300 AAC Blackout barrel twist
With a 300 AAC Blackout with a 1 in 7 twist barrel can I expect to get good accuracy with 110 to 125 grain bullets? thanks
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A 30 Carbine is like 1-16. I wouldn't expect good accuracy, but good accuracy is a tricky question. If you shoot enough ammo, the broad side of a barn can be one ragged hole. 0 -
Here's what I found. I assembled my first 300 using a Red-X 1-10 barrel. It shoots 110 supersonic up to 190 @1200fps very well. My second 300 uses a DPMS 1-7 twist barrel. It shoots the 190 very well, 150 grain Ballistic Tips well enough for hunting, and the 110 supersonic about 3-4" groups-not good enough for anything except making noise. 0 -
quote:Originally posted by Dave45-70
With a 300 AAC Blackout with a 1 in 7 twist barrel can I expect to get good accuracy with 110 to 125 grain bullets? thanks
I didn't get good accuracy using 110 to 135 grain bullets from my Remington 700 in 300 AAC. I had the 16" heavy barrel with the 1 in 7" twist. I reload tried all sorts of powder combinations but just didn't get consistent, good groups with lighter bullets. Got them every once is a great while, but very consittly got evenly dispersed +2" groups @ 100ds.
I bought the rifle to have a 30 caliber 100 yd plinker - light bulets, a little powder. Sort of a 30 caliber version of a 22 Hornet. It just didn't work out.
Looking back one thing I would have done different (have since reworked the rifle to a 6X45/223) is use factory 300 AAC brass rather than reworked 223 brass. When using reworked 223 brass what was the lower part of the case becomes the neck. I know from the differing resistance I felt seating bullets that neck tension varied. My guess is that differing case wall thickness contributed to poor accuracy. Others have done just fine with cut down 223 brass, I mention it as a possibility and not a certainty, something I'd do differently.0 -
Dave45-70,
Where barrels and ballistics are concerned you should always expect the unexpected because there is no formula or guarantee regarding which bullet/powder combination will work the best. Many time shooters read '125 grain MC bullet' and automatically think Nosler Ballistic tips or some other commercial bullet in that weight class. Don't forget that this is a project developed for the military not for the average deer hunter. The bullets are not the same.
This is and always has been a dual mission cartridge.
The project's goals were:
Create a reliable compact .30-cal solution for AR platform
Use existing inventory magazines while retaining their full capacity
Create the optimal platform for sound and flash suppressed fire
Create compatible supersonic ammo that matches 7.62x39mm ballistics
Provide the ability to penetrate barriers with high-mass projectiles
Provide all capabilities in a shorter, lightweight, durable, and low recoiling package
The difference in loads that feature the 7.62x39 ballistics is the bullet. They didn't load the lightest bullets such as you are asking about but rather concentrated on the 125 and 130 grain bullets for supersonic performance and energy. Then they used the 220 grain for subsonic performance.
From AAC:
"These were our original requirements for this caliber: Muzzle energy has to equal or exceed the AK-47. .30 Caliber projectile:
Use unmodified 30 round magazines to full capacity.
Use unmodified AR-15/M-16/M-4 bolt. Gas impingement system.
Shoot super and subsonic.
And one thing that was nice, but was not a `deal killer', was non-adjustable gas system. Cycle all four ways - subsonic suppressed and unsuppressed, and supersonic suppressed and unsuppressed."
Now, anyone who has any experience in tuning ARs, whether 5.56 or .308 knows what a job it can be to make the rifle function flawlessly in both modes without an adjustable gas block. AAC was saddled with the task of making it happen without the adjustability.
If I thought that needed to make this an 'all-around rifle', I'd try something like the Barnes 130 grain TTSX bullet for deer and then opt for something slippery and long for the suppressed side.
If I was concerned about shooting a mild cartridge at short distances for deer hunting I'd use the 30 BR in a short action and put it in a chassis system which looks and feels like an AR.
Best.0 -
Dave,
Like as has been stated above, there might be a formula, for finding the required minimum twist rate for a certain length of bullet, but I have seen no maximum formula's. They say a bullet cannot be over stabilized, but I have personally witnessed instances both ways. One of which a dumb arse was feeding a 1 in 7 twist AR-15, a 40 grain Hornady TAP round. The bullet was coming unglued in flight, due to the centrifugal force of gravity being imposed up on it.
In my experience with the 300 Blackout specifically, I have a S&W, M&P-15 upper, and am shooting the Barnes/Vortex 110 grain loading, and the Double Tap load using the same bullet. I have a 1-4x scope on the rifle, and am getting 1-2 inch groups at 100 yards. I suspect I could tighten it up with more magnification. My middleaged diabetic eyes are not what they once were.
Best
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Dave,
For what it is worth that Barnes 110 grain Tac-X, will do exactly what you are looking for. I killed two with it last year, just to say I could. I put it together for my 82 year old mother, actually. It is a real mild shooter. One of those deer, was just tad short of 200 yards, and the other was about 50 yards. Think of it as being a 30-30 that shoots flatter, with less recoil.
Also, I want to add, that for a deer gun, if your state, and/or location allows it, the good old 223/5.56 is an awesome deer round out to a t least 200 yards, when loaded with the 62 grain Barnes TSX, in the proper twist. Several companies load that load, including Barnes, Federal, Remington, and Black Hills.0 -
Many thanks for the response from all you guys I appreciate you taking the time.I love the AR platform and was looking for a short range deer rifle with little recoil.(injured shoulder)I think 150 gr ballistic tip should fill the bill for less than 100 yds.My personal feelings are that the 223 is not enough but I know some will disagree with that but just my opinion. Thanks again 0 -
If shorter range hunting on light skinned game is the goal wouldn't an AR 15 in plain old 7.62X39 work well? I have one and it shoots well. I suppose the 30 AR cartridge would do well - if it actually existed .....[V] 0 -
I have loaded 150 BT with 19 grains of AA1680 which seems fairly conservative so I'm going to chronograph the 20 grain loads to see where I'm at on velocity before going higher. I want a load that's safe and usable in both barrels with enough accuracy to be comfortable taking 100 to 125 yard shots on deer. If that doesn't play out, I have Speer 110 HotCor and/or 125 BT bullets to use in the 1-10 barrel. Just hoping I can manage a single deer load to mess with.
I, too, feel the 150 BT is an adequate compromise bullet producing better accuracy(in the 1-7) than the 110-125 with some expectation of expansion at short range. 100 yard velocities should be comparable to 250-300 yard velocities from a .308 Win and most consider the .308 an adequate 300 yard deer cartridge. The faster twist(in the 1-7 barrel)should increase expansion potential regardless of velocity vs the 1-10 twist of the .308.
"If shorter range hunting on light skinned game is the goal wouldn't an AR 15 in plain old 7.62X39 work well?"
Yes, it will and it does BUT requires caliber specific(and more expensive) magazines and has slightly more recoil. I have both 7.62x39 and 300AAC AR uppers and there is a noticeable difference. The 7.62 uses 30-40% more powder and doesn't work as well if you want to suppress it. In addition, the 300AAC works much better in a "pistol" length barrel should one choose that approach.0 -
you might take a look at the 25-45 sharps. 0
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