Made a little progress today with the 6mm BR, but still have a ways to go to meet my goal of ten shots in 1 MOA at 2700+ fps. Powder was WC844 for all loads. Several different spitzer bullets tried to see if it preferred one weight over another -- it doesn't seem fussy in that regard. Target is at 100 yards, of course.
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The bullets I was testing today. They were nose-sized in a die that matches the throat, for an Ardito-style fit. I just guessed at how deep to nose-size them so I dunno if that is optimized. The deeper you run them into the nose die, the further they have to be seated out to make contact. I generally aim to end up with the GC and one band inside the case neck. Seat about 0.020” long and let the action finish seating when chambered for a slight jam fit, following the general recommendations of John Ardito. A tip-to-tail taper may optimize support upon chambering, but similar to a bore-riding bullet the tapered bullet nose may lack adequate support when the pressure kicks in. So there may be a trade off in how much you leave full diameter vs. how much you taper to fit the leade.
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You're shooting cast faster than I'm shooting 90 gr. Bergers. I don't yet have 100 rounds through the rifle--when I discover the ins-and-outs, I'll be switching to cast only. The Bergers are doing 2587 ahead of 26.5 gr. of Varget; bullets are seated to touch the throat. Lighter bullets don't seem to group as well, but, as I say, I haven't really gotten a fair start yet. BTW: The rifle is a Savage M 12 BR with a 36 power Weaver scope. So far, I'm very pleased with the rifle. Now, if only the temp. at the range would shoot all the way up to a 40 degree Heat Wave, I could get some real shooting in. Congratulations are due you for your fine progress; obviously you're on the right track. When I get things sorted out, I'll probably be asking questions of you! Stay with it!
Bill
In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.
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Rifle is a M700 in a Richard's Microfit stock. I'm not planning to compete with it so I did not concern myself with the weight or the stock dimensions other than what fit my budget and my purposes. http://i487.photobucket.com/albums/rr235/mountainmolds/rbr_feb13_15_zpsigmsivsh.jpg Weight ended up at 16 pounds and change after adding the Sightron 36x scope.
It'll be a nutless switchbarrel used for testing and experimentation with different calibers. The 6BR and 7BR barrels are factory second Pacnors that have odd dimensions but otherwise look decent. I only paid $90 for them. 
All 14” twist except for the Krieger which is 18".
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Wow! I am thoroughly impressed! You've got a plethora of calibers, and the potential for some really great accuracy research. Silly as it may seem, I find myself sitting here getting excited at all the potential I see in your photos, (Which, BTW, are excellent.) Be sure and stay active on the forum, keeping us advised of what's going on, (time permitting, of course!). I can hardly wait for the information to start pouring out!
Bill
In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.
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I can hardly wait for the information to start pouring out!
BillI'm afraid it'll be more like a trickle :D
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After shooting the 3104 fps load, the barrel had a little grey color in the corner of the groove in a spot only a few inches long, mid-barrel.
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Looking at your pictures has my wheels spinning - slowly of course. I don't see why a similar approach wouldn't work with a 22-250. I have a barrel but I didn't know how to facilitate its switching on a donor rifle. Is the “nut” milled into the end of the barrel or is it welded on. Jim
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The hex is milled. You can also use a barrel clamp, it just takes a little longer.
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When you get a little time please say a bit more about the “poly u coated." Very interesting keep em coming. John
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John, I've submitted an article on coatings to Glenn and don't want to give the entire article away on the forum before it has been published. Basically thinned oil-based polyurethane, shake-n-dry application, 2 or 3 thin coats for a total thickness of 0.0006” - 0.0010". How To Apply. I've started to test water-based polyurethane, initial results were disappointing but there were complications so I haven't reached a conclusion yet. In general I've only achieved a slight improvement by coating GC bullets, but at high velocity I'll take every little improvement I can scrounge up. Coating can sometimes make a dramatic difference on plain base bullets.
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A lot of this is out of my league, technically. But, I have a question about your trigger. Stock Remington? I ask because I'm working with a 700 SPS .223 with a factory trigger.
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Trigger is a Jewell with the 2 ounce spring. I don't have a way to measure that low but it feels more like 3 or 4 ounces. I haven't tried to adjust the trigger other than the return spring preload. Anyway it is light enough that I can shoot free recoil and I do believe that free recoil reduces human error.
I haven't tried the new style factory trigger but based on what I've heard, if I had one I'd replace it with aftermarket. The Walker factory triggers could usually be tweaked to under 2 pounds but there were some reliability issues.
I originally bought a Basix ERV-3 trigger for this project but then decided it made more sense to put the Basix in my hunting M700 and put the hunting M700's Jewell into the benchrest gun. The ERV-3 is a decent trigger, too, going down to 4 ounces.
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I used to run a hair over 2000 FPS with a 160 grain gas checked LBT LFN bullet in a more or less stock 7mm BR XP-100, using H322, with typical group sizes of 0.75” @ 100 yards.
It's a good powder for stubby bottleneck cartridges, and it should easily get you to 2700+ FPS with the bullet weight you are using. For me, the accuracy was definitely there, so it might be worth trying if you haven't yet.
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I don't have any H322 on the shelf to try at the moment. You are the 2nd person to recommend it so it's on my “to buy next time I order powder” list. Thank you for the tip. :)
Reloader 10 has given slightly better accuracy than WC844 in this barrel, but ... I have 16 pounds of WC844 that has been gathering dust for lack of an application so I'll use WC844 for most work and maybe switch to RL10 as a Hail Mary pass. :D
But .... understand that this project is not about conventional “load development” where you try different powders, charges, etc.., to find the most accurate load. This project is about experimenting with cast bullets to understand how cast bullets work and how to make them work better. If I can set some personal accuracy records, that will be a bonus. :)
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Today I was playing with plain base bullets but the barrel showed no love for the 62 grain bullet I fed it, with ten shot 2 MOA the best it would do at any velocity between 2000 fps and 2500 fps. I'll try again with perhaps a 75 gr. plain base.
I did do a comparison test of a smooth coated bullet vs. a grooved coated bullet but I'm going to give Glenn an article on that and don't want to spoil the story so you'll have to wait for it to be published. :D :D :D
Somehow I ended up with ten 74 gr. GC loads left over from last week except with the powder charge reduced a bit, so I went ahead and shot them and they turned in about the same accuracy as last week despite the lower velocity. At least they're consistent. :D :D :D
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I don't have any H322 on the shelf to try at the moment. You are the 2nd person to recommend it so it's on my “to buy next time I order powder” list. Thank you for the tip. :)
I use H322 in an abundance of things . And I've found IMR8208 to be almost the same thing . Which means I like them both anyway if you have 8208 you can do the same things as what you do with H322 . Think I have atleast 8 pounds of both powders at all times !
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Have you given any thought to using Vit powders? I shot a 30 PPC for 5+ years and it seemed to like H-335 and N-133 with N-133 shooting slightly better. 160-180-grain CB's at about 1950-2100 fps. True, the case volumes are slightly different but maybe worth a try despite the higher cost of the Vit powders. I've never owned any H-322 so have no experience with it.
Tom
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Tom, thanks for the tip on N-133. I have nothing against Vit powders other than I don't own stock in the company. :D :D :D
I live in a remote area and everything has to be ordered, which means haz mat fees and signature required which is a royal pain because the driver won't come to my house, so I have to arrange to meet the driver which is easier said than done. That puts a damper on buying just one pound to see if my gun likes it. :(
I took a chance on a jug of RL10 for this project based on how it performed in Quickload -- it had a slower pressure rise than other powders with similar burn rates. So far RL10 has worked well but I only have 5 pounds so I am hoarding the RL10 and using WC844 as much as possible. :D
There are not that many powders that can hit 2700+fps in the 7 & 30 BR, and they're mostly fast burning like H322 and H4198 which worries me with regards to cast bullets. Colonel Harrison recommended slow powders for hi-vel cast and I have found that to be good advice, though one CBA competitor used H322 to win the 2006 national unlimited match with a 30BR at 2750 fps, so apparently it can be done and that's why I added H322 to my wish list. :D
If the fast burning powders don't work satisfactorily in the 7 & 30 BR then I may rechamber them for the 308 case so I can use slower powders. The BR case seems perfect for 6mm.
1.5” - 2” ten shot groups may not sound like much but bear in mind that I was averaging 3” at 2700 fps with previous rifles having fast twists. Occasionally they'd shoot a lucky 1.5” group but couldn't do it every time. So a consistent 1.5” group is progress, and there are many things to try yet.
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Another area to research.....the “newer” CBA BR gun category of Unrestricted Pistol. Some of the guys were trying faster twist (than typical .30 cal. rates), light weight (100-125 grain) CB's at elevated velocity in 30 BR. Check out the various match results on the CBA Forum.
Good hunting!
Tom
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