I have been adviced to use H335 when reloading for a T/CA Contender G2 in 7mmTCU, because it would give superior accuracy. I have the 2000-edition of the Contender Reloading Manual, and on page 147 it lists data for the 150gr Sierra HPBT. I chose a mild load of 26.1 grains, which promised to yield about 1700fps (maximium load was stated to be 27.2 grains).
After loading 5 cartridges I recalled that powder tables change a bit in time, so I decided to check the Hodgdon website for the most recent data on 7mmTCU/H335. I was puzzled that I couldn't find any data for bullets heavier than 139 grains.
Furthermore, I noticed that the listed maximum load for that 139 grain bullet was 26 grains of H335...and I am using a heavier bullet. After quick search on the internet I found a post on a messageboard, in which somebody said when getting 2000+ fps, some guy was using more than 23 grains...which suggests that that would be the maximum load.

I have two questions:
1. Does any of you have load data for bullets heavier than 139 grains? I would be particularly interested in data for the Sierra 150gr HPBT and the 160gr SPBT?
2. Is the Thompson/Center reloading manual dangerously wrong, and should I pull the bullets of the 5 cartridges I reloaded?

write bobby tomek in single shot handgun forum for help.

I replied in the single shot pistols forum, but here it is as well:

It's been a little over 3 years since I shot any heavy bullets in a 7 TCU, and my data is rather limited as I generally shoot hunting-weight projectiles. But here's what I had used anyway:

27 grains H335/Sierra 160 SPBT/Rem 7 1/2s in fireformed Federal brass; MV was 1789 fps from the 10" barrel.

The EXACT SAME data with the 150 grain Ballistic Tip yielded 1910 fps from the 10" barrel. (I'd estimate the Sierra 150 you inquired about would run perhaps 75 -80 fps slower given the same components)

For some reason, I don't have the seating depths available in my log, but if I remember tomorrow, I'll pull the old load boxes and get the info from there.

Neither load was what I'd consider max, but both were still upper-end.

Lastly, I do want to point out that every barrel is a rule unto itself, and custom barrels will often reach the same speeds with less propellant. As to pulling the bullets, that's totally up to you to decide. I'd weigh the history of other loads you've used in it and just let my instinct take over.

Data listed as 14" Barrel.

My Hodgdon's mannual shows H335 23.0 1680 fps to 25.0 and 1885 fps with 150 SIE HPBT.

years ago I used Accurate Arms loading data for AA2200 and the 7 TCU.
I got flattened primers but there were NO issues with sticky extraction or case life. After shooting a bunch of loads over a season I chrono graphed them . . .

NO wonder I was getting such performance out of the bullets on test medium, I was in 7X30 Waters territory according my chronograph and I was not at the listed max load in the data sheet.

Way back when I was young, a dealer sold me some H 335 as THE stuff to use in a .308.
Looked up his book and said 46 gr. would do it.
Not being completely stupid I tried 45gr.

Pressure signs, big muzzle flame etc. so I started loading down gradually.
By 41gr it still looked dodgie to me so I told him what to with his H335.
By memory it was labled as Mil surplus??
Prob. ex.bulk, and I got the dregs!

quote:

Originally posted by JAL:
Way back when I was young, a dealer sold me some H 335 as THE stuff to use in a .308.
Looked up his book and said 46 gr. would do it.
Not being completely stupid I tried 45gr.

Pressure signs, big muzzle flame etc. so I started loading down gradually.
By 41gr it still looked dodgie to me so I told him what to with his H335.
By memory it was labled as Mil surplus??
Prob. ex.bulk, and I got the dregs!

No, that was normal for H-335 in a .308. I used to use that stuff as my go to powder in a Remington 660. Killed an awful lot of deer with that rifle and load. There was something about that powder that generated a very bright flash and extremely loud muzzle blast, but that .308 sure loved that powder. I even have a very small amount of that powder left which I used in my .35 Whelen. Worked real good there. I might even have to buy some more. I read somewhere that H-335 generated a lot of excess hydrogen gas which accounted for the bright flash and loud report. How much of that was fact or BS I can't say. I forget which "egg-spurt" in what gun rag wrote that, but I guess it explains it all. Quien sabe?
Paul B.

You want to see how "flashy" H 335 is, try shooting a cartridge off at night with it...

The muzzle flash there is unbelievable...

Even when the load is no where near pressure limits...

I'd hate to be in combat having to use it in my M 16!

I went back and checked my manuals for you:

Nosler lists 27.5 grains of H-335 as max with a 150 grain BT

Sierra lists 27.1 grains of H335 with the 150 grainers and 27.3 with 160 grainers

Speer: 28 grains of H335 with the 160 grain bullet

Those are right on the money.

For a while now, there has been some confusion as to pressure limits in the Contender -- and most don't understand that that it's backthrust that is the actual limiting factor. Thus, some data has been developed under the false impression that the c.u.p. of all loads must fall into the 30-30 range (around 40-42000 c.u.p.)

That is completely wrong. Cartridges with the small case head size of the .223, including those based on the 5.6x50R,, can be run full throttle in the Contender. That is why the 6.5x50R Bellm can beat the 6.5 JDJ by 100 fps (the JDJ is based on the larger .225 Win case).

Also, yes, H335 has a bit of muzzle blast. But it has been and continues to be one of THE BEST powders for any wildcats based on the .223. I've poured more 335 into these various wildcats along with the BR series than all other powders combined -- and it continues to reward me with superb consistency and accuracy, not to mention velocities that are at or near the top of what those particular cartridges can safely reach.

I've used it a bit in the .308 as well, but here I prefer Re-15. But 45 grains of H335 and the Sierra 150 grain Pro Hunter prints 0.5 to 0.6 groups all day long from my 20" bull-barreled Savage.

I have 2 loads for the 7mmTCU. 140grsp bullet--24.0 grs of H4895=1880fps/14" barrel. and 150sp bullet--25.0 grains of BL-C(2)=1910 vel/14" barrel. this site i got this off of might have more info now,its www.reloadbench.com van

Thanks y'all!

To be on the safe side, today I reloaded a couple of cartridges. I loaded them with 24 and with 25 grains of H335, and of course I still had the cartridges loaded with 26.1 grains. (All cartridges had the Sierra 150gr HPBT #1915)
COL was 2,516 inch, which is shorter than my TC-manual says. Guess my barrel has a rather short throat.

The 24's created considerable muzzleblast and a huge flash, but recoil was very managable. The 25's were more accurate, but still no signs of excessive pressure. So I was courageous enough to try out the 26.1-loaded cartridges. The guy who was getting ready to shoot next to me on the range turned to me and raised his eyebrows when I fired. H335 is LOUD and BRIGHT....but still recoil was not bad at all. Primers were not flattened, but slight cratering was observed on some of the primers (still no excessive pressure I think). On a later day I will set up the Chrony, now that I know these charges are safe in my TC.