Opinions needed for a .20 'cat I've been mulling over.

[TAJ45]

I just read everything in the "17 or 20 BR" thread.......I did see a mention of the 47 Lapua necked to 20. This is why I asked for a decent print of the 6.5x47 y'day.

Overall idea is to increase powder capacity in the short,fat 20 BR but not to the extent of a full length 47L or say a 22-250. I guess with my general criteria, a 22-250 case will work as well in the parenting role. Yes, the small primer and Lapua brass will be a nice option for those "needing it".

OK, just a wildcat's newbie ruminations here so don't run me off the board on a rail (I know you guys won't, that's why I'm posting).

Parent case 6.5x47L or 22-250 but push the shoulder back substantially - say .200 or so - maybe more. Looking for another 3-5gr capacity over the 20BR AI.

Shoulder angle? Left up to shooter for his use: less for repeater/feed or more for single loading.

Leave a lot of neck length.....maybe .450" or better. Purpose: to be able to reach lands with ANY pill. Also this theory of the convergence point on the center line being behind the base of the bullet being more accurate and or increasing bbl life? Anything to it? I've thought about the .222 and that is a pretty shallow angle. Of course not much powder being burned either..........maybe just answered my own "hmmm".

For twist, I'm personally leaning toward 11 or maybe 10 hoping to find several someones actually producing some pills in the mid 40s. I thought I wanted to push those 55s FAST but from the thread mentioned above, it may be just one highly probable headache. Maybe the 12-15% redux in wgt and the easier twist would do the trick?

Whatcha guyz think?

[Oleman]

So overbore you don't want to really go there.

[montdoug]

I'm of an opinion that any wildcat a guy wants probably makes sense...at least to him and that's all that matters. Some fellas are real practical and are real concerned about barrel life and such which is certainly a "logical" viewpoint but then there's me.
To me most of the wilcats I've tipped over on have a purpose, like a tool in your tool chest for a specific reason. Ya don't use it everyday but when ya need it, ya "WANT IT"! No logic to it in my world.
As I read your post first thing that popped to mind was the .20 Dasher. I built mine for long range rock chucks up in the mountains, 20 or 30 in a day is a well remembered occurrence, it's cool up there and the shooting isn't fast. I chose a 1 in 11 Pac-Nor Super Match 3 groove specifically with the 40 V-Max in mind,drives tacks with em at warp speed just loafing along.



I don't shoot it much and it's never seen a p-dog town at 95 degrees but when I break it out up there it makes me giggle big-time!
Here is an often re-posted picture of it. Short, fat, small flash holes in great Lapua brass with a tight neck, "Big Grin"!

From left to right.
.20 VarTarg, .20 Killer Bee, .20 Tactical, .20 BR and last but not least the .20 Dasher or in essence a .20 BR Improved with a 40 degree shoulder. Picks up 3.5 grains or so over the .20 BR as memory serves.




Here is a picture of the 6X47 Lapua.



Just for comparison sake and seeings how I have a 6X47 Lapua, I just took a fired 6X47 case and a fired .20 Dasher case and filled em both to the juncture of the neck and shoulder with the ultra fine grained LilGun. Then I weighed both charges, the 6X47 case charge weighed 46.4 grains and the .20 Dasher charge weighed 39.8 grains. 6.6 grain advantage for the 6X47 Lapua. Not very precise but close enough to get the picture.
Now somewhere between those two case capacities there is a small niche in performance and if that small niche is causing a guy an itch then by golly I dang sure think he oughta scratch it . Then he oughta post all the results so the rest of us can vicariously enjoy the experience right along with him!!! That's what I think!!
As to twist, I'd pick it to the heaviest bullet I was gonna shoot and if the past has shown us anything I'd make it for a bullet that was available currently and hopefully gonna stay that way.Then once I found a load for it I'd stock up on enough of those bullets to last that barrels lifetime. A lot a .17 caliber fur shooters got left hanging in the breeze when Berger discontinued their various 30's, just a thought.
Good luck and keep us posted.

[Spook]

...just for comparison, I got back from the range yesterday after wringing out a 22-243 Middlestead that I built on a Howa .
The load is 44.5 gr 0f Alliant 4000MR with a 77 gr "mystery bullet" I picked up at Grafs.

It shot exceptionally well..but the point is it got hot so quickly and even after cooling down ... a five shot string had it hot enough to brand cattle ....and warm enough to make the POI wander even though it utilizes a Sendero weight barrel.

You'd have thought Id'a learned with the 224TTH

Stan Wares "wolf pup" cartridge necked to 22 is looking pretty appealing at this point.

[DAA]

Originally Posted by montdoug

As I read your post first thing that popped to mind was the .20 Dasher.

Me too. A long neck Dasher is what I was thinking as he described what he has in mind.

My Dasher is a dedicated 'chuck rig too. Stupid fast and flat with 39 BK's out of the 12T.

- DAA

[ab_bentley]

What about a 284 shortened to length?

Adam

[dungheap]

I follow this thread and others and "overbore -- overbore" rattles around in my head. Do you guys consider this when building these rifles, or is it really nothing to be concerned about to you?

Seems to me there's a reason that the .20 Vartarg, .17FB, .17AH and similar cartridges work so well, that that reason is: They're NOT overbore.

What say you (or "yous")

[junk man]

Originally Posted by dungheap

I follow this thread and others and "overbore -- overbore" rattles around in my head. Do you guys consider this when building these rifles, or is it really nothing to be concerned about to you?

Seems to me there's a reason that the .20 Vartarg, .17FB, .17AH and similar cartridges work so well, that that reason is: They're NOT overbore.

What say you (or "yous")

but what's the fun if it aint a little overbore.

[william t. oviatt]

To me, overbore as it concerns barrel life, is only a concern if the rifle is used for high round-count shooting. Some of my coyote shooting buddies love their overbore rifles, and say they will last a LONG TIME in coyote numbers. One prairie dog shoot and the barrel would be "toast". Same with elk and deer rifles. Several shots a year and the barrel is going to last probably a hunter's lifetime and more. I am just too powder stingy for anything over 30 grains of powder in a small cal rifle. Unless it is big game that is going to be the target.

I am with Mt.Doug-if the cartridge spins your beanie, go for it! As long as it is a safe project-make yourself happy!!!

Bill

[Hal]

One of the guys at Douglas rifle barrels shoot a 20-250 and uses it for long range target matches.

Hal