How much H335 behind 123 gr SST?

[603 Country]

I’m pretty much set up to reload a bunch of 123 gr SSTs. Using H335, because I have plenty of it. Starline brass. CCI450 primers. 20” Ballistic Advantage barrel. It all sounds pretty straightforward, but Hornady and Hodgdon have much different views on min and max loads. I’m sure this question has come up before, but I don’t know the answer. Hornady shows a range of 24.1 to 26.4 grains. Hodgdon shows 26.0 to 28.7 grains. Why the big difference? Surely a few of you guys have used H335, so what’s the real world safe range?

I load for several calibers and have for decades, but never bumped into a discrepancy like this. Help me to not blow myself up.

[sundowner]

The difference is between a gas gun and a bolt gun , best to see what works best for you , I run on the high side in my uppers .

[603 Country]

Do you mean you use the high side of the Hornady range?

[Mark611]

I find the Hornady manuals are very conservative, I try to find an average load listing between the Powder manufacture and book data and start somewhere in between at the lower side and work up, JMO,

[Harpoon1]

Do you mean you use the high side of the Hornady range?

If it were me, I’d use the Hodgdon data for the SST’s. I believe the difference in charge weights is, the Hornady manual includes the GMX/CX all copper monolith bullets along with traditional cup and core bullets in the data. That means they have dial the charge weights back to accommodate the monoliths, which are harder to engrave in the rifling. To my knowledge there is no official “bolt gun” load data for the Grendel. The 6mm ARC is another matter.

[Harpoon1]

I find the Hornady manuals are very conservative, I try to find an average load listing between the Powder manufacture and book data and start somewhere in between at the lower side and work up, JMO,

I used to think that too and it could be. Have you seen this? According to the Hornady ballisticians none of their published load data has ever been “lawyered up”!

https://youtu.be/PRBa3iSH2VE

[sundowner]

Do you mean you use the high side of the Hornady range?

I used the higher loads because I made those load years ago before Hornady new book . I used Hodgdon web site for info then , 28.7 and have not had a problem but you should start out lower and work up .I'm just about at max psi for barrel.

[vaguru]

Having used H335 with the Hornady 120 ELD Match, and using Hornady listed components (Hornady case and WSR primer), I have found the manual just about spot on. The only difference I used was the COL. Hornady lists 2.245", I used 2.200" as the bullet engages the lands at 2.230" in my barrel. I was looking for a .030" bullet jump initially. I really don't have any idea yet as to how much difference that extra .045" makes with pressures, but with my COL, 26.0 grs of H335 was the most consistent in the ladder, 2478.8 FPS AV with an ES of 29. Going to 26.5 grs increased the velocity by 56.8 fps (2535.6 FPS AV es 53) and 27.0 gr increased that another 91.4 fps (2627 FPS AV) and the ES went up to 86 from the average.

I have since tried Remington 7 1/2 primers as they have a thicker cup than the WSR, which had one central primer leak at 27.0 grs. Having shot thousands of .223 loads in service rifle, and having tested numerous primers with the same load with only a primer change, I felt confident this would not make too much difference. I found that most primers, in that caliber anyway, didn't change the velocity or the ES by more than a few FPS.

I was surprised with the Grendel however. A change to Remington 7 1/2 primer increased the velocity considerably, but he ES remained very close. Not a bad thing I guess, but still a surprise. One of my good loads in PPU brass shoots the 120 Hornady ELD Match, 26.0 gr H335, WSR, and COL of 2.200" at 2529.2 FPS AV, with an ES of 5 out of my 20" barrel. Exact same load with the exception of a change of primer to Remington 7 1/2, gives 2586.4 FPS AV with an ES of 20. A bit more ES than I expected, but much more velocity than expected, an increase of 57.2 FPS. It is still a very good load in my barrel.

Next up for my testing will be an increase in the COL. Seating to longer lengths without the bullet being in contact with the leade.

Hope this helps some. Just my experience.

[603 Country]

Very helpful, and I appreciate it. I’ll start a bit lower than I had earlier planned. Normally I shoot Nosler bullets, and their load data is pretty accurate. Based on that, I was thinking I would follow the Hornady data, and I guess I will, though I might venture a bit higher. The much higher loads shown on the Hodgdon manual were, I expected, for bolt guns. I’ve reloaded for and shot bolt guns for decades, and can spot pressure signs, but the Grendel pressure signs might escape me. The Grendel is a new puzzle to me, but I got the 95 gr V-Maxes working fine.

[Bonas]

My favorite H335/123 ELDM load is 27 grains. It produces 2,395 fps from an 18" barrel with 11.6 standard deviation.

[Harpoon1]

………..The much higher loads shown on the Hodgdon manual were, I expected, for bolt guns. I’ve reloaded for and shot bolt guns for decades, and can spot pressure signs, but the Grendel pressure signs might escape me…………

All of the Hodgdon Grendel data is for gas guns, AR’s! The tip-off is the max PSI generated in the data, no loads are over 52,O00 PSI!

[603 Country]

I believe I now have the info I needed. Thanks. I’m thinking Bonas’s load is about what I’ll wind up with. I wanted 2400 fps approx, and I don’t have a chrono, so this load range will give me about what I’m after. And, the guy that sold me the upper said that it was a fast barrel. All good.

And I have just the pig to try the new load on, when I have the new load.

[Harpoon1]

I believe I now have the info I needed. Thanks. I’m thinking Bonas’s load is about what I’ll wind up with. I wanted 2400 fps approx, and I don’t have a chrono, so this load range will give me about what I’m after. And, the guy that sold me the upper said that it was a fast barrel. All good.

And I have just the pig to try the new load on, when I have the new load.

Right on!

“Shoot to kill!”

[LRRPF52]

If it were me, I’d use the Hodgdon data for the SST’s. I believe the difference in charge weights is, the Hornady manual includes the GMX/CX all copper monolith bullets along with traditional cup and core bullets in the data. That means they have dial the charge weights back to accommodate the monoliths, which are harder to engrave in the rifling. To my knowledge there is no official “bolt gun” load data for the Grendel. The 6mm ARC is another matter.

This is the answer. If you look at the Hornady manuals since they started including the 120gr GMX with 6.5 Grendel data, that is the limiter.

Hodgdon’s is for the 123gr SMK, which is a much longer bullet as well.

H335 is a great powder for most bullet weights 85gr-123gr in 6.5 Grendel. If you look at Hodgdon’s data, it shows H335 generating the highest velocities with some of the lower chamber pressures, with one exception being under the 95gr V-MAX, where it generated the highest mv, and also slightly higher chamber pressure than the others at 50,200psi. Most of the others were under 50,000psi with fastest speeds.

The most comprehensive load data is in the 6.5 Grendel Reloading Handbooks we compiled, which includes AA, Hodgdon’s, Vihtavuori, Western, and various other tested combinations.

[603 Country]

Ok, consider me up to speed now. I’m ready and will start load workup in the morning. It all makes sense now, whereas it wasn’t quite so clear when I asked the question.

[natebonebusta]

This thread has been helpful, as I hadn’t considered h335 to be a great choice for the 120-123 class projectiles. I’m gonna load some up for testing also, against Benchmark. Thanks!

[Constitutionalist]

I also think the Hodgdon data is where I'd start. I run 31.0gr. of H335 with 90gr Varms. <1 Moa 100 yd groups. It's my 20"'s favorite load with CCI-450s. Its 0.7gr below book max and I get 2827fps out of a 20". I run 27.5gr with CCI-400s with a 120gr. Sierra PH and get 2400fps. Neither show pressure signs in my guns. YMMV.

[603 Country]

Update from the shooting bench. Using the H335 and the 123 gr SST, CCI 450 primers, and new Starline cases (resized and trimmed), 26.5 was good, at about an inch. 26.7 was very good, where 27 was bad. 27.2 was excellent at <3/4”. No pressure signs so far. I’m inside to warm up, but this is a sunshiny low wind day. A great day to shoot.

The 27.2 gr accuracy is more than good enough for my pig hunting, but a bit more load checking might turn up something even better.

[603 Country]

Just to bring this to a close, I settled on 27.2 gr of H335 behind the 123 gr SSTs. I had read that 27.5 gr was often the good load, and someone on this forum also used the 27.5 grains. I tried it, and even went into the low 28’s, but backed off to the 27.2 for great accuracy. Primers were looking pretty flat in the 28’s.

Thanks to you fellows for all the info. I’m very happy with the load.

[Matthew77a]

Just to bring this to a close, I settled on 27.2 gr of H335 behind the 123 gr SSTs. I had read that 27.5 gr was often the good load, and someone on this forum also used the 27.5 grains. I tried it, and even went into the low 28’s, but backed off to the 27.2 for great accuracy. Primers were looking pretty flat in the 28’s.

Thanks to you fellows for all the info. I’m very happy with the load.

What was your OAL?