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Moonie
06-14-2010, 12:16 PM
Got a new project. Just received a 6.8 recon barrel from Bison Armory for an upper I'm building for my AR. Anyone here ever cast for it? I noticed that LBT has a 110gr mold for 6.8/270 which looks like a perfect match for it. Thinking plain or paperpatched.

Doby45
06-14-2010, 05:39 PM
I was always under the impression that cast was not good for gas operated rifles. I could be so wrong it is not funny, but that is my understanding..

Echo
06-14-2010, 07:26 PM
Doby, that is the result of rationalization - a long time ago, some one wondered how lead boolits would behave in a gas-operated gun, and decided that the gas port would probably get leaded up fast, so it wouldn't be a good idea. And published that. And other folks believed it.

I theenk...

Or maybe someone tried pure Pb boolits @ 2600 fps and had problems...

Moonie
06-14-2010, 08:32 PM
Right, it is a popular missconception, lots of people on here use cast in their AR's and other gas semi's

wiljen
06-14-2010, 09:00 PM
The 150gr RCBS makes a nice subsonic loaded ahead of trailboss 7.2gr or Unique 4.5gr

Buddy of mine has a 6.8 with a can on it and an adjustable gas setup. Extremely quiet and minute of beer can at 100 yards.

dogbert41
06-15-2010, 12:20 AM
Not a bad idea, casting for 6.8! At lead velocities, that brass should last a long time too. I wouldn't worry about it plugging up the gas system. I guess in an AR system there is a very large amount of pressure going through them that keeps those tubes open. They are more or less self cleaning. If it were ever to plug up, I'd just replace the tube and maybe use a torch to melt the led in the gas system part of the front sight base. You can do all of that in about 5 minutes.

Moonie
06-15-2010, 10:05 AM
Yikes, I couldn't bring myself to heat up this beautiful SS Bison 18" Recon barrel, gas block would come off first lol. From the research I've done on shooting cast in AR's no one that does it has had an issue with blockages but of course if the action suddenly stops ejecting consistently that would be my first stop.

Still waiting on my Bator mold for the 5.56 barrel on the AR currently...

johnly
06-15-2010, 11:39 AM
I've been collecting molds, gas checks, and sizing dies with the intent of shooting cast bullets through my 6.8 SPC AR. I've collected 280412, 280468, 280473 and 280642 molds, but given the short length allowed for bullet protrusion, the 280468 might end up being the only workable choice.

My Colt 7.62x39mm is a fantastic cast bullet shooter, and hopefully I can get similar results with my 6.8 SPC.

John

Moonie
06-15-2010, 02:28 PM
I'm actually looking at the LBT 270110SP (I believe that would be the order number) 270 cal, 110gr Spitzer. 110gr is generally considered the top end weight wise for the 6.8, not that heavier won't work but going heavier cuts down quickly on the amount of room for powder.

I don't see the 280468 as being available new but it is 115gr so it would probably work but I do like the design of the LBT better and it might feed better as well.

jameslovesjammie
06-17-2010, 02:37 PM
What twist is your barrel? A 12 twist is better for bullets of the 110 grain range. People have noted increased accuracy and velocity with the 12 twist as opposed to the 10 twist that is standard in the .277 cal. This applies to lead as well as jacketed.

yarro
06-17-2010, 07:39 PM
Most of the leading up the gas port was from using the .22LR droping conversions that in the .223 uppers. If you did not shoot .223 in the upper before putting too many .22LR bullets through it, the gas port could get plugged.

Also Some of the 6.8SPC barrels have too fast twist rates for the bullet weight intended. Model1Sales is a good example at 1 in 9.5. 1 in 11 is best. 1in 10 is standard .270 Win for most bolt guns. It shouldn't be any worse than shooting lead in a .270 Win.

-yarro

Calamity Jake
06-18-2010, 08:58 AM
Don't overlook the Saeco #270.

http://photos.gunloads.com/images/CalamityJake/rem700cast001.jpg

This is how it shoots in my Rem. 700 @ 100
That's 5 rounds too although it looks like 4.

Another, shot in a Pdog match. The round out to the left I pulled

http://photos.gunloads.com/images/CalamityJake/castinthe270.jpg

Moonie
06-18-2010, 11:44 AM
My barrel is a 4 groove 1 in 11" twist Bison Armory barrel with the Spec II chamber, it works with the SSA combat loads. The 6.8 SPC isn't designed for projectiles 130gr or above as it takes up too much space in the cartridge due to magazine restrictions. In a bolt gun this would be different but in the AR platform there just isn't enough room. That is why I'm looking at the molds in the range I am.

GabbyM
06-19-2010, 12:12 AM
I've a 122 grain Lyman Loverin mould I use in my 270 win. #280468. Always thought that may work in the 6.8 spc. Boolits are .815" O.L. with a .305" nose to the first bore diameter sized band.
Crimp grove to base of gas check is .505". In my 270 WIN there's enough throat to load the boolit out a bit so the gas checks stays inside the .384" long neck. If your 6.8mm spc throat would not allow the bullet to stay inside the neck this bullet wouldn't be one you'd want to look for. They seam easy to come by on Ebay mould auctions.

I sent some of these off to a fellow over a year ago to try in a 6.8mm and we never heard back from him. I'd try again if their is any interest. believe I only have a handful of these cast and ready.
I mostly use the RCBS 150 grain to play with in my 270.

Used Mountain Mold software to draw up a bullet one day to come up with a 130 grain IIRC flat point bore ride with a base to fit into the .272" long neck of the 6.8 spc. You can have a 7mm gas check shank option on his moulds. Which would make finding checks much easier. If Verals boolit is made to fit the 6.8 spc neck it may work but 110 grains isn't much lead for a 277” bore. But I'm thinking a 125 to 130 gain bullet should go 2200 fps with a load of slow powder in a 6.8 spc. But that may be wishful thinking on my part as all I have to go on is gleaning the load book. I've wondered if close to a case full of slow stick powder like RX15 would work under a boolit in the 6.8spc.

As long as the 6.8mm has been out you'd think someone would have played around with one. Ruger even chambers the M77 for it.