H335 pressure spike info

[Milspec78]

Hello,I have been reloading for about 3 years now and I have settled on h335 powder for my .223 powder (mainly because it is available locally and my carbines liked it from the start,so why knock a good thing).
I have read it has a tendency to pressure spike when it's hot?my pet load is 24.5 grains of h335 with hornady 55gr fmjbt @ 2.250",they average about 2,900 fps.
What I am concerned about is I use mixed brass,so I assume the internal volume will differ from one manufacturer to the next(not sure it's enough to matter?)
Does this seem safe to you guys with more seasons than me?
Thanks

[chadbag]

I am not sure of that actual load (would have to do some research) but I've used a lot of surplus powder which is the same as H335 but not canister grade. I've shot it with mixed surplus brass and never had a problem in any sort of normal temperature conditions. Just make sure you are not pushing the load in the first place.

(I just looked online to see what other people are doing and saw up to 25+ grains with no issues, with 24.5/6/7 as a starting point to work up, so I would not sweat it as long as you are consistent in your powder drops).

[bigedp51]

The vast majority of .223/5.56 cases are very close in capacity, I load 25.0 grains of H335 with a 55 grain fmjbt in Lake City cases and according to Quickload it is slightly below 50,000 psi.

If I loaded the same amount of 25.0 grains of H335 in the "old Lapua" case with 28.0 capacity it would raise the chamber pressure 6,000 psi and the chamber pressure to 55,000 psi.

With your load of 24.5 grains of H335 and mixed brass you will not exceed the max chamber pressure of 55,000 psi for the M193 military load even with the "old Lapua" cases.

I used Quickload and the 25.0 grain load of H335 and 55 grain bullets to figure using "mixed" brass and not go over max pressure of 55,000 psi.

NOTE, the M885 cartridge with its 62 grain bullet is loaded to the max chamber pressure of 58,700 psi. And the civilian .223 is loaded to 55,000 psi max chamber pressure SAAMI standards.



Below 26.0 grains of H335 is the max load for the M193 cartridge and your load of 24.5 grains is a very good safety margin with any mixed brass.

[mic2377]

I also have fired thousands of rounds with virtually identical load data to yours, using 24.5 gr H335 under whatever 55 grain bullet I have handy, in mixed brass as well.

From an anecdotal standpoint, I have had ZERO issues firing this load from multiple weapons in temperatures that range from -10F to 95F. No pierced primers or other pressure signs when it is hot out, and the load is warm enough to cycle everything at low temps.

[markm]

Does this seem safe to you guys with more seasons than me?

Yes. I'm not aware of (I haven't come across lately) any current brass that I'd worry about that load. I run 25.0 for 55 gr on the rare occasion that I run that flashy powder.

[woodsman]

I have used 24.5 and 25 of h-335 for many years in all kinds of brass and never had a problem with hot weather with any kind of 55gr bullet.
The last half a dozen years I have loaded 24.5 h-335 with the Horandy 55FMJ, even with mixed brass this load works for me winter or summer.
Pretty much one of them standard loads you can feel safe with.

[ViniVidivici]

I also use 24.5gr of h335 behind 55gr FMJ and SP, generally Hornady, as well as Montana Gold. Mixed brass.

About the same OAL as you. No chrono here, (chosen because it was most accurate for me) but I've put these loads through different brands and lengths of barrels, and never had undue pressure signs.

You should be fine. H335 is a great powder for .223.

[Milspec78]

I have loaded a couple thousand +\- and fired most of it.i also have a load for pulled m855 projectiles,sierra 69 gr hpbt,and 55 gr blitzkings,never had any show signs of over pressure.i always pic a very conservative starting point and work my way up checking speed as well as accuracy,so far I have had good luck with grouping at civilized velocity levels.
Not sure where I read about spiking with this powder but I'm sure I did and wanted to see what the groups experience was.
Thank you for your replies!