#1
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Ordered a .20 VarTarg bbl...
...from MGM Monday, specified "tight neck" and specified a .224, which is the std neck for the cartridge. A loaded round should measure .2225 or so, and I'm wondering if that leaves adequate wall thickness using Lapua .221 brass? Should I change the chamber to a .226 neck and have the brass at .224?
Anybody? |
#2
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A .224 neck diameter 20VT chamber was the original tight neck match chamber designed by Todd Kindler. Neck turning is definitely required for this chamber. Based on my lot of Lapua 221 brass, the loaded outside neck diameter of an unturned 20VT is .2318 using Lapua brass. If you want a tight neck chamber w/o neck turning, I would suggest a .234 or .235 neck chamber if you plan to use Lapua brass.
PS: If using Lapua brass, I feel one also needs to be concerned with the reamer diameter measured at .200 above the base. When Todd originally spec'd the 20VT, he logically did so for Remington 221 brass. He specified a .374 diameter at .200 above the base. This is smaller than the Saami minimum chamber spec for the 221 Fireball and smaller than my lot of Lapua brass(.3754). I believe I would specify the Saami 221 Fireball minimum chamber spec measured at .200 above the base(.3769).
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John Last edited by JohnHenry; 04-30-2015 at 12:42 AM. |
#3
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You should cast the chamber you get, the neck will always be larger than the reamer is, how much depends on lots of things including the reamer bushing fit and the skill of the person doing the chamber. One thing you can always count on, the neck will never be smaller than the reamer. My unturned Norma and RP 20BR brass ends up with a loaded neck diameter of .2275 and I have a .229 neck in the chamber. Larry
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A gun is just like a parachute, if you really need one, nothing else will do. Last edited by trotterlg; 04-30-2015 at 12:31 AM. |
#4
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congrats for your own 20 vartarg from MGM. i just took a standard neck. so i won't tell you about it. i use remmys 221 fireball and 1in12" twist. right now it uses a 32gr varmageddon and a charge of h4198. it goes around .2" at 100 yards. the best i shot with it is .138" at 100 yards. the 20vt is just unbelievable. i have another MGM barrel that is a 22-250ai(27" heavy barrel) that doesn't get to shoot because of the vartarg.
20vt with 32gr varmageddon |
#5
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My .20PPC has a loaded neck @ .228, so I'll turn a coupla cases (Lapua 221) to .2225 and see if they'll hold up at that thickness. Seems awfully thin...
Thanx for the responses. |
#6
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A little delicate, but you will be fine based on my experience. I have a 20VT that the dealer I bought it from borrowed Todd's original .224nk reamer and had Butch at Cascade Arms rebarrel a Kimber of Oregon Model 84 Custom Classic. I use Remington brass in that rifle and turn the necks to a .009" neck wall thickness. Also, many 6PPCs utilize a .262 nk chamber where the brass is turned to a neck wall thickness of .0080 to .0085.
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John |
#7
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Thanks John...guess I'll leave it alone.
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