I got some 4166 to try and use in place of Varget and 4064. It is supposed to be just about the same speed, and data very close. Varget is too hard to find, and 4064 is not as temp stable as I like, even though I have always liked it a lot other than that.

I tried the 4166 in my Swift, and it seemed OK, speeds were a little lower than I thought they should be. But then again there wasn't data for the Swift at the time and I was having to try and extrapolate from 22-250 data. Then I sold the Swift and the experiment ended.

Tried it in my Creedmoor, and never could really get either the accuracy or speed out of it I thought it should have, it wouldn't touch H-4350. But then my Creed doesn't like Varget either, so I guess no surprise there.

Next was the 243 with the 87 VMAX. Accuracy has been pretty good, but it was slow initially. I blew right through the max charge weight on the Hodgedon website with zero pressure signs and low velocities. Kept heading up until I was so far about book I was getting very nervous. I really don't like running with a single data source, but that is where these new powders are at right now. Anyways, I checked back on the website several weeks later and they had upped the data. I am still above book, but not by much anymore. I still have not seen anything in primers, velocities, case head expansion, anything to make me thing I am near max. I wish I had some nice hot weather to help me find the top end, but it is winter so that is out.

I am thinking that with these new powders they are taking it ultra-conservative until they can get more real world testing and feedback in. Anyone have any experiences with 4166 or 4451?

+1! I'm seeing the same thing. I've played a lot with the new 7977, and my data is well above Hodgdon data. I use their data as a reference. I know where the speeds need to be, I know where the burn rate is of these powders, and I know how to look for pressure signs. So, I can use that as a guide to know where I need to be. I've had good results with the 7977 so far with the 208/210 in the 300WM. I have played with the 4166 and the 4451 a little bit, seeing the same lower speeds at book max data. I plan to switch a lot of my loads over to this new powder, since I can get it a lot easier than H4350 right now. And the new IMR powders are a great powder.

Good friend of mine is working with them quite a bit in his 22XC and 6.5x47. He likes them a bunch. Enough so that he ordered 8 lbs of 4451.

According to Hodgdons website, 243 data for 4166, my bullet is a 87 VMAX:

85 Barnes max is 39.5
90 SPR SP (???) is 37.7

Those are pretty dang far apart for just 5 grains of bullet weight, and the Barnes data was at least a grain under that here a few weeks ago. Average those and you get 38.6 +/- for an 87. I ran it up to 39.8 at lunch today. Finally saw a little bit of pressure on the primer. No hard bolt lift at all, not even a hint of ejector swipe, nothing. It seemed like it was wanting to find a node about 39.4 or 5. I am going to load a group of that to test tomorrow and shoot it over the chronograph to check speed.

Yesterday I took it up to 38.9, at that charge weight it was running about 3035 in 45 degree weather. Still pretty slow for an 87, even with it being cold and a 21" barrel.

But you need to keep bullets similar to compare the right data. The Barnes is a solid copper bullet, and the 90 grain is a lead bullet. They can have different bearing surfaces, causing different charge amounts. If I'm comparing data, I keep the bullets similar in design. Also, the Partition has different data compared to other bullets. So, keep bullets of similar construction to compare loading data.

4166 is a little faster burning than Varget and a little slower than IMR8208. I have tried it in the Grendel so far. Getting good velocity with 123gr Hornady SSTs at 30gr start getting sticky bolt lift and eratic velocities were seen on the couple loads I shot at that, like 50fps difference one being 2700fps which is high for that bullet in that cartridge. 29.5 grains though yielded the best groups I have shot with that bullet. That powder is a little bulky for that small cartridge and does require compressed loads.

I would think 4451 might be a better choice for the 243 and medium 6.5s

I agree Chad, I wish I had more similar bullets to compare with. Data is just so skimpy, there isn't much to compare to.

I do agree that 4451 would be better in the Creed for sure, and probably in the 243 as well. But I had the 4166 on hand so though I would try it. For the 100 grain I am testing with H4831, trying to save all og my H4350 for the Creed. If the 4166 doesn't work out for the 87 then the nex powder I will try is W760.H414, I have quite a bit of that on hand too.

JTP, H414 and W760 are exactly the same powder.

I'm about to start working up loads with 4451 in my 6mm Creedmore.

Have had good results with H414 in the 243 with 85 and 90gr bullets

I have used IMR 4166 in my 7.5X55 Swiss with 175gr Sierra TMK's.
Shooting it at 800 yds



Also in the 30-06 same bullet in fact shot it today.


Group at 100 3shot group them left 1 click

I am aware they are, that is why I put them together like that. I have 8 lbs of 760.

I have some more loads ready to test in the 243 today, we will see how that goes.

A friend of mine is trying the 4166 in his 308. It is a factory Savage with a 178 grain bullet. Website says 43 grains of 4166, but he dropped a primer out of a case at 42.5. He is really new to reloading, I told him he needed to back waaaay off that. 41 grains is giving him about 2650, nearly the same speed book data is saying for 43 grains. I told him to look for a node right there around 41 somewhere.

I started testing 4451 last summer in my .243 with 95 and 100 gr bullets. I was mostly interested in its temperature insensitivity. I did get higher velocities than previously with IMR 4350, but way short of Hodgdon's published data. Accuracy was very good. I'm waiting for the next good cold front, so I can test the same loads again at 30-40 degrees.

I'm sure I'm not the only one who'd be very interested in what you find out.

I'll be happy to share what I learn.

I would love to hear about a 243 with 4451. They have 4451 right here at my LGS. I also plan to develop a load for the 100 SGK in mine.

Been testing the 4451 with the 6.5 and it is working well.

Cool rifles DSTROUD !!!!