Boolit Design 101

[crabo]

As a newby caster, but not shooter, I am trying to understand what makes a good bullet design. It seems that some of the necessary ingredients are good lube groove, or grooves, a couple of wide driving bands, a wider meplat for hunting...... but it seems like a lot of them just look pretty much alike.

I know that from my testing, that bullets all shoot different and what shoots good in one gun may not shoot good in another. However it seems like there are some stars. The 250 K in .44 seems to be one of those.

What do I look for in a good bullet design? I know that I have high expectations in the accuracy department. I have a load that is shooting 2 1/4 groups at 100 meters with my .357, and I am wondering if a crane lock will help me tighten it up a bit.

Do you have any shooting "stars" in the different straight wall pistol calibers?

Thanks,

Crabo

[leftiye]

Crabo,
Unfortunately, I don't have a clue as to any hard and set rules. It seems like this subject is a lot like much else pertaining to cast boolits, their loading, powders etc.- if it shoots good, it shoots good. My reason for saying this is that there are a multidude of different deisgns that shoot well. Contrast the Kieth SWCs that you mention with the LEE .30 cal. soupcan for instance. Then compare some bore riding desgns with some Loverin designs.

I kinda believe that almost any bullet that has a cylindrical body behind a nose portion of some kind- even flat (I was tempted to say not too long, but remember those bore riders!), with a base that's flat plain, flat gas checked, hollow, or boattailed can be made to deliver good accuracy. I'll probly get flamed for that, oh well.

The only help I can offer you is to keep your ears open for designs like the kieth that everyone agrees shoot well. While you're at it, look at all of the kieth veriations that also shoot well.

[Lloyd Smale]

I look at my favorites. The 32 rcbs 100 swc the ballistic cast (or lyman) 230 swc 41. The 240 rcbs swgc and the lbt lfngc 280 or 300 grain in the 44s. The rcbs 255 swc the rcbs 300 swcgc and the new lee group buy mold seems to right up there in the 45. 475 is easy as for the most part they all shoot as do the .512s some better then others with different velocity levels but the big bores arent as fussy. I look at all my favorite bullets. Most are swcs with lfns comming in second. About 3/4s of them are gas checked designs. NONE have an overly big metplat. None are exteamly light or extreamly heavy for the caliber. It is argued even by some here that there is no majical bullet that shoots better its just a matter of tweaking loads to get the design your using to shoot. Ill argue till the death. I firmly believe that some bullets just plain shoot and some are like throwing a rock.

[Buckshot]

.............I think the thing about one boolit shooting well in one firearm and not another (assuming the cast slug meets all the right criteria) is due to differences in the gun more then anything else. You can find the same exact thing with jacketed match bullets.

...............Buckshot

[Adam10mm]

Seems the longer bullets with more lube grooves are more accurate than the short ones.

[Bass Ackward]

I believe that there are keys to a design that make it more practical for one gun or another. They were designed with a particular purpose in mind. Say, low velocity target work with soft bullets. That would mean you need a long bearing area. They called them wadcutters. Accurate as all get out as long as you use them within their limitations. Want to make a 1000 yard match bullet out of one and you are screwed.

And the variables are just too numerous to list. Examples:

Take a wide land Smith in say 357. With wide lands, they are going to need to displace metal more than narrow rifling. This is going to take time to occur. In the mean time, the base is screaming what in the hell are you waiting for when a round goes off. So thinner bands make this easier to occur. Unless you soften your bullet.

If you have a faster twist rate with narrower lands say in a Freedom Arms 357, (14 twist) you may need wider bands or harder bullets if your intent is to run wide open compared to a wide land gun like say a GP100. But because a freedom is line bored, bullet jump is less of a concern so the wider bands need to be on the back to hold the rifling and take advantage of the balance point to the rear.

If you have to jump a bullet for say a rifle throat, then a wider band is beneficial to withstand impact for centering. The disadvantage there is that a wide front band affects center of balance, so you may ruin the bullet for low velocity application or run it right on the top to get best accuracy. Or if you have a short throat and want to chamber a heavy bullet, you may need to reduce your nose diameter and get a bore ride design.

Even for things that seem like they are unimportant, say the width of the band behind a crimp. Elmer Keith always believed that you needed a WIDE band behind his crimp groove to open the brass crimp. Well, he was shooting 10/11 BHN. Would you need as wide a band there if you crimped light or shot harder bullets? No.

How about Loverin rifle designs. Small front grooves above bore size. Any advantage here? Yes, so that you could reach and crush slightly into the lands for centering. The thought being that they would provide enough guidance while lowering starting resistance and allow the bullet to overcome inertia better until it was supported in the bore where all bands would drive together.

See my point? Most of the common designs we have today were very well thought out plans made up by someone to accomplish some .... particular .... task. Use them outside of their intended purpose and you may have to be flexible enough to adjust by changing hardness or sizing differently or you may have poor results and say this design sucks. That's why they work for some and not someone else.

How can you get an idea of what guys were thinking when they designed a bullet? Well, Lyman published an old cast bullet manual that was more of a molds manual around 58 /60 where guys talked about some of their designs and why. Old magazine articles were another sourse of info. Or in Elmer's case, his books.

And this list goes on, and on, and on. Maybe Floodgate can point you to other sourses of information. PM him if he passes this up.

[crabo]

Is it too much to assume that if a certain design works in one acp cartridge, it should work in another caliber?

Most people agree that the H&G 68 is an awesome bullet that really works good in the 45 acp. The H&G 81 is patterened after the 68, but is for 38 Super. I guess then that it should be a good design, but is it going to be a roll of the dice to see if it works good in my guns?

I see all these group buys and I wonder how they are going to work out. I hate to wait 6 months, spend the money, and then find out it doesn't work in my guns.

Thanks,

Crabo

[S.R.Custom]

The two things that determine accuracy in a cast bullet more than anything else are: (1) The diameter in relation to the groove diameter. A thousandth or two over groove diameter (throat diameter in a revolver) seems to be ideal. And (2) the fit of the bullet to the chamber throat. Beyond that, the design of a particular bullet goes more to its intended purpose than to its accuracy.

[Lloyd Smale]

super mag i dont agree there. Accuracy is about the most important consideration when im chosing a bullet. Granted you first have to find a bullet that is proper for the job intented but take in the case of a 250 44 swc there are hundreds of designs. Some good some not so good. Ive got 44 molds for swcs that will shoot decent in all my guns casted out of about any alloy and sized anywhere between 429-432. Again granted they might to a tad better at one size of the other but they do well at all sizes. I have other swc molds that dont do well in any gun at any speed with any alloy at any size. These are just poorly designed bullets. I tend to find lots of seaco and nei molds that fall into this catagory. I think a guy just sat down and said im going to draw up a swc without any thought going into to the design at all. One prime example is the nei 260 swc .45 bullet. My buddy bought the mold and to look at it youd think it was about the altimate 45 bullet for hunting. Its a good looking bullet with a fairly large for a swc metplat. Now ive got a half a dozen 45s and hes probably got 3 times that and we yet to find a gun that will shoot that bullet well. You can talk to your blue in the face to me about how any bullet can be made to shoot but i guess that has to take into consideration what a guy feels is a load that shoots. To me if a bullet and load wont go under 2 inchs at 25 yards its not worth shooting. Sizeing means alot but ive yet to see it turn a 6 inch group into a 1 inch group. For the most part when testing loads I have favorite powder and primer combinations that have allways given me good luck. Ill take a new bullet out with say 4 of these combinations and if at least one doesnt go under 2 inch that mold is down the road. Its just not worth the long hours of casting loading and testing trying to get a ill designed bullet to shoot well when theres good designs that shoot well with about any load in any gun.

[Bass Ackward]

One prime example is the nei 260 swc .45 bullet. My buddy bought the mold and to look at it youd think it was about the altimate 45 bullet for hunting. Its a good looking bullet with a fairly large for a swc metplat. Now ive got a half a dozen 45s and hes probably got 3 times that and we yet to find a gun that will shoot that bullet well. You can talk to your blue in the face to me about how any bullet can be made to shoot but i guess that has to take into consideration what a guy feels is a load that shoots.


Lloyd,

Are you talking the GC design # 313?

I look at that bullet and see a short nose and a GC that takes weight off the back. That means that the center of balance is almost dead center. Not generally a flexible trait for a longer range design. The skimpy crimp groove indicates that he was probably shooting faster type powders in a handgun. The longer bearing and square groove probably indicated that the guy was shooting soft lead and didn't want his bullet collapsing or leading under quick pressure.

I'd say this was a good heavy AR bullet for someone that had problems with leading wanting to burn a slower powder for it, like Unique or Herco.

[S.R.Custom]

If the the #313 is indeed the bullet we're talking about, then yes, I can see where you might have a problem. But the problem goes to #2 in my previous post...

That bullet looks like the GC version of just about every machine cast, commercially sold bullet I've seen in the past 20 years. It's not a bad bullet --balance-wise it looks fine-- but the skinny little driving band forward of the crimp groove is going to make for a sloppy, cavernous fit in the chamber throat of just about anything you shoot it in. Take some Casull cases, trim them so that when expanded they just headspace, and you'll get that driving band out closer to the rifling where it belongs. Then, I think, you'll see some joy.

[Char-Gar]

It appears to me you are talking about handgun bullets... right? That is important because handgun and rifle bullets are quite different critters and in some ways play by different rules.

When it comes to sixgun bullets I would have to say, the following are important.

1) The amount of lube carried by the bullet.
2) The bearing surfaces (body) of the bullet needs to be right for the twist of the barrel.
3) The nose of the bullet will have an effect on it's accuracy and performance down range
4) The fit of the bullet to the cylinder throats and barrel grooves.

IMHO... No other design have proven more acurate in sixguns than the good old round nose. Others may cut cleaner holes in targets and do better on flesh and blood, but for pure accuracy, a round nose is king of the hill.

[felix]

Yep, the ogive must be just right for the launch speed and boolit hardness. The boolit has to slam into the forcing cone straight on, or corrected by the forcing cone to enter straight on. The easiest way for this to happen is for those boolits heavier than nominal because the launch speed is slow enough by default for the boolit to enter without being forced into an angled attack. ... felix

[felix]

Bigger the diameter of the boolit, the less able the boolit can track the lands, as well as hold together as a solid, static, composite after leaving the barrel. Tougher boolits can handle the forces, including RPM, better and therefore can be shot faster. Note that the term tougher does NOT necessairly mean harder. ... felix

[44man]

Lloyd said it best! :drinks:I have found too many similar boolits where one won't shoot any way, shape, or form. I have solid boolits that shoot super tight groups where a hollow point of the same boolit shoots bad no matter what the load or powder or hardness. I have hollow points that are super. If a boolit won't shoot, the mold goes in the back of the drawer.
What everyone has ignored to say is WELCOME to the nut case site because it will drive you nuts trying to figure out what will shoot and what won't.
I have not found any theory that works, only shooting will tell because every gun is different.
And guess which boolit design gives me the most trouble---YUP, the Keith design and all of it's variations. [smilie=1:

[Lloyd Smale]

44 man thats actually a easy statement to say. If your talking real kieths ill dissagree but every swc thats out there is sometimes called a kieth. Now with that many different designs theres bound to be some crap ones (AND THERE SURE ARE!!) Now if we go to lfns theres alot fewer variations of that design. Some lube grove changes but nothing drastic and the lfns do tend to shoot with very few bad ones being made. Wfns are where we part company. There are very few good ones and alot of bad ones. But again not nearly as many out there or bough by people. Then theres my all time most hated mold design the WLFN. If ever there was a mold that is an abortion that it it. Ive yet to see one shoot well or fly well. If you honest look at true keith designs or at least ones that are close to his design like the 429421 the 250k and some of the ballistic cast versions they for the most part are good bullets. They usually shoot and fly as well as anything going. Some guns like some bullets better then others but in anything from a 41 to a 500 linebaugh ive yet to see a good keith designed bullet that i couldnt get to shoot. Ps the *** nei mold im talking about is a plain based bullet. Its actually a good looking bullet but for reasons only the Gods know it just wont shoot. I think half the time these companys kick out a mold they just take a good design and change something on it and cut it. they dont test there designs one bit before selling them. Anyone can sit down and draw up a swc but to draw up a bullet that works is another thing. Seaco too makes me shake my head. They have the nicest blocks on the market and make a beautiful mold but make the stupidest dammed bullet designs on the market (other then lee) Whats with those swcs designs of there with the base driving band 3 times the size of the others!! The worse kick in the teeth i ever took buying molds was seacos. there was a company that was going out of bussiness on the net and closing out all there seaco molds for half price. I had just gotten the 41 special single six and was looking for short nosed bullets to shoot in it. I bought 4 different molds and there about all good for nothing but paper weights as all of those bullets were junk. Best thing in it is the old lyman keith seated deap.

[44man]

Exactly, since I sold my original 429421, none have shot as good. It only takes a small change in the design to ruin it.
I have found the exact same thing with the WFN until I played with the one I made for the .475. I almost gave it up until I found it is super accurate and has many sub 5/8" groups at 50 yd's and tiny groups out to 200 yd's. Something about it I can't nail down and doubt I could make another to match it.
I get the WLN to shoot from my .44 but not the WFN!
Thats why I call this the nut case site, we can't explain why! :mrgreen:
Theorys abound but I gave them all up because none of us knows why one boolit will shoot and another won't. That's why I have deep drawers in my cabinet. [smilie=1:

[Bass Ackward]

Well, design study is a personal decision. Realize that every standard design that was out there took many hours .... "without" .... a computer program to generate. So the designer had to feel strongly about what he was doing to at first learn HOW to do it in the first place. Then he had to think about how to do it right for what he wanted. Elmer had many molds made until he got it right for his conditions. And although the 429421 changed Elmer's design, it has continued to work for others. So has every mold out there.

The beauty of bullet for a solid bored launching system is that it gives you the flexibility to do more things wrong and still get it right. With rifle like conditions all you have to do is start it off straight and then not over tax it. You can get more design things wrong here if fit is proper and velocity allows you to compensate for it out to the distance where you lose that velocity. And long helps wide.

It's different with a handgun. Handgun design is the advanced course. It's harder with short and wide. The beauty of a handgun bullet design is it's ability to survive and maintain good flight characteristics in spite of the way you and your gun abuse it. What you are doing for accuracy with a handgun bullet at close range is adjusting conditions so that your gun distorts it less until it gets on it's way. Then you worry if it CAN fly properly that way. But to 25 yards, any design, even a wadcutter can fly correctly, so at that range, it's all on how you launched it.

When it is all said and done, it's easy to blame " a " design for your butt woopin. But some guy out there somewhere is smiling cause he found out how to do it. Why I even heard tell of someone claiming a WFN was a good long range design and we KNOW that's physically impossible, cause I can't do it. :grin: