NEW IMR Powders

[Savage Shooter]

Thanks for giving this a go, Oh Brave Leader! I decided to pass on buying the 4166, because it just didn't seem like it would offer enough advantage to have one more "orphan" can of powder around that only had a few hundred grains used up before I realized it would not best loads I had already developed. BUT -I certainly learned something - that compressed loads would have enough force to drive the bullet back out. Are you loading with low neck tension? I need to go and recheck some loads I made up tonight, because of what I encountered.

I was loading up some 165 gr SSTs and GMXs in my 30-06 tonight and the GMXs, being much longer than the SSTs are "crunching" the powder at the same grain weight that is non-compressed with the SST. I couldn't get the GMX to seat as deep as the SST, despite them having the same ogive to cannelure distance and recommended COL. Since my '06 is a semi-auto, I have to respect the COL limit and turned down my seating die .004 to match the same COL on the SSTs. Now with the info about the possibility of the bullet being being pushed out I am going to have to recheck my COL on the GMXs.

Oddly enough, Hornady shows the SAME 30-06 loads for the 165 GMX, 165 SST and 168 gr AMAX and BTHP. I am 1.2 grains below Hornady's Maximum for H4350, but 2.4 grains above Hodgdon's maximum for the 165 gr. GMX. I wondered why there was such a big difference between the Hornady and Hodgdon max loads, but now I realize the GMX would be a VERY compressed load at Hornady's max of 58.9 gr. Makes me wonder if Hornady even did any testing, or if they just took the "same weight bullet = same powder charge" approach.

I have not yet loaded any 120 gr. GMXs in my Grendel to be able to compare against the 123 AMAX, but the speculation is that Hornady set the max charge for CFE based on the GMX, because most of us have safely loaded a bit hotter than published with the AMAX. Yet, Hornady seems to have taken the opposite approach with the 30-06 loads, developing the load based on the SST bullet and assuming the longer GMX would be fine. It goes to show the importance of working up your own loads, starting well below max and carefully watching for pressure - EVEN when working from published manuals.

Anyway, NF - good luck with your tests with 4166 tomorrow, I am interested to see the results.

[pds]

Ok - here's an update on IMR4166, this time in 6.5 Grendel cases. I only have 123 Amax bullets, so that limits the scope of what I am able to check. Using Varget as a baseline, I loaded the following charges and seated the 123's @ 2.250": 25.2gr, 26.4gr, 27.6gr and 28.9gr.

Nug,
1.2 gr. increase per load is a bit much don't you think?

pds

[NugginFutz]

Date:	 02/07/15 10:33	 02/07/15 10:38	 02/07/15 10:53
Charge:	 25.2gr	 	 26.4gr	 	 27.6gr
	
Shots	FPS/FT-LBS	FPS/FT-LBS	FPS/FT-LBS
9	2183 / 1302	2284 / 1425	
8	2188 / 1308	2297 / 1441	2404 / 1579
7	2178 / 1296	2305 / 1451	2375 / 1541
6	2200 / 1322	2287 / 1429	2404 / 1579
5	2193 / 1314	2309 / 1456	2400 / 1573
4	2179 / 1297	2281 / 1421	2397 / 1569
3	2201 / 1323	2300 / 1445	2404 / 1579
2	2187 / 1307	2299 / 1444	2395 / 1567
1	2182 / 1301	2320 / 1470	2409 / 1585

[B]Avg:	2187.9 FPS	2298.0 FPS	2398.5 FPS[/B]
SD	8.5 FPS		12.6 FPS	10.5 FPS
Min	2178 FPS	2281 FPS	2375 FPS
Max	2201 FPS	2320 FPS	2409 FPS
ES:	23 FPS		39 FPS		34 FPS

First, there were no surprises. IMR 4166 granules are noticeably larger than Varget, and do not pack as densely. Even stuffed to the gills, you cannot get enough 4166 into the case to drive a 123 grain pill at velocities similar to CFE223 or 8208XBR.

I did not bother to shoot the rounds charged with 28.9 grains, as I'd already seen signs of serious compression while loading (Heck - the bullets wouldn't stay seated!). I did, however, shoot the cases charged at 27.6 after seeing nothing at 26.4 to indicate issues. 27.6 did, however, exhibit case sooting that was not evident at the two lower charges. No primer flattening was seen at any level, but that is only the absence of a warning sign, not proof that all is well.

My pet load of 28.0 gr 8208XBR shot the 123 Amax at 2530 fps this morning - a full 130 fps faster than 27.6 grains of 4166.

Perhaps someone can try this powder with other bullets and add more to these results. I would be curious to see

After the temps warm up, I still intend to revisit 4166 as a candidate for my .308. It has shown a lot of potential there, thanks in part to the available case volume of the .308 Win.

As a side note, it appears that bwaites' intuition was correct - The SD's seem to settle down when near or at case capacity.

I hope this helps some of you when choosing powders to try. I, for one, would like to develop a good load for my .308 -otherwise I'm going to end up with yet another can of OSP (orphaned smokeless powder).

[LRRPF52]

Very nice report. I think it's safe to say that this isn't an ideal powder for the 6.5 Grendel. Shorter, lighter pills use faster powders with smaller kernels, and 120gr and higher like a medium-slow high density powder.

Hopefully it works out for you in the .308 Winchester.

[Younger]

Great info. You mentioned that the 27.6 grain load exhibited case sooting. Can you elaborate on what the causes the case sooting? I have had some reloads do this and have wondered why this happens.

[NugginFutz]

Great info. You mentioned that the 27.6 grain load exhibited case sooting. Can you elaborate on what the causes the case sooting? I have had some reloads do this and have wondered why this happens.

In an auto-loading weapon, one of the causes of sooting is early unlocking, where the bolt begins to extract the case while there is a significant amount of pressure in the barrel. This allows excessive gases to flow back into the chamber, which also deposits soot on the case. In this case (pun unintended), I believe the soot was due to an abundance of slow burning powder, which was probably still burning as the bolt began unlocking. I'd apparently found the threshold at which the amount of IMR4166 I was using could not completely burn before the bullet exited the muzzle.

That's my story until someone has a better explanation.

[Savage Shooter]

Thanks for doing this work NF. I figured there wasn't any real benefit for 4166 in the Grendel, but it's good to get empirical data to support it. It might work well in my 6.5 Creedmoor - Hodgdon's manual for Varget and 4166 are very close for powder weight, pressure and velocity. But I already have plenty of Varget and a good load already, so I'd rather spend time practicing instead of doing unnecessary load development. Glad you survived with all your digits, and hope you don't end up with any "orphaned" powder.

[rasp65]

Here is my take on sooting. The powder begins burning and the gases flow around the case before it fully obturates(https://en.wikipedia.org/w/index.php...on&redirect=no). I have noticed this with LVR and BLC2. I did not notice this the time I used 5 gr too much AA1680 in a 223 load that caused early unlocking of the bolt and formed belted cases.

[kmon]

Bought a pound of the 4166, I am going to try some in the Grendel figure if it doesn't work in it then will burn it in one of the other calibers. Once fired cases 30 grains will fit with a little crunching. On the burn rate charts it is slower than 8208 and faster then Varget and CFE223.

[Savage Shooter]

Anxious to read your results Kmon - thanks for taking the plunge on this. And if doesn't work, what other calibers do you have that you might try it in? I'd love it if it shot well in my 6.5 Creedmoor and I didn't have to clean it as often. But it usually shoots H4350 with SDs in the 5-7 range, so it would be hard to wean myself off that.

[gpsman007]

I have contacted them and their reply was that it burned too slow for the grendel???

Is that a photo you took, LRR? If so, then you have some of the powder already? I can't figure out why Hodgdon/IMR/Winchester are ignoring the CFE223 and 4166 powders for the 6.5 Grendel in their load data. Have you contacted them and asked if they had some suggested loads?

[NugginFutz]

Bought a pound of the 4166, I am going to try some in the Grendel figure if it doesn't work in it then will burn it in one of the other calibers. Once fired cases 30 grains will fit with a little crunching. On the burn rate charts it is slower than 8208 and faster then Varget and CFE223.

I think you're going to find that for bullets 120 or heavier, you will run out of case volume before your velocities come up. Which bullet weight(s) do you intend to load?

[kmon]

Got some loaded in new Lapua brass with 123gr SST bullets seated for overall length of 2.26. Will run them across crono Sunday and report results. 30 grains fills about halfway up the neck without vibrating, to give an idea of what will fit. That is the heaviest load I loaded for this test. If not happy with these will burn up the rest of it in 308, 223, 7mm08 or one of the others it is listed for.

Just also loaded a box of 6.5-284, kinda makes you realize how small the Grendel is. Then again when loading the 50BMG the others all seem small.

[kmon]

As far as being too slow for the Grendel, it is faster burn rate than CFE223.

Shot in Bolt action. Would not go above 29.5 grains in an AR from what I have seen and would consider that max load to be approached with caution if at all.

Running out of room before reaching higher velocity, 30 grains crunches a little and is a little high on pressure judging by the primers but was 2665 to 2700 fps, bolt lift was easy, no wipe marks on the casehead.

[kmon]

Did a little more shooting today with 123gr SST, Lapua brass and 4166. Have settled on 29.5 grains of powder for the Boltaction with this bullet, accuracy was a little better than the best I have shot with the SST in that rifle. Velocity from the 22 inch barrel was 2605fps average with ES of 30fps. For comparison Hornady factory V-Max 123 grain velocity was 2543fps. Primer show a little flattening but very little, Bolt lift was like opening on an unfired round.

If you look at 4166 compared to 8208 in other cartridges max loads are 4 to 6 or more % higher with 4166 than 8208 and from Grendeldata.com and the manual plus what others have posted here 28.5 is max for the 123gr Hornady bullets. 29.6 grains puts it almost 4% higher in the Grendel. Next trip to the range will try it in the AR with 28.4 to 29.5 unless I stop for reason of pressure before then. One thing being an extruded powder the grains are larger so do not meter as well as say CFE 223 where with thrown powder charges using a RCBS powder thrower have had extreme spreads in the single digits with the 130gr Bergers Hybrids.

Going to take the AR (Alexander Arms 24 inch upper spikes lower) out with it next time with some loads of 28.3 to 29.5 grains and see what it does.