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Thread: 6.8 SPC cast bullet tips

  1. #1
    Boolit Grand Master Texas by God's Avatar
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    6.8 SPC cast bullet tips

    One of my upcoming projects is to assemble an AR15 in the 6.8 SPC cartridge. I haven't checked the twist yet on my barrel, but assuming that it's 1-10" it should be ok for cast bullets.
    If anyone uses cast unless in their " baby .270"- Please share your thoughts.
    Thanks

    Sent from my SM-A716U using Tapatalk

  2. #2
    Boolit Grand Master Harter66's Avatar
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    The NOE 279-124 is designed specifically for the 6.8 SPCII . The SPCII is the same but without the SAAMI throat and leade , it's slightly longer and shallower taper . Which is more in line with the original pre Rem SAAMI drawing .

    Barrels are mostly 1-10 , AR performance does them in both 1-10 and 1-11 .

    I use an alloy that is about 75-25 WW and lead tamper seals that appear to be 1-20 and pick up copper during the clean up . The finished bullets are WC and start at 18 BHN and after 4 yr hover around 20 bhn . They have a terminal impact function more like a 14-16 and a barrel function more like 22-24 . I used my modified Darrs lube and Hornady 270 checks through a .280 Lee sizer .

    I had a Wilson or Mossy barrel on the gas gun , 16" , carbine gas , 1-10 , A2 profile and fittings with M4 extension . H4198 provided my desired 2200 fps MV but was in an awkward place with the gas/chamber pressure and made function issues in 2 rifles . The conclusion was that the chamber pressure was high enough for the brass to still be holding but not high enough to over come it . The load functioned well through the work up but wouldn't reach the hold open instead holding on the mag follower as I worked up it would miss even the follower . In hind sight there was a bit of debris that may have interfered with gas flow , but I wouldn't think in 2 barrels .
    I switched to H322 at 23.3 gr in FC brass with a #41 CCI . Groups hovered around 2" after the free float handguard and low profile gas block were installed . The 30 drilled A2 flash hider trapped deposits between it and on the crown , that caused spontaneous accuracy issues . Having the step/baffle removed from the FH fixed that . Velocity however was only about 2090-2110 and wouldn't make my needed 1000#@100 yd .

    Opportunity knocked and a 20" rifle gas ARP 5R heavy barrel was dragged in kicking and screaming . The load above increased to 2240 fps MV and delivers 1.25-1.5" at 100 . Because I had another rifle I had a lot of that load loaded and will leave it as is until my daughter gets it down to a point where I can work the 4198 load again for the ARP barrel and load 500 or so again .

    Details that worked for me .
    FC brass is SRP and in the gas gun seemed cleaner .
    I had a custom mildcat in 76.8 so the RP LRP was saved for that and easy segregation .
    S&B required about a .2 load reduction and dropped to about 2040 fps MV to get the groups back to the FC levels in the Wilson/Mossy barrel . I will eventually try it again in my Granddaughters ARP equipped Stevens 200 again for brass segregation .
    Yes I used jacketed data start loads to get started .
    The ARP FH both the A2 style and linier type have a different through design and don't trap the crown fouling . 5/8-20? Not the 1/2-20 of the A2 style .
    Yes a Win LRP will slam fire I didn't have that with the CCI 300 .
    All of the loads should have been in the general area of 42-45kpsi but I don't have the test equipment to proof that .
    Both ARP barrels are closer to 1-11 than 1-10 and heavy profile .
    The NOE bullet is 130 gr ready to load and I load to 2.226 OAL for all . That runs freely in the blackened AR Stoner SS mags , and the Stevens center feed .
    I don't crimp and other than the initial uniforming trim it hasn't been needed in 5 cycles .
    I anneal before I size every 3rd loading for the gas guns , 2nd for the mildcat .
    Just wait for the RCBS and up dies to come in . The Lee is fine but ...... well it's a feel thing . I "fixed" feel in the Lee set to accommodate the .007 up size for the mildcat .

    I think that's all .
    In the time of darkest defeat,our victory may be nearest. Wm. McKinley.

    I was young and stupid then I'm older now. Me 1992 .

    Richard Lee Hart 6/29/39-7/25/18


    Without trial we cannot learn and grow . It is through our stuggles that we become stronger .
    Brother I'm going to be Pythagerus , DiVinci , and Atlas all rolled into one soon .

  3. #3
    Boolit Master


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    Anyone got a mold that is gas checked for that?

  4. #4
    Boolit Master

    Calamity Jake's Avatar
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    Quote Originally Posted by Soundguy View Post
    Anyone got a mold that is gas checked for that?
    I have a Saeco #270 for the 270 a 140gr long bore ride nose gc 2 cav for sale if your interested.

    This bullet shot very well in my Rem 700 with 1-10 twist
    Calamity Jake

    NRA Life Member
    SASS 15704
    Shoot straight, keepem in the ten ring.

  5. #5
    Boolit Master


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    I'll have to look at my 270 in my 6.8 SPC data to see if I can use that sounds like a nice mold

  6. #6
    Boolit Grand Master Texas by God's Avatar
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    Thanks, Harter66 for the info. My barrel is 20” and marked 6.8x47 5R- is that ARP made?
    Also I was wondering about the Lee C277130- is it suitable for the 6.8 nosewise and lengthwise?

  7. #7
    Boolit Buddy
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    I shoot a lyman 130 grain cast PC over with rem LR primer 19h4895 sized .278

  8. #8
    Boolit Grand Master Harter66's Avatar
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    Quote Originally Posted by Texas by God View Post
    Thanks, Harter66 for the info. My barrel is 20” and marked 6.8x47 5R- is that ARP made?
    Also I was wondering about the Lee C277130- is it suitable for the 6.8 nosewise and lengthwise?
    I can't say in either case ........ I don't recall the Savage barrel having any markings and the gas gun I'd have to take apart to look .
    I want to say the 6.847 was Black Hole Weaponry , the 5R rifling isn't an exclusive to one maker .

    The Lee bullet wasn't available when I did the 76.8 for paper patch in a Carcano action . The NOE bullet was an instant success at 130 gr , the RCBS 27-130FN taught me to weigh a new to me mould as it cast at 141 gr and a load that should have been 48-52kpsi opened up a large primer pocket to about .240 . The Carcano handles gas and spray better than you'd think .........twice .

    Look up https://www.68forums.com/forums there is piles of information there , load data , the throat/leade variations , and the specifics of the 6.847 ....... There's probably almost as much information there about the single cartridge and platforms as here about casting good bullets for pistols .

    This starts medium remedial but is the whole trip with a bargain bin Kit rifle and the quest to reach 2200 fps MV for a minimum 1000 ftlb at 100 yards . It includes all of my data , alloy , sizing , and platform information , both good and crash and burn .
    In the time of darkest defeat,our victory may be nearest. Wm. McKinley.

    I was young and stupid then I'm older now. Me 1992 .

    Richard Lee Hart 6/29/39-7/25/18


    Without trial we cannot learn and grow . It is through our stuggles that we become stronger .
    Brother I'm going to be Pythagerus , DiVinci , and Atlas all rolled into one soon .

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check