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Old September 14, 2000, 04:30 PM   #1
Knighterrant
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Current discussion among some of my fellow shooters here in the South. Some say, seat the bullet (in this case .308 Win/168 HPBT) with the base of the boatail at the beginning of the shoulder, OR, others say bullet should be within a few thousandths(maybe even touching) of lands & grooves. Anyone have a better answer than try both ?? Why would one be better than other? Max range for this is going to be 500 yds and under. Powder will be either BL(C)-2 or VarGet.
Thanks

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" A Glock is for when you can't reach your Remington 700VSSF.308Win...yet !!"
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Old September 14, 2000, 05:36 PM   #2
Southla1
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Knighterrant, Theory has it that touching the lands or just short of touching them should be more accurate, but take my word for it each rifle is a law unto its own self. Test both of them to make sure. An example of a rifle being a law unto itself listen to this. In my younger days I, in youthful enthusiasm, decided to accurize my 03A3 Springfield. First step was to glass bed it. Its amazing what one can accomplish with ignorance! Little did I know that the main thing to be glass bedded was the actionand the barrel free floated. Well I hogged out the barrel channel and bedded that and not the action . In theory it should not be able to hit the broadside of a barn but take my word for it with either 168 Grain Sierra International or a 190 Grain Sierra Match King sitting on top of a full case of the old original H4831 the old girl will go into 1/2 inch (5 shots) all day long! By the time I got smart and knew what I had done worng I was smart enough not to fix what isn't broken!


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Old September 14, 2000, 07:54 PM   #3
Jack Straw
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I would start with the longest possible OAL (either within a few thousandths of the rifling or the max length possible in the magazine) and experiment by reducing the OAL by .01" increments until you find what the rifle likes.

I have never heard of the position of the boattail in relation to the shoulder having an effect with jacketed bullets. I have heard of not seating cast bullets deep enough that the base of the bullet extends below the bottom of the neck because of the adverse effect that might have on accuracy.

Jack
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Old September 15, 2000, 10:01 AM   #4
Hutch
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Don't overlook the fact that the case neck needs to have a good grip on the bullet for consistant ingition. I've read that you should have from .5 to 1 full caliber of bullet in the neck. Stated differently, a .308 bullet should be in the case to a depth of at least .154. I can't seat my 168's out far enough to engage the rifling in my 700VS. The leade or freebore is too long. It still shoots fine, tho'.
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Old September 15, 2000, 04:11 PM   #5
labgrade
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JS, = "experiment by reducing the OAL by .01" increments ... "

That sounds like quite a bit, especially at (if) a max load. In many instances, just a .005" change can improve accuracy - towards or away from the lead.

I would suggest that if you are going to change seating depth by .01", I'd back off at least 5% max & work back up - safety first & all.

Many times you can't seat bullets out to optimum length as the magazine won't allow the longer OAL ....

If you can, I'd recommend start working up your load with the bullet about .005" off the lead. This allows the bullet somewhat of a runing start, while seating hard up against the lead can boost pressures rather quickly.
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Old September 15, 2000, 06:59 PM   #6
Jack Straw
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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by labgrade:
JS, = "experiment by reducing the OAL by .01" increments ... "

That sounds like quite a bit, especially at (if) a max load. In many instances, just a .005" change can improve accuracy - towards or away from the lead.

I would suggest that if you are going to change seating depth by .01", I'd back off at least 5% max & work back up - safety first & all.

Many times you can't seat bullets out to optimum length as the magazine won't allow the longer OAL ....
[/quote]

I guess I should have elaborated. I reduce OAL by .01" increments until I get down to the length listed in whatever manual I happen to be using. I then take the best group's OAL and try shooting at .005" above and below that length to see if I can improve group size. I do this just because it cuts down on the total number of shots needed to find the optimum OAL. I started doing that upon the advice of a Sierra technician a couple of years ago. I would think that this would be safe as long as I don't go below the published OAL; is there some error in my thinking? I don't mind changing a practice for the sake of safety.

That's definitely true about a magazine limiting the OAL. I have run into that several times. It is not necessarily an accuracy problem though. The same Sierra tech mentioned above explained to me that top accuracy is frequently found with the bullet nearly touching the rifling. As the bullet is seated further into the case, accuracy will drop off...to a point. He stated that there usually is another seating depth at which the accuracy will return and then diminish as the bullet is seated even deeper. At that point, I try varying the depth by .005" just to see if tweaking the OAL improves group size even further. My shooting has pretty much supported what the tech told me.

Jack



[This message has been edited by Jack Straw (edited September 15, 2000).]
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