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20AR (20-6.5 Grendel) anyone?

It'd be less in case capacity if the 20BR (Grendel case head @ .445" dia., capacity 35 grains H20) uses a typical 6BR (head @ .473" dia., 38.5 - 40.5 grains H20 depending on chamber, brass, fired vs. resized, etc.) case.

If anybody's tried it my guess would be Robert Whitley III. He's got several 6mm variants on the original 6.5 Grendel case, and is a regular reader / commenter on this forum.

Maybe this variant could be tagged the 20GR?
 
not necessarily. it depends on how hot you load it, the throat length and angle, the barrel manuf (some shoot longer than others), how long the bullet is, and your cleaning practices.
 
After reading this months issue of P.S.
That same thought came to my mind Steve.
Mr Whitley has written a nice article outlining the various
.378 boltface based 20 cal wildcats and the 6.5Grendel based
cartridges that he shoots from an ar.I think the 20AR
would be great with the 50's and 55's somewhere between
a 20ppc and a 20br but with better function in the ar platform.
Just the thing for long distance southern Colorado coyotes. :)
Matt
 
cmillard said:
the grendel round is based off the .220 russian (ppc) so it, as mentioned, will have less capacity than the 6BR cases.
Click to expand...

Sort of....Think of it as a .070" long PPC, necked down. It'll be almost right between a PPC and BR case in capacity.---Mike
 
That would be a great bolt gun cartridge, but not likely good for an AR-15. We considered making a 20AR, but there would be issues. The 6.5 Grendel case is around 1.520" or so long (vs a .223 Rem case that's 1.760") and we have found that the shorter case works well with bullets where you can keep the OAL of the cartridge up in the range of 2.175"+. Get much shorter than that and you start to have miss-feeds because the cartridge is too short (i.e. with a real short cartridge, by the time the bullet tip hits the feed ramp, the cartridge has to then come up at such a sharp angle, it cannot make it without jamming). The shorter case length of the 6.5 Grendel base case is what makes the case work well with the bigger and longer 6mm and .224 bullets (i.e. you can load the bullets at a good magazine length of 2.265" OAL and not have a lot of bullet back in the case hogging up powder capacity). With a .223 Rem as a base case, if you load the 105-108 gr 6mm bullets, or the 80-90 gr .224 bullets at a magazine length, there is a huge amount of the bullet back in the case hogging up a great amount of powder capacity and things are not ideal. The problem with the 20 Cal bullets (especially the 32-39 gr. is that they are so little and short, by the time you would throat out a 20AR chamber to hit 2.175" OAL, the bullets would be falling out of the mouth of the case - that's why we use the .223 Rem length case for the 20 Practical and 20 Tactical - because they have an ideal case length for those smaller bullets.

So there's a long winded answer why you won't see a 20AR from us with the Grendel case (although we do make 20 Practical and 20 Tactical uppers).

Robert Whitley
www.6mmAR.com
 
OK--that's the info i was looking for--appreciate it Robt. Great article, BTW!!

I am considering an AR in a 20 setup for the 50 and 55 Bergers. What's not to like about a fast .38 BC bullet from a 20? Look out long-range coyotes.
 
steve will the 20 AR fit the magazine with the 50's or 55's? i can tell you the 20 PPC is quite impressive and the 20 Dasher even more so but the 20 AR sounds like a near perfect size for the 50's

SDH
 
I don't know--have to take a look at that. If not i have a couple DPMS VLD magazines laying around and it'll definitely work with that.

Robert--what say u?
 
I was thinking of doing a 20 Grendel in a Howa Mini, but then I did a 20 Tactical for another Mini that shoots very well, and gives enough velocity to satisfy my needs. So now, I'm looking at the 22 Grendel - have placed orders for the reamer & a 1-7tw Krieger #4 sporter blank for it. It could well be next summer before I see the bbl blank, but I'm looking forward to getting this one up & running - have really enjoyed shooting the first couple of custom bbl'd Minis.
 
Todd Kindler designed the 20 Titan based on the 6.5 Grendel. I've built two, one on a Savage target Action (Douglas barrel) and one on a Remington 700 action (Krieger barrel).
Both rifles are 9 twist. If you do a search on this site you will see what the round is all about, or you can get Todd's "Terrific 20's" book. They both shoot the 55 grain and 50 grain Bergers
exceptionally well.
 
Gundog - I have a copy of Todd's book somewhere, had looked through piles of stuff for it with no success while I was considering the 20 Grendel, then again while trying to make up my mind between the 20 Practical or Tactical. I'd also built myself a very nice 20 Vartarg on a stainless M700 CDL in 17 Fireball a few years ago, but sold it to a guy who was looking for a Vartarg for a prairie dog safari up in the Dakotas. The Bartlein bbl I used on the 20 Tactical is a 1-9tw, and has impressed me with its accuracy with Berger 55 LRBTs at 600yds. It wasn't too shabby with Sierra 39BKs at 600 either. Really looking forward to finishing our corn harvest so I'd have some spare time to do some more load testing & chrono checking with the little 20 Tactical...
 
rcw3 said:
That would be a great bolt gun cartridge, but not likely good for an AR-15. We considered making a 20AR, but there would be issues. The 6.5 Grendel case is around 1.520" or so long (vs a .223 Rem case that's 1.760") and we have found that the shorter case works well with bullets where you can keep the OAL of the cartridge up in the range of 2.175"+. Get much shorter than that and you start to have miss-feeds because the cartridge is too short (i.e. with a real short cartridge, by the time the bullet tip hits the feed ramp, the cartridge has to then come up at such a sharp angle, it cannot make it without jamming). The shorter case length of the 6.5 Grendel base case is what makes the case work well with the bigger and longer 6mm and .224 bullets (i.e. you can load the bullets at a good magazine length of 2.265" OAL and not have a lot of bullet back in the case hogging up powder capacity). With a .223 Rem as a base case, if you load the 105-108 gr 6mm bullets, or the 80-90 gr .224 bullets at a magazine length, there is a huge amount of the bullet back in the case hogging up a great amount of powder capacity and things are not ideal. The problem with the 20 Cal bullets (especially the 32-39 gr. is that they are so little and short, by the time you would throat out a 20AR chamber to hit 2.175" OAL, the bullets would be falling out of the mouth of the case - that's why we use the .223 Rem length case for the 20 Practical and 20 Tactical - because they have an ideal case length for those smaller bullets.

So there's a long winded answer why you won't see a 20AR from us with the Grendel case (although we do make 20 Practical and 20 Tactical uppers).

Robert Whitley
www.6mmAR.com
Click to expand...
Would the .204 55 Bergers give you that OAL you need? I would love a 1-8 twist Grendel or 6.8 based .20 cal with a +2 or +3 gas tube…
 
FYI @MT Mike
Robert hasn't visited the forum since Oct 2020.
If you hover your cursor over a user's name, information pops up including the last time they visited the site.
 
Well, Hello Everyone.
I have built two AR's in 20 Grendel.
I do not have all my specs with me right now.
I will dig out the reemer sheet and other info and post later.
The reemer was designed for the 55 grain Bergers .
One AR has a 1:8 twist barrel for the 55's
The other AR is a 1:12 twist that I have shot 32's and 40's out of it.
I haven't been working with them for awhile, other projects. (300 PRC)
Like I said I'll dig out my notes and be back with some loads and other info.
Both shoot very nice.
Smudge
 
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