Questions about Bullet Jump or Lead

Hooked

Hooked

New member
So far all my reloading endeavors, I have stayed within the SAMMI recommended COAL. (mostly reloading for AR/LR and Lever w/tube magazine/crimp)
Now my newest rifle Mod.70 300 WSM, I hope to make a 165g Nosler work. Results so far are not the greatest but one 4 outta 5 round group 2" but 4 of those .960" and then I found the scope moving.
Fixed the scope issue and decided to check what maximum OAL would be with a 165g and measurement I get is 2.956" which means from 2.860 ~.096" jump. This seems like a large amount.
Anyone have thoughts or suggestions?
I did a search and found some recommendations of .030" off lands to start. I`m pretty certain that OAL would fit in magazine and feed just fine as well as have all available tension on the bullet.
Finding a good load combo seems to get a little more expensive given the price of 30 cal bullets and 60+ grains of powder.
 
maybe i am misunderstanding, are you thinking that max oal is where the lands are?

oal does not have any particular reference to where the rifle starts. it varies from rifle to rifle.

it has been written many times on this forum and others how to develop a load. that would be a good start. when i have a new rifle that i am developing a load for, i take a sized case, just barely seat a bullet and then try to chamber the dummy round. with just a little pressure the rifling will mark the bullet, coating the bullet with a sharpie makes the marks easier to see. pull the round out and seat it deeper and deeper until it will chamber fully. that gives you a pretty good idea of where the lands are and you can back off from there.

i have two winchester 94 30-30's. with one i can load a long cast bullet and it works great. put that same load in the other gun and the bullet is jammed into the rifling so hard that if you extract the case, the bullet stays in the barrel.
 
Thanks for the reply.
No, I know that COAL would not be to where the lands start but sure thought near .100" from them seems.. excessive (?).
That is along the lines of what I was asking though; in others experience does that amount seem `normal`?.
I checked what the max OAL would be w/2 different bullets, 165g Nosler, and 168g A-Max. The A-Max would only have .044" jump if loaded to SAAMI spec 2.860"
I`m going to start over with the Nosler`s and seat them out farther, .030" off.
Thanks
Don
 
You can lathe cut about .005/.008 off one of the cases neck dia
after sizing it, I do this to keep it from interfering with the measuring process.
Then set the bullet in just enough to hold, now carefully close the bolt carefully extract the round
measure it's oal.
You may need to do this several times to make sure you're getting a correct reading and that oal reading for that bullet is zero for that bullet only...
hint it might not fit the mag this way....
I move back to .010 that will give you .010 off the lands that's where I start.....
hint if you're going to run a lot of bullets through this gun I would not set it that close....
1) different bullets will have a different oal even if you have all set at .010 of the lands
2) they must fit the mag.
3) if you move the off land setting it changes the pressure the chamber sees.
4) once you have the best load you can get you can change the off land setting to see if you can pick up anything....
I don't think you gonna see much difference here unless you got it way outa whack.
 
cartridge oal has little to nothing to do with where the rifling starts. it it not necessarily "close".

every chamber is different. for example, today i loaded some 223 rounds with 70gr speer semi-pointed bullets. i seated them about .04 longer than the manual stated and then checked to see if they chambered in an ar15, no problem. then i put the round in a 700 ltr, closing the bolt pushed the bullet farther into the case by about .04. both are chambered in 223, but obviously the freebore is much different, and neither seated length is anywhere near coal. bullets of different shape will engage the rifling with different oal.
seating to some length longer or shorter than listed oal, will not result in any specific distance to or into the lands.
 
Being new to reloading this is something that I have read about but hadn't spent any time experimenting with. I have been seating my bullets to what the load data list.

After clicking on this thread this AM I decided I would at least measure my rifle. Its a Tikka T3 in 22-250. I measured it using the sliding bullet(Sierra BK 50gr) in fired case method several times, coming up with 2.520.

The data has me seating at 2.350 which is the same as the 55gr factory Nosler ammo I have used so I feel comfy with that.

At 2.500(.020 of lands) I only have .115 tension surface. In order to get the .224 tension surface the longest I will be able to go with this bullet is 2.391. That leaves a .129(or .170 with factory) jump. Like Hooked has said that seems like quite a large jump.
 
Many experienced shooters have posted that .030-.035" is the optimum clearance to the lands...some post that jamming them to the lands is best...

When my Custom .204 barrel was cut, the builder set the chamber at .033" with a 40gr V-Max and I'm sitting at .035 with a 39gr SBK,,,All loaded to magazine length and getting excellent accuracy with that chamber...
 


Write your reply...
Back
Top