My 6.5 PRC Thread

Discussion in 'Big Stuff -- 6.5mm, 7mm, 30 Cal' started by alf, Apr 14, 2018.

  1. alf

    alf Silver $$ Contributor

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    So last fall I got the itch to try the new Hornady 6.5 PRC cartridge. I already had the platform, so I really only needed a reamer and a barrel.

    After quite a bit of research, I gathered up some details:


    6.5 creedmoor: 52-53 gr case capacity
    6.5 SLR: 55-56 gr
    6.5 PRC: 66-67 gr
    6.5 SAUM: 70-71 gr

    The PRC has 25% more capacity than a creedmoor, and 5-6% less than a SAUM. In quickload, holding pressure constant at 57k psi in a 26" barrel with 140 hybrids, a 6.5 SAUM (H1000) is about 30-40 fps faster than a 6.5 PRC (H1000), and the PRC is 220 fps faster than a 6.5 creedmoor (H4350).


    Then I found this PSA on throating & overall lengths:


    The original reamer spec that most folks have been using to chamber PRC barrels is likely not going to natively work with the recently launched hornady factory ammo. This came to light due to the recently released Hornady reamer spec which JGS has as of just a few days ago. On that print, the freebore is indicated as .1882". The reamer that Travis presently has matches the spec PT&G had on file for the PRC which puts the freebore at .1302".


    I've worked with chambers on that original PT&G reamer as seen here: https://forums.gunhive.com/topic/167...and-ts-customs


    You'll notice in that write-up I was using a berger 140 hybrid and ended up ten thousandths off the lands with an OAL of 2.940". Hornady factory ammo is measuring 2.945 for both the 143ELDX and 147ELDM. Based on tip to ogive measurements, this would put hornady factory ammo jammed into the lands on the original PT&G reamer spec about ten thousandths. On the new reamer with the .1882 freebore, you'd be looking at approx 50 thousandths jump. Tip to ogive measurement on a 140 berger hybrid is about 20 thousandths longer than a 147 hornady... so you can plainly see what this differing spec can mean for those looking to shoot factory ammo in their "old" chambers.


    Some obvious things about that situation are that if you have an "old" PRC chamber, factory ammo will be jammed... while if you have a "new" PRC chamber, you'll never be able to get closer than 40 thousandths or so from the lands in max strapless AICS format magazines like Accuratemag.


    I do not know where the PT&G original spec came from, but it's clear that the hornady spec reamer print from JGS would indicate the future direction of the design and this is further supported by the fact their current factory ammo will certainly work fine in their new spec. It does present a dilemma for handloaders or custom builders however. On one spec you can run a short freebore and be able to approach the lands at mag length. On the other spec you'd never be able to approach the lands in a short action with the longest mags available for it. A mid or long action with associated mags would be the only way to get into the lands with the "new" spec.


    Both Travis and I felt it prudent to do a little PSA about this situation, as it's likely there are more than a couple rifles out there with short PRC chambers that will result in factory ammo being jammed to the tune of 10 thousandths or better.



     
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  2. alf

    alf Silver $$ Contributor

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    After reviewing the Hornady print, I found Hornady's specs for freebore were .188", and luckily my 6.5-284 reamer was the same, so I seated bullets in my 6.5-284 chamber & extrapolated seating depth to about .020" in the lands in the PRC case.

    So then I made a couple of dummy rounds with 140 VLD's and 147 ELD's to compare. Knowing the hazards of specing to the longest bullet could pose a problem if I couldn't get it to shoot, I set the reamer up for the Bergers, and resigned to the fact the Hornadys would seat quite a bit deeper.

    I called up JGS, specified the .200" freebore and narrowed the neck up a couple thou, and ordered the reamer.

    A couple months later, my prize showed up:

    [​IMG]
     
  3. alf

    alf Silver $$ Contributor

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    After the action, barrel, & reamer make a quick trip to the smith, I turn this pile-o-parts:

    [​IMG]


    Into this:

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  4. alf

    alf Silver $$ Contributor

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    Parts list consist of a stock stainless 700 long action, fluted bolt, 28" Bartlein 5R Remington Varmint contour barrel, tuned old style 700 trigger, BDL bottom metal, McMillan Marksman stock with pillars, not bedded, 30 MOA Seekins picatinny rail, Seekins medium high 30mm rings, and a Nightforce 5.5-22x50 HS ZS with the NP-R1 reticle on top.
     
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  5. simo hayha

    simo hayha

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    Choot it choot it
     
  6. alf

    alf Silver $$ Contributor

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    Dummy rounds about .020" in the lands.

    (L) 140 VLD - 2.995"

    (M) 147 ELD - 3.010"

    (R) 150 SMK - 3.090"


    [​IMG]
     
    Last edited: Apr 14, 2018
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  7. alf

    alf Silver $$ Contributor

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    Not much data out there yet except for Hornady and a blurb from GAP.

    So........ I started low, shooting 1 shot each in 1 grain increments for a base line, then went to 3 shot groups, ending at 3199 fps with the 140 VLD's and 3128 fps with the 147 ELD's, all with H-1000.



    First day out....still winter.

    [​IMG]


    Next day, I concentrated in the middle of the spectrum, starting at 3025 and ending at 3144 with the Bergers, and beginning at 2945 and ending at 3063 with the Hornadys.

    It was only around 30*, but I kept the ammo in the truck to keep it around 65* during testing. Due to the nasty little quartering tail wind making it a challenging day, I broke tradition and tested at 100 rather than the normal 200.
     
  8. alf

    alf Silver $$ Contributor

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    After several trips out shooting and comparing the 2 bullets, I couldn't come up with a clear cut winner, and I still had the nagging feeling I should try the new 150 SMK's. I broke down, ordered a big box, and got them moly plated.

    Next I loaded up some test loads with H-1000 and the Sierras, & gave them a go. With the shorter bearing surface of the 150's I figured I could go a hair more than where I did with the Hornadys. When I got to 3125, they shot damn good, but was on the edge of too much.

    A day later I tested them again, and while bolt lift was snug, I could chamber fired brass with ease.

    I finished up with this target:

    [​IMG]
     
  9. misfire

    misfire

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    Great write up, on a interesting cartridge.
    Thanks for sharing all your information.
    Hope to see more
     
  10. alf

    alf Silver $$ Contributor

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    So the next time out I decided my current load was too warm for my liking, so I aborted the shoot and went back to the drawing board.

    I consulted notes & targets from earlier, loaded up a few more test rounds, and gave them a go. Ended up at the next lower node running the 150's at 3025. Went home, cleaned the gun, and loaded a bunch to test at distance.

    Next morning I got to my spot while there was still light wind and frost on the ground, letting me drive to 600. I dropped off that target, drove back to 100, and dropped off the other target there. Got my stuff all set up, and shot the first three out of the clean/cold barrel, dead on, 1.1" high.

    Jumped in the truck, picked up the 100 yard target, dropped it off at 200, drove back to the bench, and shot 3 more. 1st hit the 10 ring, 2nd a half inch low, 3rd out to the right, dammit.

    By this time, the sun was warming things up too much to drive, so I walked out, moved the target to 300, walked back, and shot 3. Wow, now I know why the 3rd at 200 blew right. I hadn't realized how much the wind/mirage had picked up, despite being calm at the bench.

    Walked out to 300 & moved the target to the 400 line, came back & shot 3, still holding dead center. Mirage was running hard enough that I only spotted the 1st round at 2:00 o'clock off the red, the other two I couldn't see. I decided to shoot the 600 next before moving, so after waiting a few minutes to cool the barrel, I launched 3 at the top 600 yard target, of course not seeing a thing through the spotting scope.

    Walked down to 400, moved the target to 500, then on out to the 600 target to see where/if I even hit it. Cool, I caught the right edge. Hump it back to ground zero, and get on the 500 yard target. By the time I got back, the sky had clouded over, and I hadn't realized the wind had temporarily laid down. I held on the red ring on the left at 9 o'clock, & ripped off 3. The mirage had went away also, so I could see those 3 nestled together at 7 o'clock through the spotting scope. WOW!

    So I immediately dialed the scope, moved to the lower 600 target, held center, and shot 3. Staring through the spotting scope, the light mirage finally cleared out, and I saw the impacts.......Holy shit Batman!!!!!


    [​IMG]


    Targets at 400 and 600 yards:

    [​IMG]


    600 yard targets......1st group on top, 2nd on the bottom:


    [​IMG]
     
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  11. whatwind?

    whatwind? Silver $$ Contributor

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    Nice work, could you shoot some 25 shot strings and report bbl life after 1000 shots? :)

    How is Hornady brass, tight neck?

    Keep it coming
     
  12. alf

    alf Silver $$ Contributor

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    Hornady's print is .299" on neck diameter. My loaded rounds measure .2915-.2920, so I ordered my reamer at .296". I don't turn these, but still have the option to clean them up w/o making a big gap.

    Hornady's new brass is some tough shit. I'm at 5 firings each, some at "proof loads" and no sign of the pockets going south yet. Some of course are a bit looser, but still plenty serviceable.

    I'm right at 500 rounds down the bore, and the throat looks great through the Hawkeye.

    http://forum.accurateshooter.com/attachments/jgs-6-5-prc-reamer-print-pdf.1023690/
     
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  13. alf

    alf Silver $$ Contributor

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  14. wboggs

    wboggs Silver $$ Contributor

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    Very well researched article with historical
    perspective as well as current load data. It looks like the 8 twist barrel is stabilizing the 150 smk just fine.
    A job well done.
    Bill
     
    Last edited: Apr 14, 2018
  15. wboggs

    wboggs Silver $$ Contributor

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    I am in the process of building a similar rifle but will have a 7.5 30" barrel instead. alf has been very gracious and helpful with my many questions and is one of the main reasons I decided to start this project.
    I am probably a couple months out but will post my results as soon as they become available.
     
  16. alf

    alf Silver $$ Contributor

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    Thanks Bill. Part of the reason for the thread was to consolidate some of the info that's out there into one place, and to show off a bit as well.

    More to come.......
     
  17. Trophied

    Trophied Gold $$ Contributor

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    I may be going this route some time later this year, not necessarily to shoot long range targets. More as just a hunting type round. Thanks for the info.
     
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  18. Rum Punch Colonial

    Rum Punch Colonial

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    I was thinking this as a perfect all around 7mm Hunter. We will see how available Brass is in the future.
     
  19. wboggs

    wboggs Silver $$ Contributor

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    It will be a very good hunting round. I'm not sure it needs to be necked up. 6.5mm is very effective. Shot 2 bull elk with the 160gr Woodleigh out of a 6.5x55 at 2800 and they were down just as quickly as with a lager caliber.
     
  20. Trophied

    Trophied Gold $$ Contributor

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    The caliber is effective. The cartridge? The jury is still out. I'm willing to try it, just because I can, and completely getting rid of it if it doesn't suit me will only entail rechambering a barrel to something .532 with a 6.5 bore, or another barrel. No problem.
     

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