.243 AI - How fast is too fast

Discussion in 'Reloading Forum (All Calibers)' started by rchouser, Oct 17, 2015.

  1. rchouser

    rchouser

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    I have a newly installed (75 rounds) 26" Bartlein 5r 9.0 twist barrel chambered in .243 AI. I have been working up to now 45.0 gr. of WIN 760 and a fed 215 primer. Using a jump of .010 I am getting the following (same load for both bullets):

    87gr VMAX - avg vel - 3430 fps
    75gr VMAX - avg vel - 3574 fps

    I still have room in the case to up the powder, I am getting no sticky bolt and the primers are not smeared. I am not sure I see any point in going any higher in the velocity with these bullets, but, feel I have not reached the top.

    What are you veteran 243 AI shooters getting with the 75 and 87 gr VMAX's. What is a reasonable "shooting" velocity for these in an AI.
     
  2. Jaxdilation

    Jaxdilation

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    I know a guy who gets 3400 fps with berger 105s.

    I don't know that there is such a thing as "too fast" it is a question of pressure, case capacity and where the best accuracy is.
     
  3. 13red56

    13red56

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    With a 9 twist as long as the accuracy is good I don't think the fps will spin either to fast to make them come apart. There is a gentleman on here that goes buy Kanuck he uses 9twist a lot so he can shoot 58's in the 4000fps range but still able to stabilize most 105gr bullets. I have a 9twist ackley the will push a 105 in the 3300fps range. I fireform with 85 Sierra HPBT's idk the speed but I have neve had any trouble with accuracy or blowing them up.
     
  4. SeabeeKen

    SeabeeKen

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    I tested 85 gr Sierra up to 48.3 gr of H-414 but got flattened primers but no bolt stick.
    My best accuracy was at 46.2 gr. I'd also recommend a magnum primer as I also got very erratic pressure signs with several loads with H-414. I haven't used it in my 243 ai since. I tested 14 different powders with 48.5 gr of RL-22 the most accurate in my rifle. I was never interested in speed, just accuracy
     
  5. brians356

    brians356 Gold $$ Contributor

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    I haven't loaded 243 AI, but I notice Sierra's data for 6mm AI (26" barrel 1:8 twist) shown interleaved with your bullets:

    87-gr 3430 (243 AI)
    80-gr 3400 (6mm AI)
    75-gr 3574 (243 AI)
    70-gr 3600 (6mm AI)

    The 6mm AI should be good for a bit more velocity than 243 AI. Your 75-gr seems reasonable, the 87-gr seems like it's a little ambitious. (These random thoughts brought to you by what passes for my mind.)
     
  6. scope eye

    scope eye

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    At 45gr of 760 you have not reached the top, and since you still have over 10% or 5gr more room left in that case, and have no signs of pressure there is no harm in creeping up in powder. And since you know how to recognize the tell tale signs there is no reason not to. I have run a compressed load of RL17, H4350, and Hybrid HV100 all with great results. Going to an AI case just to reduce brass flow and not take advantage of they extra case capacity is a lot of work and expense, you could of got the same load 45gr of W760 and the same speeds you are getting with a run of the mill 243. And with that nice barrel you have it seems like a waste not to maximize it.

    Dean
     
  7. rchouser

    rchouser

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    I am still on my way up LOOKING for my best accuracy. I just shot the 45.5 gr load yesterday (3480 fps avg). The 87gr Vmax's are grouping well under minute of chuck but still not getting the teeny tiny groups that I keep hearing about.

    Next load for the 87gr will be 46.0 gr of 760. This is going to put my vel for the 87 VMAX cleanly into the low 3500's range. Still looking for the group to tighten up.

    I have the 75 gr vmax's ready to cross into the 3600 fps. I am getting some decent grouping at 3558 avg fps.


    I guess I will continue the march to find the max since I can. I am now 130 rounds into this barrel with no settled load.


    thanks rch
     
  8. brians356

    brians356 Gold $$ Contributor

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    I have done quite a lot of load work with 250 AI - similar but not identical of course. But it's fair to say, I think, that a powder which works very well in the parent cartridge may not always be the best for the AI. I wouldn't assume 760 would be able to "take advantage of the extra case capacity" in the sense that it will necessarily get to 100% load density. He may have to switch powders to take full advantage. And accuracy with 760 may prove elusive, for whatever reason. It may be stating the obvious, but an AI is really a different cartridge than its parent, and can behave surprisingly differently. Since the OP is watching carefully for pressure signs as he works up the charge, no problem, again just random thoughts from your 'umble narrator.
     
  9. Ackman

    Ackman

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    Really no such thing as "too fast". Find best accuracy without overpressure signs and velocity will be whatever it is. If it's faster than what's in a reloading book, doesn't matter. In that case W760 is a good one, it just works well. I shoot 70's in a couple 243AI's and accuracy window is from about 3750 to about 3850 plus/minus, depending on which gun. So even with your 75's there's still more to be had, you can go hotter looking for accuracy. No reason not to. Also do a primer test, you never know what you'll discover. In my guns there's a noticeable difference between 9-1/2's and BR2's.
     
  10. 4xforfun

    4xforfun Gold $$ Contributor

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    I ALWAYS take each load to the MAX. That way I know what I know, and it eliminates that little voice that will linger forever in the back of your mind that maybe you should see....that you are "missing something" !!!! ;)
     
  11. SHootSTraight22

    SHootSTraight22

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    Do you have any 105gr bullets to test.. I know your twist isn't perfect for the 105's but I'm interested in how much velocity you can obtain with them... I'm thinking about a 243 Imp 30 degrees to push 105gr accurately around 3,200-3,250fps if it can be done coated or not???
     
  12. scope eye

    scope eye

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    You can get way more than 3200 -3250 Fps, without getting into trouble with some RL22.

    Dean
     
  13. rchouser

    rchouser

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    Some responses to the thread as I am loading the next rounds to chrono today:

    SeabeeKen - I picked up on the magnum primers early with the 760. I may later retry the BR-2 and 210M but for now am using CCI 250's.

    kanuck: I cleared 45.5 and will shoot 46.0 and maybe 46.5 with the 87gr today. I have just been jumping .5 gr a test to avoid pulling down a load that I believe is too hot to shoot. I bought 1lb of RL-22 last weekend in case I don't find my node for the 87 VMAS with the 760. I will only start the RL-22 after finding MAX with the 760

    Ackman: What primer are you using with 760/414? Did you end up using a non-magnum?

    4xforfun: That part about "am I missing something" cracked me up because it is so true. Thanks for the most "truthfull" justification for "finding the top".

    SHootSTraight22: I have the 105 AMAX and at 48.5 of Retumbo, they ran at 2981fps AVG VEL. I only shot 5 to prove they would stablilize at 100. I have been working the 87's for the first bullet.

    A comment to all: With the 75gr VMAX and 45.0 gr of 760 I am starting to see some muzzle flash. I wonder if I am at the end of what I can burn in the barrel with the 75gr and 760.

    Thanks to all who offered their help. I am 65 and this is the first Ackley I have done since 1984 (22/250 AI). I am learning the round as I go. I DO need your input to keep me in reality and out of trouble.

    v/r rch
     
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  14. 13red56

    13red56

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    For what it is worth I have a 6-06,243AI,& 6mmAI I have better result in accuracy and speed when I run regular primers. The magnums give me muzzle flash and pressure slightly before the non magnum primers. I'm no expert by any means and 760/414 is great powder. If it doesn't satisfy ur accuracy expectations I would try any 4350 powder or any 4831 powder. On the speed side of things I was able to run the 87's 3250 out of a 22" barrel 243Win and the accuracy was superb. If u feel I can help in any way don't hesitate to pm me.

    Side note I just got the 6mmAI so still kind testing it but from a speed stand point the 243AI and 6-06 are neck and neck. I can run the 6-06 faster but accuracy suffers. I'm just a fan of the 6mm bore so I have variety.
     
  15. AckleymanII

    AckleymanII Gold $$ Contributor

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    I have had quite few of the 243 AI customs, mostly Hart 1-12 twists that were Max heavy varmint weight, and long 27-30".

    My hunting partner and I have probably had two dozen made off of minimum SAAMI spec reamer with turn necks. We shot Rem 7/08 brass, necked down.

    Between his and my rifles, all Hart 12 twists, with zero freebore,

    Fire form loads:
    69-75g What evers
    47.0-48.0g of Win 760 with a 70g TNT, 70g Nosler ballistic tip, 69g Berger
    CCI 250 primer put Standard Deviation of 10 fps or less
    3700-3750 fps
    Groups .375 area

    Formed load:
    69-75g what evers
    48.0-48.5g of Win 760
    CCI250
    3800-3850 fps
    groups .250 area or less

    Now, max loads in these barrels with the 70g Noslers was 50.5g of Win 760, with a Win mag primer, at 4030 fps, and cases needed to be full length sized after firing this load, but groups were in the .200 area

    48.0-48.5 is a milder load for the lot numbers of powders, barrels, etc that we used, and we NEVER full length sized, NEVER.

    When I kicked up the bullet weight to 85g, 45.5g of Win 760 with a cci250 was a max load with full length sizing needed after firing. What shocked me was that the 70g bullet at 3850 produced little copper fouling while the 85g copper fouled due to the extra bearing surface.

    I would expect that a change from Rem to Lapua brass would eleviate any need to FL size for a few firings on those top end loads, but you need a reamer with a web dia of .472 to handle the Lapua brass. My reamer will not handle Lapua brass.

    AA2700 proved to be very close to the Win 760 if not a duplicate on speed and accuracy with the same loads, but generated a tad more pressure, just a tad.

    For 500 yard shooting, this is a hard round to beat with this velocity and flat shooting trajectory. We shot the head off of P. dogs at 300 with regularity.
     
  16. scope eye

    scope eye

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    I concur with the loads that you posted that is what I am getting, 4000+ with 70s and 75 with H414, W760, and CFE223, with 50gr loads with my 12 twist 30" Mcgowen and 12 twist 28" Xcaliber. I also have to full resize after each firing the cases are a little on the bloated. Hey jimmy cracked corn, if that is the price for that speed and grouping so be it.

    Dean
     
  17. rchouser

    rchouser

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    ackleyman II: I really like the depth of you experience with this cartridge and want to compare my chrono speeds to yours if/when I get past 2 more grains on the way up. Based on my FPS gain per 1/2 grain increase, I am on track for a similar velocity.

    Again, thanks to all who are helping.

    v/r
    rch
     
  18. SHootSTraight22

    SHootSTraight22

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    Yea, I figure you can do better with another powder but shooting tactical/practical type matches I need first round hits and it seems Hodgdon Extreme Powder is the way to go for it's stability in many temps.. This would limit me to H4350, H1000 and maybe Varget... The Varget load would have to be really watched and most likely not the best choice here due to it's burn rate.. So with that said, do you or anyone have guesses or evidents of 3,250fps loads with any of these powders.. I read somewhere on here that people were getting above 3,200fps with H1000 but how many grains?? Sorry for any hajack just look at it as more information added to the thread..
     
  19. brians356

    brians356 Gold $$ Contributor

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    Your comments and data on 243 AI will be appreciated by the OP I'm sure. I shoot a 250 AI and I think it's just the sweetest cartridge ever conceived, but what I'm reading here makes me think I could be wooed to a 243 AI as well. Would that be considered polygamy? ::)
     
  20. rchouser

    rchouser

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    SHootSTraight22, I used some Varget with my first fire forming. I found the barrel was heating up very quickly. I moved to a slower powder and it still heats up, but, more slowly. thanks rch
     

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