7BR with cast boolits

Rifle data:

Savage PTA timed/trued by Fred
Target AccuTrigger @ 10oz
26" SS Shilen Select Match, heavy varmint contour, custom throated
Vintage B&L 24x
Bobby Hart LRT
Weighs 12.5lbs

Load data:

RCBS 168-SP, Lyman #2, gas checked and sized to .285"
WLL X-lox 2500+ in first lube groove only
Peterson fireformed brass
CCI400
N135

Removed the 6.5CM barreled action from the LRT and put it back in the factory stock, then fit the 7BR barreled action to the LRT. Loaded test rounds about 2 weeks ago and was just waiting for a good weather window which finally happened Friday.

Pulled my bench out and set up. Re-zeroed the 6.5CM then set up chronograph prior to shooting 7BR. Shilen recommends shoot 1 & clean for 5 rounds, which I did while getting scope dialed in. Fired up the chrono then proceeded to shoot 4ea 3-shot groups. Rounds 6, 7 & 8 produced the group circled in green, I forgot to adjust elevation before the first shot of the next group circled in red...

https://i.ibb.co/wBXF5Rt/7br.jpg

I use corrugated plastic for backers and they were quite wet from morning fog, so waited to measure after they dried, the three holes on left measured .712"...

https://i.ibb.co/MM6JDKN/dry.jpg

The final group at 26.5gr openend up a bit, but still respectable with only 17 total rounds shot...

https://i.ibb.co/rsB1zHv/final.jpg

Disregard markings on targets, I save unused sighter targets for home practice. When I ran my borescope down the barrel afterward I found no lead fouling at all. Hats off to Shilen for a superb finish!

This is very promising and anxious to start a ladder test from 24.5 - 26gr. The 25gr load had avg vel 2048fps, ES 4.0, SD 2.0. :-)

Nice start. What twist is that barrel?

I got my mold for the 6BR today (and sizing bushings). Will cast some up this weekend. It is also a Shilen barrel.

It's 1:9, finished prepping remainder of my brass this afternoon. Back to waiting for another weather window as snow returns Thursday/Friday, then an arctic front moves in Sat night, highs drop to mid to upper teens and overnight lows near zero through at least middle of next week.

Good to hear your mold arrived, look forward to updates!

You'll have the same problem with velocity that I will (1:8 twist). 2000fps will probably be fine. Will experiment a bit to see how fast it will hold up.

My 1:10 twist .308 holds up to just under 2100fps depending on powder being used (slower is better in it with heavy bullets).

I spent a lot of time researching CBA match reports for 6BR & 30BR, powders, primers, molds, twist rates, charge weights, alloys, velocities, and resultant groups. I focused on the competitive averages and used that info in my decision process and in running variables in QuickLoad.

From that, I was "pretty sure" ~2000fps was going to be a sweet spot, sure seems to be so far. :-)

Quote:

---

Originally Posted by PhilC

I spent a lot of time researching CBA match reports for 6BR & 30BR, powders, primers, molds, twist rates, charge weights, alloys, velocities, and resultant groups. I focused on the competitive averages and used that info in my decision process and in running variables in QuickLoad.

From that, I was "pretty sure" ~2000fps was going to be a sweet spot, sure seems to be so far. :-)

---

I think the CBA website might be one of the most used resources I have. The other (for jacketed) is the International Benchrest site.

Yep, I find that my most accurate loads in the .308 are 1800-2000fps. My go to load right now with the 210gn bullet is 1950. The bonus is that long bullet is good for 500yd ranges. It is a little too slow for 600yd.

I'll be starting at 1900fps with the 6BR and work up until the groups enlarge, then back off 100 or 200 fps.

Settled on a powder yet, Varget maybe? Was either the most popular, or 2nd most, in my research for 6 & 30BR. I couldn't find any at the time but am not displeased with my results using N135 which was another frequently used powder.

I will start with Varget. Depends on if I can reach the right powder density with it. My .308 cast does good with several different powders, including Varget.

Phil.....What is the length of your bullet, and what bullet profile ??

It's a spitzer profile, with gas check it is 1.175".

Phil,

Tried some of the 108gn today just to get a feel for things. Sized to .244 with .238 nose. But, I'm a bit high on vel right now I think, 2100fps. The IMR4198 loads seemed a little better than the Varget but I only shot 10 of each. 5 shot groups, 2 1/2" and 3" at 200yd. Decent start for the first bullets out of the mold.

Sounds like you're getting there, 2 1/2" - 3" @ 200yds with the first boolits out of the mold is nice!

Shot a ladder Saturday some ok results with 24.4 - 25.0gr that playing with seating depth might improve, but 26gr, which is where I stopped, produced this...

https://i.ibb.co/9sfQznr/26gr.jpg

Hard to believe 25.8gr opened up that much and how tight 26gr performed. Am going to load another ladder from 26 - 27gr in .2gr increments to confirm. 83rds down the tube at this point with zero leading and have completed barrel break-in.

Small cases can provide some surprises. I got the 2100fps with only 17gn of 4198. Will be interesting to see what a ladder looks like.

Following.....

Where are yinz at in particular to jump or jamb for seating depth tests ??
I would assume a good jamb with light neck tension would be forgiving.

I have a good 50 years of casting. I always thought about finding a good
supply of half jackets for the 7's, but I'd go to a smaller case then the BR
cases. My theory since the speeds are low, the BR case is not efficient.
Always had my eyes on taking a 7.62x39 case and doing a 7mm half jacket.

I'm seating to an imprint of lands on the boolit, on a scale of light --> medium --> hard, imprints are mid-way between light & medium. Neck tension is higher than I want and will correct that after fireforming the remaining 30 or so cases.

Depends on the bullet. I usually shoot bore riders. I size the nose such that it is an interference fit in the bore. If I pull a cartridge from the chamber I want to see even rifling marks around the nose of the bullet. When seating the first drive band is engaged in the throat/rifling. If shooting a non-bore rider I also seat it jammed into the rifling. One thing I am aware of when shooting is how hard the bolt is to close. If one round is too hard or not hard enough compared to the others I will shoot it at my sighter target. Sometimes it is just enough off to mess up a group.

I am shooting cast in my BR as a lark. Maybe I will get a decent load and maybe not. It is just too much of a twist rate for good higher velocity work. Not a big deal since I set it up for long range with heavy jacketed bullets.

FWIW, I am considering a new barrel to replace my .308 (1:10). If I want to go long range (600+ a little) it will be a 29 or 30" .30-06 with a 1:12 or 1:14 twist. If I want to stay with shorter range (l500yd and less) it will be a 26 or 28" .30BR with a 12 twist.

Have done some more testing and now have 101rds down the barrel. Turns out low 26gr range is looking pretty good. Will know more after my test session today, report to follow.

I've run gas checked, heat treated Lyman #2, lubed with WLL X-Lox 2500+ up to 2246fps without issue.

Sounds like a decent 'spot'.

I am having too much fun with the Vtac bullets in the 6br right now. Will cast some more for it pretty soon. Meanwhile I have about 500 .308 bullets to load and shoot :)

Fuj, it is certainly doable. There was a guy on the cast bullet forum who made up some cast for his .221 benchrest rifle. Not sure if he shot it at 200yd. He had some impressive groups with it.

Due to cascading error effect my session was a bust. Despite that, I have settled on 26.4gr as it produced the best group in my last session and best load statistics. Weather conditions suck thru Tuesday afternoon, if I can't shoot prior to, I'll load what's shot best so far and hope for the best.

Well, I've had some mixed results with the 6BR, but, not better than 1.5MOA.

Varget was a bit erratic, but, I think I need to revisit it since it gave a bit lower vel with same volume charge as the IMR 4198 (which I have used successfully in the .308 with mid-velocity cast).

My first loads with 4198 were around 2200fps. This is on the high end of spin rate for this caliber. The 1-8 twist is the problem. I tried some lower loads and have a candidate at 16.7gn and 2120fps but relatively poor es/sd. 1.5-2MOA seems average for this load. Not great and still some bad fliers (typical of too high spin rate). When I went to lower loads the muzzle vel was very erratic. This is 100yd, squares are 1/2".

[IMG]https://i.ibb.co/0VQxvC8/test.jpg[/IMG]

So, am going to try Varget a little more and see what happens. I'd like to be in the 1800fps range.

A new guy at the range was shooting his Schuetzen rifle (breech seating). Sharps Borchardt action, .32-40. He was getting 0.3" and 0.4" groups at 100yd.

I haven't posted much but I've run into the same conundrum. What started off nice, went south. Barrel leaded up even shooting loads that produced good groups initially with boolits cast at the same time and no other change in components. Tried powder coat vs traditional lube but no improvement. Sat down with my targets and notes 2 weeks ago trying to figure out where things went bad, the only constant was a 100 - 150fps increase in MV, so I reduced charge weight to velocities that previously shot well without much improvement.

During last Saturday's match my best 5 shot group was 1.52" with an agg of 1.87", best 10 shot group was 2.4" with an agg of 3.32". Score was a dismal 162. Chono'd velocity with 25.4gr N135 averaged 2167fps with SD of 5.0 and ES of 16.

Recalled I was plagued by similar problems with my 6.5CM until I slowed it down so pulled the tech data from the 2021 CBA Nationals and found 10 competitors shot 30BR. Here's what I found:

9 of 10 used linotype
8 used Fed 205M, 1 used Win SR and 1 used Win SP
Avg barrel length - 24"
Avg twist - 12
Avg velocity - 1960fps
Avg boolit weight - 194.7gr
All competitors used lube and gas checks
3 used Varget, 2 used A2495, 2 used N135, 1ea used N133, IMR3031, IMR8208

The grand national champion shot a 30BR with a 12T 24" Shilen using 207gr boolit over 29gr A2495, Fed 205M, at a chrono'd velocity of 1750fps.

I've re-run QL with the Ba factor adjusted to match actual chrono data at two low nodes with predicted velocties of 1821 & 1909fps. Had hoped to shoot this morning but is raining, maybe tomorrow if weather clears up.

RPM of my current load is over 173k, the new loads will drop rpm to 145k & 152k respectively and fully expect one or both to shoot well. Found a great deal on pure linotype direct from a printer for $1.45/lb delivered and have 110lbs enroute.

The RPM 'limit' is based on radius. For .308 it is around 144,000rpm. That means it is a little faster for smaller dia. The loads that my .308 shoots consistently well are in the 1800fps range. The only 'difficulty' I have is load density. Some powders do ok, some don't.

The .30BR rifles are usually slower twist which means they can go to higher velocities without incurring the penalty of RPM effects. It really does seem the 'normal' .30BR barrels are ideal for cast bullets. Looking at folks who shoot them with jacketed it seems to be a very forgiving cartridge.

For now I'll just keep shooting my .308 with cast and leave the 6mm alone for a while.

I think you will be better off with those slower loads, if you can find a powder combination that works.

I agree. Only way to know will be to load and shoot, maybe this week if weather and time permit.

Still following.....

It's still aways down the road before I might decide but, My thinking since casting
bazillions of pistol bullets, my idea would be to go for a much fatter style of bullet.
Maybe do a 30 cal with a smaller case, more like the 30 major/Grendel. Get that
powder charge way down but fast. It's possible the BR case is just too much capacity ??
Just thinking out load !!. Maybe also something short and shaped like one of Robinett's
30's. Thinking maybe, the least amount of twist I could get away with, and the least
amount of grooves, and hang a tuner on the end.....

Fuj, an interesting area to explore. Not sure anyone has really done all the work.

Historically cast bullets are shot at slower velocities for a few reasons. Initially barrel leading was a problem, but, current lubes and gas checks have been successful up to around 2600fps (in .30cal). Then there were the guns. Most are made with rifling twist for jacketed bullets, which means the RPM is limited, which means the vel is limited. Again, some have experimented with slower twists and reached higher velocities.

If it were me I would think a higher vel would be better, just for wind effects. Not sure where that optimal vel would be with a light bullet. If you look at the BR shooters the 30cal bullet weights vary from 130 to 230gn. Most seem to keep the vel in the 1500-2000fps range. Why? Don't know. I suspect the ones using heavier bullets do so to reduce the wind effect, but, again I am just speculating.

I would be very interested in someone pushing some of those boundaries. :)

Just for reference here is a group from this morning with the .308. Accurate Mold 31-210E adjusted for powder coating. Yes, this was 200yd and those are 1" squares. Wind had was pretty consistent at this point but I still had not adjusted enough for it. Vel was just over 1800fps. Yes, these were powder coated bullets. My 'normal' group is closer to MOA at that range. The wind 'blew out' the other groups to 3" horizontal.

https://i.ibb.co/K5XV8NQ/200yd-210gn.jpg

You can see why I like the .30cal bullets. The 165gn XCB (NOE 310-165) does just as well but is sized and lubed.

Sorry for the hijack. Probably need a new thread.

I still like my 7mm's for just about everything but this cast rifle bullet thing
can bring some good discussion. At the range myself yesterday finishing my
tuner tests for Saturdays match, I found a lone 300 Blackout case lying in the
grass.....I said " Hmmmnnnn" A Blackout with 110 to 125 grain jacketed bullets
will do about 2300 fps by average. I've heard 2450 fps with the TNT's and 4227 ??
That case looks very efficient for a cast bullet and speeds. Heck, good Ol' 2400
would work.....I need to start playing with JBM and bullet lengths to find a really
low twist rate.

Anyone play with coating cast bullets with Moly or HBN ??

You could just try some cast in 7mm as Phil is doing. Keep it in the 'family' :)

2400 is a very common powder for cast. I'd have tried it by now but I don't have any. For the mid range loads (1500-2000fps) it seems to do really well.

Cast Boolit forum has a ton of folks experimenting with cast coatings and lubes. Moly coating has been tried in several different ways and does not seem to make a lot of difference. Having said that, my bullet lube uses Stalube Extreme Moly grease as the lubricant and beeswax as the carrier. HBN I am not sure. I have not seen any mention of it. The two 'big' coatings used these days are Powder Coating and HiTek. Both are baked on. HiTek is a proprietary formula so I don't know what is in it. There are several companies who sell coated bullets that use HiTek.

There was a lot of cast experimenting in the BR crowd back in the 80's. I remember a series of articles about using moly coating. The results were ok, but, not better than standard lube. They also experimented with polyethylene wads instead of gas checks. Those did work well, but, you had to use a case with a relatively long neck (IIRC they were testing using a .32-40 case). There is still a Cast Bullet class for plain base bullets.

FWIW, the biggest area of cast bullet performance is the casting of the bullet itself. Making a bullet with the fewest voids/flaws. Not as easy as it sounds. From what I can tell the most consistent results come from ladle pouring. Of those the ones that use the Lyman ladle and hold it against the mold do the best. After that, temperature control is key. I use a bottom pour pot as I like the convenience, but, I also cull out quite a few bullets. Some of the 'pickier' shooters will only keep 25% of what they cast. My 'control' is bullet weight. Bullets are sorted to 0.1gn and I only keep the ones on the high end of the curve.

.300 BO is a popular case for cast with the AR crowd. Most of them are using faster twist barrels so they get mixed results (and they are trying to cycle the action) It does seem to be a good size for light bullets. Reminds my of my old .30 Herrett.

I'm waist deep in pulling the engine from my truck for some major preventive maintenance so check in here then head for the shop while it's still nice and cool. Almost time to head out, engine should be on the stand by noon.

Only coating I'm using is Smoke's powder, if not that, it's traditional lube, White Label's 2500+ in particular.

I use Smoke's powders as well. For the rifles I have settled on Smoke's clear for a number of reasons, but, it also seems to shoot a little better. Not sure why. My guess is the lack of pigments means the coating has a more consistent thickness. I can't prove that, but, it is the only thing I can think of that would make a difference.

Good luck on the truck :)

Just for grins I went back to the CB forum and looked up HBN info. Seems a lot of people in years past have tried it and moly. Most of the moly users seem to have stopped using it for various reasons. The consensus was that just moly or HBN on a lead bullet doesn't work. Some liked moly in their bullet lube, some not. Some tried HBN in the bullet lube but it didn't make a lot of difference.

There were a few who have tried tumbling already coated PC bullets in moly and/or HBN (those that I read about already had tumbling setups for their jacketed bullets). Those folks seem to have the same kind of results as jacketed bullet users, ie, the moly coating is contested but the HBN coating seems to be good. One guy who used the HBN on his powder coated bullets really like it with only two downsides. First, the bullets were so slippery they were hard to handle. Second, the health effects of HBM needing a good mask and gloves.

The conflict over the results of using moly in a barrel seems controversial.

If the regular PC didn't work so well as is I'd be tempted to try the HBN on top of the PC.

Fuj,

What is your take on moly vs HBN?

Back to 7BR...some success from Saturday's match, now, if I could get those to repeat and eliminate single flyers the entire match I'll be satisfied. :-)

https://i.ibb.co/jy6J5kK/5shot.jpg

https://i.ibb.co/8YZjW3h/5-shot.jpg

https://i.ibb.co/h9QY8Wv/10shot.jpg

Nice work Phil.

Quote:

---

Originally Posted by PhilC

Back to 7BR...some success from Saturday's match, now, if I could get those to repeat and eliminate single flyers the entire match I'll be satisfied. :-)

https://i.ibb.co/jy6J5kK/5shot.jpg

https://i.ibb.co/8YZjW3h/5-shot.jpg

https://i.ibb.co/h9QY8Wv/10shot.jpg

---

My experience when shots go low is the rifle is nose heavy and needs weight in the stock.
Shot fliers going high is bounce on the front bag and why some shooters claim better groups
with a soft front bag. That last target if not a sighter, looks like some wind....

Quote:

---

Originally Posted by charlie b

Fuj,

What is your take on moly vs HBN?

---

No experience with HBN, and the only moly used was to mix some powder with a 50/50
mix of Alox and bees wax for non gas checked bullets. Not a fan of powder coat because
of being uneven and screwing up stability. I guess it's fine for plinking ammo only.

Let me ask a question.....With cast bullets, how do you sort them for match's ??

Thanks. I just wondered about all the supposed issues with moly. One of the easiest lubes to make is a 50/50 mix of Sta-lube Molygraph and Beeswax. But, I don't clean the barrel after every session so it might go a few weeks. I do have a stainless barrel, but.... The other lube I like is Lucas Red N Tacky and Beeswax.

My PC bullets shoot as well as the non-PC bullets. But, that may be an issue with my skills rather than the bullets :) The 210gn bore rider I shoot requires PC to fit the bore properly and it shoots as well as the lubed bullets (not bore riders). But, I like the convenience of the lubesizer and a one step process. It just happens that the longer bore rider is a better bullet at long distance for me.

Sorting is done by weight and visual. I put the bullets in 0.1gn batches and visually inspect for flaws. I usually have 5-10 bins of bullets, eg, 167.1 to 167.7gn. For 'matches' I will pick only the heaviest bullets, eg the 167.5, 167.6 or 167.7. Each 'match' would be fired with a single weight of bullet, eg, 167.7gn.

From my experience the 0.1gn difference is not that much of a deal, ie, I could probably sort into 0.3gn batches and do just as well. But, the mental thing gets involved :) The bigger factor is the heavier bullets have fewer/smaller voids. This is a factor if you start pushing the RPM of the bullet.

Last target was one of two 10-shot group targets and wind did pick up a bit but was from ~8 o-clock position so group should have shifted to the 2 o-clock position.

One thing I noticed during the match is I cannot put any pressure on the stock, if I do, point of impact and consistency is erratic. The 1st & 2nd targets above were shot with no stock contact at all, not even my right thumb for trigger pull, instead, I used rear of the trigger guard to anchor my thumb.

Alloy used was lino/Pb @ 1:1, sized within 12hrs, then left to harden naturally. Gas checked, lubed, and loaded 2 days prior to the match.

Even though I don’t do cast, yet?, it’s good to hear from a competitor.

Yes, Free Recoil works best from the Bench for Me.

Free recoil works on some rounds for me but not others. When I push my 210gn cast bullet the stock has to be held firmly. But, same bullet at 3-400fps less vel and it likes to be free. Same with jacketed. The 6BR likes minimal stock contact. The .308 with 175SMK's has to be firm. :)

FWIW, these are only 12lb rigs.