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bullet seating depth

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deerkiller View Drop Down
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    Posted: March/26/2007 at 19:12

 

I am a beginning reloader and was wondering what method you guys use to find the particular bullet seating depth for a specific rifle.  I read somewehre that the best accuracy can be achieved by seating the bullet so that it is just touching the rifling or somewhere within 1/16 of an inch back, is this correct?  With my first load i took a factory round and just duplicated its length, Is there any real benefit to finding out exactly what the length of my chamber to rifling is in order to get the perfect length, or is this a waste of time and effort.  Any help with this dilema would be greatly appreciated.

 

 

thanks griffin

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RifleDude View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RifleDude Quote  Post ReplyReply Direct Link To This Post Posted: March/26/2007 at 19:52

Yes, bullet seating depth / cartridge OAL has a very profound effect on accuracy.  I would not recommend seating a bullet so it touches the rifling in a hunting rifle, though this is a common practice with single shot benchrest rifles.  Pressures jump dramatically without the bullet "jumping" a little to the start of the lands, so your maximum powder charge would have to be backed off a bit.  Many hunting rifles have a long enough throat that you wouldn't be able to seat to the lands anyway due to magazine box length limitations.

 

To find the best seating depth for accuracy, I first find the max OAL so the bullet touches the lands, then back off about 0.015" to start, OR start with the max OAL my magazine box will allow with a few 0.001" clearance, whichever is shorter.  Then, I test my loads in progressively deeper seating depths in 0.005" increments until I find the OAL "sweet spot" my rifle likes.  I make up dummy rounds (bullet seated in sized case, with no powder or primers) and increase the seating depth until the bolt will just close and I see marks on the ogive of the bullet.  This establishes max OAL.  A Stony Point OAL gage is also a good, inexpensive tool for finding max OAL.  I also use a Sinclair hex style bullet comparator with my dial calipers to measure OAL, as bullets will vary somewhat when measured on the nose, but won't vary much at all when measured on the ogive.  The bullet nose never contacts the rifling anyway, the ogive does, so it is the determining factor for how far off the lands your bullet is seated.

Ted


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deerkiller View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote deerkiller Quote  Post ReplyReply Direct Link To This Post Posted: March/26/2007 at 20:10

 

Thanks Rifle Dude

 

I think i will begin by using the dummy round like you stated and find the max length then back it off .015, and go back incrementally loading 10 rounds of each and see how they shoot.  I will have to go off of nose length because i only have your standard caliper style measure.  ill have to get one of those stony point oal gauges.  good stuff to know, this will get me started with more precision loading.   

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Post Options Post Options   Thanks (0) Thanks(0)   Quote pyro6999 Quote  Post ReplyReply Direct Link To This Post Posted: March/26/2007 at 20:12
Originally posted by deerkiller deerkiller wrote:

 

Thanks Rifle Dude

 

I think i will begin by using the dummy round like you stated and find the max length then back it off .015, and go back incrementally loading 10 rounds of each and see how they shoot.  I will have to go off of nose length because i only have your standard caliper style measure.  ill have to get one of those stony point oal gauges.  good stuff to know, this will get me started with more precision loading.   

 

way to go ted another satisfied customer!! you rule man!!

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Post Options Post Options   Thanks (0) Thanks(0)   Quote cheaptrick Quote  Post ReplyReply Direct Link To This Post Posted: March/27/2007 at 11:53

Excellent advise, RD!!

As usual.....

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RifleDude View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RifleDude Quote  Post ReplyReply Direct Link To This Post Posted: March/27/2007 at 19:34
Aw shucks, fellas... thanks!
Ted


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Post Options Post Options   Thanks (0) Thanks(0)   Quote pyro6999 Quote  Post ReplyReply Direct Link To This Post Posted: March/27/2007 at 20:41
hard not praise a man when he works hard plays harder and is kind enough to enlighten us with the gospel!! can i get an amen from the congregation??
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cheaptrick Quote  Post ReplyReply Direct Link To This Post Posted: March/28/2007 at 03:04
Hallelujah and amen!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RifleDude Quote  Post ReplyReply Direct Link To This Post Posted: March/28/2007 at 08:15

 

Thanks again, guys!

Ted


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