Cz 527/ 90 tnt/ 3122 fps!

[Harpoon1]

So I’ve been trying to clone the Federal American Eagle 90 TNT “Varmint/Predator” load. Both for some AR’s at low pressure, not to exceed SAAMI spec and for several bolt guns where I’ve got a lot more leeway.

So I pulled a bullet and Federal loads 32.5 grains of some type of flattened spherical powder. I’ve got 8 or 10 of those on hand that should be in ball park burn rate wise but none are identical. So then I chose some likely candidates that may be able to get close.

I pulled the plug with 31.9 of H335 in an AR, when ejector marks started popping up but, had the CZ right there, so, just shoved the rest in there. 32.2 and 32.5 of H335. 2956/9/4.5 and 2994/51/28, FPS/ES/SD………the second, fastest group was .5 MOA at a 100. Zero pressure signs! None! 2994 is right there neck and neck with the Federal load. Cool!

Now I’m wondering, just how much further to the edge of pressure there is?

So, loaded 6 more single rounds on the auto-trickler at .2 increments with .02 accuracy, starting at 32.4 grns, just looking for pressure!

CZ527 23.5” barrel, 80f/Sea Level/ LabRadar

32.4/2944

32.6/2970

32.8/3001

33.0/3100 NOT a typo! Spiked a 100 FPS , with only .2 yikes!

33.2/3095

33.4/3122

And yet, the primers weren’t even flattened all the way to the edge! i may have had the very faintest hint of a heavy bolt lift starting there at the end but it’s was so negligible, I’m not even sure of it actually happening. Still stunned there are no obvious pressure signs on the brass. Even the Federal factory stuff always shows some signs in the AR and even occasionally in some bolt guns. WTF?

Anybody with QL or GRT wanted to take a stab at the theoretical pressure?

[dexdog]

I could not adjust for sea level and did not adjust for your 80 degree F ambient temperature, although I think Quickload uses a default of about 70 degrees F, so the pressures in QL would likely be a bit higher than program indicates. In any case here are the outputs for a 23.5 inch barrel using H335 with Speer 90gr TNT: 32.4 is 50036 psi, MV is 2999; 32.6 is 51041 psi, MV is 3016; 32.8 is 52067 psi, MV is 3034; 33.0 is 53112 psi, MV is 3051; 33.2 is 54177 psi, MV is 3069; 33.4 is 55263 psi, MV is 3087

[Harpoon1]

Dex,

Thanks a million, that helps a bunch. I know there’s a debate on just how accurate QL is with the Grendel but, your data sure seems to reinforce what I’m seeing on the ground.

Wonder if I just got crazy hot over charged primer that led to the 100 FPS spike? I’m gonna reload the same ladder but with 3 rounds per charge this time to see if anything else pops up.

Thanks again.

[Happy2Shoot]

Reload that 33.4 grain case 5 more iterations of 33.4 grains and let us know how it holds up. What brand case is it?

[Harpoon1]

Reload that 33.4 grain case 5 more iterations of 33.4 grains and let us know how it holds up. What brand case is it?

Federal.

Not interested in case life for a hunting load, Just want the maximum performance, safely. I’ve got several thousand once fired Hornady cases. I’ll set 100 aside for this load and gun once I figure it out. If they only last 2 or 3 times, that should last me several years worth of hunting, at least. Having said that, I’m going to keep using these Federal for this until they crap out.

[Happy2Shoot]

Federal.

Not interested in case life for a hunting load, Just want the maximum performance, safely. I’ve got several thousand once fired Hornady cases. I’ll set 100 aside for this load and gun once I figure it out. If they only last 2 or 3 times, that should last me several years worth of hunting, at least. Having said that, I’m going to keep using these Federal for this until they crap out.

2 things.

1 this is a safety test. If your brass craps out at 2 or 3 reloads I'd say that load is not safe. If it made it to 10 reloads I'd say it was completely safe.

2 I think it would be very educational to the 6.5 Grendel community to know the answer. Some people say: "even if the load is safe in the rifle, the brass is not built for the higher pressure".

[Harpoon1]

Fair enough, we’ll have to agree to disagree.

I’ve never seen any real evidence that Grendel brass is “not built for higher pressure”. Ever! If you have some, I’d like to see it!

[northdude]

You could try some win748. I'm using it in a bolt howa with good results

[Harpoon1]

You could try some win748. I'm using it in a bolt howa with good results

That’s about the only powder I don’t have!

I’ll look into it, thanks.