6BRX Load help

[limbic]

I've been tinkering with 105VLD in my 6BRX. I found a good load .040 off the lands. 4 shot .85"at 200yards. However the ES/SD has been less than stellar. Best I can get with this load is mid teens for the ES. I had some BR4 CCI primers and tried them out. ES was great but group size almost doubled. ES/SD was 7 and 3 respectively. My question is would you keep tinkering with 205m .85" load or try and refine the load with the CCI primes. Varget powder for all loads.

BTW this is an Fclass rifle.

 

[Bob3700]

This is just what works for me.

Soft seating of bullets has given me the best groups as well as low ES and SD number on the chrono.

I seat the bullets .020" long ( you could even try .040") with very light neck tension. My chamber is a .272" no turn and loaded rounds are .2695"-.270". The cases are sized with a .268 or .269 bushing and then I run a .2425" mandrel into the necks. That way my inside neck diameters are consistent.

The weight of the Rockchucker press handle seats the bullets. Once seated, I just check the bullets to make sure they don't pull out or spin with my fingers.

The bolt closing seats the bullets the same each time and neck tension is as close to even as you can get.

I am sure that your bbl is unique, but this technique has worked in every bbl that I have chambered up for Long Range shooting.

Bob

 

[MarkS]

limbic,

Middle teens are fine . I have used 20 ES for 600 yds benchrest. Play with grip like Bob said. I use a 0.267 for a 0.2685 loaded round with a 0.272 neck.

Mark Schronce

 

[Rustystud]

Berger 105s like being jamed for me.

32.0-32.5 of Varget with a 31", 1:8, 5C, Broughton gets me 3020-3080fps. 0-9fps es.
Hard primers are a necessity. I have been shooting Wolf SR Magnum primers. Remington #7 1/2 also work well.

Reloader 15, VV550, and H4350 works well.
Nat Lambeth

 

[limbic]

Jammed gave me the worst ED/ES and the groups were >.5moa. I had them in .010 and .020. MV was increased but i had some occasional ejector marks. I'm gonna try them with the .269 bushing.

 

[Rustystud]

My chamber is .271. I do not neck turn. I am using a .266 bushing. I fire form with 29.5 or 30. grains of Varget. I have hornady hydraulic forming dies but got a lot case failures after using it. FWIW
Nat

 

[Bob3700]

Here are just my thoughts. The loads that you are using (powder wise) are proven to be pretty good.

If you are getting ES in the mid teens then your SD is single digit. To consistently get those kind of numbers and accuracy, your case prep is the key.

If your cases are weighted and are "Brothers" then you have to look at your neck prep. Consistent bullet release is what you are looking for here.

You never stated what your chamber neck dia is. If .272 (No-turn neck) then a .269-.269 bushing will be the ticket.
Pay attention to the pressure it requires to seat a bullet. They should all be the same. If you have one that has obviously higher seating pressure, set it off for fowling shots.

If you are trying for small groups, wind flags are a necessity. If no flags, shot early in the morning or late in the evening. No Wind.

Ejector marks are certainly telling you high pressure is present and you are wise to back off a bit.

Last issue, is your scope a know good unit? Is your bench technique such that you have shoot smaller groups in the past?

You should be able to shoot in the .3 range @100 yds with the loads you are using. It is just a matter of refining some of the loading techniques. What works at 100-200 yds doesn't guarantee 600 yd results but is usually a good indicator.

Bob

 

[limbic]

All good thoughts.
Neck is .271. Tight but doesn't need turning. Fired brass is .270 and loaded brass is just a hair above .269. Actually brass that has been fired still has enough tension to hold a bullet without it falling down into the body of the case.
My scope is NF benchrest 12-42. Kelby rings and integral rail on a Stiller Viper action
Technique is pretty good. I'm sure it could be better but I have shot some consistently good .2-.3 at 100 yards with this gun. Of course not everytime but I have done it before. I've got a pretty good Caldwell front rest with more screws and gizmos than I ever need. I also try to keep everything the same from shot to shot. Position and rear bag wise.
I usually try and shoot early in the morn for several reasons. Less wind and mirage and such.

I have been negligent on the weight issue. This I will admit. I've got an electronic scale and there isn't really any reason not to weight bullets and brass. Since Jackons Ms has a freakish 5" snowfall today I guess I've got something I can do. Thanks for the advice everyone and I'll keep you updated.

 

[Bob3700]

I shot a 6PPC in benchrest years ago with a tight neck. Brass was neck turned and initially, fired brass would still hold a bullet so I didn't even size the stuff.

As the brass get's used the neck tensions become inconsistent due to the brass work hardening. All pieces don't come back to the same dimension.

Lapua brass is very good but it still has production variations in wt. and neck thickness. Wt. some fired brass out and come up with some "Brothers" and see how that affects your groups.

Sounds like the rest of your equipment is up to snuff so should not be any issues there. I'll bet cash the results will come from paying attention to your brass.

Bob

 

[tclaunch]

Bob3700, where can a guy find a 2425" mandrel. My K&M expander is .244 and the pilot .242 so I`m all around the magic number. I have always run a tight neck, but am in total trust of my smith and a new barrel in the works. I will be a straight taper Krieger with my first .272 no turn 6 BRX. I have used a mandrel in a different manner with good effects, as when I come home with a few rounds not used in a match, I use a kinetic puller to reclaim components and run the neck over the .244" mandrel to place them in a "fired" state along with the rest of the empties.

 

[Bob3700]

TCLaunch,

I have a lathe so made my own mandrel. You might ask your smith to take one of the .244 mandrels and grind or turn it down to the dimension you want.

Running the cases over the mandrel is really a good way to control neck tension. You can feel the difference between cases as they run over the mandrel and sort the tight or loose ones.

Bob

 

[limbic]

Well I tried a new batch of loads. CCI BR4 primers were by far the best. .040 in the lands, at the lands, and .040 out of the lands all gave me similar 4 shot groups of .75-.84 at 200 yards. I was hoping for a bit better but.....
MV was 3007 or there abouts.
Neck was 269 which makes the bullet just barely held in there. I cant turn it or pull it with my hands but the calipers don't show much change with a loaded round.

205m primers didn't even come close.

 

[TheBlueEyedBear]

In my DASHER I have used the Fed 205M, Rem & 1/2, CCI450 and the Wolf SRM. The Wolf was by far the best for me. Loading 33.2gr. of RL15 the results are what I was hoping for: Lower ES and SD. Try the Wolf's I think you will like them.

 

[Bob3700]

You are shoot under 1/2 MOA at 200 yds. which isn't bad. You do have to begin to factor in a little wind effect here if you are not using flags.

MV sounds like it is in the ball park. Things are looking up.

At that distance your bench technique is also a factor. Work on that as well and see if the groups don't tighten up just a bit more.

Bob

 

[limbic]

Little bit of an update.

I loaded about a dozen different dummy rounds out to different lengths. At 2.770 I began to notice definate marks on the bullet from lands. I loaded up six different powder levels. 33.2-34.2. It was interesting to watch the groups change. 33.6 gave me a perfect vertical group. 33.8-34g of varget shot .5" groups at 200. I notice that when the mv got up 3090 or 3100 the POI would jump about an inch to the right. Thanks for the insight guys.