Ready for first Load! last second questions

[michiman]

I've been working on gathering as much information as possible over the last couple months in preparation of my first load of 6.5 CM. I am now ready to start my load development but have a couple last questions on where to start:

1. My rifles is very accurate even with factory ammo. I regularly shoot sub 0.5 MOA groups. I was thinking about starting my load development with the same CBTO length as the Hornady ELD-M match ammo, which is a significantly short of the lands. My CBTO to the lands is 2.2535" which put my OAL at about ~2.960" which is a bit too long for my mag (about 0.02-0.04, I haven't measured, but its close). Am I better off starting at the same length as the factory ammo that i know shoots well, or going as long as possible (still short of the lands) while still fitting in the mag?

2. Additionally, the Hornady reloading manual states that the Max length is 2.800 which is significantly shorter than what I am able (and planning) on loading, any experience loading longer than this recommended max?

3. And finally, I've noticed a lot of people post about load development with powder weights that are significantly higher than the recommended max in the Hornady reloading manual. I've seen posts of people starting at 40.0 gr and going all the way up to 43 with H4350 for a 147 gr eld-m. The manual lists a max of 40.3. I am using new Lapua brass, which i've read will likely give me more pressure than the Hornady brass. I was thinking about starting ar 39.7 and working my way up to 42.1, however I dont know if that is actually safe, but it seems that it is pretty standard based on the forums I have read. What do you recommend is a good starting point for for 147 gr ELD-m, Lapua brass, H-4350, and CCI BR4 primers?

Thanks in advance, and sorry for the noob questions.

 

[Howland]

Starting out by duplicating a CBTO that is known to be accurate, especially if you're using the same projectile, makes a ton of sense. You can always fiddle with it later to see if you can improve results once you have an idea what powder and charge weight range work best.

Manuals generally list max OAL based on SAAMI. You aren't selling ammunition commercially so your limitations are magazine length and where your lands are.

Manuals list max loads based on their test chamber, conditions and the specific lot of components used the day they tested, but they also use methods unavailable to most of us to measure or estimate actual chamber pressure. Your chamber, components and conditions are slightly different than theirs but not by too much. Knowing what to look for that are signs of high pressure are critical. For a new reloader, I would use caution approaching book maximum and not exceed them. Pressure signs can be very subtle and there are only a few tenths of a grain between safe maximum and dangerous to the point of throwing the dice. That charge is going off inches from your eyes, face and fingers.

 

[918v]

The reason people load more than the manual is because they use a longer coal. This increases case volume and allows them to use more powder without exceeding max pressure, but only if the bullet has enough jump. SAAMI assumes the bullet is going to jump at least .050” to the lands.

 

[Doom]

If I read this correctly, you are a new reloader, so I would strongly advise that you work with the manual’s data, COAL, start at the minimum load and work up from there, especially if you are using different components. Brass does have an effect on pressure but so does camber dimensions. As you gain experience with your gun then you will develop a feel for how handle changes.

You appear to have the Hornady manual. The loading process and details described in it is probably the best of all the manuals I have read. It will serve you well.

 

[jfri247]

This 100x. It won't take too long before you will be comfortable making small changes to the load, especially if you plan on using a chrono to start keeping your own specific records. This is where you become as much of a scientist as you are a reloader.