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Any general accuracy nodes for 68 Berger's in 6 BR? Yesterday's range results.

Steve Wilson

Range conditions yesterday were pretty good; low to mid 40's, fairly steady winds from the left around 5 MPH. Though they would vary in speed and direction somewhat. Anyway, I was shooting my 6 BR, 13 twist Broughton with 68 Berger's, 33.2 grains 135, 205 M primers and bullet seating was .000, -.005 and -.010. 5 shot groups at 100 yards.

Seating Depth Velocity Range ES Group Sizes Comments
-.000 .217 & .210 Horizontal, no vertical
-.005 3422-3452 30 .257 & .296 Horizontal, no vertical
-.010 3433-3453 20 .175 & .160 Horizontal, no vertical

I didn't get the chrono set up correctly for the .000 loads, so no velocities were recorded.

I dropped a bullet into the chamber and used my Sinclair OAL length tool to set the stops for the base of the bullet and then the base of the case. And measured the length of that particular bullet to arrive at my .000 OAL measurement. However, there were rifling marks on the bullet when I pushed it out of the bore with a cleaning rod. The marks were about 1/4 to 1/3 of the width, so the bullet was into the rifling a bit. I loaded that length as my .000 and noted the marks on my data sheet. Then I ran the Redding Competition seater in .005 and chambered one of those rounds. It left the faintest of rifling marks, just enough to see them. Those were my -.005 loads. Another .005 increase of seating depth was my -.010 loads and I noted that there were no rifling marks on these bullets. My assumption is that somewhere between these last two lengths is my true .000.

I bought a box of Berger 68 grain bullets from a small shop when I first had this barrel put on. Those bullets were simply magic. 32.5 grains of 135 wasn't enough though, velocities were down under 3300. Once I increased the powder and got them up to 3330 to 3360 they all went in the same hole. I found loads from 33.0 to 33.4 produced the best accuracy.

Bullet supply was getting low so I ordered 4 more boxes from Midway. Much to my surprise these new bullets were a completely different shape, so I called Berger to see if they still made my other ones. After I read off the label to him the guy laughed and asked if I had any idea how old my other bullets were? He said they were made by Walt back when he was still making bullets by hand in Arizona. I guess they must have been sitting on that guy's shelves for quite some time.

You will notice in my comments of the group sizes that there was no vertical dispersion. Well, of course there is some, but nothing more half a bullet at worst and mostly much less. The .160 group at -.010 has no more than .015 of vertical. Given that I had mostly horizontal, it seems I needed to pay more attention to those subtle changes in the windflags, even with the 5 MPH winds.

So........my question to you fine gentlemen is if there are any general velocity accuracy nodes with these "new" Berger 68's? Sorry to have rambled on to such length but I thought that perhaps the details might help to answer any questions you might have about the variables. I would like to try them back down in the 3330 to 3350 range if there is a node around that velocity or any other speeds you think would be appropriate.

Many thanks,
 
Steve....There are,or should be,several accuracy nodes to be found. First,I think I'd load/shoot around in that 3330-3350 velocity range and see. If that didn't work out,I'd go back to the 3430-3450 range and start loading down,.3gn/3 shot grps at a time,while looking for nodes. I'd leave the seating depth set(for time being) where I found the best accuracy before. After I'd found my new node(accuray permitting),then I'd work with seating depths again. Finding powder charge 1st & then seating depth & then neck tension works best for me. Also,I've found ambient conditions affect all of this. Good luck.
 
What he said and two more things....excellent shooting, and a well written post. Tell us about your rifle and what you shot it off of.
 
Steve, that is a wonderful post. Chocked full of information and easy for a guy like me to understand. Thanks.

Mike

P.S. It must be fun to shoot groups like that.
 
First, allow me to thank you all for the advice and kind words.

My 3.3 Version of Quick Load projected a velocity of 3383 with the 33.2 grains of 135 in this load, compared to the actual ~3450 average across the chronograph. I just ran the following powder charges in the Quick Load program for your review, based on the suggestion to work in .3 grain reductions.

Powder Charge Pressure Velocity
33.2 VV 135 52,349 3383 (Current Load)
32.8 VV 135 50,269 3347
32.6 VV 135 49,261 3328
32.3 VV 135 47,788 3300

Do you think I should go as low as that 32.3 load? I know, these ballistic programs are only computer projections and no substitute for loading manuals but the low pressure has my attention. I'm afraid to go check the Favorite Loads on the 6 BR Info Page right now, in fear that I will lose my post. Though I will look at it when I finish this and edit my reply.

That concern aside, I will follow oldblue's guidelines on how to proceed from this point.

This rifle began life as a new stainless Savage Model 12, 22-250 Ultimate Varminter in that weird Choate stock. This particular model came from the factory with the Sharpshooter Supply trigger, as it was before the advent of the Accu-Trigger. I was just starting to compete in 600 yard prone at the time (6 or 7 years ago or so) and was rummaging through the gun safe looking for a suitable victim to transform into a proper prone rifle. The Savage drew the short straw.

I had it re barreled with a Lilja 3 groove, 8 twist in a tight neck 243 Ackley Improved by my gunsmith at the time. We decided to do away with the barrel nut and shoulder the barrel against the action, in normal gun fashion. Then I shipped the barreled action off to Lone Wolf for one of their Tactical Master II stocks with an Anschutz under forearm rail to accommodate the hand stop. The stock is a deep pistol grip design with about a 2 inch flat forearm. I will look at their site later and see if I can post a picture or link to it.

At any rate, I found that I was really great at establishing where the bottom of the field of shooters would place in a prone match. So I turned my attention to the, fairly new at the time, 600 yard benchrest matches. I took second place in the Two Gun my first go around with it and won the Two Gun in my second match. David Green of Kansas cleaned our clocks at that first match, shooting a 30 BR with 125 grain bullets. My good fortune was that David didn't shoot in my second match.

I was using a Hart front rest with a Hoehn adjustable top and a Protector double bottom rear bag. Not to allow success to hinder my progress; I had a new rifle built that could really win for me. A 700 Remington action, 5 groove Broughton 28 inch, 8 twist, tight neck in 6.5x284 and a Jewel trigger set at 4 ounces. This one was also sent off to Lone Wolf for one of their Ultimate Thumbhole stocks with a 3 inch forearm and all the bells and whistles, including an adjustable cheekpiece. I mean, after all, 6.5x284 was kicking butt at 600 and 1000 yards then and I had to drink the coolaid.

By the time that rifle was finished and I was able to shoot in a match, the entire game had changed. 6 BR and Dasher now ruled the courses and three legged front rests had been relegated to dinosaur status. You had to have one of Viper's massive rests or a Farley to prevent looks of pity. I didn't do very well. The torque would redistribute the sand in the front bag and result in tipped crosshairs after awhile; my small rear bag would be shoved backwards by the recoil. Causing me to redo my setup completely and eat into the allotted time for your record shots. Lack of confidence, poor placing in the matches, loosing out to those little pipsqueak 6 BR's and flat out being "over equip-mented" caused me to reevaluate my entire situation.

Right away, I bought one of Edgewood's gigantemous Gator rear bags and filled it with heavy sand. That solved the problem with the rear bag getting shoved backwards during recoil. I still only had my Hart front rest; the Viper was going to cost at least $1300 and a Farley was fetching $900 or so. I quit competing in 600 yard benchrest, having made my mind up that there was no point in it until I was properly gunned and equipped.

Alright, that was enough of a highjack of my own thread. Now back to the gun at hand; the 6 BR. I took the 243 Ackley barrel off of the Savage and had my gunsmith buddy, Butch Hongisto, do the 6 BR. I did break down and buy the Farley, but only after I shot up most of my original box of the old Berger 68's. All of the old ones were shot using my Hart front rest.

The new Berger's were causing me fits with group sizes, but so was the lack of snugness on the forearm with my front bag in the Farley rest. It is the same Cordula bag I used with the Hart, but the Farley doesn't squeeze the upper sides in as much as the Hoehn top on the Hart does.

To finally get back to Boyd's question of what am I shooting it off of; the Edgewood Gator rear bag and the Hart/Hoehn front rest combination. I did stop at Ron Hoehn's shop on the way into my last range session at St. Louis Benchrest Club and bought some Teflon stock tape for it. Man, is that stuff ever slickery. The front and rear bags also got a spray of silicone to boot. Now the stock slides like a greased piglet in a barnlot of drunken would-be, crippled, captors.

To end, do you think I should go down as low as the 32.3 load? It would only take three .3 grain reductions from my current 33.2 loading. My only reservation is the hypothetical pressure that Quick Load projects.

I wish to thank you all again, for your kind words and advice. And for your taking the time and patience to wallow through my digressions in quickly answering your questions.
 
If you had done the tape and silicone first, do you think that you would have needed the gator? You can put some shims inside the side tension plates of your Farley. Remember that there is no tracking trophy. I would think that it would be much less of an issue with a Farley, given the ease of adjusting the rest. Another thing that has an effect is how square you sit behind the rifle. To the degree that your shoulder is at an angle to the butt, the butt will slide sideways into the off ear of the rear bag. If you get more behind the rifle, which may require repositioning your rest and rear bag, you may need to move your scope to get the correct eye relief. I have designed my portable bench so that I can be comfortable in this position. conventional benches may require that you set up off the back corner to get to this position. I shoot a Hart Hoehn combination with the bottom of the base turned flat, even with the center hub. Our range is slightly downhill and my stock is a low profile short range benchrest design.
 
I bought the Gator rear bag to handle the drag back issue from the recoil of the 6.5x284. That was way before I had the 6 BR barrel put on this other rifle. But your point is well taken. If I had put the tape on the 6.5 and used silicone also, there may well have been no issue with the original Protector rear bag being shoved backwards. My apologies if I wasn't clear on that. I tend to go on in too much detail or wander about in my story by bringing in other aspects that have led me to where I was at the time. It may help to answer things that come up in the mind of the reader. Like, "Oh, I see he finally got around to addressing that matter of detail." But the downside is the difficulty of keeping all of those twists straight in my mind, let alone, the poor reader's.

I have been tossing around the idea of shims on the side tension posts of the Farley but haven't settled on one yet.

You are exactly correct regarding the effect of sitting square behind the rifle. Which is something I am struggling with. I can comfortably sit at about a 45 degree angle behind the buttstock. Next time at the range I will try setting up a little further back on the bench and see if it will allow the stock to rest squarely into my shoulder and still maintain a perch for my shooting elbow. Meaning, just move the rest and rear bag further to the rear of the bench and plant my butt more square to the rifle.

I prefer and feel more comfortable when I can get the butt on the inside of my shoulder. If not, then I settle for it snuggling into where the bicep meets my shoulder. It is an all or nothing proposition between these two choices. Because the other way is to have the butt on the tip of your shoulder. And that's where the butt will slide off every time and into the off ear of the rear bag. Just as you mentioned. When that happens, the shot is usually going left for me. But it certainly isn't going where I aimed it.

Thanks again Boyd,
 
We did a lashup arm rest for a friend, on a portable bench, for his trigger arm, with a board and a cabinet clamp. I used that experience to design the top of my "portable" shooting bench. It has the arm support built in. You can sit directly behind the rifle without your chest touching anything, and both arms well supported, relaxed.
 
Since last weekend's 600 yard benchrest match is behind me, I finally had time to set the 6 Dasher aside and take the 6 BR back to the range and continue the load development with these new Berger 68 grain bullets. Following gpoldblue's suggestion, I started backing the powder down in .3 grain increments. 33.2 down to 32, .3 at a time. Here are the charges and average velocities.

32.9 3405
32.6 3379
32.3 3355
32.0 3330

Sure enough, you could see the groups shrink as the velocities came down. At 32.3 they were back in one hole. With 32.0 they were one VERY tiny hole again.

Thanks to all for their help. Next week I will start at 32.0 and play around in 1/10 grain and fiddle with the OAL, after I find the best speed.
 
I plan on copying you BR setup. I have no plans to go to the PPC, so I decided I would build a 13 twist 6 BR to shoot 68 to 80 grain bullets.

I think we could compete with the 6 ppc guns.
 
If you look back in history people abandoned the 6br in favor of the 6 ppc because if the quality of the brass (or so I have read).
 
I have a 6BR with a 13.5 twist and am using the 68gn Berger, I don't have all the sweet gadgets you have so I'm loading cavemen style... I have Redding competition dies and micrometer, I have no means to measure the chamber or the lands or anything except the length of the case with bullet.

when I seat the bullet with COL 57.50mm I have less than 2mm seating depth in the neck and it doesn't touch the lands..

what does the COL have to be to touch the lands ?

the reamer used in my rifle is standard 6mm BR Norma.
 
If we are really talking about "barrel nodes" you should find that accuracy nodes are about 120 FPS apart.

They are in the typical 6ppc bench gun.
 
I don't have my range notes handy here but I would not dispute you. My first few fouling shots, and a subsequent 3 shot group, were with 33.2 of 135 and a velocity about to break 3500 fps. The 3 shot group all went into one tiny hole. But the important objective was to get the speed/pressure back down to the next lower node. Which turned out to be right at 32.0.
 
Steve,
Thank you for your excellent posts. A long time back, a friend and I shot beside each other, he with his fully built, slow twist 6BR, and I with my custom actioned 6PPC. We shot the same bullets and both shot 133. His load was slower than mine. Based on what I saw, I have no doubt that with today's components (primarily, Lapua brass) that a well made 6BR (as yours obviously is) would be just as accurate as a 6PPC and may have some advantages. I will probably be tarred and feathered for that...oh well.
Boyd
 
Boyd,

I am running over to Wayne's right now, to make certain the fire under his tar bucket is put out. Just teasing, I'm sure he is probably on our side of the discussion.

Thanks for the compliments.
 
I finally got to do a significant amount of testing at 100 yards. I had completely fixed my neck tension issues and was eager to see how my loads were shooting when conditions and distance were not a real factor. I had low winds and clear air and the temperature was mild.
I have a 1-8 twist barrel and I have been working with the Fowler 80, as my first 500 bullets is nearly spent, I decided to pick up 400 of the Berger 80 varmint bullets and I worked up a bunch of loads jumping .020”. I decided to stick with the R-15/Ultra Long Range Match powder I had been using for 107 loads, since I have 15 pounds of the stuff.

With moly bullets, several range sessions upping the charge got me all the way to 32.3 grains without any real pressure signs on the brass but the bolt lift was getting stiff. The 32 grain load shot several groups that were easily under .25” and bolt lift was normal. The 32.3 grain load shot about the same but the bolt lift was stiffer. I had a feeling the night before that 32 grains was my practical max and would be my highest velocity accuracy so ON A LARK I decided to use the 6 PPC rule that nodes are about 1.2 to 1.5 grains apart (6 PPC/V133/68 grain bullets). So, I made up a 5 shot load at 30.8.

This load went into a 0”. It was a group so tight I really wouldn’t know how to measure it.

So, it would seem Steve and I are finding the same type of results in that respect…
 
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