Bolt gun bullet jump reload

[Briano23]

My oal to the lands is 2.330" and my seating depth is 2.260" which is 0.070" is this and acceptable bullet jump.

My development load is
123 gr SST
Starline brass
26.3 gr to 27.5 gr IMR 8208
Primer cci 450
Seating depth 2.260" CBTO 1.670"

[kmon]

You will be fine with that jump or seat the bullet for a little longer OAL, Sounds like you can seat it out to max mag length and be closer to the lands with a little more case volume. i have had good accuracy with Weatherby mags that have over .25 free bore.

In the Grendel I load to the max length that will function 100% reliable through the mag as long as they are not into the lands, for my CZ that is over all 2.285. Some bullets are more seating depth sensitive than others Berger VLD being the most sensitive that I load.

[Briano23]

Thanks kmon.
Could you explain what free bore is I am not familiar with that tirm.

[FLshooter]

[Bottomdweller]

What is the goal? Are you wanting to work up an accurate load? Break in the barrel? I start looking for my powder charge jammed. After finding the powder charge, start backing out of the lands. That's just how I learned. There seems to be quite a bit of difference in accuracy just with jump. My experience has been flat based bullets like being close to the rifling. Boat tails prefer more jump.

[Briano23]

Are you wanting to work up an accurate load?
Yes, best load with different bullets and powders available. So if changing cartridges OAL of even 0.010" can improve accuracy I'm in.
Having more than one accurate load is my goal.

[Bottomdweller]

Every combination of things will give different results. I see you are getting a new stock, bottom metal.....unless you just want to bust caps, I'd wait to start looking for an accurate round untill you have the rifle all decked out in it's new duds. It's all about harmonics.

[Bottomdweller]

Oh yeah, .01 is a lot.

[jbmarshtx]

The SST is not a VLD, but Precision Rifle Blog did a bullet jump test over a wide range. I think that they were using VLD type bullets, and likely higher velocities than the grendel. The most forgiving jump in terms of charges and accuracy was right around 0.050. The more commonly suggested 0.020 was one of the less accurate ones.

Just an FYI. I'm jumping 100 grain TTSX about 0.070 - 0.075 from my Howa heavy barrel.

[A5BLASTER]

My oal to the lands is 2.330" and my seating depth is 2.260" which is 0.070" is this and acceptable bullet jump.

My development load is
123 gr SST
Starline brass
26.3 gr to 27.5 gr IMR 8208
Primer cci 450
Seating depth 2.260" CBTO 1.670"

That depends on your barrel.

We all can tell you this are that and suggest this are that but at the end of the day. Only your barrel can tell you what's final and working.

This is what I do, start my ladder at max seating depth that is still mag feedable and not touching the lands.

Once I run the ladder I pick a few charges that look good and go shoot 10 shot strings over the graph and gather sd and es and average velocity for each 10 shot charge string. The one with the tightest sd and es is going to be my load.

I then run group testing by loading 5 round strings starting at the established charge and seating depth, then drop 10 thousands shorter every 5 shots after that. Normally somewheres between the starting seating depth and 20 thousands shorter I will find the seating depth that gives the proper bullet timing to create the groups I'm looking for.

This is what I do and works best for me in my bolt and ar grendels and non of my loads are at 2.260 coal and all of them are mag feedable.

But like I stated above only your barrel can tell you what it wants.

[Briano23]

Thanks everyone this is great advice and as you all say it's al on how my and the rifle preform.
Any suggestions on a chronograph I have a chrony now but it only give bullet speed I have calculate sd and es my self.

[Lemonaid]

Thanks everyone this is great advice and as you all say it's al on how my and the rifle preform.
Any suggestions on a chronograph I have a chrony now but it only give bullet speed I have calculate sd and es my self.

Magnetospeed.
Online SD calculator https://www.easycalculation.com/stat...-deviation.php

[A5BLASTER]

Thanks everyone this is great advice and as you all say it's al on how my and the rifle preform.
Any suggestions on a chronograph I have a chrony now but it only give bullet speed I have calculate sd and es my self.

Magneto speed sporter is what I'm useing now. It will give you the average, hi, lo velocity and sd and ES numbers.

Works great for me and my rifles, as always best to shop around and base what you buy on you specific needs.

I went magneto speed because I needed something that wasn't effected buy light conditions are weather and something I didn't have to shut down the shooting line to set up and use.

[FLshooter]

[Briano23]

With my Chrony I would write the results down and at home input the in this spreed sheet I created.

If you like I can share the speared sheet for modification to it if it would help any one.
But maybe the Magneto speed sporter might give me better results.

The V3 version is a little more that I can speed now.


Chrony 2.JPG