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20 BR Varmint Rifle

Hi Guys,

I will be ordering a 20BR barrel for my Savage Target Action F class rifle in the next few days.

I need to know what would be the right twist for 39SBK's and 40 grain Bergers. I am leaning toward 1/11 twist and having a finished length of 26 inches. Also I have about 3 boxes of 50 grain Bergers I would like to shoot. Would 1/11 twist stabalize the 50's?

I also need to know what is the best size for a no turn neck. I have read that .236 is the right size for the gold box Lapua brass. So any info you have, would be much appreaciated.


Jimmy
 
Your 1-11" twist is fine for the 32/39 grn BUT sell the 50's as Berger no longer offers them - they only offer 55's in the "heavyweights". The twists you need for either bullet weights are not going to work for the other. Figure out what you want to do with your choice of bullet and let that guide you .
 
Just curious as to which barrel you are using? I have a 9 twist 20br but all I shoot are the 55's I think to shoot the 50's you would need at least a 10, I have a 204R 10 twist that shoots the 50 Bergers great.
If you are never going to shoot the 55's I would get a 11 twist, with the br it may shoot the 50's but I doubt it. The 50's you have would be very easy to trade right now.
My 20br is a .232 neck and the brass is the blue box Lapua I turn my necks just enough to clean them up, the necks before I size them down average .0125, I had some of the older brass in the gold box but traded it off , if I remember right the necks averaged about .0135 and may get a little thicker when necked down so .236 sounds right for a no turn neck but I would size down some of your brass and check it to be sure
 
rich44 said:
Just curious as to which barrel you are using? I have a 9 twist 20br but all I shoot are the 55's I think to shoot the 50's you would need at least a 10, I have a 204R 10 twist that shoots the 50 Bergers great.
If you are never going to shoot the 55's I would get a 11 twist, with the br it may shoot the 50's but I doubt it. The 50's you have would be very easy to trade right now.
My 20br is a .232 neck and the brass is the blue box Lapua I turn my necks just enough to clean them up, the necks before I size them down average .0125, I had some of the older brass in the gold box but traded it off , if I remember right the necks averaged about .0135 and may get a little thicker when necked down so .236 sounds right for a no turn neck but I would size down some of your brass and check it to be sure

Thanks for the info. I am going to get a McGowan barrel. I have 3 .204's 2, 1-12 and 1,1- 9 twist so I probably will go with the 1/9 twist and shoot the 55's in the 20BR. My 1/9 twist .204R shoots the 50 grain Bergers pretty good, so I will shoot them in it. My friend is a McGowan rep and he does pretty good with his F class rifles.

Jimmy
 
I have a 20BR ( Lawton 7500) with a 27 inch Bartlien barrel, 1 in 9 and throated for the 50gr Berger which it shoots so well as to be a competitive Bench Rest rifle.

I have been using 39gr SBKs to good effect on avian targets and again sub 250 yard foxes, again to good effect. The terminal effect on a crow at 80 yards when a 39gr arrives at 3500 or so is usually quite dramatic, crow is mostly in several parts.

Accuracy wise the 1 in 9 shoots the 50s best ( mid/ low .2s when I do my bit) as you might expect, the 39s are high .3/ low .4 usually. 40gr Vmax are around .5 but they wont take being driven over 3700fps, in my rifle they vanish, ie break up.

My loads are cool, usually 3500 fps at the muzzel, using BR4 and N150, makes a sweet shooting rifle.

Building for the 39s today I would opt for a 1 in 11.

A
 
Alycidon said:
I have a 20BR ( Lawton 7500) with a 27 inch Bartlien barrel, 1 in 9 and throated for the 50gr Berger which it shoots so well as to be a competitive Bench Rest rifle.

I have been using 39gr SBKs to good effect on avian targets and again sub 250 yard foxes, again to good effect. The terminal effect on a crow at 80 yards when a 39gr arrives at 3500 or so is usually quite dramatic, crow is mostly in several parts.

Accuracy wise the 1 in 9 shoots the 50s best ( mid/ low .2s when I do my bit) as you might expect, the 39s are high .3/ low .4 usually. 40gr Vmax are around .5 but they wont take being driven over 3700fps, in my rifle they vanish, ie break up.

My loads are cool, usually 3500 fps at the muzzel, using BR4 and N150, makes a sweet shooting rifle.

Building for the 39s today I would opt for a 1 in 11.


A

I guess I will just have to decide for sure what I will be shooting 39's or 50' or now 55's and then decide on what twist. I don't even have my F class together yet, so I will finish that first. I have all the parts except the barrel and I believe it is waiting at the McGowan rep's home as I type this.

Thanks for all the replys.

Jimmy
 
I built a 20BR last yr...Savage Target action & PacNor 9 twist/3 groove

28" w/no taper...shoots like a laser...40 V max or 55 Bergers
 
Decide your bullets, fox etc under 250 yards the 39 SBK will do fine, over that on a regular basis or for specialised target work the go for the 55s. Then opt for the twist rate to suit that bullet, just make sure your builder throats it for that bullet.

I suspect that the 39 will be vermin acceptably accurate in a 1 in 8 required for the 55 as long as you dont drive it to hard. Dont bother with 40 gr Vmax as they will break up, or they did in mine at about 3700.

A
 
Here is my experience with the 20B BR Varmit rifle. I have a Savage Model 12 LRPV Rifle with an 11:1, 3 groove Pac_Nor barrel. I shot 5, 5 shot groups at 100 yds with Nosler, Berger and Hornady V-Max 40 grain and the 39 grain Sierra Bliz King. 5 shot groups ranged from .25 to .5 inches. 39.5 grains of Varget was used, giving measured 3900 to 3950 ft/sec. Sierra gave the best group average with V-Max next, then Berger followed by the Nosler. I had expected the best groups to occur with the Berger. Have got good groups out to 400 yds with the Sierra, accurate enough to have what I think is a 90 % hit probability of a Pdog with no wind. Gun with scope weighs 16 lbs so not much recoil and can see hits with no problem. Have a 8-32 Nikon scope; use maximum of about 20 power to maximize field of view. Really like the Pac-Nor Barrel. JL
 
I decided to order a barrel yesterday. I went with a Shilen 26in finished length select match 1/9 twist. Shilen has a reamer with the .234 neck and throated for the 55 grain Berger. I ordered the barren through Northland and it will probably take 4 months to get it. I don't have any dummy rounds to send in for the throat length, so how will they know what length I need? Any ideas?

I was going to get a McGowen, but they don't offer a 1/9 twist.
Thanks

Jimmy

Here is a picture of my F class 6BR which I will put the 20 cal. barrel on.
2013LasVegas242.jpg
 
joghotrod said:
... I don't have any dummy rounds to send in for the throat length, so how will they know what length I need? ...
Are you having a custom reamer built, or are planning on using a standard reamer?

If it is a nominally standard reamer, then there are rifles built using it and some of those users will likely have learned the max COAL for the 55 gr Berger.

If it is to be a custom reamer, then the person designing the chamber and throat should have the skills and knowledge to get a good fit at your desired working COAL.
 
A 1-11 twist is perfect for Vmax 40's. If you're interested in approximating 220 Swift performance in a smaller package that combo will do all that and then some. Going to heavier bullets will require a tighter twist. As already mentioned, Berger has axed to 50 grainers. Considering the capacity of the BR case you might want look at doing a dedicated longer range setup. A properly barreled 20BR shooting heavy bullets is a vicious combo.
 
Ask Shilen to chamber with -0- freebore...this is my request with PacNor on all my orders...the throat will only 'grow' in length with use...start out with 39-40's...then the 55's..my OAL w/40's is 2.030" burning IMR4007ssc & OAL w/55's is 2.095" burning VV-N140...Norma brass is what I have in use...Rem 7.5 primers...used a new Savage Target action & 28" P-N 9T/3G barrel...Vortex 6-24 PST glass...approx 750 rds down the tube so far....

Jimmy.........? typo on the 39.5/Varget ??
 
Yes, typo on the 39.5 grains of Varget which is impossible. I used 30.5 grains Varget for all loads during my various bullet testing. Thanks much for calling out this typo. On another note with Shilen barrels, I ordered a 20 cal with 11:1 twist about 6 months ago, still waiting. I was told that there was a manufacturing problem and they expect to send my barrel any day now. Jimmy
 

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