This topic contains 12 replies, has 4 voices, and was last updated by  Jniedbalski 1 year, 7 months ago.

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  • #46500
     Harter 
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    I’ve been shooting a couple of variations of the 6.8 SPC for 4 yr I guess .
    1 in a Carcano action as a 7×6.8 and more recently a bottom of the bargain barrel AR .

    Our fearless leader is responsible for the Carcano and it does spectacular things that make me weep with joy . But that’s not what I’m on about because semi auto forum .

    I have a BlackThorne products 6.8 SPCII carbine kit with 700 or so on target . It is a bones M4 with and A2 profile 16″ barrel . I changed the fore end to a free float and the A2 sight/gas block to a low profile on a scale of 1-10 it’s a matt black AR with holes in the fore end devoid of any sort of character . BlackThorne uses Mossberg and Wilson over run barrels (blems and 2nds are probably more correct) . From the start I wanted a 20″ rifle gas barrel ,more so with the need to make a power level with cast bullets….
    The OM set up had the ribbed M4 for stock with heat shield and would shoot Hornady 120 SSTs and FC 115 FMJs into about the same 3.5-4″ . Careful loads got the 120s down to 3″ from the carbine barrel and gas with 4198 but the action behaved out of time so I went to H322 and was back in the saddle but still with a 3″ rifle . So I snagged a free float fore end and a low profile gas block and a B nut wrench . (See how I didn’t abbreviate oil drum?) I changed the grip which had rub lines from the gas tube and marvelled at the weight saving barrel shape or something like that . The pinned on sight/GB was fun . I’m smarter now . All back together with the bird cage fixed I was off again . The bird cage trapped bbl trash against the muzzle and jacked up the crown shape . It was relieved from 30 to 50 cal and had the threads extended . It is much happier now . The groups returned and improved . But I can only get 2050 fps with the 279-124 NOE at 130 gr . No big deal the 120s will make the 1000# @100 I need for NV big game . 5 shot groups will go 2.5″ so I’m not completely upset .

    The new , honor of a man’s word , the take off has 200 rounds down it . It should be in hand in a few days . It is an ARP 20″ rifle gas length . So 200 fps and no other drive train changes ….. Or something .

    Currently load data says and the rifle don’t agree . It ejects at 2:00 instead of 3:00 . I’d fix it but the groups are inside what factory ammo will do . My Hope is that the load will be close . And eject where it should . I don’t know if the new barrel is a 1-10 or 1-11 . For obvious reasons I’d rather it were an 11 . If it is a 10 well drop back and punt . I have a 270-140 I can size .265 and paper if it will feed .
    That’s just ridiculous a paper patched cast bullet in an M4 🙂 .
    Memory jog ! I can put that 27-130 that pours at 142 gr to work too .

  • #46506
     Goodsteel 
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    I’m just thrilled to death you’re not screwing bubbles on your receivers anymore. LOL! (seriously, when I read the abbreviation “bbl” I physically cringe.  It’s a pet peeve I just can’t help.)

    Cool project. Keep us posted!

     

  • #47614
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    After a fashion I got the barrel . It took far longer to arrive than I’d hoped it would .

    I was unable to determine if the OM barrel is Wilson or Mossberg . The ARP 5R is a somewhat better quality barrel than the others . It came with a paired super bolt , wow . The polish on the parts and smoothing of hard edges is night and day ahead .

    Bugs ….
    Well I couldn’t get roll pin out of out of the low profile and I probably could have abused it into submission but I opted to use a different gas block . Of course I still needed a roll pin for the rifle length gas tube . A trade worked out for a new/better quality low profile gas block that came with the roll pin .
    Fully reassembled , a few of each available round , FC 115 , Hornady 120 SST , and a hand load featuring the NOE 279-124 . Greased glass I tell you . Manually with parts separated I was under able to lock the bolt in the extension on the hand loads but the factory ammo was a slip fit . I was relieved that it fed and ejected the short sized ammo when assembled . I have 500 rounds assembled and I’d rather fire form than tear them down .

    Other notes
    The gas port only just cuts the trailing edge of a land so with any luck at all it won’t abuse cast bullet .
    The bore/groove is of course a joy to measure but it looks to be just under .278 x .271+ .
    The muzzle device doesn’t have the shoulder in it that was present in the OM that I had removed . It became a debris trap and with bullet metal gasified or carried out the muzzle made the crown look like a gravel road . So at least I get to bypass that bit of fun .
    The barrel is FDE while the rest of the rifle is black on black .
    To me with this specific rifle it makes little difference as this is just a tool vs a sculpted walnut , high polish blue , art work testament to a craftsman .
    The barrel replaces an M2 profile with the M203 cut with a .900 dia from the B nut and chamber taper to the gas block step . Having switched from a 16″ carbine (16.128 including the barrel extension) to a rifle length 20″ barrel everything on the muzzle end is +4″ out .
    It feels more muzzle heavy now . For those that can relate it has gone from a lively skeet gun feel to that of a 32″ goose gun and the feel of the H bar . I think the 26oz weight gain and the 4″ of barrel are going to get me where I should have been in the first place .

    I changed the trigger from the GI to a drop in one piece assembly promised to be 4-4.5# . The GI trigger was a crisp short trigger with no felt movement until that place where it actually moved with maybe a 32nd of net movement at finger pad center . The replacement has a short reset and 2 stage like feel but creepless after the takeup . Total movement from stop to reset 1/8″ or so . I didn’t get out to shoot it yet . Hopefully this weekend .

  • #47679
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    Well , as far as bolstering my confidence , this is a mediocre presentation ………

    Things that had a marked change .
    I’ll start with the recoil impulse ….duh , the rifle is about a 1.5# heavier . The action action is however less snappy .
    The factory 115 fmj shot much as I expected it to with a tidy 3:00 ejection at 4′ . The cast load that worked in the former barrel and ejected at 2:00 is now somewhat lack luster and ejects at 4:00 . That means a rework of the cast load a careful inspection of the bore is still pending . Sight adjustment was rather a surprise as the irons went 2′ low ……. So much for easy hold over , failing light contributed to the minute of interior barn wall . Back to the optics .

  • #47689
     Goodsteel 
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    Sounds good Harter. Keep the updates coming buddy. I’m just munching the darn popcorn and following along.

  • #48629
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    I bought a tool for the sights . $10 ……. Damned money pit tinker toy erector set modular …… Where was I ?

    Oh right some load work up .
    After a little bit of inspection and a modification to see sideways with the $19 cell phone endoscope I decided I should shoot some more jacketed in it . The barrel is a 200 round take off and should be slicked up but had some copper stuck to it that seemed to be causing me some grief . I’ve stumbled onto some 90 gr HP Speer bullets and …….well that’s too easy . Looks like 29.8 of H322 will drop brass at 3:00 and off a 3 point sitting knee rest shoot an inch as long as I do my part .

    The $140 trigger is nice but at this time I see no gains on either end over the run in polished GI trigger it replaced . The ambidextrous safety is nice though so it can stay .
    My buddy Jorge hates the bird cage . No guesses about speed but the groups are a huge improvement .

    This will give me the opportunity to revisit H4198 with cast .
    The gas block moved and one load displayed no left right deviation but 3″ of vertical stringing . As the loads decreased in charge the groups opened up but this one was the 3rd load the only thing touching other than the B nut is the gas tube so I got nothing and have to write it off to load quirk .

  • #48724
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    Well I can’t find the data I wrote down for the last round so I’m flying blind again for the 120 SST bullets . I’m once again dumfounded by the lack of data for such popular bullets …. I didn’t remember this being so hard to find data .
    In fits of frustration I tinkered with some other things . I have several 6.5 moulds so I rolled a few up in paper just to check to see if they would feed . The OM barrel would slash and wad up patches not the ARP . Clean feed from the mag with bolt drops dry patches stayed where they were supposed to be . OAL was a little short after the first feed test but the second and third time there was no change .

    I think all of my notes are in the Lyman manual I gave my buddy Jorge to read on to get started reloading .
    I’m thinking about leaving him his dies , a press , scale and a few odds and ends of brass .

    I didn’t do any shooting and probably won’t until I find that data again ……it’s with the 7×6.8 data so it’s pretty important that I find it soon .

  • #68695
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    So this has been stagnant for a while . I’m not set up and I know living at virtually sea level is going to change things too .

    Wow I’m wowed .
    I went to just burn some ammo , I burned off a few FMJ just find the feel , face plant etc . It’s been so long since I loaded the mags I had forgotten until I was picking up that I had loaded work ups in the magazine . 3 each as it happens .
    It looks like H4198 might be a winner here . The target as luck would have it had 5 identifiable clusters of 3 . Half inch group at 50yd off a 3 point sitting knee rest with 2 in the same hole .
    Looks like I have a candidate to spend some time with on bags .
    FC brass
    CCI #41
    H4198 @ 23.6 gr
    NOE 279-124 @130 gr ready to roll .

    The barrel is a 5R at .277x.271 it’s hard to measure 5 skinny lands . These drop round at .279 and sized .280 to lock the check .
    Ejection was at 2:00 with the FC 115 FMJ but a perfect 3:00 in a coffee can with the 12 rounds of work up .

  • #68699
     Rattlesnake Charlie 
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    Where are you at Harter? I wish we could see “location” of our members.

    Just for all, I’m in the mountains of northern New Mexico, elevation 7400 ft.

  • #68700
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    Charlie , I’m currently not that far from GS . Had dinner as a matter of fact .
    I moved in June from Nevada about 70 road miles from Ca 120 into Yosimite to a little Arkansas town about 90 north of Texarkana .

  • #68712
     Jniedbalski 
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    Harter I thank i have been to the town you talk about. We where coming back from tx and stoped at a little town going to crater of diamonds park . The one town was kind of like a meusiem town. Houses ,court house, but I don’t thank any body lived there. I rember the little towns around there looked real nice. Nice place to live

  • #68713
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    About 6,000 people here . Mena .

  • #68714
     Jniedbalski 
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    I live in a town of about 130 in south east mo

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