Discussion in 'Small Stuff--22s, 20s, and 17s' started by jpthomso, Nov 13, 2008.
Anybody know where I can find a 20 Practical upper? The 6mmAR.com website is down.
Talk to Mike at,
I suspect that it would take awhile to get it. But his work is worth the wait.
http://www.whiteoakarmament.com/ talk to John or Paul. Current wait is 16+ weeks on a Krieger. Pac-nor barrels have shorter lead times. Only 14 more weeks to go
Whoever you get it from, make sure the throat on their reamer is spec'd correctly if you want to be able to seat the bullets to the lands and have the cartridge still fit in the magazine. I have heard of reports of looooong throated 20-223 AR-15s being sold as 20 Practicals.
Need some help please on deciding the FreeBore. Have a Kreiger 1-11" and Pac-nor 1-8" on order for an AR15 project. Would like to shoot the Berger 40grs and the new 55grs out of magazine. The 55s will only work in the 1-8 and haven't been able to get a box yet. Anybody have some and can make a recommendation?
I had my 20 Practical reamer made with 0.000 free bore,shot great.40gr bullets
I think some people use long throats to avoid lawyers.long throat less pressure. that is how weatherby gets their hyper velocity. also some chambers with long throats shoot really well. just some thoughts.
You may have to throat the 1-8" long if you want to shoot those bullets without loosing too much case capacity and thus no way they will fit the magazine and touch the lands. You could always load them one at a time like folks who shoot the 600 yard stage.
If I were you I wouldn't chamber an AR-15 in 20 Practical to shoot those 55s. I would use a bolt rifle for them. Is there a reason you want to shoot them from an AR-15?
When we did the 20 Practical project AR rifle, it was felt that if you go with the heavier bullets,like 50+ gr bullets) you might as well just shoot a .223 and not bother going with a 20.
With the 40 gr or less 20 cal bullets, you can run with more relaxed twist,less pressure) like a 1:11" twist that allows you to shoot the bullets very fast and flat. When you get up to the 50+ gr 20 cal bullets, you have to go with a much tighter twist,pressures rise) and it's hard to get the velocity up much more than you can do with a 223 shooting the 50 or so gr bullets.
The whole point of the 20 Practical is to take advantage of the niche it has to offer, not to try to make it do what a 223 already does.
With the 40 gr or less 20 cal bullets, stick with a zero free bore, as you need to do that to keep close to the lands and still have a reasonable amount of the bearing surface of the bullet in the neck of the case too.
Watch out for reamer designs too. There are some 20 Practical reamers out there that are definitely no good for running out of a semi auto AR-15. There is a definite difference on the reamer designs that are appropriate for running the 20 Practical out of an AR-15 and the reamer designs that are o.k. for bolt gun use,been there, done that).
Appreciate the advice.
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