Imperfections on bullet tips.

[joshua]

OK, I've seen this too often on some of the so called match bullets.

See how the tip of the hollow point is not perfect, would you trust bullets like this in a match you've dedicated the whole year for? I have shot bullets with the mentioned imperfections, but I don't shoot benchrest or very long range often enough to tell if there is a negative effect on accuracy or trajectory. josh

 

[Bullet94]

You might find this interesting -

http://www.sinclairintl.com/cgi-bin/category.cgi?category=search&item=05-49XX&type=store

 

[30Cal]

See how the tip of the hollow point is not perfect, would you trust bullets like this in a match you've dedicated the whole year for?

I would. Without a doubt. That bullet has "X-Ring" written all over it.

If you don't have confidence in your ammo though, then you need to fix it (whether the ammo actually needs it or not).

Ty

 

[Ares45]

Will it effect accuracy - Absolutely!

I don't shoot BR or HP but most of the guys I know that do either trim their own meplat or have a custom manufacturer do it to exact specifications for them.

 

[Trapper L]

The idea of using a small HP like the one pictured is to create a small air bearing in front of the bullet. It helps the bullet to buck any air turbulence it might encounter on the way to the target and helps the bullet slide thru the air. If you have a bullet loaded to 3000' ps and shooting a 1:12" twist, the bullet is spinning at the rate of 180,000 rpms or 3000 rounds per second. The non-perfection in the HP at this point becuase of the extreme spinning and the air bearing makes the imperfection a non-issue. If you feel a little more warm and fuzzy straightening the tip, have at it but don't expect the groups to shrink. Now who want s to answer the magic question- when a bullet slows down in flight, does the rate of spin slow down at the same rate?

 

[Mike Irwin]

Numerous tests over the years have proven beyond any doubt that the condition of a bullet's base is FAR more critical than the condition of the bullet's tip.

Bullets with malformed tips are capable of extremely fine accuracy.

The reason the "hollow point" is there in the bullet is smiple -- it's a remnant of the manufacturing process. Match bullets have solid bases to promote the best possible accuracy, and it's pretty much impossible to fully close the nose of a bullet of this type.

 

[Mike Irwin]

"when a bullet slows down in flight, does the rate of spin slow down at the same rate?"

No.

Rotational decay is EXTREMELY slow. Over 1,000 meters a bullet may lose less than 2% of its original rotation.

 

[Clayfish]

Do you guys remember that sniper movie where tom lliota (I think) was perfecting his bullet points with a file while sitting around a campfire?

 

[snuffy]

Do you guys remember that sniper movie where tom lliota (I think) was perfecting his bullet points with a file while sitting around a campfire?

Hollywood BS or hype for mixed company!

As was said, the bullet that is supersonic has a shock wave out in front of it. The tip never really "touches" the air it's moving through. Now after it drops below the speed of sound, that "cushion" goes away, then the tip imperfections MAY have some influence.

Also a bullet fired from a 1:12 twist barrel will still ONLY rotate one full revolution every 12 inches! Yes the RPM or RP/second, is high but it still cannot turn 1 RPM in less that 1 foot. Since the rpm decays slower that the feet per second, it will start to rotate once in leass that 12 inches because it's now going slower in FPS.

 

[WIN71]

Or

it still cannot turn 1 RPM in less that 1 foot.

It's a little easier to understand if you substitute "Revolution" for RPM in this instance.

In this case with a 1 in 12 inch twist and a fast bullet, i.e. 204 Ruger at 4000fps, it would equate to approximately 240,000 RPM. This is instantaneous and prior to any outside forces in effect.

 

[P-990]

joshua,

You'd better believe I'd take that bullet to the match with 100% confidence. No question! Like 30cal said, that thing has X-ring all over it.

I've put hundreds of match rounds through my AR-15 after *shudder* tumbling them. The points were filled with media. After I beat a few of my old scores, I decided it is a non-issue.

Those imperfect tips are also the cause of much pulled hair and aggravation for people looking for every loaded round to be at the same .001". Myself? I don't worry that much and go shoot! This applies (IMO mind you) to weighed versus thrown charges, deburred flash holes versus just toss a bunch of ammo together, etc.

To make it short; stop worrying and go shoot!

 

[joshua]

To make it short; stop worrying and go shoot!

I'll take your word for it. For now...

I'm the kind of guy that will throw a powder charge with my powder measure the same way I did the first, 2nd, 3rd and so on. If I tap the base of the powder measure once then it's one tap. When it comes to bullets I try to weight them and segragate them by weight. Maybe I should just stop worrying and start shooting. josh

 

[30Cal]

IMHO, consistancy is great. But if it requires a significant investment in extra time, then it'd better give me results that I can point to on paper.

Ty

 

[amamnn]

Differences in meplats will cause the ballistic coefficeint to be different, which is not really noticable until the velocity has dropped off at long range. Then, inconsistencies in meplats will be seen as vertical stringing on the target. The rule of thumb is that meplats become significant at 300 yards.
I don't bother trimming for 100 and 200 yd matches.

At all distances, something that I do concern myself with, beyond the usual variables, is base to ogive length. If this distance is not consistent, your seating will be inconsistent, whether you use a custom seating die that actually seats on the ogive, or a standard die that seats who-knows-where. Most casual loaders do not deal with this variable, which is a much more significant factor in accuracy, and without addressing it, meplat trimming is wasted effort.

 

[Peter M. Eick]

On the short ranges (out to 300 yrds) it would not bother me a bit. Out of my M1A's that type of deformation is nothing. Try shooting the first 19 rounds out of a 20 rnd mag and pull the last round out of the action to see how beat up it is. Much worse then that.

Now at 600 to 1000 yrds, it might have an impact but I have not shot enough at those ranges to really have an opinion.

To me this is more a question to you. Do you believe it is an issue? If so fix it, otherwise it will be an issue. The older I get and the more I shoot, the more I realize that at longer ranges, target shooting is much more of a mental sport then a physical one. This is probably true at the shorter ranges also but I am still fighting it...

 

[Buckythebrewer]

The SMKI wondered the same thing about that tip until I used the bullet.under 1/2 M.O.A.(all but 1 out of five shots) in my home built DPMS barreled ar15 to at least 600 yards with better than M.O.A being the norm..Maybe some would want better and could get better by making the tip look nice and neat,but its of no concern to me(as long as im getting M.O.A or better).They have fired very well for me in the last 500 count box(77gr smk) I used.I have also fired the 80gr smk and they worked great as well.One group was near 1/8 inch 5 shot at 100 yards using the 80's not drivin to hard.The 77's have been 1/2 inch at 100 yards with a couple of groups at or near 1/4 inch.
Seeing(the targets) is believing for me. The 77gr SMK is impressive to me being magazine feed capable as well as accurate in my experience.The 80's I believe are capable of better accuracy but I have not fired enough of them to find a PROVEN load for 600+ yards in my rifle.

Don't pay any attention to the tip,,Its just bad looks for the most part.
Its whats on the inside that counts

 

[joshua]

Thanks for all the inputs guys. When I get back to CONUS I will assemble some of my proven recipe to be .5 moa through my H-Bar, but I will pick the bullets with imperfections with their tips. I just got to see it for myself. josh

 

[mc223]

100 Yds = 300 ft. 1 in 12 twist will rotate the projectile on its center axis 1 time every 12 inches regardless of velocity. = 300 revolutions per 100 yds. not taking into account the gradual reduction in rotational speed from friction of the air and whatever other forces may be present.
A bullet leaving the barrel at 2850fps will arrive at the target in about .11 seconds at a velocity around 2585 fps using a bullet BC of .331.
Trimming the meplat will decrease the bullet BC which in turn will also reduce the velocity at the target and increase the time in flight. Accuracy will likely not be noticable at shorter distances. Long range accuracy may be improved, although vertical will be considerably lower due to the more rapid deceleration due to the increased frontal surface of the projectile. Vertical dispersion at longer ranges will be better because all the projectiles will in theory be uniform.
Horizontal dispersion will also be affected due to less steering effect at the nose of the projectile by the irregularities of the meplat area.