Velocity and powder conundrum

[trubulator]

I started loading Grendel this summer. I am working with factory starline brass and 123 grain SSTs fired out of a 20" BCA upper. I have been working with the powders I could get, namely TAC and H335. My goal is a 350 to 400 yard load for deer on a piece of land where there is little cover and shots might be quite long (could not get closer than 400 yards last year with a rifle that was good for 200). I have been loading to a couple thousandths over the Hornady book min of 2.245" and ran through a couple rounds of ladders to arrive at a couple of good loads. The best TAC load was 27.0 grains with ES of 21 and SD of 8 and average velocity of 2358. The best H335 load was 27.4 grains with ES of 30, SD of 14 and average velocity of 2401. I am running out of time to do load testing, so I decided that the H335 load would have to do and loaded up 3 boxes for the Fall. So at least for now, I am going to run with what I have.

My question is where do I go from here? Hornady Black chrono'd at 2525 FPS out of my rifle and is very accurate, so I imagine that I could do better velocity wise with the SSTs. I also would ideally like good temp stability from whatever powder I use, as the place I hunt can be below freezing or 90F in the Fall. Should I simply be looking for a more suitable powder? Based on what I have read on the boards, it sounds like 8208 or perhaps Accurate 2520 would fit the bill, assuming I can find them. Seat longer? I imagine I need to stay within the 2.26" for magazine purposes. Something else?

Has anyone tried the Hornady 120 grain CX bullet yet? Seems like a candidate for my application as well.

[sundowner]

My load for the SST is 28.7 of H335 chono'd at 2541fps out of my 20" PSA and sum moa .

[biodsl]

My load for the SST is 28.7 of H335 chono'd at 2541fps out of my 20" PSA and sum moa .

Nice. I have a couple of pounds of H335 but no experience yet. Bought it for lighter bullets but might have to try it under some 123s.

[trubulator]

My load for the SST is 28.7 of H335 chono'd at 2541fps out of my 20" PSA and sum moa .

Groups above 27.4 fell apart quickly, so I did not pursue them.

[Harpoon1]

Groups above 27.4 fell apart quickly, so I did not pursue them.

This is highly controversial but, find two or more groups that have the same relative point of impact, ignore group size for the moment. Ideally these groups will coincide with the lowest ES/SD spread. Think “OCW”, Optimum Charge Weight test. Pick the middle charge weight and adjust the “seating depth” to modulate the group size. The F-Class guys recommend .003” increments for that test, so as not to jump over sweet spots!

[Harpoon1]

Groups above 27.4 fell apart quickly, so I did not pursue them.

Also, accuracy nodes are “generally” 3% apart, in charge weight. Same goes for scatter nodes, 3% apart……….or 1.5% apart from one another! Accuracy nodes can be hard to identify but scatter nodes stick out like a sore thumb! Find a horrible group and the accuracy node for that area of the powder charge is likely around 1.5% on either side!

[grendelnubi]

My load for the SST is 28.7 of H335 chono'd at 2541fps out of my 20" PSA and sum moa .

What coal are you running with this load and what brass?

[trubulator]

This is highly controversial but, find two or more groups that have the same relative point of impact, ignore group size for the moment. Ideally these groups will coincide with the lowest ES/SD spread. Think “OCW”, Optimum Charge Weight test. Pick the middle charge weight and adjust the “seating depth” to modulate the group size. The F-Class guys recommend .003” increments for that test, so as not to jump over sweet spots!

Interesting. In this case the most accurate load with each powder also happened to be the lowest ES and SD loads.

[CJW]

Great thoughts Poon1………..

[trubulator]

The funny thing is that none of the groups were what I would call horrible. Some might have been as bad as 2 MOA, but none were spread all over the target, etc. Actually, aside from trying to make velocity, it was trivially easy to get a 200 yard minute of deer load with this cartridge.

[muvef]

My suggestions would be (take them with a grain of salt):

Of the two powders you have, stick with TAC. I've tested dozens of powders in the Grendel and TAC always ends up being one of the better performers. H335 never did work out for me, but every barrel is different.

I have no experience w/ SST's, but have read they are finicky. I use Nosler Ballistic Tips for hunting. They are expensive and hard to find right now, but accurate and always perform well on deer.

Increase your COAL if your chamber will allow it. I've always had good luck starting around .0300" off the lands in the Grendel.

Gordon's Reloading Tool suggests 27.8 grains is your max load at a COAL of 2.256" using TAC. Just an FYI. Always work your loads up slowly and watch for pressure signs.

Again, these are just suggestions. All barrels are different and none of them may work out for you even though they have worked for me in the past.

[dexdog]

Sundowner, not to be jerk, but Hornady Ten says that max load using 123 SST and H335 is 26.4gr with velocity of 2300fps. Also Quickload shows that 28.7gr of H335 pushing a 123gr SST has velocity of 2553, with pressure of 58,585psi. Your velocity agrees well with the Quickload numbers. I am well aware that QL is only an estimation, but it seems that you have really hot load at 28.7gr. QL gives a velocity of 2365 fps sat the Hornady max load of 26.4,with pressure of 44,759psi using standard QL parameters for temp and elevation. I have used 25.5gr H335 and 123 SSTs with an 18 inch Grendel Hunter upper and have chrono'ed about 2250fps.

[jasper2408]

Hodgdon shows 28.7gr for max load of H335 on their reloading data page. That's with a Sierra 123 gr bullet.

[dexdog]

I don't have a problem with someone posting that they use one load or another, but if someone is using loads that are outside of published data they should clearly state that they are doing so.

[DHD]

There are magazines that will not make you stick to the ole 2.260" OAL. Lots of threads on them. You just need to know how much space you have in that chamber. I have and use AA (from around 2008), ASC, C Products, and a PRI 6.8 mag that I cut the front out of (long OAL). Lots of choices and some actually work....

I personally don't use either of the powders you have so no help there and I haven't use that particular 123 grain bullet. I use 8208, 2520, and LeverRevolution with a big nod to the LeverRevolution. 2520 and LeverRevolution will give you all of the velocity available in this little case. A few other powders may equal 2520 and Lever using the heavier bullets but won't surpass them by much.

In my experience if a load will group good and give me good es/sd on a low node, I will go up and see what I can find. As you mentioned seeing, I will get into a scatter node. If I just went by that, I'd stop and settle for a good grouping slow load. Using an Oehler and paying attention, I'll go up to see what I can see. More often than not I'll start to get the bullets back together and the es/sd back to where I can smile. Again, I tend to use powders that will allow all the velocity available for a cartridge and I can seat a bullet out a long way (especially with that modded PRI magazine) so I'm not as foolhardy as I may seem.

[VASCAR2]

If factory Hornady Black ELD-M 6.5 Grendel ammo shoots well in your 6.5 Grendel I’d use it for hunting if you have any. The ELD-M has been used effectively in the 6.5 Grendel as well as the 123 grain A-Max. My only concern using an ELD-M or A-Max is at very close range with high velocity. The ELD-M/AMAX do not have a bonded core and at close range with high velocity they shed weight which can limit penetration.


There are many threads where the factory Hornady 123 grain ELD-M/AMAX have taken medium size game.

[trubulator]

If factory Hornady Black ELD-M 6.5 Grendel ammo shoots well in your 6.5 Grendel I’d use it for hunting if you have any. The ELD-M has been used effectively in the 6.5 Grendel as well as the 123 grain A-Max. My only concern using an ELD-M or A-Max is at very close range with high velocity. The ELD-M/AMAX do not have a bonded core and at close range with high velocity they shed weight which can limit penetration.


There are many threads where the factory Hornady 123 grain ELD-M/AMAX have taken medium size game.

I thought about it and it was my backup plan, as I do have a few boxes of the black. My quibble is that as I sneak up to my overwatch spot there are several spots where they could be bedded down. If I bump into the herd as I am creeping up to my spot, I might have a very short range shot in a hurry. I also want to use an actual hunting bullet since I have some. Since I got very good accuracy with 2400FPS, I think it will do what I need it to with the SSTs and H335. Hopefully I get a chance to find out.

[trubulator]

I don't have a problem with someone posting that they use one load or another, but if someone is using loads that are outside of published data they should clearly state that they are doing so.

Agreed. In this case you have significant discrepancies between Hornady and Hodgdon data. Which one is right? Who knows. I chose to start well inside the Hornady data and walk up the charge looking for pressure signs.

[Modoc]

Agreed. In this case you have significant discrepancies between Hornady and Hodgdon data. Which one is right? Who knows. I chose to start well inside the Hornady data and walk up the charge looking for pressure signs.

I had the same issue with Nosler Vs Hodgdon with the 120gr bullet and H335. I discovered that my mid level load from Hodgdon was actually the MAX load from Nosler. This was after loading 100 and then seeing pressure signs of the ones I shot, flattening primers and shiny spots on the case heads.

I’m now cross checking my loads with multiple Published sources.

[trubulator]

I had the same issue with Nosler Vs Hodgdon with the 120gr bullet and H335. I discovered that my mid level load from Hodgdon was actually the MAX load from Nosler. This was after loading 100 and then seeing pressure signs of the ones I shot, flattening primers and shiny spots on the case heads.

I’m now cross checking my loads with multiple Published sources.

Always a good idea. I got no pressure signs, but I also know that can be deceiving with an AR.