Bullet Jump

smedley · October 13, 2005, 10:43 PM

Howdy to all!!!!
Hey got a starting of a new bullet question.

When you grab a new bullet to slip into some nice shiney brass, over a nice bed of powder, waiting for the primer to heat things up, what do you start with for a "bullet jump?" Now all things being that the brass has been once (or more) fired, neck sized, trimmed, primer pocket reamed and flash hole deburred. (maybe even neck turned)
Going to Barnes they say to set back 0.050 off the lands. I usually do a 0.020 set back. Just a wondering what you all out there do.

Thanks,
Smedley

Squeeze 'em at the press and relaease from the chamber

Dave Haven · October 13, 2005, 11:48 PM

.020" - .050" should be about right. Weatherby uses a bit more freebore for their cartridges.

Smokey Joe · October 16, 2005, 01:25 AM

What I do is experiment to find out what each of my rifles prefers in the way of bullet jump to the lands. It's part of load development research.

Having decided on a powder & bullet, I load up likely loads, in a series of weights of powder. All bullets seated equally deep. Having found the best powder charge, I then load up another series, all with the optimum powder charge, this time varying the seating depth, to find the optimum distance from the lands.

All this requires a lot of shooting, reloading, and trips to the range. Awwwww, gee, what a terrible thing!!

smedley · October 16, 2005, 11:52 AM

Thanks Smokey Joe,
I do a something very close to that when working in a load but, what I was looking for is a starting point for new bullets.
I had some good bullets but there may be an even better one for my rifle. I wanted to just get a perspective of what others have found as a good starting point for jump.

Thanks again,
Smedley

Not sure how deep to put em in at the bench but I know how to get rid of them.

AJ Peacock · October 16, 2005, 12:52 PM

I have found from personal experience and have read on the net, that Barnes bullets (at least the solid's) require more jump. the reason is that you will get a higher pressure with those bullets because it takes a little more energy to force them through the rifleing (compared to thin jacketed bullets).

With Normal bullets, I'll go from .030 down to .010 or so. Any closer than .010 and you might as well put them into the rifleing for best consistency.

I have been told that some rifles like a larger jump, I haven't personally experienced those though (probably because I usually stay within the above range).

Just my personal experience, your mileage may vary.

AJ

ClarkEMyers · October 16, 2005, 01:23 PM

I start with OAL per the manual where I took the load. That's probably no better than starting with respect to the throat given that I have no idea what the throat in the test barrel was.

Just the same I like to start with the book load in all details and fire over skyscreens and try to get a notion of velocity and pressure before I move around in the throat. Then I look at how the magazine and feeding and the book OAL stack up in my rifle. In general I'll seat out close to the throat but I'll look at grip in the neck and in hunting rifles damage to the bullet tips as well.

Foxman · October 16, 2005, 04:30 PM

According to one or two industry experts in the US, Rifles over .25 cal prefer .030" and down and under .25 cal .050" down to 025". I have found this to be a pretty good rule of thumb. My 243 shoots best with .040" any less and the groups open up. My other small cals all shoot best between .035" and .0 30". The 270 goes best at .025" and the 6,5 swede the same, the 30 cals all seem to like .020", so I guess these guys do know a thing or two. The 243 had me for a while I tried from .010" up to .030"and it was not very good ready to sell it, then I read "metallic cartridge reloading" by Ed Matunas who at the time was I think head of testing at Winchester. it opened my eyes and I made loads from .035 up to .050" and at the .040" loads it worked a charm, tight groups and very consistent. Sadly it is 25yrs old now and has gone off for a new barrel, so I will have to start again with it, but at least I have an idea where to go.

October 13, 2005, 10:43 PM	#1
smedley Member Join Date: June 21, 2005 Location: NW washington with property in E. Washington Posts: 43	Bullet Jump Howdy to all!!!! Hey got a starting of a new bullet question. When you grab a new bullet to slip into some nice shiney brass, over a nice bed of powder, waiting for the primer to heat things up, what do you start with for a "bullet jump?" Now all things being that the brass has been once (or more) fired, neck sized, trimmed, primer pocket reamed and flash hole deburred. (maybe even neck turned) Going to Barnes they say to set back 0.050 off the lands. I usually do a 0.020 set back. Just a wondering what you all out there do. Thanks, Smedley Squeeze 'em at the press and relaease from the chamber

October 13, 2005, 11:48 PM	#2
Dave Haven Senior Member Join Date: February 1, 2000 Location: near Flagstaff, AZ Posts: 790	.020" - .050" should be about right. Weatherby uses a bit more freebore for their cartridges. __________________ NRA Endowment Member FCSA Life Member Subs are cool, but belt-feds RULE!

October 16, 2005, 01:25 AM	#3
Smokey Joe Senior Member Join Date: July 14, 2001 Location: State of Confusion Posts: 2,106	Bullet back from the lands What I do is experiment to find out what each of my rifles prefers in the way of bullet jump to the lands. It's part of load development research. Having decided on a powder & bullet, I load up likely loads, in a series of weights of powder. All bullets seated equally deep. Having found the best powder charge, I then load up another series, all with the optimum powder charge, this time varying the seating depth, to find the optimum distance from the lands. All this requires a lot of shooting, reloading, and trips to the range. Awwwww, gee, what a terrible thing!! __________________ God Bless America --Smokey Joe

October 16, 2005, 01:23 PM	#6
ClarkEMyers Senior Member Join Date: November 13, 2004 Location: PacWest Posts: 455	I start with OAL per the manual where I took the load. I start with OAL per the manual where I took the load. That's probably no better than starting with respect to the throat given that I have no idea what the throat in the test barrel was. Just the same I like to start with the book load in all details and fire over skyscreens and try to get a notion of velocity and pressure before I move around in the throat. Then I look at how the magazine and feeding and the book OAL stack up in my rifle. In general I'll seat out close to the throat but I'll look at grip in the neck and in hunting rifles damage to the bullet tips as well.

October 16, 2005, 11:52 AM	#4
smedley Member Join Date: June 21, 2005 Location: NW washington with property in E. Washington Posts: 43	Thanks Smokey Joe, I do a something very close to that when working in a load but, what I was looking for is a starting point for new bullets. I had some good bullets but there may be an even better one for my rifle. I wanted to just get a perspective of what others have found as a good starting point for jump. Thanks again, Smedley Not sure how deep to put em in at the bench but I know how to get rid of them.

October 16, 2005, 12:52 PM	#5
AJ Peacock Senior Member Join Date: October 17, 2004 Location: SE Michigan Posts: 127	I have found from personal experience and have read on the net, that Barnes bullets (at least the solid's) require more jump. the reason is that you will get a higher pressure with those bullets because it takes a little more energy to force them through the rifleing (compared to thin jacketed bullets). With Normal bullets, I'll go from .030 down to .010 or so. Any closer than .010 and you might as well put them into the rifleing for best consistency. I have been told that some rifles like a larger jump, I haven't personally experienced those though (probably because I usually stay within the above range). Just my personal experience, your mileage may vary. AJ

October 16, 2005, 04:30 PM	#7
Foxman Senior Member Join Date: August 13, 2005 Posts: 466	According to one or two industry experts in the US, Rifles over .25 cal prefer .030" and down and under .25 cal .050" down to 025". I have found this to be a pretty good rule of thumb. My 243 shoots best with .040" any less and the groups open up. My other small cals all shoot best between .035" and .0 30". The 270 goes best at .025" and the 6,5 swede the same, the 30 cals all seem to like .020", so I guess these guys do know a thing or two. The 243 had me for a while I tried from .010" up to .030"and it was not very good ready to sell it, then I read "metallic cartridge reloading" by Ed Matunas who at the time was I think head of testing at Winchester. it opened my eyes and I made loads from .035 up to .050" and at the .040" loads it worked a charm, tight groups and very consistent. Sadly it is 25yrs old now and has gone off for a new barrel, so I will have to start again with it, but at least I have an idea where to go.