Pastor12 Posted September 1, 2014 Report Share Posted September 1, 2014 New to this forum, must say I've already learned some new things. I'm trying a special build, building a 6mm dasher on .308 frame. Has anyone tried this? If so, what issues did you run into? I've already realized one issue is going to be feeding into the chamber. Was wondering about modifying the barrel extension to change the feed ramp. Thanks for any help Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted September 1, 2014 Report Share Posted September 1, 2014 I don't think this will work... The Dasher is too short for the longer action of the 308AR. I suggest modifying a standard AR15 instead. The Dasher is just a .243 in a short (1.5") .308 casing. The OAL of the Dasher vs the 5.56x45 is almost identical. You'll just have to find someone to make a bolt for you.... I think you can use a .458 SOCOM bolt??? I believe the .458 has a .308 Winchester rim... but I'm not 100% on that. Definitely a wildcat build. Why not just make a .243 Win AR? The ballistics I found on the Dasher aren't that far off from the .243.... And all the parts are already available. Quote Link to comment Share on other sites More sharing options...
Pastor12 Posted September 2, 2014 Author Report Share Posted September 2, 2014 Are you saying that the dasher won't cycle in a .308? One of the main reasons I'm looking at the .308 frame is that with the AR15 the magazine length becomes a real issue loading anything more than an 80 grain bullet. I have a 6mm ar turbo built by Robert Whitley and I have to go in .045 from the lands just to fit the magazine. This begins to cause other issues with seating etc. He used the 6.5 Grendel case in order to fit the AR15 bolt. Dasher aol is 2.408 the AR15 mag is approx 2.315, even if I get a bolt to work I'm still seating the bullet nearly .100 into the case. As to why the dasher over the 243, yes they are similar but the dasher certainly has become much more popular with bench rest shooters, accuracy, less powder, doesn't burn up barrels. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted September 2, 2014 Report Share Posted September 2, 2014 The smallest cartridge I've seen for the 308AR, has an OAL of 2.7 (but that's just what I've seen. There may be smaller). I'm not saying it can't be done with the Dasher. I'm just saying you'll have your work cut out for you. Modifying magazines. Modifying barrel extension/feed ramp. You may have a strange ejection as well. That short casing is going to fly out much sooner than the rifle was designed. I doubt it'll even touch the shell deflector. Quote Link to comment Share on other sites More sharing options...
Pastor12 Posted September 2, 2014 Author Report Share Posted September 2, 2014 It would seem like I'm caught in the middle, too big in some ways for the AR15 and too small in other ways for the 308. As far as cycling do you think a regular gas tube and gas block will have enough gas to cycle it? I figured that the barrel extension/feed ramp would be the biggest issue. If that's the case how would one go about getting a modified extension? BTW thanks for your insights. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted September 2, 2014 Report Share Posted September 2, 2014 I don't know what you mean by "regular"... If I were building a wildcat, I'd stick with a carbine length gas tube and add an adjustable gas block. You'll be able to adjust the gas accordingly, for your desired loads. As for custom parts... I'm assuming you're not a gunsmith. Which means that you're going to need one... A really good one. The parts will need to be fabricated from scratch. I won't lie when I say that one-off parts will run about 5x normal cost. Then you'll have to look at hourly rate. You're not going to find simple "plug and play" parts. You may very well be the first to ever attempt this. A gunsmith will likely spend hours doing a trial and error of parts, trying to get your gun to fire/chamber/eject reliably. It may behoove you to wait for LWRCi to finish their new 6.8SPC rifle. It has a larger than standard receiver, that uses a new/larger 6.8SPC PMAG. This design is under contract to a foreign military right now, but they already stated that it will become a domestic rifle in the near future, after they (LWRCi) have satisfied their end of the contract. From what I understand, Magpul has agreed to make a shiit ton of these mags to distribute with the rifle. If your google-fu is strong, I'm sure the measurements are out there somewhere. Quote Link to comment Share on other sites More sharing options...
Pastor12 Posted September 2, 2014 Author Report Share Posted September 2, 2014 Boy you are a wealth of information. I was thinking a rifle length gas tube, but the adjustable gas block makes sense. What I've heard a great deal that generally the AR is over gassed, which is why rifle length came to mind. When you say oversized lower that means just in the magazine area, with bolt and everything else the same? Quote Link to comment Share on other sites More sharing options...
MONTANA308 Posted September 2, 2014 Report Share Posted September 2, 2014 Have you considered the 6creedmore with is nothing but 6.5 brass necked down. I do believe GA Precision is having brass made up as well and can purchase it from them. Im planing a 6creedmore build for this winter with a fast twist barrel to run the 105 Berger. Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted September 2, 2014 Report Share Posted September 2, 2014 Are you trying to build a bench rest gun? Why not go with a 6.5 creedmore? What's a "turbo AR"? If you do continue down this road, it will be very expensive, as you will be pioneering a new AR cartridge, because I'm guessing this is something only run in a bolt gun. Quote Link to comment Share on other sites More sharing options...
FaRKle! Posted September 3, 2014 Report Share Posted September 3, 2014 It may behoove you to wait for LWRCi to finish their new 6.8SPC rifle. It has a larger than standard receiver, that uses a new/larger 6.8SPC PMAG. This design is under contract to a foreign military right now, but they already stated that it will become a domestic rifle in the near future, after they (LWRCi) have satisfied their end of the contract. From what I understand, Magpul has agreed to make a shiit ton of these mags to distribute with the rifle. If your google-fu is strong, I'm sure the measurements are out there somewhere. Unfortunately, this isn't an option. The Six8 PMAGs are designed with a max COAL of 2.32, still less than the 2.408 he needs. Quote Link to comment Share on other sites More sharing options...
Pastor12 Posted September 3, 2014 Author Report Share Posted September 3, 2014 Have you considered the 6creedmore with is nothing but 6.5 brass necked down. I do believe GA Precision is having brass made up as well and can purchase it from them. Im planing a 6creedmore build for this winter with a fast twist barrel to run the 105 Berger. I have thought of the 6creedmore, I too am trying to use the 105 & 108 Berger VLD The 6mm AR Turbo is built by Robert Whitley. It's a necked down 6.5 Grendel case. Here's the web site http://6mmar.com/6mmAR_Turbo_40_Improved.php Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted September 3, 2014 Report Share Posted September 3, 2014 Unfortunately, this isn't an option. The Six8 PMAGs are designed with a max COAL of 2.32, still less than the 2.408 he needs. I had a feeling YOU would be the one to find this first. Farkle is honestly the "Ip Man" of Goggle-Fu. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted September 3, 2014 Report Share Posted September 3, 2014 Did the 6.5 Creedmoor beat out the .260 Remington, as far as mainstream production goes?? I was always a .260 fan. Quote Link to comment Share on other sites More sharing options...
FaRKle! Posted September 3, 2014 Report Share Posted September 3, 2014 I had a feeling YOU would be the one to find this first. Farkle is honestly the "Ip Man" of Goggle-Fu.Not going to lie, I had the same train of thought as you after reading his post. "What about those larger Six8 receivers and PMAGS?" Then I looked it up, and yeah, disappointing. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 3, 2014 Report Share Posted September 3, 2014 (edited) Pastor, research the Olympic Arms UMAR. You need this rifle to accomplish your goal. We, here, know nothing about that rifle, and none of us here have that. Don't ask us questions about it - it will do you zero good, in search of information on it. I'm just sayin'... Now, with that information, the UMAR was designed to be able to shoot the 22-250. The rifle itself is between the AR15 and 308AR - they made it that way, to shoot the 22-250. Sounds like that's what you need for your wildass wildcat round. Keep in mind, you CAN NOT ORDER A RIFLE FROM OLYMPIC ARMS. You don't live in Washington State, so they won't sell to you. Your only choice is to order it, or get it, from an Oly Dealer. Now, once you get this rifle, and it's mags, you can begin the heinous quest of finding a reputable AR Gunsmith that will custom-chamber a barrel for you, maybe machine a new bolt for you if that's necessary, etc. Good luck. Here's the link - surf away: http://www.olyarms.com/shop/umar.html Edited September 3, 2014 by 98Z5V Quote Link to comment Share on other sites More sharing options...
MONTANA308 Posted September 3, 2014 Report Share Posted September 3, 2014 Did the 6.5 Creedmoor beat out the .260 Remington, as far as mainstream production goes?? I was always a .260 fan. Don't think you can go wrong with either IMO. They both shoot lights out in a gas gun or bolt. I believe the 6.5 is just a tad shorter case. If your talking about necking down a Grendel case then we are talking AR 15 platform. I know GA Gap 10 can be had in a 6creedmore so it's been done already. I haven't been around a 6 gas gun but the bolt guns in the 6 creedmore I was truly impressed with. Such is why I hope to be building a 6 gasser this winter! If you want a 6 cal in the larger frame run a 243 or 6creed IMO. other wise ya can't go wrong with the 6.5 or 260 either. Quote Link to comment Share on other sites More sharing options...
Pastor12 Posted September 4, 2014 Author Report Share Posted September 4, 2014 Thanks for the info on Olympic Arms, been in contact with them, looks like they may be able to help me out using their UMAR platform. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 4, 2014 Report Share Posted September 4, 2014 Thanks for the info on Olympic Arms, been in contact with them, looks like they may be able to help me out using their UMAR platform. There's a pretty good forum out there, too, and I'm positive that guys there have used the UMAR - Olympic Arms Owner's Association: http://www.oa2.org/Forum/ Quote Link to comment Share on other sites More sharing options...
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