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Posted: 12/21/2014 5:13:13 PM EDT
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gonna build out a .243 Winchester deer/coyote/pig rifle, and im thinking about a Krieger barrel with the 5R rifling, however they don't offer the 5R in anything slower than a 1-9.. which i have no problem with since it will be a hunting rifle and ill be using heavier rounds anyway, my only question is...
exactly what weight bullets ,, grain>90? grain>100? thanks in advance. anybody have a preference(or even just some insight) between Krieger or BHW?? |
Don't know how many .243 AR folk are out there, but I'll mention what the Armalite tech note on this says...then you can take that for what it's worth on your potential build and setup. The tech note is #23 on their site if you want to read it at length. They say this info is specifically related to their .243, but they indicate that the AR-10 design is suited to the .308 cartridge. Therefore there is less latitude in the gas and buffer system for the .243, and so it's more picky about ammo. They claim the Armalite .243 with 20" barrel will reliably function with between 80-100 grain bullets. Yes, that's pretty much the meaty area of .243 bullets anyway, but it does tend to leave out the 70 and 75 grain versions as well as the 105's. That said, I also reload for .243 and .308, and I've fired quite a few 75g bullets without issue. Then again, that tech note indicates the Armalite .243 is a 1:12 twist, but the 2014 manufactured .243 I recently bought is 1:10...so go figure. I'm no firearms engineer...just repeating what I've read and experienced with a 75g bullet...and this is supposedly just for the Armalite...but only a 1:12 twist model. LOL!...are you as confused as I am now. I have an identical .308 Armalite too, so I bought the .243 to be kind of my varmint caliber.
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DaveS...on your links, I wonder if my Armalite references are more concerned with cycling issues than accuracy in their comments. They specifically mention the gas system possibly needing "tweaking" if you go outside the recommended bullet weight parameters. Aren't bullet weight charts and twist rate analysis usually based more on accuracy issues? Like I said, I'm not a firearms or ballistic engineer...by any stretch.
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While .243 shares the same case geometry as the .308 until the neck, the gas system needs to account for a different animal when it comes to burn rates, bullet weights, and bearing surfaces.
Once you start going off the map with bullet lengths, the gas system needs a way to deal with them. The AR10 was built around the 147gr FMJBT M80 7.62 NATO cartridge, with fast powder. When we depart from that, there are several things that need to be reevaluated and tweaked for the new cartridge. |
| Take a look at www.blackholeweaponry.com. They have 1:8, 1:9, and 1:10 twist barrels. I have 2 wildcat barrels made specially by them and they are top notch barrels with plenty of accuracy. I have not been disappointed yet and will be going for a 3rd barrel in 20 Practical this coming summer. Good luck and stay safe. |
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I shoot this rifle with 87 to 107 grain bullets using H4350 powder, So far, I have not had any feeding issues with this rifle while using the old style Armalite magazines. It has proven to be reliable and very accurate shooting at ranges from 200 to 600 yards. |
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I'm not saying the .243 Winchester can't be made to work, just that its gas conversion has to be accounted for by someone that knows what they'e doing. Heck, there are several factory .243 Win. rifles from ArmaLite and DPMS, as well as Remington.
A lot of competition shooters are using 6mm XC, 6x47, 6mm Creedmoor, 6mm Competition Match, as well as .243 Winchester. The popularity of the 30 degree shoulder has really increased over the years, and shooters seem to find it easier to load for and find accuracy nodes. The 6 XC has a 30 degree shoulder, as do the Creedmoor's. The 6x47 Lapua has a 31 degree shoulder, and the Lapua brass is probably the strongest in the world, also using a small rifle primer, and able to push pressures if you're into torching throats. I have always been impressed the x47 Lapua performance in the real world. 
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The 6x47 is very accurate with around 38 grains H4350 with rem 7 1/2 or CCI 450 primers.
A 24 inch barrel with rifle gas should be easy to tune with an AGB and get good velocity with excellent accuracy. It could use long bullets like the VLD's,115 Dtacs,etc. With 95 grain hunting bullets it would be pretty much the same as a 243 Win. |
| Diggler, I'm just curious on your preference for a slower twist rate for an AR .243. More traditional twist for a .243 is about 1:10...generally, not something that has to be set in concrete. Will you be shooting a very specialized bullet, powder, or such? I may have missed the barrel length you want to go with. I reload for my .243 and .308 AR-10's in bolt rifles and will soon start experimenting with a favorite bullet or two in my AR's. You notice I mentioned my Armalite .243 earlier. I'm not really a brand addict. I'd be proud to own a big caliber AR in several other quality brands out there. I wanted 20" barrel rifles to be more of a hunting and longer range setup. CDNN just happen to have both of those rifles on a huge closeout since Armalite is doing a new rifle roll out for 2015...a good $500 drop on each rifle in the models. Your twist preference got me to thinking more about the principles of twist rate. AR or bolt rifle, 1:10 seems pretty well on the mark for most bullets. It seems clear to me that Armalite spent the time to get the gas and rifling right on their .243. I think that change I mentioned earlier where they've changed from a 1:12 twist to the 1:10 shows that they're not static in their attention to the .243. Not trying to talk you out of a ground-up build on your own. Not many manufacturers do the .243. It looks like Armalite paid proper attention to setting up theirs. |
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DirqDiggler, I use a factory DPMS lr .243 Win. with a 20" bbl. 1:10 twist. Been shooting pigs, beaver, coyotes, snakes and anything else that needs shooting now for about 6 months with zero problems. I put a rather inexpensive 1 - 6X primary Arms scope on it and it still groups .75 in at 100 yds with 100 gr factory ammo from several manufactures.
My favorite bullet is a 100 gr Rem PSP, but the lr will shoot whatevers on sale. 
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