I have read that you can ring a chamber if you don't use Dacron. I use Dacron in the 470NE with RL15, and weigh each tuft to make them all the same. I picked some up at the fabric store.Originally Posted by Doc Highwall
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I have read that you can ring a chamber if you don't use Dacron. I use Dacron in the 470NE with RL15, and weigh each tuft to make them all the same. I picked some up at the fabric store.
I see fillers as another crutch to get you around design flaws or using a powder that is less than ideal. Very useful, but not necessary in this project.
Precision in the wrong place is only a placebo.
Lamar, I am happy to report that at long last, I am very satisfied with your rifle. I stripped out the bedding and redid it giving a very good gap on the forend (there just isn't much wood to remove on this stock) and I bedded in the entire box and bottom. She's tight as a drum. I loaded her up with 150gr bullets and I screwed on a better scope. Today I was cutting 3/4" groups shooting off the hood of my truck. There was horizontal stringing over that 3/4" group, but this time, I know it was me as I am no target shooter, and controlling a light weight stocked rifle is very challenging for me.
Still, I am absolutely sure that in the hands of a shooter of your caliber, this will be an absolute tack driver. I'm not the best shot in the world, but I know when I'm behind a real shooter, and this rifle is definitely that.
I don't know what made the difference, if it was the bullets, the scope or the bedding, but based on past experience, it was probably a little of all three. What was really concerning me was the specter of a bad barrel, but my mind is totally at ease about that after today.
Stick a fork in it it's done!
Bust out the bubble wrap and the packing tape!
Again, I sincerely apologize for the long wait, but I am absolutely committed to making these XCB rifles to hold a standard of accuracy that is above average. Thank you sir for your patience!
We will ship this week.
Precision in the wrong place is only a placebo.
WOO HOOO!!!.
I think it was mostly the bedding.
I have seen the magazine box cause a good mauser rifle to shoot poorly or erratically just because it rubbed/touched in the wrong spot.
I always fully bed the magazine area [and everything else from the barrel to the tang] when I mess with one now.
I may end up with another stock before it's over with, depending on it's bench versus field time.
now to round up some other tools to make this a complete set-up.
How about a Remington receiver with a pinned factory .186 recoil lug to allow for quick barrel change and test. A simple HS Precision or Bell & Carson stock that requires no bedding and a nice looking Remington Varmint/Sendaro contour barrel.
What works best 4,5 or 6 groove rifling (I hear a 4 or 5 groove barrel works best with this type bullet), Narrow or wide land rifling? 1/10 or 1/14 twist (we all know 1/12 works best).
detox
"best" for what?
"this type of bullet"? are you referring to cast bullets in general or the 311466, LBT or the new 310-1650FN cast bullets in particular?
If it's the cast bullets then are you interested in just accuracy or accuracy at higher velocity?
BTW; the 1/12" twist does not work "best" regardless of what "we all know"! Actually a 1/13" twist works "best" for jacketed .30 cal bullets and the 1/14" twist works "best" for most cast bullets, especially at higher velocities with accuracy. Jury is still out on the 16" twist.
The 4 groove barrels with standard "military land dimensions are working quite well. The most often have about 30% lands.
As to the M700 action, no reason that wouldn't work. But let's not forget what seems to be getting forgotten about one of the 30x57 (30 XCB) original design concepts; that is the ability of the cartridge to be used in a standard Mauser action (M91, M93, M95, M96 and M98) with magazines of 3 - 3.3" in length w/o action or bolt face alteration. The 30x57 (30 XCB) retains the case taper of most Mauser cartridges for this reason. The 30X57 (30 XCB) seems to be working out as a well balanced cartridge for cast bullets; the case capacity and long neck features seem very well balanced. so it could be a very good choice. However, there are numerous other "standard" cartridges that would do as well in other actions that don't need feed rail alteration.
Tim (goodsteel) is building rifles with the entire "system" designed to keep the bullet as concentric as possible to the bore for better accuracy. What he does for the 30x57 (30 XCB) he can do for those other cartridges also.
My concern here is if we stray to far from the original intent of the cartridge it just becomes "another cartridge". Quite frankly, given equal quality of rifles, barrels and chambering, with 10 or even 12" twist I don't see the 30x57 (30 XCB) giving any better results of accuracy or even velocity with accuracy as any other similar cartridge of .30 caliber or case capacity. Where the 30x57 (30 XCB) really shines is in Mauser actions w/o feed rail action modifications, the longer neck for cast bullets and the well balanced case capacity.
Larry Gibson
Last edited by Larry Gibson; 09-13-2014 at 10:46 AM.
I was referring to the 310-1650FN or the Lee 160 Harris design.
Just kidding about the 1/12 twist, but that is the twist I would use.
My Remington 700 VS with its large 308 NATO chamber (.3115 diameter and long .150 leade) loves the taper nose designs. Barrel is 1/12 twist, 26 inch long, with six groove narrow .040 rifle lands. Looking at pound cast, chamber is cut slightly off center, but still shoots verygood. I have cut dime size groups using 24 grains of 4759 powder with the Lee 160 (linotype alloy sized in .311 die and spring back to .3115) velocity about 2300-2400fps. Bullets were hand dipped in thinned Lee Alox then rested on bases, top of wax paper to dry over night.
I have to flare gas checks to make them fit the Lee 160 without shaving. I also sand skirts evenly on granite slab. I then size and seat GC dry upside down in my Lubramatic using RCBS 165sil hollow tip nose punch.
When casting I open the sprue plate by hand to cut sprue flush with base of bullet. This allows for a better flush gas check fit.
Last edited by detox; 09-13-2014 at 11:19 AM.
Page 107 of Lee reloading manual states Linotype bullet with BHN of 22 can tolerate a max pressure of 27914 psi. Monotype goes higher. Higher pressures than recommended for certain alloy will cause inaccuracy.
You may prove them wrong.
he is incorrect. and correct at the same time.
for our uses he is incorrect.
I have never and never will shoot a lino-type boolit at 24-26-2800 fps.
wait I take that back I tried a batch of 50 at 2800fps in my 9 twist 223 and went back to half that for accuracy reasons.
Detox,
Read post #604. Larry is shooting Lyman #2 at 40K psi pressure with good accuracy. The right alloy can take more pressure than what Mr. Lee suggests.
Bjornb is correct. I already have disproved Lee's pressure/alloy theory as have numerous others. While pressure plays an important part it is not the primary part as Lee's theory suggests.
Larry Gibson
Larry I read all post, but could not find dimensions of reamer used. What is the throat taper angle and leade diameter and length.
tight saami 0-6
http://www.saami.org/pubresources/cc...pringfield.pdf
this should help.
I am quoting this from another forum, I hope it helps:
"When I was building and shooting bench rest cast bullet rifles we approached the fitting of tapered bullets to the guns's throat a different way. We used a bump press to taper any cast bullet to fit the tapered throat of the gun. There was an added benefit as by bumping the bullet in a die, the gas check and the base could be made dead square with the centerline of the bullet. The gas check was also very flat on the bottom and the amount of bump force was adjusted to still maintain a small radius at the base edge of the gas check.
Most used one degree included angle tapers on the lands with a short freebore that was around a thousanth of an inch over bore dia.. Some shot bullets up to 4 or 5 thousanths over bore but I didn't subscribe to that practice. I stayed about a thou. over on the straight cylindrical part of the base of the bullet. My idea was not to size the bullet down in the throat of the gun under the tremendous, violent conditions of combustion but to do it under much more controlled conditions in a sizer/lubricator where everything could be controlled and held straight.
I once had some of my bumped bullets checked on an optical comparator (shadow graph) and they were dead square bases to the centerline of the bullet.
I had my 30BR reamers made with the freebore dia. at .0003 to a half thou. over groove. That way they could be used for jacketed bullet guns too. Then I had a throater reamer made to the dia. and taper I used and throated the barrel to that taper after chambering it. Throating was done in a separate operation but in the same machine setup. I would throat the barrel till the bullet seated about 25 thousanths into the case mouth would just push back a little with the bolt was in battery. That way the bullet was pushed snugly up into the taper and didn't jump to the lands. As soon as it moved, the tapered lands started engraving the whole lengty of the nose instantaneously. Marks on the nose of recovered bullets showed no slippage of the bullet in the lands. And very little distortion to the bullet skin.
I also used that same throater reamer to make the bump die. As you can see, it then allows you to make a bullet that is the exact dimensions of the throat for perfect support when it enters the barrel.
Don Eagan used to use the taper of a standard taper reamer for his moulds. It was a little different than a half degree per side. They all worked well but as Ken mentions a half deg. per side gives you a max length of taper and still leave some straight side on the bullet for the match to the freebore. I made the bullets a slight interferance fit to the freebore to get the best seal and support possible of the bullet to throat.
If you're looking to maximize accuracy, you want to concentrate on bullet to throat fit. Most things that happen that at detrimental to cast bullet accuracy happen in the throat of the gun. By making a bump die, almost any bullet could be swaged to match the throat of the gun. This opened the door to a whole lot of bullets to try.
If you search the archives of this list you will find this discussed in detail several times over.
Tom Gray"
Last edited by detox; 09-14-2014 at 12:09 PM.
Here's another interesting quote:
"Yes, it's not hard to bump up a bullet in an RCBS Rock Chucker press setup. I've heard that this press can generate ~60,000 psi. when it rolls over center at the top of the stroke. It takes very llittle effort to do it. When trying to bump up, I used to get stretching of the bump dies if they were made of 7/8" stock so, I took the bushing out of the top of the press and used stock that was much larger in diameter. Even Drill Rod would stretch and that's pretty tough stuff. Having a thicker wall on the dies solved the stretching problem.
Bumping lead bullets up is less desirable than sizing them down. It's better not to choose a throat that is over .309" and then everybody's 30 cal. bullets can be made to fit by sizing down. In bumping them up, die stretching and bump force make it very hard to maintain a consistent diameter unless you use a soft alloy and shoot them slow. My bump press design was made in such a way as to control where the taper started on the bullet as well as the bump force when the press rolled over center.
Yes, I used alloys of monotype and Foundry type to shoot in the 2500 to 2700 fps. range. This was to minimize wind drift. These alloys always cast very easily too which added to the consistency of the bullets. With properly sized bullets and my proprietary lube, leading was not existent.
I always figgered that using bumped bullets, match prepped Lapua brass in a 30 BR chamber and a match grade SS barrel, with a Stolle action, Jewel 2 oz. trigger, and a 36 power scope, the guns were capable of .3 MOA. Now, shooting that well in the conditions was another story!!!
Tom"
Last edited by detox; 09-14-2014 at 12:09 PM.
No, that's not the throat I used sgt.mike.
Precision in the wrong place is only a placebo.
Bumping up and sizing down too much will give you a bullet where the center of gravity does not coincide with the center of form. That means the center of spin will not coincide with either. All very detrimental as we push the velocity up and increase the RPMs.
Bumping up the nose may be the thing to do in some instances with some bore rider bullet noses but it's not the thing to do for HV shooting. We need to have a bullet that fits very closely the throat diameter. The bearing surface should fit the case neck length and the throat to the leade. There should be no or as little as possible bore riding nose. The lube grooves should be multiple and shallow carrying only enough lube to prevent leading. The NOE 310-165-FN was designed to precisely fit the 30x57 (30 XCB) exactly so with the chambering reamer goodsteel has that was also designed with such a bullet in mind.
Yes that chamber/throat length design limits the bullets weight. One of the goals to this project was to push to 2800 - 2900+ fps with the ternary alloyed cast bullet. That required a bullet weight of 150 - 165 gr maximum as, even with the 30-06 case capacity, you aren't going to safely push that velocity with a 200+ gr bullet. With the case capacity f the 30x57 (30 XCB) increasing bullet weight drops the velocity back down and defeats the purpose of our goal.
Larry Gibson
Throat taper should be very close to bullet taper. What is the bullets taper or angle?
I once emailed Lee asking what the taper was for their Harris designs. So I could have a custom throater cut very similar. Here is their reply:
.
C312-155-2R- 1.62° INCLUDED or .81 degree per side
CTL312-160-2R- 1.13° INCLUDED or .565 degree per side
Lee Precision, Inc.
4275 Highway U
Hartford, WI 53027
phone: 262-673-3075
that's not the numbers ED specced to LEE it's the numbers they changed it to.
the old walt melander molds and the newer HM-2 molds are the correct design..
the serengheti numbers are too loose for what we want to accomplish, in fact things may be tightened up in the future.
and Larry has a firm grasp on what is happening here.
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