300 PRC update

b2lee

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  • Dec 30, 2018
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    Went to the short range today and did some 100yd testing. I was reverifying a speed node......everyone put your drinks down so you don't get any on the monitor.....but I was reverifying the LOW node. Yes I dropped about 100fps and went down to the lower speed node. I know...crazy right? Anyway, it was right where I thought it was.....verified it at 75.0 grains of RL-26 with a muzzle velocity of 2866....which averaged very well with the later in the day seating depth testing.

    After verifying my speed node I loaded up 3 rounds across 10 different seating depths....yep...that's a lot of testing on a barrel that has 1300+ rounds through it. I'll post the OAL measurements because my measurements using the comparator will be useless to you guys.

    Bullet is the Hornady A-Tip 230gr. I started at 3.812" and moved about 5 thou out with each 3 shot group. The markings on the Wilson micrometer seating die equaled 1 thou...I just went longer 5 thou with most sets. I ended at my old seating depth of 3.860".

    After a ton of seeing what I expected.....shot gun patterns when I was too close to the lands....and a smooth dialing in and getting smaller....I verified that 3.860" OAL is still exactly where my particular gun likes them to be...even after all this time.

    After 35 shots today...well 34..because I excluded the first shot on a slightly wet bore....I averaged 2866fps, 2.7SD with an ES of 9.1. I don't think I can complain about that at all....or even expect better...even with a new barrel. FGMM 215s were used and held that SD very nice. ADG Brass 7x. Annealed.

    So, brass is wet tumbling right now....next will be dried, annealed... full length resized, neck mandrel expanded, primer, 75.0gr of RL-26 and a 230 A-Tip seated at OAL 3.860".

    Tomorrow...the long drive up to Thunder Valley Precision. I'll judge my accuracy at 1 mile...then hopefully take it out to 2200 and 2300 yards and see if I can make the blinky light go blinky!

    And if it fails at long range....no worries...new barrel vise installed....new breaker bar and torque wrench purchased.....and new barrel on the way.

    And no matter what....I'll have fun tomorrow...should be close to 80F and sunny.
     

    DellaDog

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    Feb 23, 2017
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    Barrel length? (Curious because I feel I’m in a mid node at 2900)
    I spent 200 rounds with H1000 and R26 with 28” Bartlein and 2900 was best with both powders using 230 hybrids. RL26 @ 76 gr. and H1000 @ 77 gr. (holds .3 MOA at 100, 1/2 minute at 500 with decent vertical)
     

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    b2lee

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  • Dec 30, 2018
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    Barrel length? (Curious because I feel I’m in a mid node at 2900)
    I spent 200 rounds with H1000 and R26 with 28” Bartlein and 2900 was best with both powders using 230 hybrids. RL26 @ 76 gr. and H1000 @ 77 gr. (holds .3 MOA at 100, 1/2 minute at 500 with decent vertical)
    DellaDog,

    Barrel is a 28" Bartlein with a 1-9 twist with over 1300 rounds through it. ADG Brass and Hornady A-Tips. I've found lighter weight bullets hitting pressure signs way earlier than these A-Tips. I have pushed the 230's well over 3k...but that is most likely stupid on my part. In the summer...I found my best loads were in the 2950fps range.
     
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    b2lee

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  • Dec 30, 2018
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    Well....pretty good day at TVP today. Man was it beautiful. Great day to be at the range. 300PRC update.... 1 mile was like taking candy from a baby. Moved up to the new pavilion and made a second round hit at 2239yards....I thought I had missed....but it takes 3.5 seconds to get there....blinky light was so bright it almost put my eyes out....woo hoo!!! Next I dialed up to 2333 yds....there was like 500 black birds pecking at the ground around the target....I pull the trigger and 4 seconds later....all the birds take flight....but I never saw a splash.

    Ground was pretty wet....no dust. I fired and fired and never saw splash.....so...I came back down to 2239....hit....back up to 2333...nothing.....so..if the blinky light was broken...I would never know if I hit that heavy target out there....and I had nobody with me to help spot. I could see trace get close...then nothing. So...no call :(

    ~1350 rounds through the 300PRC....still making 1 Mile shots fairly easy on an 18" plate.... 2239yd 36"x36" plate fairly easy...and no call on the 36x36 plate at 2333.....the 2444 was off limits today...so no joy there either.

    Had a great time today though.....barrel still has life in it.....but will change it out when the new one arrives.
     

    b2lee

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  • Dec 30, 2018
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    During 1 Mile GBA Benchrest matches....our sighters are done on 4" clays to the left of the target....to help dial in wind first...then elevation...every now and then you hit 1 or 2 and that makes your head so big....you can't get it in the car for the ride home that day :)
     
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    Defender3

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    I think the mile shoot here in VA is 36x36. You have to have two hits at 775y and two at 1260y before they'll let you try the 1760y target. I was going to shoot it with my .260, but a new barrel was delayed 7 months and I bought the 300PRC, so I'll cheat and make it easy. :)
     

    Defender3

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    During 1 Mile GBA Benchrest matches....our sighters are done on 4" clays to the left of the target....to help dial in wind first...then elevation...every now and then you hit 1 or 2 and that makes your head so big....you can't get it in the car for the ride home that day :)
    We shoot 4" clays at 1035 at Quantico, it's boring. ;)
     
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    b2lee

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  • Dec 30, 2018
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    We shoot 4" clays at 1035 at Quantico, it's boring. ;)
    Not boring with my 308....hell...hitting the 12" plate with the 308 at 1000yds on a windy day can get interesting some times...I've been known to drop below 50% on that....wait....did I just say a 308 can make hits past 800 yards?.....blasphemy ...heh
     
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    Defender3

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    168 SMKs do not perform here past 800y, must be the bearing surface as the Hornadys seem to work. The 260 at 1000y makes you look like a genius with your wind calls.
     

    b2lee

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  • Dec 30, 2018
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    168 SMKs do not perform here past 800y, must be the bearing surface as the Hornadys seem to work. The 260 at 1000y makes you look like a genius with your wind calls.
    I'm shooting some 168 Match from Everglades Ammo. They do ok at 1000yds...but at 1100 they start getting frustrating. On a 12" plate you can be 4" right...Hit.... 6" left......6" right....1" high.....2" low....4" right...Hit....all with a dead center hold. 1200yd plate is just a little wider misses than that. Really frustrating...but that's why I built the 300PRC...to make those shots automatic....boring even.
     
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    b2lee

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  • Dec 30, 2018
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    action.png

    Spun off barrel....removed scope...removed chassis....going to clean everything up. After ~1350 rounds...the barrel still looks really good. Letting it soak over night filled with Boretech Carbon Remover....then a good scrub...but it was already almost a mirror finish. Barrel looks better than every other rifle I own.

    When new one arrives...I'll put it on...confirm if it has the same velocity and seating depth node....shoot it until it stops speeding up...and then put the old one back on for practice sessions.
     

    Jmcmath

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    Anyone used the berger 200.20x hybrid?

    Considering trying it out but worried it will barely be in the neck near the lands. Seems to have a really long nose and short bearing surface
     

    Ledzep

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    Was playing around a little last weekend. Initial results with RL-26 and the 37" barrel with 225's didn't really impress for speed. Not sure what was up, probably just a fresh barrel (was the first thing I tried). I had switched to shooting Retumbo with 250 A-tips, and it was okay. Like 7 or 8 of 10 would rock and roll but 2-3 would go a bit wonky. Sub-MOA, but kinda mehh. Anyway Covid killed the local ELR stuff and I put the 300 on the back burner ever since. I've been doing large sample size testing with 6.5 Creedmoor and the results there show that optimum accuracy is achieved with mild charges (like .5-1.5gr under max book load, or less) so I figured I'd try RL-26 at 71gr and see what happened.

    Hornady Virgin Cases
    Fed 215
    250 A-tip @ 3.745"
    71gr RL-26
    37" Bartlein 5R 1:8.5" MTU

    15 Shots
    2849fps Avg.
    27 ES, 8 SD
    1.37" group @ 200yd (.65 MOA)

    A single data point in this cartridge, but seems to be flier-free and pretty tight. I know everyone wants speed, but my testing in the 6.5 Creedmoor shows 20-35 shot groups going from just over .5 MOA @ 1-2gr under book max up to 0.8-1.2 MOA at book max. Going over book max has produced 1.3-3 MOA results, indicating "high nodes" don't exist. Not for that barrel anyway. That's with 6 different powders. Only 2 or 3 shot very well (The usual suspects, RL-16, H4350, H4831). All of them trended worse with increasing powder charge past a certain threshold. SD was more tied to powder type than powder charge. In other words, H4350 always produced 8-10 fps SD's, regardless if it was 40gr, 43gr, or anywhere in between.

    Anyway, moral of the story is I dropped the dispersion irregularity considerably in exchange for 90fps at the muzzle. I intend to play with hit probability calculators here at some point to see if speed is ever worth it. My initial thought is "No". Tighter dispersion will help until the point that MV spreads string out the vertical axis and my ES/SD numbers didn't change dramatically.