A 6BR load

M

macv

Guest
Hello, I am going to start a ladder test for the 6BR Norma useing Varget powder and the Sierra 107 BT bul. The brass is Lapua and the primer is Fed 205M. According to the 6BR site, they say to start with 30.0 grs. of powder. What I would like to know, is what would be a safe Max load. I don't want to load up only to find out that I now have to pull bullets apart because of too much pressure. The rifle is a single shot Sav. with a Shilen Sel. match brl. of 26". Thanks for looking in.
 
That is one of the results you can find out by ladder testing. Go up in .2 grains increments and look for pressure signs. If you can load at the bench you should not have to pull any bullets, but if not, and the test taken to it's fullest potential you will more than likely have a few to pull.
Terry Pohl
 
If your brass is unfired brand new out of the box it is best to fireform it atleast one time with a load at 28 grains of Varget.Varget tends to run hot and cold so saying start at 30 grains is usually fine but sometimes it hurts new unseasoned brass.
Your primer choice will limit your maximum load.
In the golden days the Fed 205M would get you to about 25 fps extreme spreads on the top node(2935-2980 fps) then they would pierce.The top node using a 107 Sierra naked bullet was around 31.2 - 31.7 grains of Varget.The 205's would get you around 31.2 maybe 31.3 then start piercing badly.
A switch to CCI BR4's or CCI 450 Magnums would get you to 31.5 without any hint of piercing and with a 0.062 bushed firing pin 31.7 was do-able with 0.105 freebore or more with more being better.
If your doing a Ladder test I would go up in 0.2 or 0.3 grain increments using once fired neck sized only brass and since your using the Fed205 primers I would stop before 32 grains.You might lose 1 or 2 bullets to the puller but they make great fireform bullets for when you get new brass.
I get those 1 gallon plastic Mayonaise jars from family and friends and after a quick trip through the dishwasher they make for good storage bottles for old worn out brass and pulled bullets.
Waterboy aka Lynn
 
My new batch of 205 Match primers are softer that some of the older one I have used in the past. They pierce sooner than expected. I made the firing pin shorter and this helped a little. I still had to stay on the light load side. Went to CCI BR-4 Primers and no problems. The new 205 Match primers repeat and keep the spread down but can not be used with the higher pressure loads.
 
OK, my first try at the ladder test went ok. I started at 30.0 grs. of Varget and went up to 31.8 gr. Did not show any signs of pressure or pierced primers, and cases extracted easily. My best grps. were from 31.2, 31.5, and 31.8. This morning I will shoot those 3 grps. over again to see which looks like the one for me. The fed. 205m's primers were ok. When all is said and done, I will then go to the BR4 primers and work with those for comparison. Cases were full length sized with a type S bushing die. Brass was Lapua. But did I make a mistake? I wanted this to be a 300 yd. load and yet I tested it out at only 100. Any comments?
 
Macv
If your not seeing pressure at 31.8 you probaly have a long freebore or a slow lot of Varget.
You said your best groups were at 31.2 31.5 and 31.8 grains.Did you shoot groups or do you mean those three loads showed the least amount of vertical stringing? My load for around 10 years now has been 31.5 grains of Varget.Seating depth changes will shrink your groups alot so don't skimp on your testing.
Waterboy
 
Of the three gr. wgts. that I mentioned, I was referring to group size. 31.2 gr and 31.8 grs. gave me 9/16" grp. 31.5 gr. gave me a 3/4" grp. These were shot useing BR4 primers. The Br4 's were even better than the 205M's. The 205m's were a little flattened, but not even a sign of piercing. The br4's still had a little of the rounded edge of the primer visible. The grps. were slightly better with br4's than the 205m's. Will play with oal next.
 
I had a very well respected 600 yard shooter tell me he tunes his 6br's to 2850fps. He claims its that simple. In my 6br with a 105vld thats about 30.5gr of varget. It shoots darn fine in my rifle. Lee
 
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