas system, they would rise and not really settle for me. This is attributed to the mass of the bolt carrier and buffer slamming back into battery.  I am looking forward to trying this rifle out this year.  Running the data through my Strelock app on my phone, I think it will work fine for digging them out of the brush on my property.


Nicholas C

Co-Founder of KRISSTALK forums, an owner’s support group and all things KRISS Vector related. Nick found his passion through competitive shooting while living in NY. He participates in USPSA and 3Gun. He loves all things that shoots and flashlights. Really really bright flashlights.

Any questions please email him at nicholas.c@staff.thefirearmblog.com


  • Anonymoose

    That sounds like a real PITA to go through just to use an underpowered round (for hunting deer anyway). A cheapo Mosin is better suited to deer hunting than an unblocked AR15.

    • iksnilol

      Or get one of those mini-mausers in 5.56 or 7.62×39.

      • Kelly Jackson

        CZ 527 all day long

      • Evan

        I just use a Mauser Kar98K in 8mm

    • Echo5Charlie

      The .300BLK is a fine round for deer hunting in PA.

      • Anonymoose

        I’m just gonna leave this here: http://www.thetruthaboutguns.com/2015/12/tyler-kee/hunting-sometimes-you-cant-fight-bad-luck/
        From now on I’m not going to trust anything less than 175gr out of a .308 for deer.

        • Don Ward

          I am assuming this is meant to represent a deer shot by a .300 Blackout round? If so, you have to admire that stopping powah!

          • RocketScientist

            Nope… form a .308 win. loaded with Monarch 150 gr soft points.

        • manBear

          Yes – rely on a larger/fancier/faster/heavier bullet, rather than shot placement? Always love this one… Not sure exactly what went on here, or if it’s even legit – don’t really care. But if you double-lung a deer – it will die. I’ve killed a truckload of deer with bow, .223, .243, .270, 30-06, .muzzleloader, even 12 gauge slug. All about where you poke em

        • nadnerbus

          Holy crap! Necro dear laughs at your puny bullets…

    • BryanS

      Or, use the rifle you have and are proficient with.

      I would love to use my M1 for PA deer season. Although I will wait for someone to tell me that 30.06 isnt good for deer……

  • Ramsey

    It is hard to tell from the photos how much clearance you have between the machined gas port block and the handguard. Is it possible they interfere under recoil? I have also heard of using weights to tune the harmonics of the barrel. If the gas port block is much lighter than the normal gas port assembly it might be causing strange harmonics.

    Could be a good excuse to drop $25K on high speed photography equipment.

  • TheNotoriousIUD

    Doing all that to cycle each round sounds like a pain. And probably loud too, at least you can work a bolt action quietly.

    • Phaideaux

      What, you can cycle in another round quietly after the cacophony of noise that is a gunshot? Doesn’t seem that important somehow.

      • TheNotoriousIUD

        I dont hunt anymore so I dont care but I know people who are slightly fanatical about extraneous noise in the field.

      • iksnilol

        Think about chambering a round before the shot? Then it is important.

        • Phaideaux

          Unless there’s some crazy law about having an empty chamber in PA that I am not aware of, why would you not have one already chambered?

          • iksnilol

            I dunno, common thing for hunters to do here in Norway. Something about not trusting safeties.

          • Phaideaux

            Generally speaking neither do Americans, and you shouldn’t trust that the chamber is empty either frankly. Your first and best line of defense against an accident is to not point it at anything alive that you don’t want dead, and to keep your finger off the trigger.

          • iksnilol

            Makes sense. I just remembered it because I always see hunters carry their rifles with the bolt open – only chambering when they actually need to shoot. So quiet rifles are appreciated in Norway. Others decock their rifles while keeping one in the chamber. IIRC the Sauer 303 was applauded for allowing you to decock it quietly.

  • JBC

    Hopfully Tom Wolf will see this and get the game commission going…As far as comments about it being an underpowered round, do what you want. So long as its legal, moral, and ethical who cares. I’ve come across anonymous douchebags that poach out of season with their “cheapo” imports. I also know plenty of successful hunters who won’t go with anything but primitive. Shooters choice.

  • Eric S. Nagy

    Never heard of this bs? Most states I know you can have a semi-auto rifle you just are restricted to a 5 round magazine.

    • Nicholas Chen

      PA laws are different. It has to be manual but there is no capacity limit.

      • Jsim

        Also no hunting on Sundays, and you are now able to use semi-auto shotguns but limited to 3 rounds

        • lardmonkey1

          there are a small number of thing that can be hunted on sundays but not large game.

      • WT

        You need one of these Australian made straight pull bolt action rifles with spring assist.

    • Kelly Jackson

      That’s why they call the Remington 7600 an Amish machine gun

  • Jpaul

    Why would you use an ar for hunting?…… Kids these days.

    • RocketScientist

      Yeah, I agree! Who the hell wants to hunt with a lightweight adjustable modifiable ergonomic rifle they already own? Just go out, spent another $500 bucks on a less-comfortable single-purpose rifle so you can make other people feel better about your firearms choices for chrissake!

      • Echo5Charlie

        While I obviously don’t speak for the OP, I did take his comment as tongue-in-cheek.

      • Don Ward

        Or, you know, get a rifle in a proper caliber to reliably and ethically take down game animals.

        • RocketScientist

          Like the .30-30? One of/the most popular deer cartridges in America? The one that uses the exact same bullet diameter as the .300 blk, and which there are several .300 blk loading that get the same velocity out of as 16″ barrel as? That sort of proper cartridge?

          • BryanS

            Cant use those new fangled 1950’s designs to take an animal, you have to reply on 1880’s tech. Just not “‘tridishinl”.

          • Don Ward

            More like the Mall ninjas need their 30-round magazine and 8 more in their battle carrier just in case you need to lay down suppressing fire on the deer or ISIS terrorists show up wanting to convert you to Islam while you’re out deer hunting.
            And yes, you can see this out in the woods during hunting season.

          • Don Ward

            Comparing a .300BlackOut to a 30-30 is a slur to the latter.

          • Quasimofo

            Let’s be honest here with this comparison. 30-30 is typically pushing a heavier bullet at least as fast out of a typical barrel length, so it has a noticeable energy and sectional density/penetration advantage over the 300 BO.

            That said, 300 BO is a perfectly adequate medium game cartridge with the right loads and right ranges. But, unlike the 30-30, I’d be hesitant about using it on game larger than deer or pigs.

        • iksnilol

          Is 7.62×39 too light for deer?

          Because 300 BLK is basically the same (slightly weaker tho).

      • Jpaul

        Bro calm down, I was mainly only joking, do you need your pacifier back in?

        • RocketScientist

          Ummm, my reply wasn’t exactly funeral-serious itself, “Bro”. At least mine was obviously sarcasm, yours wsa very believable as an honest opinion, based on other comments above, and even some of the replies to my comment.

          • Jpaul

            Bro, they make stuff for butthurt. You’ll be fine

  • MrEllis

    If it’s true guns are tools, sometimes there’s a better tool for the job. I mean grats on getting it done, of sorts, if it was just the technical challenge you wanted.

  • Rick5555

    You could’ve put an adjustable gas block on the AR. And turn the gas port off using the adjustable gas block.

    • Nicholas Chen

      Unfortunately that is not acceptable by Game Wardens in PA. I asked.

      • lardmonkey1

        It cannot be field modifiable to semi-auto

        • Laserbait

          Heh. The bunny sheriffs in PA must not know about allen wrenches. Takes about 2 minutes to swap out a gas block (in the field even).

          • Cymond

            I think you could build an entire AR in the field with tools that would fit in a large purse.

  • UCSPanther

    A Steyr M1895 or a Ross style straight pull in .300 blackout or 7.62×39 would be a cool idea.

  • Don Ward

    Holy heck guys. Just get a lever action 30-30 with a proper hunting cartridge or pony up for a bolt action gun in .308, 25.06, .243 or any number of cartridges that have been getting the job done for 50 to 100 years.

    • Nicholas Chen

      Archery has been around even longer. What’s your point? Just because you have different ammunition/firearm preferences does not mean everyone must conform to your ways.

      • Don Ward

        Yeah. And I have seen the aftermath of plenty of stick slingers who poke a deer or elk and have it run off and die and rot because they can’t get a proper hit. That’s after cutting the fence on your property to hunt illegally.

        Fair Chase rules apply.

        • JK

          Divide and conquer, boys, divide and conquer.

    • RocketScientist

      A) why the f**k would any intelligent person shell out $500+ for an entire additional gun, to be used for a single purpose, when they already have a lighter, more ergonomic, more modifiable gun on hand?

      B)You do realize that there are many .300 blk loadings that give identical performance to some of the most-favored .30-30 cartridges?

      • BryanS

        This. I think too many people think that just because you own one rifle and nice scope, you have the cash available to buy 5 more for doing different things.

        It would be overkill for hunting small game, but for this, its ballistically proper.

        These guys are the reason we cant have semi-auto hunting in PA, or Sunday hunting, or any number of things.

        • Don Ward

          The reason you can’t have semi-auto hunting is because of Mall Ninjas who wound too many deer. That and they’re the sort who get bored when bambi doesn’t wander into their sights in the first 30 minutes of hunting season and spend the rest of the time mag dumping at squirrels.

      • Gruul

        A). Because people who primarily use a rifle for hunting don’t really need a mall ninja gun to do what we’re doing. And my marlin weighs as much as an ar and can do everything I need it too.

        B). You do realize 30-30 is easier to find (least in PA) and is much cheaper. Maybe you shouldn’t judge people based on what caliber and firearm they use

        • RocketScientist

          You missed my point entirely. It was this, if someone already has a gun that is well-suited to the task at hand (or can be turned into one for a trivial cost and time investment), it is stupid to shell out hundreds of dollars on ANOTHER gun, just to satisfy some random person’s ideal of an appropriate firearm. In line with that belief, the effective Marlin that you already have and (presumably) shoot well with, and does everyhting you need it to sounds like an awesome gun. I like my old Marlin immensely, its a beatiful gun and handles like a dream (the newer ones I’ve handled I’m not so enthusiastic about). More importantly, in the spirit of the point of my comment, it doesn’t matter AT ALL what I think about your rifle, so long as you’re happy with it.

          OP had this AR already, he added a few bucks and a few minutes of time to it, and turned it into a perfectly functional perfectly effective game-taker. And there are people like the person I replied to harranguing him for not going out and buying an entire new rifle, just because they don’t like him hunting with an AR. THATS what I was railing against. Not people using traditional hunting arms or chamberings, not at all.

          And as for ammo availability, I don’t know the last time I bought ammo in a physical store. I purchase mostly off the internet (found that even with shipping it works out being cheaper or at least the same as buying in a store, usually have better selection and the hassle factor is a lot lower) or reload, for which the price difference in .30-30 or .300 BLK is inconsequential once you have the brass (which i do). So I guess if you don’t reload and only buy from a physical store I’ll take your word that it’s hard to get your hands on .300 Blk (though again, in the case of OP, he already has the gun, and presumably already has the ammo, so its a moot point).

          • bmiller

            Yes I reload for the 300 blk. Actually use my .556 brass with cracked necks to make the .300 cases. I actually purchased the blackout because I love experimenting with cast bullets. The v-max bullets pictured is the first purchased jacketed bullets I have fired in it. Everything else has been a coated homemade cast bullet. I just didn’t have time to whip up a batch before season. I even go as far as making my own gas checks from aluminum flashing. This project was just for the heck of it. I also have a Marlin 1895 Guide Gun in 45-70. It has flattened quite a few deer. My favorite load for it is a 400 grain hollow point cast from wheel weights at 1550 fps. Typically there is no tracking involved. I am not exclusively tied to mall ninja guns.

          • Tom

            “. I even go as far as making my own gas checks from aluminum flashing. ”

            Keen to try this out, linky pretty please?

        • raz-0

          You sound pretty judgy. You own a marlin. Why replace it. He owned an AR in 300 black, why replace that?

          The price of ammo isn’t going to change the overall economics. I’ve got a variety of guns, and if you told me I was hauling one around all day hunting, the two I would consider are my 16″ marlin and my 16″ AR. If accuracy was going to matter, I’d pick the AR all day long as the marlin is MAYBE a 2.5 moa gun with it’s favorite ammo.

          If I didn’t own a marlin and I did own a 300blk upper, I can say that a welded up $30 gas block would be a heck of a lot more attractive than $500 for a marlin. I’m pretty sure the other $400+ would cover some ammo.

          • Tazz

            You sound judgy

          • raz-0

            Yes, but I’m not lecturing people on how they shouldn’t judge while being judgy.

      • Don Ward

        Or, you know, hold off on building that 10th AR which is nearly identical to the other 9 ARs gathering dust in the safe and get a gun that gets the job done.

    • iksnilol

      Proven fact: The rifle you already have is cheaper than buying a new rifle.

      • Don Ward

        Proven fact. The majority of gunowners who own guns, own multiple. But yeah, I’m the one here with the outlandish notion that a gunowner should have a proper deer rifle in his arsenal.

        • iksnilol

          I’m the guy who doesn’t harp on people to buy another tool because they might not want to spend the money on another rifle that won’t get used much or a rifle they can’t afford.

          Also, what constitutes a “proper” deer rifle? Sounds awfully fuddy to me.

  • bmiller

    I have an update. I was able to take a doe with the rifle. It was completely relaxed, grazing, it was looking at me, but didn’t seem to care. That is the way I prefer to take them, I have shot deer that were pushed and stressed out and they seem much stronger tasting to my taste buds. The shot was approximately 150 yards quartering toward me. With this rifle and load, it has a 50, 150 zero. I took the shot. When the bullet hit, it sounded like a water balloon popping. It juked down and ran off into the woods. It was recovered about 20 to 25 yards inside the woods. Not much of a blood trail, but good enough. I hit it between the neck and shoulder where I was aiming. It destroyed the lungs and the top of the heart. About a nickel sized entrance hole, no exit. I did not recover the bullet. My friend who processed the deer thought it wasted less that a cup of meat. All in all, I think it is a great meat gun for deer. Does it hit them with as much authority as my .300 ultra mag? No, but it doesn’t have 6″ exit holes either. I really enjoyed hunting with the rifle. I put my Vtac sling on it, and that made getting in and out of my ladder stand very easy. (I am NOT fond of heights!). I had the rifle laying around and always wanted to take a deer with it. I would love to see Pa make semiauto rifles legal for hunting, but I am not holding my breath. I also found I got normal groups with racking the charge handle and just letting it drop, rather than using the bolt catch. I am still not sure what is going on there. I do not think this is the ultimate deer rifle, but it served me well and sure was fun! I think my next project is going to be a Savage short action in 6.5 Creedmoore in a Ar-like chassis coming in around 6.5 to 7 pounds in weight. That just might be the perfect rifle.

  • JBC

    Stop being different bmiller, people are about to fight!!