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Wildcat and AR-15

Posted: Tue Dec 19, 2017 3:25 am
by Precision
I am in the market for a semi auto rifle that has 308 performance (or better) but is not bigger than an AR-15. In a perfect world, it would be an AR-15 chambered in "awesome".

My search for that turns up nothing or comes close but needs to be in an AR-10.

So that got me thinking of wildcats. I searched around for some of those and found some answers but figured if I was gonna go that route why not make my own wildcat.

Long winded way of asking, what is needed to successfully build your own wildcat beyond a chamber reamed in your new dimensions?

For the record they are two 6.5 cartridges that would have cut down oversized cases for large overbore brass. One should be a rough approximation of 6.5 Creedmoor speeds but in a short action, working name "6.5 AR Thumper". The other would be an approximation of 6.5 x 284 speeds in a short action, working name "6.5 AR Overkill".

The second would likely be a barrel burner in a big way.

Re: Wildcat and AR-15

Posted: Tue Dec 19, 2017 3:35 am
by Netpackrat
Precision wrote:Long winded way of asking, what is needed to successfully build your own wildcat beyond a chamber reamed in your new dimensions?


Off the top of my head, you would need a bolt with the appropriate face dimensions to match your custom chambered barrel, and magazines that will actually feed the thing. A supply of brass and reloading dies. Ideally you would be able to make the brass from some other commercially available case.

I kind of doubt you are going to get it done in a way that will exceed 6.5 Grendel performance by any appreciable amount, if you insist on staying with the AR-15 platform.

Re: Wildcat and AR-15

Posted: Tue Dec 19, 2017 4:14 am
by Precision
Netpackrat wrote:
Precision wrote:Long winded way of asking, what is needed to successfully build your own wildcat beyond a chamber reamed in your new dimensions?


Off the top of my head, you would need a bolt with the appropriate face dimensions to match your custom chambered barrel, and magazines that will actually feed the thing. A supply of brass and reloading dies. Ideally you would be able to make the brass from some other commercially available case.

I kind of doubt you are going to get it done in a way that will exceed 6.5 Grendel performance by any appreciable amount, if you insist on staying with the AR-15 platform.


bolt face for one definitely exists as the parent case is used in AR's already, the other, not so sure but should be easily done.
Barrel is a given. Brass should be easy to resize with the dies after trimming as they are not changing dimensions below the (new) shoulder on currently commercially available brass.

By using a case that is significantly wider than Grendel wouldn't that allow for more powder, more push and more velocity. I realize powder selection would need to change to utilize the extra room without going overpressure. I am looking at a case over .500 in diameter with the roughly the same length brass from primer to shoulder as the .4433 case of the Grendel.

I realize that would reduce the number of rounds in a mag...

Re: Wildcat and AR-15

Posted: Tue Dec 19, 2017 4:25 am
by HTRN
I think the 50 beowof is the most powerful cartridge, followed by 458 SOCOM.

30 rar bottlenecked to 6.5mm might be interesting, but the only source for components (gun and ammunition) is remington, leaves alot to be desired.

Re: Wildcat and AR-15

Posted: Tue Dec 19, 2017 6:38 am
by Steamforger
There is something called 45 VRAP. Don't know anything about it, just stumbled on it the other day.

ETA-Nevermind. It apparently runs on an AR-10 lower.

Re: Wildcat and AR-15

Posted: Tue Dec 19, 2017 7:08 am
by Netpackrat
Isn't the .450BM .452" groove diameter (pistol bullets)? .458 Socom uses rifle bullets, which is probably a good thing when you are launching 300 grains at 1960.

Re: Wildcat and AR-15

Posted: Tue Dec 19, 2017 3:06 pm
by Precision
HTRN wrote:I think the 50 beowof is the most powerful cartridge, followed by 458 SOCOM.

30 rar bottlenecked to 6.5mm might be interesting, but the only source for components (gun and ammunition) is remington, leaves alot to be desired.

My goal is to allow the use of the heavier 6.5 bullets and still get a high velocity. The goal is Creedmoor + velocities out of a short action.
The 30 rar seems to not be able use the heavier bullets and thus has little application at distance and also seems to be mostly for bolt guns?

For simplicity's sake, one idea is a necked down 458 SOCOM. Not exactly, but uses 458 SOCOM parent brass. The bolt already exists so it would really just be a different barrel / chamber. The mags, parent brass and the projectiles exist. Figuring out load data / proper powder choices... would take some work, but are doable. The biggest question is what weight (length) bullets would be easily usable. with a .240 neck, .750 left for bullet past the end of the neck, most bullets up to 129gr should work as they (excluding some VLD's) are under 1.1inches. The 140 class of bullet would likely suffer from being seated too deep in the case for adequate powder. Rough math says I should get 12gr more space for powder than the Grendel. Would likely make it a barrel burner.

The other idea is taking a 308 case and cutting it down then making a new shoulder and neck. Much more complicated forming process, but would increase case capacity over Grendel by several grains. Probably not enough to worry about, but it entertains me to go through the mental process.

Re: Wildcat and AR-15

Posted: Tue Dec 19, 2017 4:37 pm
by BDK
A family member is a serious long distance shooter. His next AR is going to be a 6.5 Grendel necked down to 6MM, for long distance shooting. He suggests 105gr bullets

Re: Wildcat and AR-15

Posted: Sun Dec 24, 2017 3:53 pm
by randy
I'll just leave this here:

The Phoenix Weaponry 1873 45-70 AR

Re: Wildcat and AR-15

Posted: Sun Dec 24, 2017 6:32 pm
by First Shirt
Since you're in Nashville, you might want to check out these guys:

http://ar15performance.com/

They, at one time offered a Six5, which is a 6.8SPC necked down and trimmed to 41 mm (vice the 43 mm of the 6.8, but longer than the 39 mm of the Grendel) which showed a lot of promise with the heavier bullets.

Re: Wildcat and AR-15

Posted: Fri Jan 05, 2018 6:58 pm
by Termite
randy wrote:I'll just leave this here:

The Phoenix Weaponry 1873 45-70 AR

So now we have the best modern rifle/cartridge combination for ........grizzly. :mrgreen:

Re: Wildcat and AR-15

Posted: Fri Jan 05, 2018 11:08 pm
by 308Mike
randy wrote:I'll just leave this here:

The Phoenix Weaponry 1873 45-70 AR

Did you read the article all the way to the end? This part really caught my eye:

"The base price of the rifle is $4,800, and evidently there are a wide array of custom options available to enhance your enjoyment of the new weapon platform."

Re: Wildcat and AR-15

Posted: Sat Jan 06, 2018 4:46 pm
by randy
Well, Precision did not list price point as one of his criteria ;)

Re: Wildcat and AR-15

Posted: Fri Jan 12, 2018 3:54 pm
by Precision
randy wrote:Well, Precision did not list price point as one of his criteria ;)


For the record.
Unless I win lotto or win the heart of a very loaded women, price will be a criteria.

Seeing as I forgot to buy tickets for the big powerball, I guess it is back to manwhoring. lol

Re: Wildcat and AR-15

Posted: Fri Jan 12, 2018 3:58 pm
by Precision
upon further research, it looks like I will have to limit the projectiles to the 123-129 weight range and perhaps exclude some of the VLD's due to COAL issues.

I have two people with machining ability to help with the project. If it entertains them enough, we may build one or both of them and see what happens. Not sure I want to put a grand or two into the process, but it might be fun. Doubt it would be a commercially viable idea, but having a +2800 fps 129 gr 6.5 in an AR-15 would be awesome fun.