I know that this could probably be posted on the handloading section, but I know that there are a couple of 7TCU users here. I fireformed my brass without a problem. I then started loading at suggested starting point for AA 1680 which is 24 Grains w/ 120 grain nosler bal tip. I shot 5 rounds & got a whole array of pressure signs. Is this a normal for this cartridge? Does it tend to show pressure easy? I think that part of my problem was OAL too long with a too small amount of powder. Does this sound like a possiblity to you? If not, I'm a little confused. I did shoot two rounds with 24.5 grains & pressure signs seemed to be less. I don't know whether to continue on or to stop. I would greatly appreciate any help with this.
Rich Jake

[ 07-11-2002, 05:28: Message edited by: Rich Jake ]

Rich-
Exactly what are the pressure signs you are referring to?

With that info, we might be able to help.

(And yes, seating a bullet next to the rifling can raise pressures. But in return, it opens up more capacity, which to a small degree lowers pressures. But I'll get into more detail after I hear more of the pressure signs you got...)

Bobby
I had 2 with cratering. 2 with large flat primers. 1 with a pierced primer. The bullet was not engaging the rifling. Tha OAL was out far. Probably too far.
Rich Jake

One other thing the rounds with 24.0 grains had blow by on the whole case. The ones with 24.5 had no blow by at all.
Rich Jake

Bobby please check your mail.
Rich Jake

Rich-
Soot on the case (blow-by) indicates a low that doesn't develop enough pressure to seal the case against the chamber walls. And on occasion, you get erratic signs such as cratering, etc.

Will type a bit more shortly...have my hands full with a 10 year-old who's got an "emergency." Must go see what it is...

Rich-

Sorry for the delay...

The pierced primer and cratering are indicators (given the load you are using) of a low pressure round that failed to seal. The additional back pressure caused by the escaping gases forced more rearward movement and thus spiked pressures (high pressures within a low pressure load...sounds strange, but that's what it is), resulting in the cratering and pierced primer. And your more normal results with another half-grain of powder confirms this.

And my 10 year-old's emergency: his hamster wouldn't come out of its tunnel while the cage was dissembled.

AA1680 WILL generate the highest pressures for 7TCU of the AA powders that work in it. I have been using AA2015BR for several years now without a single problem. If you really like Accurate Arms powders (like me), 2015, 2230 & 2460 will give you the highest velocities with a little lower pressure....

Rich-
I also intended to add: H-335 has been THE powder for me in the TCUs. It generally offers the highest possible velocities and usually the best accuracy.

Bobby & Mike

Bobby I hope your childs hampster is ok, I thought that my results sent you off the computer.

Thanks to the both of you for the help. I think that Because I seated the bullet out so far contributed to the problem as well. I had it seated to 2.67 which probably left way too much empty case in the process. So I will adjust the OAL. Then start working up again. I was worried about the shoulder of the case, because I have read if you push back the shoulder it causes headspacing problems. I was concerned that maybe I did that while seating the bullet.

Mike
I have AA2015 as well. I used it to fireform the brass & it did well. Incidentally it was with the same OAL that is a problem with 1680 with the smaller amount of powder. 2015 didn't seem to have a problem with the OAL. I have the powder so to test it also won't be a problem.

Thanks agian guys.

Rich Jake

Rich, I think Bobby and Mike covered most of it.The only thing that I have had similar problems was with once fired commercial brass, I have used a lot of LC brass but I annealed it. I have had problems with RP and Federal Gold Medal 223 brass. The last batch of federal I used I anneaed down to the edge of the shoulder. It sealed after the initiall fire forming and has not sooted since then. The strange thing is that I started annealing all of my brass this way and the federal is the only one that does not soot back to the shoulder now??
BTW AA 2015BR is what I have used for all of my TCU's. The only thing that I heard a while back was that someone stated it eroded the throat real bad?? Think it might have been an x spurt writer though.
On the other hand I did run across a case of H335 real cheap, so hope it works in somthing I have, 6x45 ??
I have had several 7 TCU's in various barrel lengths and have not found the perfect load yet, some are down right tempermental, but they were all good shooters.
Jeff

Jeff

The brass I was using was RP, maybe that played a part as well. I have seated the bullets a little deeper & will try them this weekend & see if I get different results. If not then I'll start looking at some other options Annealing maybe different brass,or powder. We'll see.

Rich Jake

With as much AA2015BR that i have shot, i should have burned out a few barrels then! LOL! Well, they are all still shooters so i guess i aint gonna worry about that.....

Musta been an x spurt writer....

Musta been an x spurt writer....

Anybody we know????

Rich Jake

Rich Jake, as far as the x spurt author I don't remember but he probably had a "pen name".

Shot a perfect IHMSA 40x40 with the old 7 TCU today. Missed a couple of shoot off chickens (10)though, I called both the misses before they hit, so it was me. Still 48 out of 50 ain't all bad.

Here is a AA2200 fire form load for ya;
Federal Gold Medal Brass
Sierra 150 BT Spt
AA 2200 23.7 Grains
Rem. Small Rifle BR Primer
This is what I shot today, from bullet splash would guess about a 3-4" group at 200 meters

This is the load that I used on the 200 Meter chickens;
RP brass
Sierra 130 grain Match King
AA 2015 BR 25.7 grains
Rem. small rifle BR primer
2-3" group with bullet splash at 200 meters

This is not the greatest group, but this was all fire form loads for new batch of brass.
Jeff