Round or flat nose ?

[DEC505]

Has there been any studies done on boolit accuracy between flat point and round nose boolits ? Only reason I ask is now after being a reloader for several years, I would like to learn to hand load for more accuracy. Thanks, Derrell

[glockfan]

Has there been any studies done on boolit accuracy between flat point and round nose boolits ? Only reason I ask is now after being a reloader for several years, I would like to learn to hand load for more accuracy. Thanks, Derrell

the only thing i know is i prefer FP's .the terminal ballistic is maybe less than a round nose because of drag, but it makes nices holes on the uspsa cardboard targets lol.

i think that at the handgun typical distances, there's no real noticeable + or -.

for higher velocities rifle rounds, sure enough a flat meplat is dragging more than a profiled tip.

as for accuracy, i'm only guessing that the flat noses are keeping their trajectory better assuming the round is stable enough . why? well,i'm no expert at all, but i tell myself that the flat meplat act a little like a sail in the wind, the tip doesn't slice the wind, then stays on its trajectory more easily ; while, this is just wishfull thinking lol.

i'm sure some more knowledgeable users will chime in to give another perspective on my thought about it.

[brewer12345]

Every firearm has its preferences, so you will have to tinker with yours. That said, look at what match bullets are in 30 caliber. They are almost all long and pointy. I imagine a high ballistic coefficient and sectional density are an important element.

For me, the important question is how much accuracy do I need? I decided that 1 inch groups for the small boolit load in my 3006 are good enough for anything up to coyote size at 100 yards. In the same rifle, a 1.5 to 2 inch group at 100 yards with a 198 boolit is a dead deer to 150 yards. Could I try lots of variations and shrink my groups? Probably. But what I have will do what I need it to and given the limits of my vision and shooting ability, I might not be able to tell.

[osteodoc08]

You are going to be better served with alloy consistency, decreasing weight variations, etc with a profile that shoots well in your rifle regardless of profile. Read some of Larry Gibson’s work here (among several other members). He has discussed this subject (of long range accuracy) in painstakingly exquisite detail.

[Oily]

Hunting or target is the question. Lyman 311041 and 311291 are the same boolit but 41 is flat nosed and 291 is round nose. both shoot great in almost all 30 caliber applications. Increased velocity with your rifle will tell you what you need to know. I have a 06 that loves the flat nose 311041 and my CVA Optima in 308 seems to like the 311291 round nose at 2000 fps. You never know until you try different loads. Of course at longer distances 3 to 4 hundred yds there may be a more substantial difference in these 2 but at 1800 to 2000 fps I limit my shots at game at 100 to 150 yds and they both shoot minute of deer at these distances

[Mr_Sheesh]

For pistol boolits for SD I prefer flat nose by far, longer range rounds I'd expect the usual suspect (which is more like a spitzer - long pointed nose) seems best. Tho at 100 yards I've seen a number of people shoot small groups with whatever they're used to (revolver guy I know shoots scarily small groups, iron sights, at 100 yards. Semi auto Uzi owner who got the tax stamp to make his into an SBR enjoys shooting small 100 yard groups off iron sights. Peoples' accuracy capability definitely varies!

[Guesser]

In my 50+ years of casting, loading and shooting 38 Special in 50+ different revolvers I am convinced that a well cast Lyman 358311, 158 gr. RN is consistently the most accurate bullet I have ever used in revolvers.

[Outer Rondacker]

I can tell you this. Flat pont in my 40sw will leave a dent in ar500 steel at 20 yrds. Round nose will not in my 10mm.

[Uncle Grinch]

Your firearm may be the deciding factor, especially if shooting lever actions. Overall length also is a consideration with certain revolvers.

[tazman]

Has there been any studies done on boolit accuracy between flat point and round nose boolits ? Only reason I ask is now after being a reloader for several years, I would like to learn to hand load for more accuracy. Thanks, Derrell

You didn't mention if you were using a rifle, revolver, or semi-auto pistol. This makes a difference due to the mechanics, pressures, and velocities involved and changes the way I would answer the question.

[CJR]

DEC505,

The answer to your question is: Yes. The research was done by the US Air Force(USAF) in the 1970s. The USAF used their established equations, developed to produce accurate ammo for aircraft, to improve the accuracy of a round nose 9mm bullet. That effort resulted in an accurate truncated cone(T/C) flat nose 9mm followed by an accurate T/C 45ACP. The USAF technique, which was patented, was to increase the spacing between the forward aerodynamic Center of Pressure(CP) and the rearward Center of Gravity (CG) as much as possible to increase the bullet's accuracy. So when random aerodynamic forces/winds would act through the bullet's CP, the bullet would momentarily tip/rotate about its CG. Since a bullet, spinning at a high RPM, is a gyroscope it exhibits gyroscopic properties, i.e. it has an orientation in space and if tipped will always return to that orientation. Returning to that orientation is caused by the Gyroscopic Restoring Moment which instantly acts to pull the tipped bullet back on course everytime it is aerodynamically tipped.

The typical tools used to improve bullet accuracy is to increase the spacing between the CP and CG. Flattening the nose tends to move the bullet CP more forward, while hollow-pointing the bullet tends to move the CG rearward. The same procedure, increasing CP-CG spacing, is also done with jacketed bullets. The jacket profile is first selected to minimize aerodynamic drag and then the forward position of the lead core is selected to give an adequate CP-CG spacing. The CP-CG spacing then insures a reasonable Gyroscopic Restoring Moment to instantly correct any aerodynamic tipping of the bullet and improve accuracy.

Obviously, when we use flattened nose solid bullets, to get CP-CG spacing, the aerodynamic drag increases and bullet drop increases at long range. So, if we want to use a solid CB at long range we have to either hollow-point a spitzer/sharp point CB ; OR, use a composite CB with a lighter sharp point nose(i.e. aluminum) to increase the CP-CG spacing( for accuracy) while minimizing aerodynamic drag to minimize bullet drop.

The USAF published research and patents documents this well-tested technique. A Dr. Mann barrel test fixture was used to extensively test the accuracy of the new T/C 9mm ammo and the accuracy was impressive. One of the USAF contractors, Bob Whyte, went on to form Arrow-Tech (Burlington,VT) which now sells a very expensive computer program to design accurate bullets. Many of the jacketed bullet manufacturers now use the Arrow-Tech program.

Best regards,

CJR

[Texas by God]

Thanks, CJR. I thought the flat tip fmj was brought out to increase the slap factor- which it does.
I had no idea there was USAF research involved.

Sent from my SAMSUNG-SM-G930A using Tapatalk

[gwpercle]

You talking handguns at 75 feet or rifle at 500 yards. Black powder or smokeless .....what you shooting and how far makes a difference. Get specific , the details matter.
Gary

[Mr_Sheesh]

Yes I remember that research. Soon as the J-Word boolit made based on that research started being sold, I changed my SD handloads over to it; And now I have moulds so I can cast my own, PCing is next. Now if I had a flying car and more ammo loaded it'd be an even better world, but, this isn't TOO bad :)

[DEC505]

WOW, thanks for the input. I guess I should have mentioned that my question was for 9mm and 45 ACP . Main reason for working up constant loads is that I'm getting ready to take the Florida "G" licence test,which involves target scoring. I will need to qualify with pistol I intend to carry, which is a Sig SP2022 in 9mm.

CJR, thanks for the in depth info, I'll try to wrap my feeble mind around all that info. Thanks, Derrell