Home Forums Reloading Big Game Rifles Pressure Signs?

Yesterday I was at the range and started load development in my 7mm STW shooting 168gr Berger VLDs.

The first batch of loads I was shooting I was using RL-25. The maximum charge Berger recommended was 75.3 grs. I started lower and was working my way up. At 73.0 grs I started to get alot of burnt powder residue all the way down the casing. With 73.5 grs I had 2 cases where there was a large dent in the shoulder (the dent was running vertically).

What would be the cause of this? Low pressure?

I was using CCI 250 Magnum primers, Remington once fired brass.

To touch the rifling with the Berger in my rifle the COAL is 3.865" but to have them fit in the magazine I had to seat them at 3.660". Would this have something to do with the issues I was having? I know Bergers like to be seated alot closer to the lands but I just wanted to try jumping them this far to see how they shoot in my rifle.

Does anyone have any insight or past experience with issues like this?

Without a little more data, like chrono results, I would guess that your are correct in that pressures is low, or even worse, erratic. These slower powders are designed to burn efficiently in a rather specific (narrow) range. The STW was designed from the beginning to be a pretty intense round operating at max, or very near max pressures.
Adding .2" of what is essentially freebore, adds to the problem, perhaps enough to make all the difference.

Unfortunately I wasn't running the loads I was shooting yesterday across the chronograph. The would be a helpful piece in the puzzle. The load I shot at my max charge of 75.5 gr didn't show either of these signs.

The next 2 powders I plan on trying are IMR-7828 and RL-22. I will be sure to have the chronograph set up for those.

Im working with a gun with nearly the same dimensions. Bergers data is pretty conservative for guns set up this way. Probably would be on the money for a tight chamber plus jamming into the lands. Ill wager a hillbilly bet that when you are done working up you will be at least 2 grains over their data.
The gun Im working with had a long magazine box installed....so I can really hang out the bullets. Really makes a awesome looking cartridge.

My plan was to shoot the loads with the current COAL to see if they shot. If they aren't accurate I will have a Wyatt's extended magazine put in and be able to increase the COAL a good bit.

You might want to go over to longrangehunting.com and check out some of their postings. Seems like the stw is a fav over there. You find lots of losds being used to cross reference.

Thanks.. That might be a good idea. I will post over there as well and see what information/experience they can provide as well.

ive been using a 7x300 weatherby for many years. it is a very
similar cartridge to the 7stw but uses 300 weatherby brass.
loading those to work in a 700 rem factory magazine has posed
no problems for me and others i know.
we use 162 gr hornady amax bullets along with 7828 powder. you might find rl 25 a little slow for max results in the 7stw.
h1000 is also a good powder for those cartridges. i have a friend who uses 79.5 gr of h 1000 with a 180 berger in his
7stw. he claims 3150 fps.
my 7x300 load is 80 gr 7828 with the 162 amax. it produces about 3350 from a 28" barrel.
ive found the 162 amax will run with the 180 berger to about 1200 yds. thats about max for those guns anyway.

i would first be trying a longer seating depth to assure thats
not the issue.
but by all means try a different powder.

I've got load data from berger twice, 257WBY and 7Rem mag. Both times I ended up a ways past their max data, Mid range loads didnt even have enough pressure to expand the case enough durring fireing to seal the chamber and the cases came out all sooty.

We have run 75-Rl25-160 gr in the 7mm Mashburn Super for about 3200.....and te powder works great in the 7 RM as well with 150's for me, so I don't think it's too slow.

The STW is a larger case still;plus the OP's rifle has freebore.I would not be surprised if the guys above are right,and the charge is not high enough.

I'd be inclined to run a Fed215 as a primer;increase charges. other options as stated above are 7828 and H1000,which I like a great deal in the Mashburn....not too much smaller than the STW.

This is a good example of why I wont shoot any test loads without a crony, velocity will tell a lot. Dont give up on RE-25, load up a couple more of the top end and run them over a crony.

Jamie : Agreed....the chronoraph gives useful info.

I will revisit RL-25 and start at the max of 75.3gr Berger stated and slowly work my way up while looking for pressure signs and see what kind of results I get. I will do this across the Chronograph and list the velocities I am getting.

I have some loads worked up with 7828 right now waiting to be shot but I won't get to it till this coming weekend. Yesterday's time at the range was spent with alot more time waiting for the barrel to cool than actual shooting. So I didn't get through quite as many loads as I was hoping.

theres certainly nothing wrong with shooting test loads over a
chronograph. lets face it some of us are more technichly inclined than others. some of us just want the best load for
our particular gun. we want to arrive at that decission sooner
rather than later. ive been using mostly wildcat cartridges
for most of my hunting life.
that further complicates the process due to lack of published data. and even more so in past years before the internet.
your gun and not your chronagraph will determine which powder and how much of it is best at least initially. once youve narrowed it down you can shoot for group and velocity over the chronagraph.

i would be aquiring the reccomended powder for that cartridge.
id be starting on the low end and load 1 round with 1 gr increases in charge weight. do that with each powder. just shoot each shot into a dirt pile. check each case as you extract them. when the bolt starts to stiffen when you open it stop and back off say 1 or more grains.
you now know your max load with that powder and have only shot a few rounds to determine that. now go load say 3 rounds for group. you will in very short order determine whats best for at least that gun.
otherwise you could spend days and many rounds getting there.
retumbo is another excellant powder you could try.
my opinion however is that 7828 or h1000 are best suited.
id also agree with the other poster on the fed 215 primers.

No experience with that cartridge or powder, so this may or may not be applicable.

I have a Ruger 7x57 Mauser with a lot of free bore. With slower powders I get sooty case necks,low velocities, and high ES/SD. With faster powders the effect was not nearly as pronounced. I'm not saying faster powders are better, or slow powders are bad. Just that in my experience, slower powders are effected more by free bore than faster powders. I'm sure there are more experienced reloaders here that can dispute or agree with that statement.

Jamie beat me to it!
Not enough pressure to expand the case and seal the chamber.

I have two custom 7 STW's with very little freebore, 26" barrels.

IMR 7828 with the 154g Hornady INterbond is very accurate at 3350 fps, which is the safe working max load for this one rifle, and I do shoot either Fed 215's, or a hotter primer the Winchester Mag primer depending on what the gun likes. CCI 250's are a very soft mag primer that I use for smaller cases if the load likes that primer.

Seat the bullets out to touch the lands and start your load development from there. The Berger VLD's will shoot their best usually no further than 0.020 off the lands. Best accuracy will be within 2.0g of what is a max load for your rifle, and I just bet your rifle can not read a reloading manual. I want the best accuracy out of my first shot, so single load that round if you have to. Rounds that are in the magazine WILL be loaded to a shorter OAL, and you can check and see how that OAL affects accuracy.

Best accuracy in Rem brass in the STW is right at a point to where you get one or two firings out of the brass, it is soft make no mistake about it. Winchester brass in the STW is a very different animal to work with, Rockwell's at 8% harder. Best brass for the 7 STW is out of PMC fire formed 300 Weatherby brass, you simply can not wear it out.

R.W.Hart sells a tool that will tighten up primer pockets on brass as they loosen up. Also, when your primer pockets get loose when using fed 215's, Winchester Mag primers will be very tight when seating them.

good luck