.223 through 1:7 twist

[jetech]

I am moving from .30 cal to .22 and have begun gathering reloading info. I would like to hear from those reloading for short barrel (16") with 1:7 twist semi-auto's. Here is the background.

The rifle is a IWI Tavor.

I have on hand H335 powder, CCI 400 primers, Win brass, 69 gr. Sierra HPBT Matchking, 60 gr. Hornady SP, 62 gr. and Nosler HP Varmageddon bullets.

I also have the RCBS small base full length X-die set.

Can you tell me your experience with semi-auto loads for short barrel accuracy and velocity. I have several sources of load data including the Sierra load data for the AR. I am mainly interested in real world results for the 16" barrel.

Thanks for any help.

 

[jwalts27]

I don't have my notes as I am at work, but the 62g will probably be your bullet that works well. Most people I believe prefer the 1:9 twist

 

[Bart B.]

While a bit fast for 69 grain bullets, shoot the darned things any way.

Be careful using that RCBS X die. Anything in the die that limits how far the case neck lengthens prevents all cases to be uniform correctly for best accuracy. There's about a .010" to .015" spread case overall (or neck) length that's good for any accuracy level you want. Overall, groups are smaller if you just trim cases back once every 8 to 10 reloads using standard full length sizing dies.

Yes, RCBS says "Cases repeatedly sized in the X-Die will initially grow a few thousandths of an inch, and then stabilize below the maximum case length with no discernable loss of accuracy or case life. ", but I think they're assuming only ordinary rifles and shooters will do that then get those results. If you shoot stuff that is no worse than 1/2 MOA at 100 yards, you'll see the difference. Even if you and yours doesn't shoot that well, I'd use a standard full length sizing die.

 

[DeadEye9]

Well these days I typically gravitate towards 1:9 for my 16" guns as it's just a personal preference, however I can share some info with the one 16" 1:7 AR I've built and tested with some of the components you mentioned. I'm a big fan of CCI primers and use them whenever possible so for all loads listed CCI small rifle primers are used. All the brass I used for these loads is surplus; WCC, LC and TAA NATO stamped 5.56 brass, full length sized and trimmed to spec every few loadings then spot checked thereafter.

For H335 and the 69 SMK BTHP, I liked 22.5gr at 2.245 OAL. This gave me 3/4 MOA from a 16" carbine which is very respectable. I also did well with Varget and the 69 SMK 24.9gr was my pet load with Varget for that rifle. Groups in the .85" size. Taking the cake with this bullet though was Viht N140. 25gr loaded again to 2.245" was the most accurate 69gr load through that rifle. I have since switched to Barnes 69gr BTHP "Match Burners" because they perform equally as well for less money and are always on the shelf in my area. If you can find those for cheaper I wouldn't hesitate as they are awesome. Weighing out 100 leaves maybe 10 that don't weigh 69 exactly, and those 10 will only be maybe .1 over/under. I pay like $15/100 so it's a good deal for Match accuracy.

Next the Hornady 60gr SP. I loaded some of these for testing on a buddies varmint control gig, and they worked very efficiently. If you leave the velocity around 2600-2750 range they don't explode like a typical Vmax and mushroom nicely. They typically created an exit wound almost every time which would have helped tracking except they all pretty much dropped on the a spot for him so he was very pleased. My load for that was with H335, 24.2gr, loaded a bit long at 2.260". This wasn't a match load, but was good for around 1.3" groups. Very lethal on game though.

Another good bullet for cheap accurate target shooting in the 1:7 for me was the Hornady 62gr FMJ-Bt. I was able to get solid 1 MOA groups with 24.6gr H335 and these bullets loaded to 2.235". .9" groups could have been realized with this load using a better rest/optic than i was using at that time.
I still use a variation of this load in my 1:9 carbines with excellent accuracy potential for a plinking priced component.
Good luck with your new loads and let us know what works for you!

 

[jmr40]

All 3 of my AR's have 16", 1:7 twist barrels. I shoot cheap 55 gr FMJ ammo into 1.5-2" groups at 100 yards regularly. They do better with 62 gr FMJ and are tack drivers with 60 gr Hornady V-Max bullets. I should be able to do better with heavier bullets, but have not tried anything else.

 

[jetech]

Thanks for the replies. I am not sure what to expect from this rifle. It has an EOTech holographic sight, I am assuming that I can expect reasonable accuracy out to around 200 -300 yards with the right load.

 

[carbine85]

Thanks for the replies. I am not sure what to expect from this rifle. It has an EOTech holographic sight, I am assuming that I can expect reasonable accuracy out to around 200 -300 yards with the right load.

You can expect 3/4" - 2" groups. Your EOTech will cover most of your targets so you won't get scope type accuracy.
The small base dies are fine. I have used RCBS SB dies for 30 years. I also use Lee dies.
The 1:7 in only popular because the military uses it to stabilize the longer tracer rounds and everyone wants what the military has. I have a 1:7 that shoots great and accurately.
My most accurate is a 1:8 with 69 gr SMK. People are starting to catch on to the 1:8 and manufacturers are providing more offerings.
My go to powder is IMR4895. H335 is a close 2nd for me in the AR15.
You will just have to experiment and see what works best for you.

 

[Reloadron]

I have two AR rifles with the 1:7 twist. The first is a Colt Sporter Target with a 20" barrel and the other is a stainless match barreled home brew affair with a 24" barrel. Only the latter is scoped and for both rifles my best shooting is Sierra 80 grain HPBT Match loading one at a time. Either rifle shoots the 69 through 80 grain bullets just fine. So while I don't have a short barrel 1:7 the loads I like best are using Win 748 and H 4895 for the 69 and 80 grain bullets. I have also been using the CCI #41 primers with good results. Obviously your mileage will vary. As to brass, this past summer I loaded quite a bit of LC 11 surplus stuff I got from Brass Bombers and it shot quite well. That's all I got...

Ron

 

[SlowFuse]

My sweet spot for the 69 grain SMK was right at 23 grains using 1:7 twist, 16 inch barrel.

It wasn't hard finding a good load with these bullets, easier than most regarding 223.

Edit: Forgot powder, this was with H335. If you find Varget it's even easier. I got better grouping with Varget over H335.

 

[jetech]

I was finally able to shoot a few test loads today. Here is what I got.
From the Sierra service rifle data for .223, test barrel 20" colt AR, 1:7 twist, H335 powder, 69 gr. Matchking.
Today's conditions:
temp = 18*F wind chill 1*F
Wind 90* left @19 mph with gusts.
Distance 100 yds.

Published load Published Vel Average Vel today
21.2 gr. 2500 2367
22.5 gr. 2600 2452
23.8 gr. 2700 2512

My best group was 2.5" with the 23.8 gr. load. This was my first time firing the Tavor so I think I can shrink the group some with more practice and a better day.

 

[Rickt300]

The 1-7 twist really shines with the 75 grain bullets, especially the 75 grain Hornady BTHP. I run 24.5 grains of BLC(2) and the CCI 400 primer. My rifle has a 20 inch barrel and it will run these into .6 for three shots. I have killed deer and feral hogs with this bullet. It tumbles after about 3 inches and still penetrates very well.