Chasing the lands VS Finding Jam

[Steeliedrew]

I’ve never reloaded before but am starting my journey with a lot of research. Mainly cause that’s what’s in the budget at the moment. I came across Eric Cortina’s YouTube channel and watched the video titled “Chasing the land's is stupid”. In regards to finding seating depth he argues that finding jam and then starting a ladder at 0.020 less than jam and working back away from the jam point in 0.003 increments is the way to go. what do you like to do for finding a seating depth node? are there methods other than Eric’s I should research. Am I getting too into the weeds before I’ve even started?

For reference I’m going to be reloading for my Browning A-Bolt II .300 Win Mag. I have a box of 185 grain Berger VLDH’s I’ve chosen to start this journey with. I’ve heard they can be finicky with seating depth so I guess that’s why I’m researching how to find seating depth at the moment.

 

[83cj-7]

I’m just going to say that I don’t agree with Cortina, and leave it at that.

VLD - Making it Shoot

VLD bullets are designed with a secant ogive. Berger VLD bullets are consistently and exceptionally capable of putting game down quickly

bergerbullets.com

Read through this thoroughly. This info is directly related to the bullet you want to shoot and it’s from Bryan Litz and some of the smartest ballisticians in the industry.

Here is my method:
Using a Sinclair OAL tool and Hornady bullet comparator, I find where the bullet is jammed in the lands with light pressure on the rod. You will also need a cleaning rod down the barrel from the muzzle to un-stick the bullet from the rifling.

After measuring for Base To Ogive(BTO), I will set my bullets either .030” off the lands for normal bullets such as the Accubond, ELD, or any other bullet other than a Hybrid. The Berger Hybrid bullets seem to “jam” further into the lands and I will start them .060” off the lands otherwise I will find pressure too quickly in load development.

Once I find a load with promise, I will adjust seating depth in .010” increments closer and further from the lands. Ideally I want to be in the middle of a node and if the node is only .005 wide, it can make loading ammo consistently and accurately a real challenge. Usually I can find a node .010 wide and I will load right in the middle. I usually like to be able to do this for powder charge as well.

I just went through this process with my 300 Win Mag and the 215 Hybrid. I ended up at .060 off the lands in a .010 window for seating depth and a full 1 grain powder window that shot the same speed. During this process, I found that anything closer than .030 off of “jam” caused excessive pressure. I believe this to be because the “jam” measurement is actually engaging approximately .030 to .040 of rifling. Hence the reason that I started .060 from the “jam” measurement.

These are at .060 off the lands. The steel was shot a 732 yards. (Yes, those are all 3 shot groups)






This was the same powder charge but .040 off the lands and this load showed quite a bit of pressure, where .060 off shows none.


This is a good visual of a seating depth test shot at 400 yards. I chose .045 off and left it there.

 

[Steeliedrew]

That is some impressive shooting there! I’d be absolutely thrilled to be shooting groups like that. Thank you for the info!

 

[Chris in TN]

Read this:

https://precisionrifleblog.com/2020/04/05/bullet-jump-load-development-data/

Then find your depth to lands, back off from that maybe 0.050" to 0.060", and if those fit into your magazine and feed from it, forget you ever heard of seating depth, unless you really enjoy wasting components and believing what you want to believe based on insufficient sample sizes.