6.5 creed: How much to back down a load when switching primers?

Discussion in 'Big Stuff -- 6.5mm, 7mm, 30 Cal' started by esp42089, Jun 3, 2018.

  1. esp42089

    esp42089

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    Hi all,

    I've got a ruger precision rifle in 6.5 creedmoor that I've been playing with. I'm shooting 147 ELDM with RL17, hornady brass, RWS large rifle primers from 1977 all seated to 2.840" (longest the stock magazine will allow, but jumping maybe .090" or more).

    My ladder up to 42gr resulted in no measurable case head growth or flattening of the primers, but the cratering and primer extrusion into the pin hole gets worse as I go up. 40.5gr is 2670fps, 41gr is 2700, 41.8 is 2750, 42 was 2770. I stopped there because the craters were standing 0.020" proud at that point and I didn't want to risk piercing a cup. I've got some Fed 210 and some CCI 250 magnum primers in hand for other guns and thought I'd give them a try here. Any advice on how much to dial it down for the change in primers? Would a few tenths be ok? Ladder from 41.5 on up for each primer again?

    At 40.3, 41, and 41.7 it groups pretty nice: holding 0.5MOA out to 800yards (furthest I've gone so far on paper) with single digit SD and low teens for ES. I've been very pleased with it. It's very rewarding to shoot the 6.5 Creedmoor with this rifle platform after spending more than a decade behind a 300 Savage in a Mauser 98 hunting rifle shooting 155s at 2600fps. Feels almost like cheating. :D The thing is a laser beam as far as I'm concerned!

    On a related note, does anyone know if Greg (GreTan) can bush the rpr bolts? He's not too far from me. If no one knows, I'll get in touch with him.

    Thanks
     
    rap36case likes this.
  2. #40Fan

    #40Fan

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    I live dangerously, so I'd swap primers without a powder weight change.
     
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  3. MagnumManiac

    MagnumManiac

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    Firstly, a cratered primer does not always mean excessive pressure. If you look closely at the firing pin hole with a magnifying glass, I bet there is a bevel that is causing the crater.
    Secondly, if you want ACCURACY from your loads, then switching primer should be only done with a NEW set of work up loads.
    Many years ago, shooting F-Class, I believed that primers made very little difference to loads...boy was I wrong.
    Just changing the primer can influence pressure as wildly as 10,000psi on the START load, sending groups haywire, it can throw out a known accuracy load so much that you’d think the barrel had gone bad.

    I test 3 primers with the same powder/bullet combo when working up my F-Class loads because I know ONE of them is going to be the most accurate.
    Generally, I try Fed normal match, Fed magnum match and Winchester magnum/standard depending on cartridge.
    Certain standard size cases, like 6.5-284 Norma and 6.5x47 have shown a preference for magnum primers for me.
    My .222Rem likes magnum primers and groups shrink using them with 748 powder.

    Yes, GreTan can bush your firing pin hole, that was what I would recommend to fix your cratering problem. I had the same issue in a Rem 700 VSSF II that I used as a donor for my F-Class build, I replaced the bolt with a one piece from PT&G.

    Cheers.
    :)
     
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  4. esp42089

    esp42089

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    In my other rifles, I've always seen the primers flatten, then the case head grows, then the primers start popping. I'm assuming that I'm safe on pressure for the 6.5 because the primers are still round and I had no measurable casehead growth or ejector marks. My primer pockets aren't loosening up appreciably either and I'm nowhere near the fantastic (original meaning) speeds and corresponding nuclear pressures that people seem to be able to run in these before they see signs that things are too hot.

    I was thinking that the Fed210 and/or CCI250 might have harder cups that would allow me to go further up in pressure before the cratering turns into piercing. I originally started at 40gn and took 3 shots every .2gns (3x at 40, 40.2, 40.4, etc.) arriving at 42gn with very cratered primers and a pretty much linear velocity gain over the ladder. The gun always shoots 0.75MOA but at 40.3, 41, and 41.7, the velocity spread tightened up and the groups shrunk to 0.5MOA out at distance. I have since shot 50 rounds at each node (over the past month or so) and found my SD and ES to be 6-8 and 14-17 respectively for the three different loads. I've not messed with seating depth since I'm already jumping so far and don't want to single load the rifle.

    I got a wonderful group of 5 shots at 800yards measuring 3.7" of mostly horizontal movement on the 40.3 node and a wallet group of 5 shots at 200yards measuring 0.55" on the 41.7 node. Groups only a little bit larger are common and I believe this to be pretty much at the limit of my personal capability. Get a better shooter behind it, and it probably has more in it. These seem like pretty solid loads though that I could run with but I'd love to see if there is a node up at 2800. I'm pretty happy at 41.7gn and 2750, but figured there might be a better node up higher.

    Would your recommendation be to start over at the bottom (40gn) and run my ladders all the way up again? I feel like that would be the conservative approach, but it may not be necessary since finding another node down low with new primers isn't what I'm interested in. I'm specifically trying to find a higher node to run at.

    Thinking about it again, perhaps I should cut back to 1 shot every .2gn so that I run up the ladder faster to find the max while still covering all my bases and staying safe.

    For those interested: I'm very happy with the ruger precision rifle. I did not expect this level of accuracy from an out-of-the-box rifle from ruger with a hammer forged barrel. Anyone who says the trigger is great though has never shot a quality Timney or Jewel trigger. It's workable and is a huge improvement from the dark days of old but it has a long way to go before it matches the double set triggers on my mausers or the jewells and timneys on my remmys. The trigger will certainly be my first upgrade.
     
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  5. MagnumManiac

    MagnumManiac

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    I find small rifle primers more accurate, so you may or may not get a variance switching them. The only way to find out is to test.

    If you’re able to, can you try SR brass made by Lapua.

    I always work in .3gr variations when working up a load for LR, this tends to be optimum for cases from the 22-250/22-250AI size on up. For any of the 222 based cases .2gr is about optimum.

    When you find a node, then do a test with .1-.2gr above and below, if a .2gr variance blows out, then the node isn’t stable.

    A 3 shot group is what’s necessary, when you find a node and fine tune it, load 10 rounds and slow shoot a group, if it stays stable as the bore fouls, you should be good to go.

    Cheers.
    :)
     
  6. esp42089

    esp42089

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    Thanks! I don't have any SR primers on hand so I bought hornady brass to get going with and use the stuff I have on hand. I plan to switch over to Lapua when this batch of brass is done.
     
  7. ZenArchery

    ZenArchery

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    I’ve had zero issues swapping between CCI34 and Fed210 but I only load for 1 MOA hunting accuracy. When it comes to Mag primers I’ll tone it down then work up.
     
  8. rap36case

    rap36case Working up loads for new Shilen 308win

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    Thank you for the insight. I am working up a load for my anticipated build. I'm an 'experimentalist' and agree about a new ladder every time you change something. I am guessing I will work up a new load when I finally get my can.
     
  9. riflewoman

    riflewoman Gold $$ Contributor

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    For the Magnum primers drop it 0.5 grain. For the others load them as per normal. There isn’t a big diff between Federal and RWS primers. Chronograph them and work up to the same velocity. Same velocity—same pressure.
     
  10. alinwa

    alinwa

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    I am solidly with MagnumManiac here.

    I wouldn't join in except some are saying "just pretend it never happened" and my experience is that changing primers can have serious effect.

    I once got 2000 free primers from Federal because I "just changed primers" and had a catastrophic event. After an hour on the phone with one of the engineers I had a VERY different view of primer "hotness" and brisance and different primer compound's reaction to different powders.

    I SCREWED UP!

    FEDERAL DID NOTHING WRONG!!!!

    And they still sent me free primers, go figger.

    Be Careful Out There
     
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  11. #40Fan

    #40Fan

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    Maybe I should change my first post. I have only ever swapped between CCI primers. From regular, to magnum, to bench rest.
     
  12. alinwa

    alinwa

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    Dude No, never change, yer fine.....

    Ain't nuttin' wrong with livin' dan'rously, unless you'se also wants to live LONG.........my liddle brother useta' spend half his time clutchin' at the ass-gasket but since't he DID made it past 40 he's now wearing his safety gear.


    It's just a choice thing, not a right or wrong thing ;)



    LOL
     
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  13. esp42089

    esp42089

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    I really appreciate all the input. I think that I'll drop a grain and work up. Not all the way back down, but enough to give me plenty of pressure headroom if things change a lot. I'll report back here how it went and what the different primers did for speed and pressure signs.
     
    LGKLAS likes this.
  14. LGKLAS

    LGKLAS

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    I think, limited experience, I'd start out, as you say ESP, at one grain less. But, to clarify- one grain less than maximum published charge weights. This is because of what Magnumania and Alinwa posted. And I've seen some published loading data that also published the pressures generated by the charge weights listed. And at max charge listed, the pressure came up to or just a tad below SAAMI pressure specs for our cartridge (63,000). So, if you are currently loading above a max charge weight and subtract a grain from that weight, and your new brand primer does affect pressures experienced by Magnumania and Alinwa, I think you could find yourself over SAAMI pressures. If the belief is 'change of primer to try to gain MV', then a gain in MV will produce an increase in pressure.

    I'm plenty happy at my level in reloading and experience and with my personal goals in my loading with Fed 210s so have not contemplated changing primers. So the above is just my (un-fact based) thinking. :) lg

    PS: do follow up, please, and let us know how it turns out.
     
  15. Bc'z

    Bc'z Gold $$ Contributor

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    Window the front of your magazine. Then you'll be able to have a little morecartridge length.
    I picked up .13 in my 6x45 doing this.
     
    Last edited: Jul 8, 2018
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  16. esp42089

    esp42089

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    I'm going to use up the last 1000 of my RWS, then try the federals. I'll report back, but it'll be around September at my current rate.
     
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