Ramblerman Posted March 11, 2017 Report Share Posted March 11, 2017 Hi all. Just finished the first, to my knowledge 375 caliber AR-10-type rifle. It's my own design, the 375 KPM (Kinetic Performance & Machine). Uses a 284 Winchester case necked up and shortened but with a full powder column. So far, it looks promising with load development under way. Test loads thus far are using more powder per grain of bullet than a 35 Whelen, so it looks promising. It is a hammer!! Excited to do more testing. Pics show a 375 KPM next to a standard 308 and a clear bore size increase ?. Thanks for looking! Quote Link to comment Share on other sites More sharing options...
shepp Posted March 11, 2017 Report Share Posted March 11, 2017 Damn!!! welcome to the forum feel free to tell us about yourself in the intro section Quote Link to comment Share on other sites More sharing options...
Ramblerman Posted March 11, 2017 Author Report Share Posted March 11, 2017 (edited) Will do shepp, thanks! Edited March 11, 2017 by Ramblerman Typo Quote Link to comment Share on other sites More sharing options...
Armed Eye Doc Posted March 11, 2017 Report Share Posted March 11, 2017 Wow that looks mean. I like it! Quote Link to comment Share on other sites More sharing options...
washguy Posted March 11, 2017 Report Share Posted March 11, 2017 Elephant gun ...gun bearer...bring me my rifle... Wash Quote Link to comment Share on other sites More sharing options...
Ramblerman Posted March 11, 2017 Author Report Share Posted March 11, 2017 Hahahaha, thanks gents! Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted March 11, 2017 Report Share Posted March 11, 2017 Wowser! I love big bore rifles. This might be the biggest I've seen on this format rifle. Well done!!! Quote Link to comment Share on other sites More sharing options...
beantown Posted March 11, 2017 Report Share Posted March 11, 2017 OH hell YES!!! Quote Link to comment Share on other sites More sharing options...
planeflyer21 Posted March 11, 2017 Report Share Posted March 11, 2017 Very impressive Ramblerman! I love that big slug poking out of the case. You are rekindling my desire to build a .358 Winchester LAR-8. Quote Link to comment Share on other sites More sharing options...
Sisco Posted March 11, 2017 Report Share Posted March 11, 2017 Nice! Always good to see some skilled creativity. Quote Link to comment Share on other sites More sharing options...
Ramblerman Posted March 11, 2017 Author Report Share Posted March 11, 2017 (edited) Thanks for the comments guys?. I built a 338 Federal and heavy 260 REM prior to this and both are excellent. It stilI amazes me how darn well these things shoot, considering they go together like Legos, haha?. I think a 358 Winchester would be excellent as well. Build it!! Now the gears are already turning to see if a 400 or even a 416 KPM is feasible ?. Hehehe. Semper Fi! Edited March 11, 2017 by Ramblerman Typo Quote Link to comment Share on other sites More sharing options...
unforgiven Posted March 11, 2017 Report Share Posted March 11, 2017 Damn good job brother. Being that Rock River sez that their parts are proprietary how did you pull that off ??? Quote Link to comment Share on other sites More sharing options...
unforgiven Posted March 11, 2017 Report Share Posted March 11, 2017 Do you use the same Fal mag ?? How many does it hold ?? Quote Link to comment Share on other sites More sharing options...
planeflyer21 Posted March 11, 2017 Report Share Posted March 11, 2017 21 minutes ago, unforgiven said: Do you use the same Fal mag ?? How many does it hold ?? Not sure about volume but my polymer RRA mags have a good 0.020"+ clearance on ammo. Seems like an ideal platform for heavies and bigger calibers. Quote Link to comment Share on other sites More sharing options...
unforgiven Posted March 11, 2017 Report Share Posted March 11, 2017 Impressive..... Quote Link to comment Share on other sites More sharing options...
Sisco Posted March 11, 2017 Report Share Posted March 11, 2017 When you are willing to share, I would be interested in chronograph and pressure info, understanding you may not want to release that right now if you are going for a proprietary cartridge.Looks like an interesting and entertaining build with some new ground being broken. Quote Link to comment Share on other sites More sharing options...
Ramblerman Posted March 11, 2017 Author Report Share Posted March 11, 2017 Thanks for all the encouragement gents! As far as mags go, the cheapo metric fal mags so far work best as they are better (looser??) suited to the fatter case (the steel mags allow a longer oal as well over the factory plastic mags). As far as how many, I can get 16 in the mag, but some work needs to be done here too as I haven't stuffed more than five live rounds in it, due to the fireform ammo being delicate because of the donut in the neck from necking up brass from 6.5mm. Once I get a decent number of fireformed cases to better test with, I can work on the magazine feeding and let everyone know how it works out. It will probably be a bit before I can get chrono data, but the 200 gr. fireform loads I'm shooting in theory should be around 2800+fps. The goal was to be able to shoot the Speer 235gr at 2600fps and the 270gr pushing 2400 to maintain the 3500 ft.lbs. m.e. I was shooting for. Thanks again for all the posts, it's very encouraging and humbling!? SF, Ramblerman Quote Link to comment Share on other sites More sharing options...
Ramblerman Posted March 11, 2017 Author Report Share Posted March 11, 2017 BTW, if anyone has any WW 284 win brass lying around they don't want a buck apiece for, I'm interested, as they finish the forming process much cleaner. The Lapua brass is awesome as always for its intended purpose, but not as easy to work with the aggressive forming it takes to get a case just to fireform. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted March 11, 2017 Report Share Posted March 11, 2017 Pretty damned impressive! I like it! Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted March 11, 2017 Report Share Posted March 11, 2017 I'm still waiting for a .400 Blackout/whisper type cartridge on the .308AR format rifle. Quote Link to comment Share on other sites More sharing options...
Ramblerman Posted March 11, 2017 Author Report Share Posted March 11, 2017 (edited) How about we knock the shoulder back about .375" Robocop and shoot a 375 Cal. 350gr Matchking? 400 caliber bullets are a lot harder to come by?. Even with the "cheaper" 375 bullets I'm using the price per shot is getting significant. Edited March 11, 2017 by Ramblerman Quote Link to comment Share on other sites More sharing options...
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