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Thread: .308 chambering issue driving me nuts

  1. #1
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    Default .308 chambering issue driving me nuts

    I'm fairly new to reloading. By new I mean only one caliber, trying to develop hunting and plinking loads.

    Started out with 168 SMKHPBT and have had alright accuracy. (Inside of 7 inches for 5-10 shot groups) Not quite down to precision and accuracy. I have been wanting to try and get a load down for Barnes TSX and or TTSX bullets, all 168 grain.

    My issue is the OAL or the seating depth. All my cases I neck size only, and all my brass is all initially single fired factory ammo brass before I resize. Factory Federal ammo measures out at 2.8" OAL. and chambers with no issue. 100% every time. But once I seat my bullet for 2.8"OAL, and chamber it, it feels like its pressing on the rifling. And starts to fight fully engaging the bolt. It has to be at 2.7" in order to chamber correctly. It is frustrating as all hell because it tends to make every load a 'crush' load. which I'm trying to avoid at the moment. Any one have ANY idea on what the problem may be or any ideas on how to resolve the issue? Much appreciation for any info.

    -Boots

    P.S. My gun is a Rem. 700.


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    Go ahead and shoot them at 2.7". A tenth of an inch is probably not significant in its effect on accuracy. If you were shooting benchrest competition
    , Then I would say go ahead and neck size, and crush fit the bullet to the rifling. But for an average gun, it probably won't make much difference. And note I say PROBABLY. Not every rifle is the same. Your lot of Sierras may not be identical to the lot of Sierras that Federal is using.
    "A strong body makes the mind strong. As to the species of exercises, I advise the gun. While this gives moderate exercise to the body, it gives boldness, enterprise, and independence to the mind."

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    You are on the first step to determing the maximum O.A.L. for your rifle's chamber. There is nothing wrong with a compressed load unless there are signs of excessive pressure, sometimes compressed loads can be a good thing and improve accuracy.

    If you have some other reason for not wanting a compressed load (I cannot think of one) then you will have to switch to a smaller grain/faster burning powder or select a different bullet, one that weighs less and is shorter, or one with a different ogive that will not contact the rifling before the bolt is fully closed.

    Every firearm is unique when it comes to chamber dimensions and thus, each handload recipe you build will be unique to that chamber.

    Also, Max. O.A.L. established by SAAMI does not mean that your rifle will accept MAx dimensions, it means that the chambers should not be manufactured BEYOND what is set forth by SAAMI.

    So to summarize; you will need to seat the bullet deeper and if you do nont want a compressed load you will need to change the bullet and or the powder selection.

    I do this with all of my firearms and recipes, per bullet selection. This is the poor mans method, or the way to determine OAL without a gauge:

    Make a "dummy" round for that particular firearm and bullet selection. Resize and deprime a casing, DO NOT insert a primer, DO NOT dispense powder into the case, seat the bullet you wish to use to the 2.8 OAL as you have done with the others. Now turn down the seating die 1/8th of a turn and seat the bullet to this depth, afterwards try chambering it. If you feel the stiff resistance, repeat by turning the seating die down 1/8th of a turn as before, then rechamber as before. Repeat this until you determine the OAL for your firearm.



    When you are satisfied with the results, mark on the case with indelible ink the bullet spec. and store with your die set. Next time you want to reload that bullet you have a handy gauge to set up your seating die.

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    Thanks guys! I'll respond more throughly once I get to my computer!


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    I reload for two different 308's but I use small base dies and full length resize, due to the fact that one of the weapons is a AR platform. I mainly use 165 Sierra's and can keep all/most loads inside 3/4" at 100 yards. Have you check the OAL of your chambers? It is easy to do, if you have the tools. I have found that the 308 is very easy to reload for and can give some really good results.
    What weapon are you reloading for?

  6. #6

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    With crush fits, be REALLY leery about cycling the bolt to remove a live round, rather than firing. I've seen the bullets stay in the throat while the case is extracted. Aside from a case full of powder dumping into your magazine and everywhere else, you now have a slug stuck in the bore. I doubt you could mindlessly chamber another round with it there, but....

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    Gunbug:


    I have noticed the SMK's are very inconsistent as far as getting a exact equal length on the bullets. The Barnes all are pretty close so I wasn't sure if it would make a huge difference because they are a bit longer of a bullet

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    Quote Originally Posted by AK Bearcat View Post
    I reload for two different 308's but I use small base dies and full length resize, due to the fact that one of the weapons is a AR platform. I mainly use 165 Sierra's and can keep all/most loads inside 3/4" at 100 yards. Have you check the OAL of your chambers? It is easy to do, if you have the tools. I have found that the 308 is very easy to reload for and can give some really good results.
    What weapon are you reloading for?

    The rifle is a Remington 700 VTR.
    No I have not measured it. Any insight as the process? or tools?

  9. #9
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    Quote Originally Posted by .338WM View Post
    You are on the first step to determing the maximum O.A.L. for your rifle's chamber. There is nothing wrong with a compressed load unless there are signs of excessive pressure, sometimes compressed loads can be a good thing and improve accuracy.

    If you have some other reason for not wanting a compressed load (I cannot think of one) then you will have to switch to a smaller grain/faster burning powder or select a different bullet, one that weighs less and is shorter, or one with a different ogive that will not contact the rifling before the bolt is fully closed.

    Every firearm is unique when it comes to chamber dimensions and thus, each handload recipe you build will be unique to that chamber.

    Also, Max. O.A.L. established by SAAMI does not mean that your rifle will accept MAx dimensions, it means that the chambers should not be manufactured BEYOND what is set forth by SAAMI.

    So to summarize; you will need to seat the bullet deeper and if you do nont want a compressed load you will need to change the bullet and or the powder selection.

    I do this with all of my firearms and recipes, per bullet selection. This is the poor mans method, or the way to determine OAL without a gauge:

    Make a "dummy" round for that particular firearm and bullet selection. Resize and deprime a casing, DO NOT insert a primer, DO NOT dispense powder into the case, seat the bullet you wish to use to the 2.8 OAL as you have done with the others. Now turn down the seating die 1/8th of a turn and seat the bullet to this depth, afterwards try chambering it. If you feel the stiff resistance, repeat by turning the seating die down 1/8th of a turn as before, then rechamber as before. Repeat this until you determine the OAL for your firearm.



    When you are satisfied with the results, mark on the case with indelible ink the bullet spec. and store with your die set. Next time you want to reload that bullet you have a handy gauge to set up your seating die.


    The only reason I was concerned about the crush load was exactly what Brownbear had brought up, but with your insight my mind is more at ease.

    I had originally made a dummy round (just took a dremel and cross cut the neck of the case in a '+' pattern so it would hold the bullet) and had determined that the 2.7" was the OAL for my gun. I guess I was just over thinking that fact that it was off 'by that much'. I was just trying to figure out what the reasoning for the length between my loads and factory loads having different chambering "issues".

    another question I have is what is considered a good consistent seating depth? As in do. .01 of an inch make a difference in accuracy/precision?

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    Quote Originally Posted by AKboots7 View Post
    I'm fairly new to reloading. By new I mean only one caliber, trying to develop hunting and plinking loads.

    Started out with 168 SMKHPBT and have had alright accuracy. (Inside of 7 inches for 5-10 shot groups) Not quite down to precision and accuracy. I have been wanting to try and get a load down for Barnes TSX and or TTSX bullets, all 168 grain.

    My issue is the OAL or the seating depth. All my cases I neck size only, and all my brass is all initially single fired factory ammo brass before I resize. Factory Federal ammo measures out at 2.8" OAL. and chambers with no issue. 100% every time. But once I seat my bullet for 2.8"OAL, and chamber it, it feels like its pressing on the rifling. And starts to fight fully engaging the bolt. It has to be at 2.7" in order to chamber correctly. It is frustrating as all hell because it tends to make every load a 'crush' load. which I'm trying to avoid at the moment. Any one have ANY idea on what the problem may be or any ideas on how to resolve the issue? Much appreciation for any info.

    -Boots

    P.S. My gun is a Rem. 700.


    Sent from my iPhone using Tapatalk
    Seat the bullet deeper so that it DOESN'T touch the lands. .030 off is good.

    Smitty of the North
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    Quote Originally Posted by Smitty of the North View Post
    Seat the bullet deeper so that it DOESN'T touch the lands. .030 off is good.

    Smitty of the North

    I'm good as far as having a correct seating depth for loads. I guess I was more looking for a reason to why the .1 of a inch was making a difference

  12. #12
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    If you measure the length of your SMK's, you will probably note that they differ in length slightly. This is because of the way they are formed as open tip, or "ballistic" hollow points. The reliable way to set the seating depth is to use a sinclair, or similar measuring device that reads the length from a datum line on the ogive, or curved portion of the projectile, like this one.Click image for larger version. 

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    This will give you a repeatable, consistant measurement. The way you are doing it now, even though the bullet is actually seated to a consistant depth, your OAL is slightly different from round to round.
    "A strong body makes the mind strong. As to the species of exercises, I advise the gun. While this gives moderate exercise to the body, it gives boldness, enterprise, and independence to the mind."

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    I have a tool that uses a shell casing and rod to seat the bullet against the lands, with a bullet, that one can measure the OAL. It comes in handy.

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    Quote Originally Posted by AK Bearcat View Post
    I have a tool that uses a shell casing and rod to seat the bullet against the lands, with a bullet, that one can measure the OAL. It comes in handy.

    http://www.midwayusa.com/product/570...ge-bolt-action

    This I assume?

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    Quote Originally Posted by gunbugs View Post
    If you measure the length of your SMK's, you will probably note that they differ in length slightly. This is because of the way they are formed as open tip, or "ballistic" hollow points. The reliable way to set the seating depth is to use a sinclair, or similar measuring device that reads the length from a datum line on the ogive, or curved portion of the projectile, like this one.Click image for larger version. 

Name:	estate 1 2099.jpg 
Views:	35 
Size:	80.4 KB 
ID:	76458
    This will give you a repeatable, consistant measurement. The way you are doing it now, even though the bullet is actually seated to a consistant depth, your OAL is slightly different from round to round.

    Very useful info! I appreciate the insight! I'll be picking one of those up for sure!

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    Quote Originally Posted by AKboots7 View Post
    That is it, only mine is not a Hornady brand. When I got mine, I also got the cases for all of the rifles that I load for. It came in handy when I was working up loads for Barnes bullets.
    Have you attempted to chamber a case after you neck sized it, but before you put a bullet in the case? This step might give you an idea, if your neck sizing is working or not.

  17. #17

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    I bought the Hornady over all length gauge about a year and a half ago with a couple of the cases that go with it. I was planning on getting more later an have still not found any more local as of yet. When I bought the gauge the guy said he had the other cases on order. I have checked with him and several other gun shops and all I have been able to get is 270 Win. and 22-250. I would like 7mm Rem. Mag, 30-06, 243 Win., 6mm Rem. and a few others. I have not tried to order any of these. I keep thinking they will start showing up soon. I would not buy the gauge without checking to see if you can get the modified cases you want to go with it first. The tool works good if you can get what you need to go with it.

  18. #18
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    Call Hornady direct. They should have the cases you need.
    "A strong body makes the mind strong. As to the species of exercises, I advise the gun. While this gives moderate exercise to the body, it gives boldness, enterprise, and independence to the mind."

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    Quote Originally Posted by gunbugs View Post
    Call Hornady direct. They should have the cases you need.
    +1. They'll also accommodate custom chamberings if you send them your brass.
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    Quote Originally Posted by AKboots7 View Post
    I'm good as far as having a correct seating depth for loads. I guess I was more looking for a reason to why the .1 of a inch was making a difference
    .

    If the ogive, (curvature of he bullet is contacting the lands, the bullet needs to be seated deeper. Regardless of the OAL TIP to base of he case. There are 40 jillion ways to determine YOUR rifles distance to the lands.

    You can use a wooden dowel, or a cleaning rod. You can seat a bullet long and chamber the round. There are special tools, but they're not usually needed.

    I'm suggesting that you determine that distance, and seat your bullet to less than that, and suggested .030

    You said, "it feels like its pressing on the rifling". If it's on the lands now, just seat it deeper, for a shorter OAL (for that bullet) Another bullet design might allow a longer Cartridge OAL.

    The 2.8 COAL is a spec for feeding/function through the magazine. It is not a hard and fast length for COAL in every rifle, for every bullet.

    Smitty of the North
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