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Thread: Seating depth ???

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    Default Seating depth ???

    Hey guys,

    Just getting ready to load up some 110gr V-Max's for a prairie dog party. I opened up the Hornady book and they recommend a COL of 2.740" with a case trim length of 2.005" in the .308 Winchester using their 110gr V-max bullet. These measurements will only allow a seating depth of .202" which is far less than the bullet diameter of .308, is this considered to be OK?

    I was under the impression that seating depth should be at least the diameter of the bullet being loaded if not deeper to achieve proper spacing from the lands in your particular rifle.

    Thanks in advance for your opinion.

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    The dia of the bullet in relationship to bullet seating depth isn't relavent to distance from rifling. Normally, seating as deep as the dia is done to help align the bullet in the case neck and to have enough tension to hold it under recoil. With your very light for caliber bullets, you are going to have to seat long to get the bullets close to the rifling. So, you are going to end up with not much bullet in the case. Not a real problem, just don't bang the loaded ammo around a lot, and if varmit shooting, loading one round at a time directly into the chamber will help prevent banging the bullet into miss alignment .

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    Quote Originally Posted by marshall View Post
    Hey guys,

    Just getting ready to load up some 110gr V-Max's for a prairie dog party. I opened up the Hornady book and they recommend a COL of 2.740" with a case trim length of 2.005" in the .308 Winchester using their 110gr V-max bullet. These measurements will only allow a seating depth of .202" which is far less than the bullet diameter of .308, is this considered to be OK?

    I was under the impression that seating depth should be at least the diameter of the bullet being loaded if not deeper to achieve proper spacing from the lands in your particular rifle.

    Thanks in advance for your opinion.
    Whew! Several points here which almost require a long indepth discussion.

    First: Hornady doesn't recommend that seating depth, that is what it was when they developed the data.
    Second: There may have been many considerations for that seating depth to include; Feeding in different types of guns, a compromise for that very short bullet and the above, to keep it in the case with some alignment, etc. (The max SAAMI cartridge length for the 308 is 2.800")

    You rule about needing at least a caliber of bullet in the case is not a bad one at all but some times we can't do that with short bullets and we may not even have a caliber of case neck, in which case it would be invalid. This rule would have to do with enough bullet in the case to insure alignment not placement with regard to the lands. The 110 bullet will have little or no full diameter shank to lie in the throat and would never be aligned.

    If the throat of your rifle is of correct dimensions (.309" diameter) and short enough in leade to support the bullet in alignment with the bore, you may get very good performance. But if the rifle is long throated for 180 grain semispitzers, which seems to be the norm, it won't shoot the short bullets well. An important aspect of the chamber is also the alignment of the case portion with this throat. If the diameter of the cartridge case neck portion of the chamber is over sized, (lawyers at the design table) the alignment will be lost. I say all this off the subject because they are much more important points than seating depth unless you have a custom chamber. In other words; the usually sloppy chambers of factory rifles negate any attempt to find appropriate seating depth and this is worse with short bullets that don't have any full caliber bullet in the throat.

    Seating depth is very much overrated as it pertains to accuracy. There certainly is a place where each particular rifle/chamber/barrel combination will be happiest with any given bullet but that cannot be determined from afar, as is the case when using data developed in another rifle.

    If you have a rifle with a custom chamber dimensions, such as throat and leade for one particular bullet, as are many match guns, then only that bullet with the predetermined depth will give best results. Otherwise using the mill run more or less SAAMI dimension chambers we are stuck with the middle of the road approach.

    To be blunt your choice of bullets, in my experience with the 308, which is extensive, is not the best for accuracy at the longline or even at the normal prairie dog range of 200 to 500 yards. A prairie pup is generally considered a 1 MOA target at 400 yards. The Vmax is an accurate bullet but too short for best accuracy in the caliber, compared with other choices. The shortest bullet I've ever had doggin' accurcy from in the 308 has been the 125 grain ballistic tip and it has given 1/2 MOA at about 400 and that is the best short bullet prformance I've seen form a 308 (which is the best of any 30 caliber) and this gun has a 1 in 12" twist which works best in the 125 to 155 grain range out to 600 yds for most barrels. This 125 grain BT bullet can be driven to 3100 fps or so and will be faster than the lighter 110 grain of similar design at 400 yards, maybe sooner. But if you have a quantity of the V-max load them with Benchmark, 10X or N135 and find you best velocity for the smallest group.

    I really like the 308, in general, and even more as a dog gun. Partly because it feels like a rifle. It can also be good practice for hunting season when doggin'. It is also one of the most accurate calibers ever in existance. I once shot five shots into a group that was completely covered with a quarter from a standard weight barrel Sako hunting rifle at 300 yards, from a bag and pod, prone. This was with 150 grain BT's seated at 2.800".

    I haven't loaded much for the 308 in the past few years and haven't been doggin in as long, it would be nice to get back on a good hill just as the sun gets high with a good 308 or one the 6.5's I've used. Do ya know why the dogs don't come out before the sun is high or when its overcast? Since it's just past Ground Hog day and apparently he saw his shadow, I'll tell ya. Without the sun, they cannot see the shadow of the hawks and falcons overhead and it would lead to their untimely demise. It's fun to watch the prairie dog wave as shadows from clouds come overhead on a high population town and see them duck into their holes. I luv doggin'.
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



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    Thanks Murphy, I was hoping you would chime in on this one.

    I use COL 2.818 with Sierra Match King 175gr HPBT over 40.8gr of Varget in my .308 with great results. My rifle has a 1:10 twist.

    The load in this post is for a friend with a FN PBR 22" .308 with 1:!2 twist. He shoots retail Hornady 110gr TAP ammo which I think is loaded with V-Max bullets. He loves this particular set up so I volunteered to load some or him.

    Once I cracked open the box I noticed how short these rascals are and started marking and measuring.

    If set to COL 2.740 as Hornady lists, the bullet is only .205 deep in the neck. At COL 2.80 it's a wimpy .145 of neck holding the bullet.

    I understand that the bullet will most likely contact the lands before it leaves the case or this round wouldn't preform well in his rifle. Since it so short I wasn't worried about it not chambering. I just thought it was a little strange to have such a small amount of neck holding this bullet.

    All of the .308 bullets I've loaded in the past seat fairly deep in the case given their long pointy shape and popular weights. This current combination was strange to me so I thought I would ask.

    Below is a picture with scribes at 2.74 and 2.80

    http://s258.photobucket.com/albums/h...t=DSC00354.jpg





    [IMG]file:///C:/DOCUME%7E1/MARKMA%7E1/LOCALS%7E1/Temp/moz-screenshot-4.jpg[/IMG]

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    110gr bullet is too light for a .308. You should try something heavier. But if you are going to use a 110gr bullet, it's not going to seat deep, because the bullet is going to be short. You should be fine with the seating dept that you have found in the book. That appears to be enough to hold the bullet in place.

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    Quote Originally Posted by Northernl View Post
    110gr bullet is too light for a .308. You should try something heavier. But if you are going to use a 110gr bullet, it's not going to seat deep, because the bullet is going to be short. You should be fine with the seating dept that you have found in the book. That appears to be enough to hold the bullet in place.
    I use a heavier 175gr in mine. My buddy shoots great groups with production Hornady 110gr TAP ammo. I plan to duplicate that ammo for him, possibly better. TAP ammo use the 110gr V-Max. I just wanted a second opinion or two about the seating depth.

    Sitting in the airport in Phoenix as I type. Flying to Anchorage in a few minutes. Renting a car and driving all night to Fairbanks. My Brother is running the #14 Ski Doo on the Iron Dog. I plan on being there for the finish. Should be a good party tomorrow night.

    Perhaps I can meet Professor Murphy at the after race party?

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