6mm SLR neck tension

[Julien]

Hi guys I didn't want to highjack some of the other SLR threads so I figured I would ask here.

I just rebarreled one of my f-class guns to this chambering and have been doing some load developement .
So far I tried h4831sc and h1000 with the later giving slightly better velocities around 3165 avg with 105 berger vld's.

Yesterday I tried sizing the neck partialy the first 3/16" then 3/4 of the way down and all the way to the shoulder, all the way grouped better but the ES was higher than 3/4 of the way down with better ES .

Loading 46.5gr h1000 [pretty full] and the speed didn't go past 3190.
Now the tension on the necks might not be enough I dont know my loaded round mics out to .2715 and I am using a .269 bushing.

I tried win brass and lapua both group well but the lapua has less vertical and groups a bit better.
I am shooting a 1-8 28 3/4" heavy varmint Gaillard barrel.

To be honest I was expecting more speed with a 105 am I maxed out or should it go faster should I try more neck tension to build up the pressures I had the bullets stuck in the lands about .014", or should I try different primers.

 

[1000yardstare]

3190 with 46.5 gr H1000?? I am getting 3000 fps with 47 gr H1000, 105 Scenar, Win brass, 28 inch 8 twist barrel.

Using .269 bushing. Gives .272 loaded neck diam. COAL 2.785, 20 thou off the lands.

Bill

 

[Julien]

Bill looking at my notes now and was getting 3139,3128,3111 neck sized all the way seated 14 tous in the lands.
I made a mistake at 3190 the highest I got was 3139.

with the same load 46.5 gr h1000 soft seated in the lands about 4 thous 3080 3096 3096 3137 3134.

If you mic a 105 berger and a lapua 105 scenar the bergers are a few tenths bigger this will build more pressure.

Bill I was pretty full at 46.5 I started the load at 44gr to be safe and got 2770 ish it started lighting up at 46 I will try and see if I can squeeze 47 or more in the case .

How fast should I be able to go with a 28" barrel I figured 3250 anyway.

I am quite certain more neck tension should give me more speed but I am scared it will give me worst groups .

 

[Bob3700]

I am running about 1/2 thou on neck tension and seating the bullets (115DTAC) .020" into the lands. Am using H4831sc and with Win brass and Wolf primers, 3100 is very doable.

Same load behind a 107 SMK and I was up around 3150 fps.

H1000 might be a bit slow for the 105gr bullets, but that is a guess as I have not tried it behind the lighter bullets.

You might want to look into N165 with your 105s. Several who shoot a straight 243 are using that and pushing the velocities up pretty fast with good accuracy.

Bob

 

[Rtheurer]

I Ran the 6SLR with a 105 Berger through Quick Load and the two Velocity Demons where 7828SSC and Norma MRP. Both right at that high 3100 to low 3200 with good case volume.

I shot one of these early on and used R22 for the 115 class And R19 with 105 Amax and 105 Bergers. I love H4831 SC but could not get it to work for me in this barrel. 30"

I need to slap this barrel back on the gun and see if these two powders look as good as the program says they do.

RussT

 

[Julien]

How far back are you guys sizing the necks ,I have tried a few ways and so far it seems to like the whole neck sized.
Russ how temperature sensitive is mrp and 7828?

 

[Rtheurer]

Not Enough to matter. I think folks get all wrapped around this whole powder sensativity thing for no reason at all. Unless your hunting in Africa and then in Alaska then it does not really matter all that much for 99% of the applications the we use.
A benchrest shooter said the powder increased 10FPS in a 50* temp change and his gun came out of tune. Not that big a deal for me. I have to admit in my hunting rifles, I like to shoot the Extreme Powders when it gets down below Zero. But my Match rifles.... Not so much. Just my stupid opinion and most likely not shared by some folks.

Any way I cant answer your queastion as I have not tries either yet. Would love to heare some feedback from some other folks about both on this subject non the less.

Best of luck
Russ T

 

[HPMike800]

In many places, pressure / temperature may not matter much. If you want to shoot in the Arizona summer heat you will need to account for it.

I running about 0.2715 loaded with a 269 bushing and don't get bolt lift until 3250fps. I've settled in around 3180fps as a good speed. I'm very happy with that. I can't see more neck tension giving more velocity by itself.

Ive shot my 6slr about 300 rds now and my problem was neck clearance. I had to get to 0.003+to get any consistant grouping. I don't know why but 0.002 just ain't enough for this cartridge at these speeds.

I've used H4831sc and N160. N160 being the better of the two.

 

[Julien]

Mike I seem to be using the same tension as you and as far as neck clearance my 22br doesn't like it to tight either.

I have been getting good groups so far with the slr I just want to bump up the speed a bit.
Maybe this week I can make it out to the range again for more testing and put a bit more h1000 maybe 1gr will do it .
Last time out things really came together once I got to about 46.5gr or so I had no speed below this.