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.308 Bullet jump????

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sniper13 View Drop Down
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    Posted: June/07/2009 at 11:52
Hey...Whats everybody using for jump on their .308 reloads????
pulling a trigger is easy....hitting your mark is intelligence
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Mike McDonald View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike McDonald Quote  Post ReplyReply Direct Link To This Post Posted: June/07/2009 at 12:23
0.060" to 0.100"
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steelbenz Quote  Post ReplyReply Direct Link To This Post Posted: June/07/2009 at 12:55
I pull mine up a little closer .040
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sniper13 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sniper13 Quote  Post ReplyReply Direct Link To This Post Posted: June/07/2009 at 16:25

WOW ....Thats alot further than I thought I would hear....

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crosswire Quote  Post ReplyReply Direct Link To This Post Posted: June/07/2009 at 17:15
"...Whats everybody using for jump "
Hardly know what eveyone else is using but mine is 28 thou with one bullet, 52 thou with another.  ??
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sniper13 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sniper13 Quote  Post ReplyReply Direct Link To This Post Posted: June/07/2009 at 20:44
I will be a little more specific...168gr hpbt...with various other combinations, I am just trying to get an idea of which direction I want to go.... If I use 2.8 0AL then I end up with .26 jump wich I just think is very sh*tty for accuracy....

Edited by sniper13 - June/07/2009 at 20:46
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jonoMT Quote  Post ReplyReply Direct Link To This Post Posted: June/08/2009 at 10:08
There's no one answer to that because different rifles have a differing amounts of throat, even among the same make and model (because of manufacturing tolerances, throat erosion, etc.) You can start by seating a few thousands off the lands but even then, depending on the bullet and other variables in your load, your rifle may or may not like the load.

Personally, I have a .308 with a throat so long there's no way to seat close to the lands. So I've always loaded to an OAL of 2.8 or 2.81 just to keep them magazine length. The rifle, with the right load, shoots .5 MOA, which is good enough for me. Point is, you can worry about quite a few other variables in your loads other than seating length. Good, uniform brass, quality powder and primers, and quality reloading equipment are all important factors.


Edited by jonoMT - June/08/2009 at 10:09
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supertool73 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote supertool73 Quote  Post ReplyReply Direct Link To This Post Posted: June/08/2009 at 10:16
All remington rifle are going to have a huge jump.  I think they are lawyer proofed chambers.  Big Grin  But most of them still shoot very good even with the jump.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steelbenz Quote  Post ReplyReply Direct Link To This Post Posted: June/09/2009 at 08:40
Originally posted by supertool73 supertool73 wrote:

All remington rifle are going to have a huge jump.  I think they are lawyer proofed chambers.  Big Grin  But most of them still shoot very good even with the jump.


My factory 700 has .147 of free bore. But I know one of our better known shooters told me he has his chamber cut to 3.00 inches and loads to factory length. And without naming names, I, nor none of us would dispute his results. I only dream of the groups he gets.

So I think that with barrels it is a matter of..
 1.) material, diameter, taper and the craftsmanship of the barrel maker.
 2.) He who's shoulder is at the other end of the gun stock.   

Just IMHO!
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post Posted: June/09/2009 at 09:49
Bullet jump varies from rifle to rifle and best to check your own "rolled" ammo. Most of my rifles operate best at about 1 or max 2thou off the lands.
I had a remmy barrel with a throat so long it must have been a beer drinker in its previous life. It unfortunately did not shoot very well either. The new barrel on it has very tight tolerances and I load 1,5 thou off the lands.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steelbenz Quote  Post ReplyReply Direct Link To This Post Posted: June/09/2009 at 10:45
Originally posted by 8shots 8shots wrote:

Bullet jump varies from rifle to rifle and best to check your own "rolled" ammo. Most of my rifles operate best at about 1 or max 2thou off the lands.
I had a remmy barrel with a throat so long it must have been a beer drinker in its previous life. It unfortunately did not shoot very well either. The new barrel on it has very tight tolerances and I load 1,5 thou off the lands.



It was the Operator on the reamer that was drinking the day your 700s barrel was reamed.
And most of us cringe every time we think of your plight!!!   Brother Wouter, your a stronger man than I.  I do not have the patience of Job.


Edited by Steelbenz - June/09/2009 at 10:46
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rick983 Quote  Post ReplyReply Direct Link To This Post Posted: June/09/2009 at 13:50
In my FN 308 I use Sierra 168 HPBT and set them .005 off the rifling as determined by the Stoney Point comparator and it shoots great. However, all rifles are different and yours may shoot better with a big jump. Good luck. Big Grin
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike McDonald Quote  Post ReplyReply Direct Link To This Post Posted: June/09/2009 at 18:50
I did have one rifle.no, two, cut with the throat length determined by dummy rounds provided.  SOmething in the order of ogive + 0.002" or so, very short. 
I found no accuracy difference with these rifles, but did find in comparison to a long throat rifle that Sierra bullets, at least in 22, 30, and 33 caliber, are very length ( jump) tolerant with little or no accuracy degradation, and no appearent bullet deformation as evidenced by longer range groups.
  Hornady Amax bullets as one example haven't proved so forgiving in that regard.
My shooting partner has tried a couple other brands, some that are tolerent, some that are not.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sniper13 Quote  Post ReplyReply Direct Link To This Post Posted: June/12/2009 at 08:55
Thanks guys....all good stuff........Mike I am in fact using an A-Max right now, just rolled some up to find out the optimal charge weight. With the Hornady HPBT Match, with them .005 off the lands and 44.5 Varget I am getting consistant .19''-.26''. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote blmfgym Quote  Post ReplyReply Direct Link To This Post Posted: June/22/2009 at 20:35
Is there any data anywhere that will help analyize you group patterns to make them better? For example, does a vertical pattern indicate I should adjust powder, jump length, or brass trim, etc. and so forth?
bye ya'll blmfgym
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Post Options Post Options   Thanks (0) Thanks(0)   Quote safariarms man Quote  Post ReplyReply Direct Link To This Post Posted: June/29/2009 at 19:44

All are correct.  Jump to the lands and grooves cannot be given as an absolute number as each rifle will react differently to that distance.  I have had some rifles in some calibers that I had no choice, but to load to SAAMI specs.  Others, if I wanted to load out to 0.02 inches off of the lands and grooves, I could not eject a misfire from the chamber (Savage Model 40 22 Hornet).  While others, to load out that far, I ran out of room for seating the bullet.  However, for the most part, most rifles will accomadate my demands and the best success I get, is 0.02 or even 0.01 off of the lands and grooves.  But, again this is always rifle dependant.  My rifles are confined to several brands, yours may be different.  I have a Zastavia in a .308 that I loaded 0.03 inches off of the lands and grooves and it shoots less than 0.75 inch groups at 100 yards.  I have never tried another distance, as this was more than adequate for hunting.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post Posted: June/30/2009 at 04:24
I have just increased the distance to the lands on my 308Win and it has improved accuracy. I am now 0.106 (no typo error) off the lands. Max length I can load is 2.818 " and I am seating to OCL of 2.712 ".
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steelbenz Quote  Post ReplyReply Direct Link To This Post Posted: June/30/2009 at 15:22
Wouter,
 My Hornady  manual says to seat 155s a 2.735 so your not that far into the case, how much powder are you loading percentage wise to what the case can hold?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post Posted: July/02/2009 at 04:32
Steelbenz, I would have to check and will let you know. I think about 45gr is max it can hold and still seat the round. I am at 43.3 gr.
The Somchem manual also called for a deeper seating then what I have been using, that made me test it out and it seemed the right way to go.
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