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Posted: 2/21/2010 12:51:54 PM EDT
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I'm looking into building a couple AR-15s chambered in 20 Tactical for my father and myself. I'm trying to find somewhere to get the barrels from and so far haven't had a lot of luck. I was hoping the hive-mind could point me in the right direction.
Thanks!! |
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Definitely go with John at WOA. I had the first 20 Tac from him because he had to order the reamers.
He uses Pac Nor blanks and will want to know what twist you want. Also, I went with a 26" instead of a 24" and wish I hadn't. The gas port is farther out and you will be under gassed, plus it looks goofy. It's also too muzzle heavy. Go 24", you don't need the extra 2". The barrels are extremely accurate. You'll be looking at 1/4" for 5 rounds with the right combination. Reloading brass is another story. |
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Quoted:
What is the velocity difference in the 20 Tac vs the 204 Ruger? all other things being equal? They are supposed to be really really close. Here is some info http://www.6mmbr.com/20Caliber.html |
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I can't speak for the 20 Practical (if it might have some of the same neck tension problems below).
First of all, the reloading data you'll find is for bolt guns. None have anything to do with the proper operation of a semi-auto. When you reload, you first full length resize with your 223. This is the time to trim and chamfer using your 223 tools. So far, same as 223. For forming, you'll want the form die from Redding as the next step. If you try to go straight to the 20 Tac dies, you'll just be crushing the shoulders. Once formed, it's time to run them through the 20 Tac dies and you now have your brass. Here's where I find problems. I first used mil brass, thinking it would be a cheap and plentiful option. (Now, all have been thrown away) But, after being necked down, you'll find the neck thickness varies a lot, and does not hold a bullet securely since you don't crimp these. In fact, there can be almost no neck tension at all. No problem in a bolt gun. In a semi-auto, the bullet is driven back in the case raising pressure and causing jams. I've since gone to R-P brass as this has a higher percentage of good results for neck thickness. When sizing, you can feel the relative tension when you withdraw the case from the sizing die as it passes the expander button. If you don't feel it expand, there isn't any tension at all. If you feel resistance, you know you have a neck that is suitable to hold a bullet. These get segregated for pdogs and match. If you are unsure what it should feel like. Seat a bullet into an empty case. You should feel some resistance as it seats. If you didn't feel anything, press the dummy round's tip against your bench or piece of wood. With moderate pressure, the bullet should remain in place. GTG. |
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20 Practical requires no forming die and no fire forming. It's headspace dimensions are identical to the .223 parent case. It is merely a necked down .223 with no other change. All it takes is a Redding .223 bushing die with a smaller bushing and a .204 cal stem.
With all the load data I've seen published the velocity of the 20 Tac and Prac are usually within 100fps of the .204 Ruger and in many cases higher because the smaller 20s are loaded to a higher pressure. That higher pressure might cause some function problems in an AR. You might want a smaller gas port or and adjustable gas block to slow the bolt speed down a bit. This is just me thinking in print, I have no personal experience with the small 20s though I'm working on changing that if I can find a barrel that matches what I want (1:8 or 1:9 twist). I'd be going with the 20 Practical myself. |
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I saw that video on 6mmar.com, they say to use a .225 bushing, but I've seen other places say to use a .228 or .230. Seems like pretty big difference in neck tension. I was wondering if someone who has a 20 practical could say what they use and why. |
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I was working on my 20 Prac brass last night. I have a WOA 24" AR. I happened to make this batch from FC brass. Other brands may be different. I use a Redding .223 FL bushing die, a .227 bushing and a .20 cal carbide expander button that Redding supplies separately. (Only took about three orders to Sinclair to get the stuff together.) With the .227 bushing, the inside of the case neck never hits the expander button. However, I have adequate neck tension. I didn't think I had quite enough when I used a .228. Some Winchester brass I also made up was similar. I have not yet made any brass with military cases.
I picked the practical because of ease of making brass and fact that I would not need to buy expensive die sets. The design differences between it and the Tac are negligible to me and I am sure that both cartridges would use the same loading info. Bullets are seated in a regular .223 die. BTW, I made this brass on my progressive press with a variety of Redding dies and different neck bushings, coming down about .007 in each station from about .246 to .227. Worked ok but was a hell of a cobbled together set up. John told me that his .20 Prac chambers were at .236 in the neck, indicating that therefore there would be no need to neck turn. That means that I have likely a bit too much clearance in the neck for bench rest type accuracy when you compare .227 (springs out a little when bullet seated) and .236. However, the rifle shoots like a house a fire. 1/2" groups easily and 32 gr Sierras at 3950 fps. Saw some velocities at 4200 when developing loads, they were just a wee bit too hot and a few primers fell out of the pockets. Enjoyed shooting the rifle on a prairie dog trip last year. |
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