The Components of Going Faster

[waco]

This was a few years ago. Rem 700 .308 1:10 twist 30xcb at 2600fps, sub 2moa at 500 yards.
Nice job on the results you are getting!
https://www.youtube.com/watch?v=l9VDouNYi7A&t=2s

[popper]

I'll elaborate a bit on bases. I see vids of guys hammering the plate to cut the sprue. Looks good right? One end is free and the other is under bevil washer tension. Base sprue hole is small but is cut at an angle and is very difficult to measure. It is very difficult to get a good square cut! PB or GCd, same.
Flatness of the plate and squareness to centerline is another problem area. Right, it could be a small angle but at 45-50K psi, the radial component of force on the base could be 5k psi, pushing the base sidewise in the neck. GC fix it? Nope, just seats flat to the base - we hope. High quality moulds help a lot.
Yrs ago I nicked the base of 40sw and got a nice 3" circle @ 7 yds on target. Otherwise an accurate bullet.

[charlie b]

This was a few years ago. Rem 700 .308 1:10 twist 30xcb at 2600fps, sub 2moa at 500 yards.
Nice job on the results you are getting!
https://www.youtube.com/watch?v=l9VDouNYi7A&t=2s

Thanks.

Yep, I followed your video when you first posted it as well as the other thread that is locked now.

My quest goes on, <MOA or bust!

[centershot]

I'll elaborate a bit on bases. I see vids of guys hammering the plate to cut the sprue. Looks good right? One end is free and the other is under bevil washer tension. Base sprue hole is small but is cut at an angle and is very difficult to measure. It is very difficult to get a good square cut! PB or GCd, same.
Flatness of the plate and squareness to centerline is another problem area. Right, it could be a small angle but at 45-50K psi, the radial component of force on the base could be 5k psi, pushing the base sidewise in the neck. GC fix it? Nope, just seats flat to the base - we hope. High quality moulds help a lot.
Yrs ago I nicked the base of 40sw and got a nice 3" circle @ 7 yds on target. Otherwise an accurate bullet.

Popper,
I've found that correct timing of the sprue cut eliminates that angled nub on the base. Cut when it is solid but not too hard. My first step in the inspection process is to stand it up on it's base and see if it wobbles. If it does, it gets re-melted.

[missionary5155]

Always remembering fit of cast projectile to the throat / lead is principle.
But your sure moving that chunk of lead along in good form.

[Larry Gibson]

The use of a properly designed cast bullet, such as the 30 XCB, for higher velocity shooting is one of the ways to push the RPM threshold up. The same with adding copper making the alloy a quadra-alloy instead of a ternary alloy. As does adding a "jacket" of PC, paper or copper/brass.

Charlie b is certainly pushing the Threshold up with the techniques he is using. He is doing well in his quest for MOA accuracy at HV.

[charlie b]

The difference with mine is the LARGE bore riding portion of the bullet. I keep threatening to make up a large catch box so I can recover some bullets without distorting the noses just to see how much they engrave in the bore or if they upset to fill the grooves.

I do not take a lot of care with the sprues. I do know that they are mostly flat, but, I don't inspect them that closely. I do make sure to put the GC's on square to the bullet and inspect to see that they are. At one time I used a dial indicator, but, it showed so little variation I quit that one.

I have two theories there. 1) the chamber pressure is enough to drive the GC onto the base and 'flatten' any irregularities. 2) the pressure really does nothing to move the GC during the trip through the bore so it stays where it was seated. Don't know which and don't really know how to check. I've measure the grease groove above the GC before and after firing and find no differences. Don't know if that means anything or not, except maybe the few bullets I have recovered were ones with 'flat' bases before seating the GC?

A lot of these questions we are asking could easily be solved if we could gather the correct data. It may also tempt me to do some 'test engineer' stuff. I used to get paid a lot of money for doing that kind of stuff, so will see what I can do without deep corporate pockets

[charlie b]

Always remembering fit of cast projectile to the throat / lead is principle.
But your sure moving that chunk of lead along in good form.

Very true. The bore riders I use are an interference fit in the bore. I also try to set the bullets such that the first drive band is slightly engraved into the rifling. If I decide to unload a cartridge I have to 'tap' the bolt handle to get the bullet out of the bore. And, yes, sometimes the bullet stays in the bore and has to be tapped out with a range rod.

So, there are two 'reference points' on the bullets. The lands touching the nose section and the drive band engaging the tapered portion of the throat.

I also check runout on the loaded cartridge to make sure the bullet is not angled in the case. I ended up modifying a Lee seating die to make that a non-issue anymore. The Lee die had just a bit too much 'slop' on the sliding section of the die so I shimmed it to be a closer fit.

[405grain]

This is an excellent thread, with a treasure trove of information. My skill sets haven't progressed to the point where I'm ready to extend my cast bullet ranges out the point where I'd need high velocity, but much of the information that has been presented will certainly benefit accuracy improvement at regular velocities. Some of the recent posts have mentioned how cutting the sprue can leave a bullet with a less than perfect bullet base. When I read this I had a thought. When reforming brass to convert one caliber to another, they make a thing called a "cut-off die". This is a reforming die that's made from hardened steel, so that the brass that protrudes from the top of it can be cut off with a hacksaw. Why don't they make something like this for cast bullets?

What I'm visualizing could be made from a pair of blocks of heat treatable steel and a drill press: Make up a pair of blocks that have alignment pins and faces that match together, not too different from a set of bullet molds, but don't need slots for mold handles. Machine a hole into the center of this block set, again - similar to a bullet mold. There doesn't need to be any features in this hole, ie: driving bands, lube grooves, ojive, etc. You don't need any of these, it's just a smooth hole. The inside diameter of the hole is the same as the outside diameter of your bullet. I'm going to call this a "guide hole". When you place a cast bullet nose down in the hole in these blocks the base of the bullet will be flush (actually slightly above flush) with the tops of the blocks. You can even have a threaded hole under the guide hole, or shims, or something, so that you can use a set screw to adjust the height of the bullet when it's held in the blocks. Now heat treat the blocks so that they're good and hard.

The way I envision this working is that you close the hardened blocks with a cast bullet inside. The blocks hold the bullet in place. The bullet base is ever so slightly above the level of the tops of the blocks. With one or two swipes of a sharp file you will have a flat & perfect bullet base. If you want to go crazy you could even make up a set of blocks with multiple holes. Will it work? Who knows!? To the best of my knowledge it hasn't been tried yet, but on paper it sounds like something worth trying.

[Digital Dan]

This discussion makes me smile a bit. I’ve learned how to make lead do what’s needed for my purposes, some of it on this forum. Fastest I’ve used are in the .30-30 in the neighborhood of 2200 FPS. Another thing learned before I started casting was the art of paper patching. 300 gr of pure lead properly patched is good for 8 shots sub MOA at 100 with max loads in a .44 mag., velocity ~1600 FPS. It is also quite the hammer on hogs and deer.

Should I ever feel compelled to go fast with lead it will be a bit harder than pure, and paper patched.

[charlie b]

Some of the accuracy 'nuts' in the past developed nose pour molds for the reasons we are discussing. I think Pope used some in his accuracy testing. Eagan was also one of those. The bullet I use is a copy of one of his designs, originally in a nose pour mold but mine is a conventional design mold from Accurate.

Yes, there are all kinds of dies you can make to 'fix' issues with cast bullets. I know at least one person who made a special die for seating gas checks. As above, a bored hold to precisely fit the bullet and a slightly rebated section where the gas check was placed. An arbor was used with a 'standard' nose punch to seat the bullet squarely in the gas check.

FWIW, I paper patch bullets for my muzzle loader.

[Bigslug]

I think Charlie b is pointing in a good direction with his mention of nose-pour molds: getting the perfect sprue cut is a challenging thing. I've definitely proven to myself that protruding spurs under the gas check are detrimental to accuracy, and if pits torn out by the cutting action cause problems as well, moving that entire process to the nose would have much to recommend it.

[Larry Gibson]

When I inspect my match cast bullets, if they pass a visual test under a magnifying glass and have an uneven sprue cut, I lay the bullet on a block of lead and cut the uneven sprue off with a sharp knife. The bullet is then weighed for sorting. With such bullets the Hornady GCs fit evenly and the shnk bottoms out evenly in the GC using the GC seater on my 450 Lyman with a .311 H&I die which initially crimps the GC.

[charlie b]

Well, a bit of a setback today. Loaded up some more. The 38gn load of 4166 and then three of n150, 38, 39 and 40gn. The max load for n150 and 208gn bullets is just over 40gn at just under 2400fps. Should be about right.

Set everything up at the 600yd target line this morning. Temps were in the mid 40's and small gusts, less than 5mph. Lots of mirage.

I started out and couldn't hit anything. Then realized I had the scope set for 500yd. Changed that and tried again. Then remembered the last windage was for a 5mph wind and it was near calm today, so more adjusting. Finally got a few close to the gong. The mirage was making things a little difficult as well.

The funny stuff started with the 39 and 40gn loads. 3 rounds into a smaller area, then one off the board. 3 more ok, then two off. All of this tracked with some large jumps in vel. Then I realized it was really easy to chamber some of the rounds. Another duh moment. One of my more brilliant ideas was that my crimp die might be damaging the bullets so I backed it off a little. I think too much. I was probably just pushing the bullets deeper in the case, resulting in wild velocity swings.

And just to add to the problems, the mirage made the video not as informative. No 'trails' to follow, just impact points.

Back to the drawing board.

Good news is, the bullets that did show 'correct' velocities tracked pretty true to the target at 600yd. So, I have a couple of loads that will work at this range.

[Forrest r]

A couple years ago I was testing the xcb in a 308w. Kept getting groups like these.
[IMG][/IMG]

Didn't matter what powder I used/tested I kept getting fliers and when I ran them faster I got shotgun patterns instead of groups (+/- 12" groups for 10-shots @ 100yds).

When I cast my bullets I always run the sprue plate back and forth over the bullet bases several times. Doing this gets the bases flat and shows any imperfections.

I make my own gc's out of aluminum and tried flat cup bottoms along with a beveled edged bottom pictured below.
[IMG][/IMG]

I made special dies for the lyman 450 and a swaging press to nose form bullets along with seating the gc's.

I've ran into nose slump issues pictured below with using bullets cast from a 2-cavity crmer mold. 1 cavity is a sp bullet the other a hp/flat nosed bullet.
[IMG][/IMG]

Ran into lube issues with the lee 312-160tl bullet blowing out at 2600fps.
[IMG][/IMG]
Added more lube and the 2600fps group tightened up.


I can drive the lee tl bullet pretty fast with reasonable accuracy. But every time I tried to push the xcb bullet it was a disaster. Same alloy, same gc's, same dies, rifle, etc. I can use the lee bullet with 37gr of h335 and get 2600fps+ 10-shot groups @ 100yds that are 2" or less. 37gr with the xcb and it was hard to keep 10-shot on paper @ 100yds.

Finely decided to order 1000 hornady gc's and seat 20 of them on the cast xcb bullets. I loaded those 20 bullets up with that 37gr load of H335 and went to the range & set a target up @ 100yds. I shot 2 different 10-shot groups and I couldn't believe it. I still had fliers with 7/8 bullets touching. The fliers made the groups +/- 1 1/4". Of all the times not to take a picture, darn wasn't thinking. Actually I was ecstatic with what I saw.

The only thing I can think is that my al gc's were too hard and weren't staying on the xcb bullet with the higher pressured loads.

[Larry Gibson]

Forrest r

I never got any consistent accuracy with aluminum GCs [my own make using .014 flashing] over 2000 - 2200 fps with any bullet. Best success up through 2200 fps was in the 14' twist. N ever tried in the 16" twist. My own brass GCs (.014) do well up through 2600 fps in the 14" twist. Again, never tried them in my 16" twist. Have been using Hornady GCs mostly for HV.

At HV/RRPM the loss of the GC can definately have a detrimental effect on accuracy.

[charlie b]

I had horrible trouble with fliers until I tightened up the weight sorting. I started out using batches of bullets in 0.5gn groups (eg, 165.5 to 165.9). That helped a bit, but, I did not get to 1 1/2 MOA without going to 0.1gn batches.

I also found same as Larry has mentioned. Selecting only those at the high end of the weight spread also helps. For example, I usually have a spread of about 1.0gn when I cast, eg, 210.6gn to 211.6gn. The 211.6gn bullets give a bit better groups than the 210.6gn batch. This is even more noticeable as the speeds increase.

I will only use Hornady checks, simply because of how deep I have to seat the bullets in my .308. If the GC is not a crimp type I don't trust it when seated below the case neck.

[charlie b]

Well, pushed the limit a bit again. I tried the n150 and the accuracy was not there at all, even with loads in the 2200fps range. But, I found some H4350 for sale so I got some. This is a lot slower than the previous 4166 so I was hoping it would help a little.

For reference the Sierra max load for a 200gn SMK is 45.1gn and 2450fps. I loaded up my 'reference' load of 31.0gn of 4166 and then 43, 44 and 45gn of H4350. Bullets were all 211.6 or 211.5gn. Bad news is the video camera battery went dead. The good news is I still track where the shots hit so I have a decent idea (within limits) of how well they shoot.

Surprise, the 45gn load average was 2425fps with an es of 33fps and yielded almost as good a 'group' as the 31gn reference (1970fps). Temp was in the low 40's.

Also, unlike the max 4166 loads, the cases were not sticky at all to extract.

So, Larry's idea about a 'softer' push from the slower powders has shown some better results. This is as fast as I will drive these bullets given all the book data out there.

So, will load up some more and see how they do at 600yd. Also will punch some paper with it next time. Will have to wait a while as other things come up.

[charlie b]

So, have done a lot of shooting since last post.

The heavy 4350 loads and 4166 loads did not show consistent performance. One week I could keep everything on a piece of paper at 500yd (including 5 round 4 and 5.5 inch groups), other days I was lucky to hit it (8.5x11 targets). I have compared loads with bullets at the top of the weight curve and they sometimes do better, but, not always. Also tracked wind and temperature and they do not seem to matter. The only thing I can come up with is that I am on the edge of rotational stability.

I still get decent groups at 500yd if I keep the vel around 2000fps so that is what I will do for now.

So, I am back to the lower velocities I started at.

I am still considering a slower twist barrel so my quest is not over

[4575wcf]

I have been shooting cast bullets for quite awhile in the lever action/military cast bullet matches. Bullet performance on game didn't matter, I had unmentionable bullets for that. I always cast with Hornady hard lead shot and quenched from the mold into cold water. I had good accuracy with my bullets on the 200 yard ram, and enough stomp to knock him down as long as I used the heaviest bullets I could get for the caliber. Then the shortages hit and I was not long building up a hunting rifle for cast. I chose the 8 x 54KJ round because it fits the small ring '91 Mauser I had so very well. It is a necked up 6.5 x 55 Swede and it has killed literally thousands of Scandinavian moose in the Norwegian Krag Jorgensen and the Swedish Mauser. Not that the 6.5 x 55 won't put them down, but the 8 x 54 puts them down a bit better, and so it exists. Now it has gone obsolete more or less, Scandinavian shooters are no different than any one else when new and better products become available.
So with the rifle built up on the '91 with a '93 Turkish 8 x 57 barrel shortened up from the breech end to clean up the chamber and a modified 6.5 x 55 Lee die set, we are off and running. The rifle shoots the Saeco 8 mm 190 RN cast in my regular alloy into an inch at 50 yards all day long up to about exactly 1700fps. The it just quits shooting. Period. I exhumed a few bullets from the soft dirt bank on the property and really there isn't anything noticeably wrong with them at a higher velocity. The target tells a different story with obvious oblong holes. I think I have been confronted with the maximum rpm that this cast bullet alloy will withstand without the rifling grip breaking loose. I am already casting them a bit hard for hunting IMO. With my Mauser 1-9.45 twist that threshold should and does seem to happen at almost exactly 1700 fps. One manufacturer makes an 8mm barrel with .324 grooves and 1-12 twist; I think that will be the blank going into the rifle next since it is almost affordable, but a heck of a lot of work. Again. So many folks that have fired so many more cast bullets than I seem to be arriving at the same conclusion I don't think I need to reinvent the wheel.