Free Hornady 129 Interlock

Hello and welcome to THR. There are lots of experienced people around to help as you learn. I'm sure they will be chiming in before long.

For starters it would be helpful to know the specific cartridge that you are loading for.

.40

In my 6.5x55 (A CZ 550 American rifle) my max load is 47 gr RL22 and a 123 gr bthp with a 2.915 oal, WW cases, Fed standard primers.

I don’t think it’s a “max” load, but it’s as high as I’ll go in this rifle. .85” @100 is my best 5-shot group shooting this one benched.

You could start at 45.5 gr and work up with the 129 gr interlocks... if it’s fired in a modern Swede of course .

Stay safe.

I will second the need to know what chambering you are loading for. That said, www.hodgdonreloading.com should have the recipe you're looking for.

A scan of LoadData.com's data for the 6.5 Creedmoor doesn't return anything with the 129 grain Interlocks and IMR4451.

QuickLoad shows IMR4451 way down the list of optimal powders for the 129s; RE17, H414, IMR4895 are all listed much higher. So in answer to your question, I'd try a different powder.

That said, and USE AT YOUR OWN RISK, QuickLoad indicates a load of 42.0 grains of IMR4451 under the 129 Interlocks from a 26-in barrel will give you approximately 2,900 fps at 59,879 psi. You should be safe starting at 38 grains and working up.

Oh, and welcome to The High Road!