Temperature sensitivity?

[Trailblazer]

I have finally got my work situation where I can do a little shooting again! I am working up a hunting load for my 356 Win with the Saeco 352. The bare bullets weigh 252 grains. I got the mold used and it looks like the previous owner opened up the bore riding portion and did a fairly crude job of it. I haven't had much success getting good groups out of the bullet until last week. I had loaded three rounds with 43 grains Varget and those three rounds went into 2" at 100. Good enough for me!

It wasn't simple getting 43 grains under that boolit. I would seat the boolit and it would pop up and I would tap the case a bit and reseat it and it would pop up a little less so I tapped it some more and got it to stay at my desired COL. To try to simplify the process I loaded two different combinations to try. One with 43 grains and a little longer COL so I only had to tap it once and the other load had 42.5 grains Varget at the original COL which I still had to tap once. Went to the range and the 43 grain load went into 2" at 100 again. Still looked good, but then the 42.5 grain load went into 5". Velocities are running just shy of 2100 fps.

Now I'm worried! I am shooting now in 80 degree weather and I am going to be hunting in much colder weather. What am I going to have at 10 degrees? A 2" group or a 5" group? I really can't get anymore powder in the case. I have other powders but none have shot this well. I am wondering if there is something else that might work to give me a wider comfort zone?

[Bass Ackward]

What am I going to have at 10 degrees? A 2" group or a 5" group? I really can't get anymore powder in the case. I have other powders but none have shot this well. I am wondering if there is something else that might work to give me a wider comfort zone?



TB,

Hard to say for sure here, but I highly doubt that you are seeing anything that is going to be traced to temperature sensitivity at this point. You have another problem.

I would say that you may have a neck tension issue that may be improved here by a crimp. I suspect that since the powder is pushing your bullet out so easily, that when you chamber, that bubba'd nose may be too big and pushing your seating depth back which is why you get weird results from the .5 grain lighter charge. Might not take much. Were you loading single shot or letting the gun do it? That could be another area to look at here that would also be aided by a crimp.

What I would do is load one of each to appease your mind at the seating depths you did. Put something on the nose like a magic marker, LLA if you got it would be better because it would help with extraction, and see what you get.

But you have more investigation to do at this point. With that slow of a powder in that size of a case, you should NOT be seeing what you are now.

[44man]

Isn't the .356 a lever gun? That loose neck tension will never do, Bass nailed it down. Either the boolit is way too small or the expander is too large and I am betting on the boolit although I do have suspicions that a Lee collet sizer is being used and it is not set right. Varget is a good, stable powder but needs held back with that much in the case. Both neck tension and a crimp for a lever gun.
We need more info on the loading procedures! :coffee:

[BD]

I load a compressed charge of Varget under a 77 gr. condom for most of my AR uses, (my old high power load). I do this by using a Redding bushing neck sizing die followed immediately by a Lee FCD on a turret press. The neck tension needs to be firm enough to keep the powder column from pushing the bullet forward while you get it in the FCD. Once crimped this allows the cartridge to be cycled semi-auto with no issues, and this is a max OAL cartridge so maintaining OAL is critical. I tried seating and crimping in a single operation at first with no luck. To get that type of crimp tight enough to hold the bullet caused the neck to swell a bit losing the neck tension needed for accuracy. I've had no temperature issues with this load, and I've used it in Maine near 0 deg, and in SC near 100 deg. Getting the neck tension right is pretty straight forward using neck turned cases with the Redding set up. I imagine using a lee collet type die would involve carefully taking down the mandrel a bit at a time until you got the tension you needed, but turning the case necks wouldn't be as necessary.
BD

[MT Gianni]

I don't have my notes here, but to feed reliably in my BB94 I have to crimp the 352 in front of the crimp groove. If that cannot be done and you are loading singlely you need to fix the neck tension problem. Gisnni

[Trailblazer]

Arghh! Neck tension! I forgot that little detail! The boolits are loose. In fact I can push them and pull them with my fingers. I was going to keep that in mind but clean forgot.

Rifle is a Winchester 94 levergun(just had a thought: if I said leverGUN in front of my old DI I would be chanting "This is my rifle and this is my gun, this is for shooting and this is for fun" and grabbing my crotch.) Anyway the RIFLE has a modified pre-64 carrier so that it will feed 2.73" rounds. My first attempts were with a COL=2.69" These stuck in the bore and would pull the bullets when extracted. All rounds were crimped with a Lee FCD. Then I went to 2.61" where the bullets just touch the lands and those with 43 grains grouped into 2". These were crimped into the front edge of the crimp groove. My last trials were seated at 2.625" however the crimp die pushed the boolits a little deeper in the cases which got my attention. The crimp falls over the rear tapered portion of the groove. The boolits were pushed deeper in the 42.5 grain charge and they ended up under 2.62". The 43 grain charge ended up 2.622" or 2.623" . They were all loaded in the magazine before a shot string and fed from the magazine since thats what will happen in the field. Normal feeding and extracting did not change the COL. I did not measure any to see what happened to them in the magazine under recoil. They could not be pushed any deeper than 2.61" because at that they would be hard against the front end of the crimp groove.

Dies are RCBS 356/358 dies without the expander ball. I bell the cases with a 357 Mag M-die. Looks like I will have to polish the M-die down a little. It could be the dies aren't reducing the neck enough too. Don't know how I might deal with that. Maybe the 357 dies would reduce the neck more if I need it smaller. Will have to measure and see.

Bore is black with just a touch of lube star. Looks good to my ignorant eyes!