31.5 of N140 in 6BR

[marchx]

I was testing today different powder charges for 105gr Hybrids. Unfortunately my Labradar died in the middle of my session at -4 degrees Celsius and my best groups have unknown speed. My groups of 30gr and 31.5gr of N140 show some promise. In fact 31.5 was a one hole group, I think it's a decent 0.2. Isn't 31.5gr N140 a little too much for straight 6BR?
Are there any pressure signs in your opinion (two different fired cases below)?

https://imgur.com/0pTbhtD

https://imgur.com/5pL4iGw

 

[Lance21]

Both look fine to me, primers are still rounded on the edge.

 

[Kracken McGraw]

Vihtavuori load data with 105 scenar bullet shows 28.9 as max load.
Where were you set in relation to the lands for that great group?

 

[Cfshooter]

Look fine, but most likely will only be warmer out when your shoot it most.

 

[marchx]

@Kracken McGraw you are totally right. I raised this issue on this forum and many members point out to the fact that VV reloading data are very conservative. I was usually shooting 29.8 but decided to go out of my comfort zone.
All bullets were seated 20thau off the lands.
@Cfshooter That's my primary concern. I assumethere are other people here shooting 31.x charges in 6BR if not with N140, then with Varget.

 

[Cfshooter]

@Kracken McGraw you are totally right. I raised this issue on this forum and many members point out to the fact that VV reloading data are very conservative. I was usually shooting 29.8 but decided to go out of my comfort zone.
All bullets were seated 20thau off the lands.
@Cfshooter That's my primary concern. I assumethere are other people here shooting 31.x charges in 6BR if not with N140, then with Varget.

I guess if you need the max speed for like 1000 yards f class or similar, but if there is a lower area that groups tight, I would probably play with it if it is in the 2800 area anywhere. That should do well out to 600 and much easier on brass.

 

[marchx]

I am working on my load for 800m. Hence the extra speed experiment. GRT says 2867fps initial speed. The speed is satisfactory but GRT displays a warning about dangerous load. The max pressure would be 68152psi whereas 31.5gr of N140 has 8036 psi. Of course it's a GRT estimation.

 

[Pav67]

I’m using n140 in a bra with alpha brass.I’m at 31.42.At 31.5 I started to get stick bolt lift.A buddy with a br and 29.8 is right at 2800 fps

 

[Bc'z]

I rat a charge weight/ preasure test in a straight 6 with N140 with fresh Peterson brass. Started getting bolt lift at 29.1
I ran it up to 29.7 group was in mid .1's brass may not have survived.
I dropped back to 28.5 for seating depth testing after putting 5 remaining sighters of that charge into a .25" group.

 

[marchx]

I rat a charge weight/ preasure test in a straight 6 with N140 with fresh Peterson brass. Started getting bolt lift at 29.1
I ran it up to 29.7 group was in mid .1's brass may not have survived.
I dropped back to 28.5 for seating depth testing after putting 5 remaining sighters of that charge into a .25" group.

VV reloading data page says 28.9 max whereas many people run 31gr of Varget/N140 with no issues.

 

[Bc'z]

VV reloading data page says 28.9 max whereas many people run 31gr of Varget/N140 with no issues.

Agreed, but....
Your rifle ain't thier rifle and N140 ain't Varget. Just saying
I will be turning my necks after I run seating test, as I know my reamer spec is built off of Lapua brass.
I'm not concerned so much with the speed as I am in making Itty bitty holes.
If I was after speed I'd go to a different 6mm cartridge.
The straight 6 is supposed to be the easy button, I want to keep it that way.

 

[marchx]

@Bc'z What would be your 800m load then...? My idea was to push 6br to the edge before pressure signs to have a fighting chance at 800m.

 

[Bc'z]

@Bc'z What would be your 800m load then...? My idea was to push 6br to the edge before pressure signs to have a fighting chance at 800m.

I haven't got that far in tuning yet, only the initial test has been shot in this rifle.
If load shoots good @300 & 600 I'll be happy. This is a fun gun for my wife.
I'll also test SWP and Varget when I find time.
First I need to run seating, turn necks, revisit charge, neck tension in that order.
Afterwards I'll strap on the magneto speed and get a velocity report.
Not trying to sound like a smart ass, but I'm not worried about what other guys are doing in charge and velocity, more in what im doing for precision.

 

[Kracken McGraw]

I rat a charge weight/ preasure test in a straight 6 with N140 with fresh Peterson brass. Started getting bolt lift at 29.1
I ran it up to 29.7 group was in mid .1's brass may not have survived.
I dropped back to 28.5 for seating depth testing after putting 5 remaining sighters of that charge into a .25" group.

I was wondering if you had got the 6br going yet. Sounds like a great one!

 

[Jdne5b]

I was piercing primers at 29.8 in a BRA. So it sounds a little hot.

 

[Kracken McGraw]

I was testing today different powder charges for 105gr Hybrids. Unfortunately my Labradar died in the middle of my session at -4 degrees Celsius and my best groups have unknown speed. My groups of 30gr and 31.5gr of N140 show some promise. In fact 31.5 was a one hole group, I think it's a decent 0.2. Isn't 31.5gr N140 a little too much for straight 6BR?
Are there any pressure signs in your opinion (two different fired cases below)?

https://imgur.com/0pTbhtD

https://imgur.com/5pL4iGw

Do the primers look any different to you on your pics compared to your lighter loads. I can‘t tell f they have flowed just a wee bit around the firing pin hole.

 

[marchx]

@Kracken McGraw no, they do not. But anyway I will play further with 30gr charge due to the fact that outside temperature will increase and I will be shooting my most important match in June (I assume 25 degrees Celsius outside).

 

[Bc'z]

I was wondering if you had got the 6br going yet. Sounds like a great one!

Zack built it!!

 

[Bill Norris]

Zack built it!!

There's your sign.

 

[mjl650]

I also have a Zack built 6 BR. During initial powder testing with N140 & 105 BTT my primers started showing pressure at 29.9gr with 40 degree temp. It groups well at 28.4 gr and a little better at 29.4.