20 caliber build.

[Skattergun]

When necking down .223 cases to .20 caliber can donuts form inside as well as outside shoulder area?

Yes I believe so, at least on the inside. I short chambered a .204 ruger to same length as .223 then shortened a sizing die. I ran a mandrel through the neck after to uniform Inside then skimmed the neck. One I did for my friend just seats the bullet in front of the neck shoulder junction. Plenty of freebore with saami spec reamer and the .035fb match version I used. I made new headspace gauge with 30 degree shoulder that matched the headspace dimension of the .223

I did this cause I already had reamer and dies, and figured 30degree shoulder might be an upgrade to the traditional 20 practical

 

[charlesasmith]

I recommend paying attention to VinceMule's 1st paragraph, as I ran into a problem of blown primers due to seating below the neck/shoulder junction of my 20P. Setting up a reamer for adequate clearance of the base of the 55 gr bullet above the neck/shoulder junction would be most helpful.

 

[Elnicko]

A 9 twist will stabilize the 55's in a BR case or larger. There's a bunch of info on accurateshooter if you haven't checked there yet.

 

[bfarms]

I think the 20-250 or 20-250ai case would be the right route on this. There is a guy on predatormasters that has a 20-250ai he has hit coyotes way out there with it. You could google the 20-250ai and maybe it will come up on that forum and you could message him. I was going to do this but went a different route talked into by a gunsmith since there was only a couple bullets that would meet my end result. So I went 22-243ai. Black hole bullets used to make some heavy 20cal bullets also. Also like Vince Mule said make sure the reamer is not saami with lapua brass you will have issues. That happened to me with my first 22-243 barrel.

It will be a ai for sure. And my reamers are never Saami spec. I try sticking to lapua if they make it. Lots of good info posted in here. Thanks guys

 

[65WSM]

A 9 twist will stabilize the 55's in a BR case or larger. There's a bunch of info on accurateshooter if you haven't checked there yet.

I had a 8 twist barrel built for this rifle. At the back of the club range, 500 meters, it would shoot five inch groups. The same barrel shot several groups under two inches with 40 gr Bergers and Hornady V-Max. I had a barrel built with a 7 twist and it performs much better with the 55 gr Bergers in the .20 BR. I would recommend visiting the Berger Twist Calculator rather than posts from on-line forums.

 

[jrkotz]

I'm a fan of 20 BR for 55 Berger, you're not terribly far behind with 204 ruger (around 34gr capacity vs 38gr), but brass options are much better for the BR

 

[mulish]

I have a good collection of 55gr Berger long range varmit in 20 cal building up. What would be a good case to push them down the barrel? I don't want to get into neck turning. I have enough of that to do. I've thought about building a 20br
But I've heard they can be finicky with feeding, so im up for suggestions. I know very little about 20 cal case options

20BR ai with a MDT mag
Or
20-223ai

 

[65WSM]

I use 6mm BR cases, multiple options, Peterson, Alpha, Norma and Lapua in the past. I have worn out two .204 Ruger barrels and have two others in current use. The eye opener for me was when I built a .20 PPC, which from Norma .22 PPC cases had identical water volume to the .204 Ruger Norma cases. I could use the same load data for both but the .20 PPC was much more accurate with the same bullets. For the .20 BR you can drive the the 55 gr Berger to 3500 fps without breaking a sweat. You can go faster, but it is your barrel. My second tube is the "new harder alloy" from Bartlein, it is nitrocarburized and I coat all my bullets with HBN. All are steps to extend barrel life. No naked bullets!

 

[Joel Russo]

We found the easy button on the .20 and the 55 gr Bergers. Designed the reamer and had JGS grind it. 20 GT shooting the 55 gr Bergers comfortably at 3,850 out of a 22" barrel.
SAC die, Wilson in-line seat die and using 22 GT brass with one pass in the SAC due to bring it down to .20 cal. Feeds like butter out of an AI style mag. Will use Lapua 6 GT brass when it hits the streets later this year, but can't argue with the results so far.

Accuracy is astounding at both 500 and 1,000 yards. Yes, I shot it for group at those distances.

My rifle is built on the Terminus Apollo.

Feel free to contact me if you would like have a barrel done.

Two different groups at 518 yards, and one group at 1,003 yards.

 

[bfarms]

We found the easy button on the .20 and the 55 gr Bergers. Designed the reamer and had JGS grind it. 20 GT shooting the 55 gr Bergers comfortably at 3,850 out of a 22" barrel.
SAC die, Wilson in-line seat die and using 22 GT brass with one pass in the SAC due to bring it down to .20 cal. Feeds like butter out of an AI style mag. Will use Lapua 6 GT brass when it hits the streets later this year, but can't argue with the results so far.

Accuracy is astounding at both 500 and 1,000 yards. Yes, I shot it for group at those distances.

My rifle is built on the Terminus Apollo.

Feel free to contact me if you would like have a barrel done.

Two different groups at 518 yards, and one group at 1,003 yards.

View attachment 592908View attachment 592909View attachment 592910View attachment 592911

That is impressive! What would the velocity difference be on a 20gt vs 20-250? Just asking because I have a bunch of 250 brass here

 

[bfarms]

I had a 8 twist barrel built for this rifle. At the back of the club range, 500 meters, it would shoot five inch groups. The same barrel shot several groups under two inches with 40 gr Bergers and Hornady V-Max. I had a barrel built with a 7 twist and it performs much better with the 55 gr Bergers in the .20 BR. I would recommend visiting the Berger Twist Calculator rather than posts from on-line forums.Im

Pretty sure it says 7 twist minimum on the box. Couldn't a person slow the twist down for a 20-250, drive it harder than a 20br and achieve the same results with more velocity? I could be wrong. Wouldn't be the first time lol

 

[Joel Russo]

That is impressive! What would the velocity difference be on a 20gt vs 20-250? Just asking because I have a bunch of 250 brass here

Lots of variables come into play here… powder used, internal dimensions of the brass, seating depth, barrel actual bore size…

 

[Justice1327]

We found the easy button on the .20 and the 55 gr Bergers. Designed the reamer and had JGS grind it. 20 GT shooting the 55 gr Bergers comfortably at 3,850 out of a 22" barrel.
SAC die, Wilson in-line seat die and using 22 GT brass with one pass in the SAC due to bring it down to .20 cal. Feeds like butter out of an AI style mag. Will use Lapua 6 GT brass when it hits the streets later this year, but can't argue with the results so far.

Accuracy is astounding at both 500 and 1,000 yards. Yes, I shot it for group at those distances.

My rifle is built on the Terminus Apollo.

Feel free to contact me if you would like have a barrel done.

Two different groups at 518 yards, and one group at 1,003 yards.

View attachment 592908View attachment 592909View attachment 592910View attachment 592911

What is your freebore?

 

[Justice1327]

Pretty sure it says 7 twist minimum on the box. Couldn't a person slow the twist down for a 20-250, drive it harder than a 20br and achieve the same results with more velocity? I could be wrong. Wouldn't be the first time lol

Lots of shooters use a 8.5 twist. When I called berger that is because they designed that bullet with the idea of it going into a 223 case and much less velocity. I just got my Mullerworks Barrel back so I'm deciding on a 20 GT or another 20 BRA. If I go the 20 GT route, I think I will have the Barrel nitrited along with my 22/243 AI.