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andym79
09-23-2016, 07:37 PM
Hi guys, I was just hoping fro some feed back, opinions and evidence as to a correlation between calibre size and accuracy in cast bullets.

From my more limited experience I would say that getting larger calibre bullets to shoot well is defintely easier.

But assuming you cast perfect bullets and do everything else right do larger calibre hold any inherent properties that make them more accurate or are they just less finicky?

Say for example if I were to be have a single shot built would a .338 or .323 have much advantage over a .308 or .284 bullets out to 200 yards given a similar BC?

I ask because a lot of the single shot guys still gravitate to 32 cal!

I note the 22lr as an exception, beating all my centerfires at least to 100 yards almost every time!

wv109323
09-23-2016, 09:11 PM
I have near zero experience to answer this question, but I would defer to the benchrest guys. They use between .22 to 6.5 caliber bullets for 100 and 200 yard accuracy. I don't know why that would not be true with cast boolits as well.

M-Tecs
09-23-2016, 09:26 PM
The 30 BR is the raining king for the cast bullet bench rest crowd. Pope preferred the 33-40. If I remember correctly the Rowland/Pope record was set with a 32-40.

GhostHawk
09-23-2016, 09:35 PM
Well I have never shot a 6.5, but going by my experience only it can be a confusing game.

Early on I had very good luck shooting Jword 60 grain bthp in a .243 out to 400 yards. I missed very very few long shots and only when the wind was blowin.

Yet I never saw a true cloverleaf till I started working with my .357Mag and .444Marlin Handi rifles.

Both will show a cloverleaf at the drop of a hat if I can do my part right.

I suspect straight wall or nearly straight wall cases may be easier than necked.
Much comes down to boolits and load but much resides in the rifle itself.

I do think that larger boolits resist wind better, but the rifle range I shoot at is underground, no wind there.

In a small boolit traveling at high speed I think any little imperfection can have a much bigger impact.
Be it a bit of lube left on one side, a poor crown, or a bit of runout in setting the boolit in the case.

Takes a lot more to move an elephant than a Gazelle. And the bigger ones are still plenty deadly at half the speed of the little ones. Less rpm, less shove, less stress. But it seems so many fall into the "more power, more speed" trap. As I did myself back then.

HangFireW8
09-23-2016, 10:14 PM
But assuming you cast perfect bullets and do everything else right do larger calibre hold any inherent properties that make them more accurate or are they just less finicky?

Say for example if I were to be have a single shot built would a .338 or .323 have much advantage over a .308 or .284 bullets out to 200 yards given a similar BC?

I ask because a lot of the single shot guys still gravitate to 32 cal!

I note the 22lr as an exception, beating all my centerfires at least to 100 yards almost every time!

Larger caliber/heavier/longer bullets have more wind resistance.

Smaller caliber/light bullets have less recoil, and thus are easier to maximize the accuracy of the human element.

Flat base bullets settle in flight sooner. Slow twist barrels cause bullets to settle in flight sooner, but do not stabilize long, high BC bullets. Short/light bullets have less wind resistance.

Boat tail bullets have a higher BC, retain velocity and retain it more consistently at long range. However they require faster twist barrels, which cause the bullet to take a longer time to settle, limiting short-range accuracy (100M).

The search for accuracy is always a battle of trying to balance these factors.

castalott
09-23-2016, 11:08 PM
Oh boy..Here we go......

From a practical standpoint, I think the cast 30 calibers out shoot everything else. But I've always had good equipment to load/ sight/ shoot them too. That may have a bearing on that outcome.
'
Was this your question?

Dale

country gent
09-23-2016, 11:25 PM
Heavier bullets have a couple things going for them a 60 grn cast bullets 1% range is .6grns while a 500 grainers is 5.0 grains. Form and fillout seems easier and better with the heavier bullets at times. WHile heavier bullets seem to fight wind better than light ones the light ones seem to shed velocity faster. I also think bigger bullets may swell better to seal the bore. The bigger bores also have more surface rifling to grip the bullet. I believe a correctly cast bullet of the correct alloy and sorted lubed accordily will be good to go in any caliber. But you need to test and try the diffrent alloies lubes and weight ranges in YOUR rifle to find whats best

MT Chambers
09-24-2016, 12:28 AM
The .30 Br. and the .308 dominate cast bullet br. competition and my experience confirms their supremacy at up to 200 yds. prolly more.

runfiverun
09-24-2016, 12:37 AM
the outside of the little bullets are closer to the centerline of the rotating mass so small defects don't affect them as much.

andym79
09-24-2016, 01:20 AM
Makes sense in theory but that has never been born out in my limited experience! Of all my cases the 38-55 is best with cast.

Shiloh
09-24-2016, 08:47 AM
Aren't most capable of support accuracy with good equipment, good loading and shooting technique??

Shiloh

Bigslug
09-24-2016, 10:17 AM
One real advantage of bigger is that the little bits of variability add up to a smaller overall percentage of whatever it is you're measuring.

To take a couple extremes, a tiny little high pressure cartridge like the .221 Fireball is notoriously finicky about having consistent case weight (which affects internal case volume), and consistent charge weight (which affects amount of gas generated in that case volume).

On the other end, we have the .45-70, that you could probably almost fit two Fireball cases inside of. It sets off big charges inside big spaces and does it at low pressure.

Loads for the .45-70 can often be worked up in half-grain increments without seeing a dramatic change on the chronograph from one to the next. When I'm working with something in the .308 or .30-06 family, it's usually in three-tenths increments, and you'll want your cases within 3-5 grains of each other so that the effect of increased or decreased volume changes things less than that of an added or deducted tenth grain of powder (which is typically as fine as we can measure it with most loading scales). In something like the Fireball, single tenths can matter on the charges depending on where the load falls on the pressure curve, and I'd want the case spread to be under two grains - preferably under one - for good pressure consistency.

Same general thing with the bullets - whatever you generate for a defect in your casting it will be functionally "bigger" on a little bullet. Bolt the same size anvil on the back of an F350 and a Miata; which will have its handling affected more? A teensy little bubble just under the skin of a .22 might be the equivalent of you having to walk with a 30 pound dumbbell in one hand. The same bubble in a 500 grain .45 is a pimple on the butt of a blue whale.

With cast, the bigger stuff running at lower pressure will be less susceptible to base deformation. Probably less sensitive to the alloy being "just so" for this reason. Of course, the smaller stuff more often tends to get gas checks as a matter of course, and they do have magical bore-locking properties - but they can be applied to the big stuff as well, so really no edge there.

That's the internal ballistics end only. For the in-flight stuff, you have to consider that the material of our choice - cast lead alloy - is often your limiting factor on velocity. assuming roughly equal shape, if, say 1500-1600 fps is your top end, 500 grains is going to hold onto more of that speed longer than 200 grains, and thus spend less time being blown around in the wind.

Another thing to consider is that our cast pills usually start out much closer to the sound barrier than our jacketed, and that some bullets get weird when dropping back down below 1150 fps. Fortunately, it's more a worry with long, slender, jacketed designs than the blunter profiles of cast, but it's worth being aware of. If you plan to still be supersonic at your impact distance, no worries. The 535 grain .45 Postell bullet is often LAUNCHED at subsonic speeds to avoid this, and it relies on its mass to keep it sailing along for really long distances. In this regard, it's kind of a mutant monster T-rex version of a .22LR match cartridge.

Then you have to consider the human side. How many rounds is your match? How long are you going to be holding the rifle up? How much of a thumping are you up for? If you're playing the short range games at 200 yards, and you're doing it offhand, the .32's were a classic for juggling all these variables nicely. If you plan to go a little farther, I would also look HARD at a fast-twist barrel for 300 grainers in a .38-55. They shoot pretty soft and REALLY well.

runfiverun
09-24-2016, 10:36 AM
the little guy's can be super finicky and any issue with the boolit is a greater amount of the total,
but it sure seemed a lot easier to get my 223 to shoot 2700 fps in an 8 twist barrel than it was to get anywhere near there with a 30 cal in a 10 twist barrel.

andym79
09-24-2016, 11:53 PM
I will ask all of this from another viewpoint!

If I wanted to shoot a bullet like this:
177396

and have it reach a target a 200 yards without going through the sound barrier and going subsonic what muzzle velocity would I need to start out at. In other words hoe slow could I shoot it and still ensure that it reaches 200 yards still supersonic?

warf73
09-25-2016, 12:52 AM
Just ran a few number and getting around 1600fps, you should still be supersonic at 200 yards. It would be just supersonic around 1160fps so depending on your altitude, humidity and temperature you might need more fps or less to stay super. That was me guessing the BC of that boolit you showed.

andym79
09-25-2016, 07:00 AM
I was hoping that 1450 fps might do it, I will be relying on modeling to try and get this sort of thing right, because I don't want to spend hundereds to test it out in the real world and find it isn't fast enough!

Digital Dan
09-25-2016, 08:16 AM
Why are you concerned about going subsonic?

44man
09-25-2016, 08:49 AM
Not true at all. But might be some truth in revolvers since my real big bores were easier to find THE load. The process is the same for all.
It is why I hate gun rags today. Long ago everything was shot but now all are used with factory loads. The number of gun writers that even use a jacketed hand load is on a count down. BOOLITS, they don't even know what they are!

runfiverun
09-25-2016, 10:57 AM
transitional buffering.

white eagle
09-25-2016, 12:06 PM
my take on it is that bigger cals (boolits) run slower than say 22-7mm cals
its easier to get a moderate velocity boolit to work than it is to get a high
velocity cal to work with cast IME like the 220 swift vs.358 win.
the smaller cals will and do work but there are velocity thresholds that need to be addressed
unless you paper patch or maybe powder coat

Blackwater
09-25-2016, 01:25 PM
This has been a very interesting thread! I'd have been in the bigger bullet clan in answer to this question, until Run came along with his comment. Now, I'm thinking on it. I hope he's right, too, because I've got an idea for a small caliber substitute that's centerfire, and can be used in place of .22 LR's, with added versatility. Run, your comment really has me thinking now, and I'm at least a little more hopeful my idea might work out well now. Thanks. I think .... :Bright idea:

runfiverun
09-25-2016, 11:09 PM
I'm not an enabler, I'm not an enabler.
but i have got to the point i can help justify just about anything..

TXGunNut
09-26-2016, 12:06 AM
It's not the size of the boolit, it's what you do with it that matters. ;-) With the proper rifle, cartridge design, cartridge prep, loading technique, boolit design, fit and alloy virtually any caliber boolit (within reason) can shoot better than most of us, IMHO. Some are easier than others because some folks have already done all the research and developed a formula for success.

country gent
09-26-2016, 10:48 AM
A couple friends and I recently shot 22 rimfires at the clubs 300 yd gong this is a 40 grn bullet at 1160 fps definitly not whats normally thought of as a 300 yd load, but once we found the zeros for the 2 rifles hits were quite regular on the gong. Took awhile for the bullet to get there but it did. Once an accurate load is found then it simply getting the "zeros" for the ranges you want to shoot.

Wayne Smith
09-27-2016, 07:47 AM
There was a time when .22 rimfire was routinely competitively shot at 200yds.

runfiverun
09-27-2016, 12:16 PM
it's still done here.
we hold a monthly 200 meter miniature silhouette match.
well we were until no one could get any 22's.
maybe next year....sigh.

Thumbcocker
09-27-2016, 03:03 PM
Some of the old military .22 trainers have sights graduated waaay out there.

GMW
09-29-2016, 09:14 PM
the outside of the little bullets are closer to the centerline of the rotating mass so small defects don't affect them as much.
Wow...........I Love this forum!!!

Digital Dan
09-29-2016, 10:42 PM
.02 worth, free of charge: If all else is equal, caliber has nothing to do with accuracy or precision. Making all else equal may be a challenge.

Differentiate accuracy and and precision please. The former relates to placement while the latter refers to repeatability of placement. Lacking precision, accuracy is a matter of chance...if all else is equal.

With that said, there are variables which separate 1st and 2d place. Atmospheric conditions come to mind, as well as BC/wind/velocity/range and sometimes gnats. An extreme example: at 50' my 4mm German built Zimmer is boringly precise. So precise that none of my longer range rifles can best it, not for 3 shots or 50. It fires a lead BB powered by a RF primed case with no powder, reaching about 800 fps in its 7.5" RH twist 12 groove barrel. It is capable of pencil eraser size groups of 10 shots at the range. It is also beyond worthless at 50-100 yards or with any crosswind above a faint breeze.