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.308 seating depth / COAL question.

Discussion in 'Handloading and Reloading' started by Centurian22, Jun 22, 2014.

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  1. Centurian22

    Centurian22 Member

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    Background: .308 savage axis 22" 1:10", 168gr Sierra Matchking BTHP (or HPBT depending on who you ask), with IMR4895 (for now, next will be trying 4064), Federal cases, CCI LR Primers (until I run out and have to switch brands). I've found a safe accuracy node around 43.6gr with a 2.80 COAL.

    Question: Is it worth / how much can be gained by playing with the seating depth? My lands are at 2.845 and that length round WILL fit in my magazine. I've heard that Sierra's like to be close but not touching, any goto recipes? How do you do seating depth workups? 3-5 rounds each every 1/100th": 2.80, 2.81, 2.82 etc? Also once tuned for COAL, do you go back to tweak powder again for any reason?

    Thanks!
     
  2. jwrowland77

    jwrowland77 Member

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    How far is your ogive from the lands?

    I recently did a test where my known load ogive was .125 off lands. I tested to .025 off and my accuracy did improve. My MV did drop though, but accuracy was a lot better in my case.

    Only way to know is test it if you don't mind single loading. I was testing a match load where I can only single load anyway, so I don't mind.
     
  3. Blue68f100

    Blue68f100 Member

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    My std starting point is 0.020" off the lands. But you need to determine what the COAL is for each bullet size/weight/mfg.
     
  4. ironworkerwill

    ironworkerwill Member

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    It looks like you have a logical plan. I tune in almost the same manner. 2.79" to lands and then tweaking the powder one last time won't hurt.
     
  5. WVRJ

    WVRJ Member

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    I load my 308 to about .005 off the lands.That gives the best accuracy for my rifle using Berger Hybrid target or Hornady A-Max's.SMK's don't seem to be very picky about OAL,and shoot good at magazine length in My 700,which has a long throat and a short magazine.I think best accuracy can usually be expected when close to or touching the lands,and would consider it to be great if the magazine would hold rounds loaded as such.Not the case with factory Remington barrels,Savage has em beat on that one.
     
  6. gamestalker

    gamestalker member

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    I've almost always found best accuracy up close to the lands or touching them. So the way I go about it is I first start either right up to the lands, or off .005". This is where I start my powder work up also, as pressures will never be higher than at the closest point to the lands. Once I have the powder charge figured out, I begin checking accuracy in .005" increments until I find the sweet spot, which is usually within the first .010" of the lands for me.

    If you end up fairly close to the lands, make sure you chamber check every cartridge to avoid having one get stuck in the lands when opening the bolt. Though this has never happened to me in several decades of reloading, I have heard some horror stories of such.

    GS
     
  7. ArchAngelCD

    ArchAngelCD Member

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    IMO, you are already close to the rifling and since that rifle is obviously a hunting rifle I see no reason to waste components trying to find what will be a very very small increase in group size. (but that's just me)
     
  8. Centurian22

    Centurian22 Member

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    I don't have a gauge to measure off the ojive yet unfortunately (Its on the list but not at the top). What would you recommend? Between meplate and seating variation, I think (I would have to double check) that I see a variation up to around .006 (+/-.003). I should have also stated purpose, I am not a 'bench rest' shooter, I don't compete yet, but am trying to prepare for a factory rifle match at my local range coming up in Aug/Sept, as well as looking to start working on 200 and 300 yard shooting. ArchAngelCD: Do you truly consider 0.045" to be "close to the rifling"? I guess it depends on your definition of close. While I do use this rifle for deer hunting, I spend a lot more time with it at the range than in the field/woods. I'm also, in a way, on a 'quest' to find the limitations of this 'entry level' platform that so many people are very quick to dismiss.

    As I favor reliability over razors edge accuracy, I prefer to stay away from jamming the bullet. If the above mentioned variation in seating depth is correct I would opt to stay 0.005-0.010 off just to be safe. Gamestalker: I LOVE the idea of starting powder work up at .005-.010 off lands for the reasons you list, makes a lot of sense and will become my new procedure from here on out. Avoids most if not all of the need to retune powder a second time. WVRJ: I was very pleasantly surprised to discover that my magazine would hold 'land length' rounds. I have not yet loaded any this long to test for possible feeding issues but based just on looking it over I don't expect a problem. Jwroland77: I wouldn't mind having to single load for my match rounds and may do that anyways for consistency purposes, but as stated above I'm lucky in that my magazine will hold cartridges that are loaded as long as my lands allow. I would assume the drop in MV would be from lower pressure as the case capacity increased from the bullet being seated longer correct? I'm not (nor do I intend to) chasing speed with this round and don't even have a chrony yet though hope to get one sometime in the next few years.

    I appreciate all of the input and hope to see even more. I think for my next load up / practice session I will load 5 each at 2.80, 2.81, 2.82, 2.83, 2.835, and maybe 2.840 depending on my seating consistency and if I can obtain an ojive measuring device by that time (again any recommendations for that are appreciated).
     
  9. JDGray

    JDGray Member

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    ^^^This^^^

    For hunting bullets, its hard to beat Nosler 150gr BTs.
    Unless your intending to build a target rifle from this axis, we assume its for hunting?
     
  10. jwrowland77

    jwrowland77 Member

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    I like the Hornady OAL gauge and Hornady bullet comparator.

    It really just all depends on what your rifle likes. I personally, don't feel comfortable enough yet to get any closer than .02" to the lands. It's a personal choice. I've been able to find a OAL that suits my needs and preferences and shoot great.

    If this is a hunting rifle and your load is shooting great, no need to get any closer like Arch said.
     
    Last edited: Jun 23, 2014
  11. USSR

    USSR Member

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    I always stay at a minimum of 0.010" off the lands. The reason is, with even the best match bullets, bullet ogive location can vary by that much due to them coming off of different machines at the factory. You don't want to end up with some bullets into the lands and some not.

    Don
     
  12. amlevin

    amlevin Member

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    With the usual caveat "For My Rifle", I find that there are tow different OAL's that perform well.

    I'll start with a load workup using powder increments of .4 gr and the bullet in the lands by the amount that my bolt "cams" them in when closing.

    Once I find a load that offers the accuracy I desire I then load a large batch using THAT powder weight and starting with the "In the Lands" OAL, I shorten the OAL by .005" after each group of 5. I merely take my Lee Hand Press with a Lee Seating die and my caliper to the range. After shooting 5 I shorten the next five and shoot them. For accuracy purposes I use a comparator when "shortening" the rounds so I'm taking any base to meplat measurement variation out of the process. I move the ogive back each time which is insuring that I am getting the same "jump" each time.

    I continue shortening the loads until I reach the specified Magazine Length of 2.800".

    Using this process I have almost always found two OAL's that deliver (with MY rifle) sub .25 MOA loads. One is a "single load" length that won't feed from the magazine and the other which feeds from the magazine which I use when I need a "Repeater".

    Loads with bullets "in the lands" aren't as sensitive to neck tension. You can load from "loose fit" to "Factory Sizing Die with expander ball" neck tensions. With the magazine length loads I've found that more neck tension is required for better SD/ES readings.
     
  13. Blue68f100

    Blue68f100 Member

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    Since you need to a way to determine this. I use a spend case and just barely put a very small sizing, just enough to hold a bullet so it will slide. Then carefully feed the bullet and the lands will push the bullet back into the neck. Do this a couple of times to confirm your readings. Then make up a dummy round and paint the bullet with a marker. Chamber it and see if the rifle contacts the bullet. If it does bump it back a few 0.001" till it clears. This will be your MAX OAL for this bullet. Then you can reduce the OAL to where you want to start. Save the dummy round and label it so if you change bullets you all ready have a reference for this one.

    I do this but measure the bullet using the RCBS Precision Mic. With this tool you can measure your final product and know where the ogive is in reference to the lands. I use the measurements as reference only because some other methods give you a slightly different reading.
     
  14. Sunray

    Sunray Member

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    Well, an Axis is a hunting rifle, not a target rifle. Using match grade bullets won't make much difference. Barrels aren't up to 'em. That doesn't mean using match ammo loading techniques is bad though. Loading a 165 grain hunting bullet using those techniques might astound you. The .308 loves 165's and they'll kill any game you care to hunt.
    The OAL to be 'just off the lands' thing is a load tweaking technique done after you have a group. No sense doing it until you do. Use the max OAL in your manual until then.
    So is going back to the previous load before the best group load and going up by .1.
    In any case, it's a rifle thing, not a bullet thing. Every chamber is slightly different and the distance to the lands will be slightly different.
    IMR4064 gives more consistent accuracy than IMR4895(or its Hodgdon cousin). Been using it with 168 grain match bullets out of my 1903A4 for eons. One hole group on a good day.
    And its HPBT's. snicker
     
  15. Centurian22

    Centurian22 Member

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    Ok so sounds like I'll cut out 2.840 and stay at least .010 off at 2.835. Blue, I did exactly what you describe with my lee neck size die. Did it three times and got the 2.845 that I listed in my original post all three times.

    Amlevin: great idea with the lee hand press to set the bullets back at the range. I have been thinking of doing a load work up at the range with my hand press but I like this idea better. Less time and work at the range. Less to drag along to. I'm looking at the Sinclair hex bullet comparator here: http://www.brownells.com/reloading/...et-comparator-1-sku749002942-34262-66673.aspx

    And AGAIN yes I do hunt with this rifle but plan to use it as a target rifle at the range much more often than the couple times per year she comes with me out into the woods. When I work up my load for my 165gr Sierra Gamekings, (hoping the 168gr work up gets me close) I will likely stay further from the lands if not at the standard 2.80" and will consider anything close to 1" @ 100 'good enough'.

    I'm enjoying my learning experience with this rifle and figure there's no reason not to chase all the accuracy I can while I practice. I'm not 'wasting' any components in the search because every round fired is helping me learn more about shooting, marksmanship and reloading.
     
  16. jwrowland77

    jwrowland77 Member

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    Actually, the Savage Axis did good for me when it first took up F-Class shooting. Very accurate. Didn't matter much that it only had a 22" barrel. Did great for me while I was learning the game.
     
  17. Centurian22

    Centurian22 Member

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    Sunray: you perfectly depicted the bias / opinion I'm out to destroy. Match grade bullets HAVE absolutely outperformed hunting rounds so far both in factory loads and hand loads. My first day with this gun (the first centerfire rifle I have owned) out of the box after sighting in it was shooting 1" @ 100 with Federal Gold Medal match 168's. Do I expect to beat top shooter with a $2000 bench rest gun? No obviously not. But I do expect to surprise the heck out of people who think this is 'only a cheap entry level hunting gun with "junk glass" (yes it sports a $70 centerpoint 4-16x40)'. I also expect to be able to get effective accuracy to at least 500 yards if not possibly even 800 yards; both of which are far beyond 98% of any available shots in my state.

    Jwrowland77: thanks for the 'backup' and affirmation that my quest is not all for naught. Mind sharing what you used for a scope and what type of accuracy and max range you were getting with the axis? Thanks.
     
  18. jwrowland77

    jwrowland77 Member

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    Lol. It's funny you say that. I used a Truglo 8-32x44 when I first started. Great glass actually as long as you made your adjustments slowly. Pretty dang clear.

    I didn't switch rifles until I decided to start shooting 1000yd as well. Just so I could get extra velocity. It was a great learning rifle to learn to read wind at 600yd distance.
     
    Last edited: Jun 24, 2014
  19. amlevin

    amlevin Member

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    On the "junk glass" Centerpoint, one of the local shooters made a nice sticker for his Walmart Centerpoint scope that said "Zeiss". When asked what model it was he just said it was a prototype he was evaluating and it hadn't been released yet. He then proceeded to create a series of "bugholes" at 100 yards using that "Prototype". :)
     
  20. Centurian22

    Centurian22 Member

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    Lmao at the Zeiss 'prototype' that is awesome! I've been very happy with my CP so far. Some day I'll step into the $300 scope range but not for a while. Many more projects demanding finances ahead of that in priority. Especialy when my CP is having no problem giving me 0.8"-1" groups thus far.
     
  21. Centurian22

    Centurian22 Member

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    If Sunray or anyone is still following this thread, have a look-see at this:

    For those following this ill post here but will also be starting a new thread with results:

    I'll start with Gamestalker I *Bleeping* LOVE YOU!!!

    Had an awesome day at the range! Found my winner in the upper right. Best group I have ever shot in my life. 4 rounds, 3/8" center to center @ 100yards in variable winds from calm to 12kts. .308 fed cases, CCI LR primers, 41.2gr IMR4895, with 168SMK seated at 2.835". One slightly elongated ragged hole! I was stoked! And before someone tries to call me out, I was shooting round robin back and forth working my way down. When I shot this group I skipped the last three (40.8, 40.4 40.0) as there was no way they could compare. 43.2 wasn't bad either at 3/4-7/8". Oh by the way this was shot with a SAVAGE AXIS and Walmart Centerpoint scope! So all the haters and nay-sayers that dog on these 'entry level' rifles can..... potentially reconsider their opinions! LOL

    [​IMG]
     
  22. Blue68f100

    Blue68f100 Member

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    Now you need to see if it's repeatable. Sometimes yes sometimes needs to be tweaked. If your going to use for hunting you will need to know how it shoots on a cold barrel. And cold weather depending on where your at.

    Nice group. Now push the distance out and see if it holds.
     
  23. Centurian22

    Centurian22 Member

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    You mirror my exact thoughts on it. Next step is to load up a few boxes, make sure its repeatable, tweak if needed (I hope not), test cold bore, and start stretching out to farther distances. It won't be used for hunting as its a match bullet but I will be looking to this recipe when I load 165 Sierra Gamekings. I will start with a safe workup just to make sure, but load testing after that will start here. Then I either need to find / borrow a chrony or get someone with quickload to give me a rough estimate of my velocity.
     
  24. spitballer

    spitballer Member

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    As a rule I seat well into the lands with all my loads, although it could be argued that seating off the lands might help by filling the barrel with forward-moving gases before the projectile squeezes through.
     
  25. Potatohead

    Potatohead Member

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    Does all this "x inches off the lands/into the lands" stuff really matter? Or is it another symptom of the disease known as Reloader's OCD?

    Im not being critical, Ive got a strong case of it too, but Im just wondering about how important all of this off the lands stuff is..dont know much about it.
     
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