Getting Load Data From Different Sources?

[Blue68f100]

LOL!

Thanks for all the info. Being former EOD, I have a pretty through understanding of explosives and how pressures can effect things. I understand there are a lot more intricacies in reloading but the properties are still the same. I did a ton of reading on safety before I ever got started. Generally what I do for my loads is I take the max, drop it by 10% and work up in .2 or .3 grain increments, checking for pressure signs after each round. But I have not been happy with the results I have been getting with CFE223 and Hornady 68gr BTHP-M bullets. So I found a place local that has 8206 XBR and Varget, I wanted to start working on my 69 TMKs, 55 V-MAX, and 75 BTHP. The TMKs give me the most concern because I need them to fit at mag length and there is virtually no data on them. Sierra says use the SMK data but the TMK is much longer. At first I tried to use Varget but you cannot get enough powder in the cartridge. I didn't feel it was safe so I switch it to XBR instead, the final 3 weights in the workup (using Lyman 50th) are pretty compressed and I don't think I will make it to them before I start seeing pressure signs. Funny thing is, in the Lyman manual for a 69gr round, their accurate load called for 27.something grains of Varget. That much Varget completely filled the case.

Once I find a good round and charge that my rifle likes, that what I will stick to. Me and my gun are capable of .75 MOAish so that is what I hunting using Black Hills 69SMK, so that is what I am hunting.

What twist is your barrel?
I have found that with the 69gr HPBT-M (SMK) work extremely well with Varget near the top end with a length of 2.260" which fits the magazine. I have not tried the tipped version. But I shoot these out of a 1:8 twist Wydle chamber AR. My 1:10 twist barrel has problem with them and prefer the lighter bullets. The Hornady 68gr BTHP-M does not shoot near as well as the Serria. With the Hornady bullet being 0.09" longer the loads to do not transfer. I use the 65gr SGK for my hunting round. Shoots the same POI as the 69gr with the same charge.

 

[texasveteod]

What twist is your barrel?
I have found that with the 69gr HPBT-M (SMK) work extremely well with Varget near the top end with a length of 2.260" which fits the magazine. I have not tried the tipped version. But I shoot these out of a 1:8 twist Wydle chamber AR. My 1:10 twist barrel has problem with them and prefer the lighter bullets. The Hornady 68gr BTHP-M does not shoot near as well as the Serria. With the Hornady bullet being 0.09" longer the loads to do not transfer. I use the 65gr SGK for my hunting round. Shoots the same POI as the 69gr with the same charge.

Mine is a 1:7 chambered in 5.56. Just curious, what is the top end of Varget you are using? The Lyman manual had it at 27+ which completely filled the case.

 

[jmorris]

I generally get all the data I can. From the powder manufacturer/outfit that puts their name on the label, various bullet manufacturers etc. Then I can get a pretty good idea where to start.

 

[Blue68f100]

Mine is a 1:7 chambered in 5.56. Just curious, what is the top end of Varget you are using? The Lyman manual had it at 27+ which completely filled the case.

I'm using Serria Data don't recall which version. Don't have the book is front of me, but my load is 25.7-25.8gr Varget, CCI #41 primer. If I recall I'm close to Max (26.0 ???) which is a Compressed load. I'm using Lapua brass for my most accurate loads but have found LC-15 to be very close in case volume. Which means I'm able to use the same load in each. The LC is not quite as consistent over all.

 

[Bart B.]

Generally what I do for my loads is I take the max, drop it by 10% and work up in .2 or .3 grain increments, checking for pressure signs after each round.

I've never seen any real accuracy nor precise shot location difference shooting 20 or more rounds per group through 300 yards with over a grain spread in charge weight average. There's a 3X to 4X spread across the first few 3- to 5-shot group segments starting out. Rarely is either one of the first two segments the smallest of all few-shot segments fired. A 1 to 2 grain difference in good charge weights of the right powder shoots many-shot groups the same size statistically up to 300 yards with rifles fired off ones shoulder. Shoot a few to see what happens.

Visible signs of pressure are very inaccurate. Showing people fired 7.62 NATO proof load cases having 67,000 cup (80,000+ psi), their response is often maximum but safe and normal around 50,000 cup (60,000 psi). There is no industry standard for primer and case metallurgy and dimensions so they'll all deform the same for each size and type with a given peak pressure. Rubber rulers show different results depending how much they're stretched to measure something.