THE ONLY WAY YOU CAN HIT THE CENTRE OF THE TARGET IS WITH A CENTREFIRE!!!
What it is bullbarrel033 is that many can't shoot cast at high velocity (which means high rpm) from fast twist barrels. There are a good number of people here past and present that can do it. It takes what I call extreme reloading to achieve it and it can be done and it can be done without using the very hard alloys like Linotype. Runfiverun and his daughter can do it with a very fast twist AR 15 in 5.56. RPM only acts upon bullets that are not started straight in the bore or have a defect in them. It is very hard to do with shallow rifling. Cast does require deeper rifling. Over the years manufactures have been making rifling grooves more shallow. Custom barrel makers will give you just about anything you ask for.
all of my testing has shown that the twist just finishes off what would have been poor on paper performance anyway.
Getting a PERFECT bullet straight and truly centered in the rifling is far more critical than twist rate - provided twist is not TOO SLOW. The slower twists are more forgiving to bullet imperfections and chambers and throats that allow a bullet to enter the bore without being aligned properly. Bullets that can be damaged by the rotational stresses also benefit from the slower twist.
That's absolutely right MostlyLeverGuns. When a bullet goes to sleep what they are talking about is the bullet is unstable right out of the muzzle. By the bullet spinning there is a gyroscopic action that is constantly trying to stabilize it. When it finally does that's when it goes to sleep. That is unless the bullet is very defective or was started into the bore very crooked. Higher rpms have a stronger gyroscopic force. Lack of this is mainly what is wrong with a slower twist and it's slower rpm, especially if the twist was just barely fast enough to stabilize the bullet. The thing that is really going on is what the rifling is doing to the bullet while it's in the bore. This explains one reason why paper patched bullets shoot better then naked cast. Larry Gibson knows this and is why he came up with his rules to shooting cast at high velocity. Hey! Who made him boss on telling us what rules we have to follow? Some of his rules are it has to be a ternary alloy. We can't paper patch it. Then he imposed some group size with so many shots and groups. He has it set up so it's hard to beat his theory. Back to the rifling damaging the bullet. You can paper patch a very soft alloy and get good accuracy with high velocity and high rpm. A cast bullet that is hardened is not the same hardness in the center as it is on it's surface. Yet this hardness on the surface isn't strong enough for some rifling. These riflings are of either a very fast twist or are very shallow. The 5.56 is a very good example of this as it has both attributes. Something changes on the surface of the bullet after it's been subjected to the above. I don't know what it is, but I'm thinking it's molecular. To tell more on my not knowing what it is, if you were to capture a fired bullet that was exposed to fast twist and/or shallow rifling and was undamaged you wouldn't see anything unusual. I've recovered bullets fired at high velocity from fast twist, not in good shape, but enough of the back end of the bullet to show me the rifling grooves. There was no skipping what so ever. There wasn't even an abnormal force side of the land ridge. An example of this is that it's extremely hard to shoot high velocity with accuracy from a 7 twist 5.56. This is because most all of them have shallow rifling grooves. On the other hand, a rifle that will shoot high velocity accurately is the 6.5x55 Swede and that rifle does have deep rifling.
Previously a few of us have searched for a formula to figure out the force put against the force side of the land in the rifling. All along it was right under our noses in the NRA Cast Book. Here it a copy of that formula.
I know many of you are not interested in high velocity cast bullet shooting, but many of you do have rifles with the faster rifling twist. Don't let someone try to discourage you from shooting high velocity cast loads and don't let that person dictate what rules you have to follow. One thing is certainly true about shooting high velocity with accuracy from the faster twists and that is it isn't easy but it can be down. One of the posters in this thread has been doing it for a long time and that is runfiverun. There are many more. Another thing is that shooting Linotype at high velocity willwear your throat out exceptionally fast! You don't have to use Linotype to achieve this. It's very satisfying to shoot cast bullet at jacketed bullets with accuracy at high velocity even just at paper targets.
Now to decide 3, 4, 5, or 6 grooves.
Fair question. I have a switch-barrel Sako with 14" and 16" twist .30-'06, pillar bedded into a McMillan M40A1 stock reinforced with 600 mesh stainless steel wire and aluminum box girder stiffened fore-end. Barrels are by B.J. Obermeyer with Min. SAAMI body dimensions and 0 degree, 45 minute basic forcing cone from .3104 major diameter with .339" neck.
With Sierra 155 Palmas and 52 grs. of IMR4064 in FA60NM cases neck turned 0.012", Federal 210M at 3.34" OAL series of five 10-shot groups off return to battery rest at 300 metres average 5.5cm, about 2".
Good cast loads with 40 grs. of IMR4064 with HM2-.312-160-5 quenched wheelweights, same components, light press into rifling origin with nose engraving run 6-7 cm, not too bad for cast at 2200 fps. Edge is to the 16" twist, but hard to nail down solid without access to a tube range, which I don't have anymore...
The ENEMY is listening.
HE wants to know what YOU know.
Keep it to yourself.
Here's what I call "scary accurate"....the distance is 100 yards but both hold 1.5 moa at 300 and 400 yards. Both bullets cast of Lyman #2 alloy, WQ'd and lubed with 2500+.
308W with 311466 out of 14" twist barrel taken off a Shultz & Larson Palma M98 and refitted to my M98 action (byf WWII make). Chamber finish reamed with a Clymer M118 Match reamer (that's not a ".308W chamber" btw even though they are, in actuality the same). That is not a throat that was cut to fit the bullet.......however, the bullet was sized to fit the throat which is what is important. Note the velocity is 2600+ fps.
Attachment 208768
Here's a 20 shot group out of the cold clean 16" twist Broughton barrel on my CZ24 M98 action chambered in 30x60 XCB. This one does have a throat cut to fit the bullet; a NOE 30 XCB 310-165-FN. I marked the 1st shot, the fouler which is out of the group at 11 o'clock. The 2nd shot is out at 2 o'clock and the other 19 went into basically moa. This is my standard load for this rifle. The velocity is 2950 fps.
Attachment 208770
That is what can really be done as demonstrated and proven using sound testing and understanding the science of ballistics and physics. Those who continue to believe in the old disproven myths will continue to babble on but actually show us nothing.
Larry Gibson
“Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
― Nikola Tesla
Larry that is some very good shooting from both twist rates, and velocities of 2600 fps in the 1:14 twist and 2950 fps in the 16T, superb! Now for a question, do you think either one of those loads would put any or all of the shots even on 100 yd paper at the same speeds out of say a 10T barrel? I'm thinking maybe a few random hits and some sideways impacts, I guess if 4 or 5 landed close to each other you could circle those and claim accuracy. What do you think, I know you've actually tried it.
Charter Member #148
swheeler
"Now for a question, do you think either one of those loads would put any or all of the shots even on 100 yd paper at the same speeds out of say a 10T barrel? I'm thinking maybe a few random hits and some sideways impacts, I guess if 4 or 5 landed close to each other you could circle those and claim accuracy. What do you think, I know you've actually tried it. "
Depends on how large the "paper" was.........On a standard 100 yard military target of 21x21" aiming at the center with the 2600 fps load you may or may not keep 10 shots on paper. Probably 1 or more would be off paper. Keyholing would be apparent in some oblong shaped holes. it is possible several of the bullets would form some semblance of a "group". You might even get lucky (not really luck but simply "random dispersion" within the cone of fire) and have 3 or so land close together.
With the 2950 fps load......some might be on paper, most probably not. Keyholing would be the norm, either partial or full keyholing. If you shot enough shots you might get 10 on target with maybe 3 or so landing close together due to random dispersion.
I have pushed both the 311466 and the 30 XCB to 2700 fps in the 10, 12 and 14" twist test rifles (.308W). The results with the 10" twist were as described. With the 12" twist most of the bullets were "on paper" but above 2500 fps keyholing began. Up to 2400 fps +/- results with the 12" twist were actually quite good. With the 14" twist results were very good as shown by the target posted above.
I also have duplicated a supposed 3100 fps load with a 122 gr cast bullet, the 311465. The braggart claimed a 4 shot incredible group out of a 10" twist AR10 with a 20" barrel pushing that weight cast bullet (he use the comparable Lee bullet) with H4198. I found I could not duplicate the velocity he claimed w/o getting 65 - 70,000+ psi as measured in the test rifle. The test rifle also has a 24" barrel. At 250+ fps less than the 3100+ fps the braggart claimed I had severe keyholing and a very large dispersion on the military target with a couple shots not hitting paper. The braggart posted the "group" but it was a cropped picture showing what he claimed was 4 shots in basically a moa group. Close examination reveals there is one shot and a complete keyhole next to it. When we look at his un-cropped picture of the whole target (actually he had a couple targets side by side) we see a very large dispersion with keyholing predominant. He probably just shot a lot of rounds at the target and then claimed the close hits as a "group" cropping the photo. He also posted that in his usual attempt to "one up me" as I had just posted the 2950 fps groups and he goes out of his way to prove me wrong. Thus he had to claim a higher velocity with better accuracy out of a faster twist......his usual absurd claims.
What myself and others have shown here, plus others in other threads, by posting actual results is we can actually accomplish what we claim. Those that just talk about what they've done or what someone else has claimed are....well.....just talking about it.......
Larry Gibson
“Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
― Nikola Tesla
Yes they would swheeler, it's just that you and Larry can't do it especially with plain stock rifles. In fact I've never seen you get into the 6.5 Swede threads except to just run your mouth. There have been many that have done it. Ask Runfiverun about his daughter shooting the seven twist AR 15. Plus you've seen the 1/2 hole stametal shot with his 6.5 Swede, but you and Larry called him a liar. 45 2.1 has more then one Ruger scout doing that.
Notice that Outpost posts his shooting results and he filled us in pretty well on the equipment, loads, etc.. But no target pictures no and no chronograph pictures, and no ES's, SD's, etc. Outpost this by no means to demeaner you. It's a point to show the members, read on. Now if me, starmetal, or 45 2.1 done this Larry Gibson and his minions, especially swheeler would be all over us for those pictures of the targets, chronograph screen, etc., etc., and calling us liars to boot.
BTW Those cast bullets not only will stay on the target at 2700 fps or whatever high velocity, but shoot pretty respectable groups. Don't let those two birds fool you.
Vzerone
Try actually reading the posts before whining. All 10 shots were counted in the top group. All 20 shots were counted in the bottom group......it's written right there....a 1.6" group including the fouler.
As to what outpost75 posts....he does indeed post lots of detail along with pictures OF WHAT HE DOES. All you post is what someone else does or says they do.
Before you call the kettle black you should remember what you, your twin, 45 2.1 and others have called me and many others on this forum.
You need to get a life, try actually casting some bullets, shooting them and posting the results instead of regurgitating what you can plagiarize off the internet.
Larry Gibson
“Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
― Nikola Tesla
BP | Bronze Point | IMR | Improved Military Rifle | PTD | Pointed |
BR | Bench Rest | M | Magnum | RN | Round Nose |
BT | Boat Tail | PL | Power-Lokt | SP | Soft Point |
C | Compressed Charge | PR | Primer | SPCL | Soft Point "Core-Lokt" |
HP | Hollow Point | PSPCL | Pointed Soft Point "Core Lokt" | C.O.L. | Cartridge Overall Length |
PSP | Pointed Soft Point | Spz | Spitzer Point | SBT | Spitzer Boat Tail |
LRN | Lead Round Nose | LWC | Lead Wad Cutter | LSWC | Lead Semi Wad Cutter |
GC | Gas Check |