7 Shehane First Outing

[GSPV]

Everything ready to roll to do first load development for my 7 Shehane.

52.0 to 55.0 of R17 in 0.5 gr increments. 6 shots per. One three shot to establish, the second to confirm. All 180 gr Berger Hybrids.

All at 10 thou off as my chamber will need a little throating to get any more jump. Uni-Throater on its way. Have some 180 gr Scenars, too. Will wait till after throating to play with them as they are longer than the Hybrids.

The plan is to shoot across, plotting how far POI is above POA to find a sweet spot.

 

[ShootDots]

Make sure you keep us posted on the "Step-by-Step" results as you move thru development..

 

[GSPV]

Will do. No joy today. The range opens at nine and it has been raining cats, dogs, frogs and fishes since before. Heavy sigh.

 

[GSPV]

Rain ended and I could sneak out. Keep in mind that this is my first trip out other than 5 shots to get it sighted in.

I started out at 52.0 gr of R17 incrementing by 0.5 till 55.0 gr. 180 gr Berger Hybrids. 0.010" jump, 307 bushing.

My MagnetoSpeed wouldn't register. I don't know if it is the big barrel or what. Something else to figure out.

I'm not happy with my rear bag. I've got some lateral wiggle. I'll try more in the ears, bit I might have to get another bag or get new ears on this one.

Hard bolt lift and a blown primer at 54.5. I took a couple of shots at 55.0 to confirm and will pull the bullets from the others.

I can't jump any more till I get it throated a bit. The Uni-Throater shipped today. But, I have some info to work with and that's a relief after getting started so late.

 

[GSPV]

Gosh, the more that I look at that, the more embarrassed I am...

 

[ShootDots]

RL-17 is only a SLIGHT shade slower than H4350.. I would be more inclined to be in the 52.0-54.0 range, with 54.0 being REALLY TOPS.. You stated you are using a .307 bushing. What is your neck tension? I just "clean up" my necks (neck turning) (about 90pct. cleaned) and I am using a .310 bushing for 1K neck tension. I have terrible vertical at 1000 yards with 2K neck tension. When I went FROM a .309 TO A .310 bushing, all the vertical went away..

 

[GSPV]

It's a 313 neck. Loaded rounds measure 309. I bought the brass, dies from one guy and the reamer from another. The other guy had a 312. There is a place at the lip of the brass that was less than the diameter of the bullet, while the rest of the part of the neck that's sized was large. So don't take the neck tension as gospel just yet.

Gotta run. More later.

 

[ShootDots]

Well you have 4K neck clearance>>> that's good! A LOT of people use a .313 neck. Properly turned brass with light neck tension would go a long ways>> and you may have that as well>>> I just don't know..

 

[GSPV]

I think that I'm good on the neck thickness. Just need to run it through my chamber once. I have a 308 that I can play with, but that will have to wait till I get it throated.

 

[6mmcldasher]

I found the 180 hybrids in my Shehane and .284 liked to be on the lands or a thou out.

 

[GSPV]

Thanks. I'll give that a try.

 

[its only light]

I shoot the same setup as you. .313 neck with .307 bushing. .3095 loaded round on mine. I run 180 hybrids with 4831sc. I just started load development on it and let me say it shoots everything pretty well. So far 57.2gr with a .01 jump is the best ive found. Shoots under .5 moa all day long. Havent chronoed yet but anxious to see where its at. Of course work up accordingly but I see people shooting up past 59.0 grains of 4831sc. Rl17 was less consistent.

 

[lrgoodger]

It's a 313 neck. Loaded rounds measure 309. I bought the brass, dies from one guy and the reamer from another. The other guy had a 312. There is a place at the lip of the brass that was less than the diameter of the bullet, while the rest of the part of the neck that's sized was large. So don't take the neck tension as gospel just yet.

Gotta run. More later.

I have exactly the same thing. I've measured the tip of the neck on my reamer a dozen times to verify it is .313 all the way to the end. Then I though maybe a carbon ring was building up and keeping the tip of the neck from expanding, but I knew it wasn't because I have a borescope and I always check the carbon ring area when I clean. The only other thing I can think is that the case neck is too long and I need to trim them back a tad, but I haven't tried it yet.

I also need to get mine throated. I bought a reamer with a .189 freebore, which was supposed to be good for the Berger 180 hybrids. Well, it wasn't. I sent it back in and got it reground to .225 as shown on the 7mm page. It still is not enough. If I seat the bullet out of the lands, it snaps down the last bit because the bullet pressure ring gets into the swelled area caused by the donut and neck tension goes way down as the bullet final seats. I tried keeping it in the lands just enough to stay ahead of that point and it doesn't shoot worth a darn in the lands. I've gotten some pretty good groups out of it in spite of snapping down while seating, but it is not consistent. I think the throater is the answer.

I've also inside bored a few cases and the reamer just hits the tight spot at the lip and again at the donut. I don't think that is going to solve anything, but I haven't actually loaded and tried any of them yet.

Keep us posted on what you figure out about that tight lip at the tip of the neck.

Ron

 

[ARshuter]

I shoot a straight 7 win with a .317 neck my 180's like to jump a long way I'm at 30 off. I tried in close then a fellow I shoot with, he shoots a 7 shehane, told me to try jumping at 25 plus. Might be worth a try.

 

[GSPV]

10 thou is all that I can do till I get it throated.

I'm going to set the throat such that I can seat the 180 Hybrid up to 25 off without getting the boat tail/bearing surface junction into the donut.

 

[GSPV]

Got out again yesterday. Was at my mom's farm. Had to shoot prone. I have a lot of respect for the F Class guys. There is a lot to shooting prone that you don't have to worry about off a bench.

It was 82 in the shade. I was out in the sun on a slab of concrete, so the temperature there might have been warmer.

I intended to run a test from 55.5 to 58.0 in half grain increments. I shot some fire form rounds to foul and got busy.

To be complete, 284 Shehane, Lapua brass, Tula LRM primer, 55.5 to 58.0 gr of H4831sc, Berger 180 gr Hybrid, seated 10 thou jump.

I was pretty uncomfortable. I haven't shot prone since college many eons ago. There is a lot to getting comfortable down there. My neck still hurts.

The POI trended down but leveled out centered around 57.0. Bolt lift got heavy at the end and showed other signs of pressure.

I have other rounds loaded to test, but I'm going to pull them and twiddle right around 57.0. It's going to work and there is no sense wasting barrel life.

 

[Alex Wheeler]

Your using a large rifle mag primer? Is the Tula really a mag primer or just a thicker cup?

 

[GSPV]

It's really just a thicker cup. Seems to be slightly larger in diameter, too. More seating effort than domestic brands.

You use them for the same reason that you use 450s in the 6 BR...to prevent primer piercing.

 

[GSPV]

Correction - My primers are Tula KVB-7 LR primers, not LRMs. My bad.

 

[thomasholbrook43]

My load is 56.5 H4831sc 210 fed primers .315/220 freebore. .001 neck tension or so maybe less.30" brux barrel 2910fps across chrono. shoots real good. have fun this cal. is real good.