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Discussion Starter #1
I have been reading about meplat bullets and the DIY method of filing off of lead bullet noses to create a FN

What effect will this have on Muz-Energy and could anyone estimate the reduction in BC by changing from a round nose GL or RA4 drag (22lr) to a FN with around 75% of it diameter being Flat..


So KE= (.5 x Mass X V^2)
so for CCI CB long (code 0038) With 29gr and 727fps
=766367
therefore if i hold the energy output as constant and change the weight to 20 i calc a new theoretical speed of 875fps:):confused: Is this correct or will the reduced chamber pressure dictate an other out come.

Thanks for any help with this one lads

Ivan from Ireland
 

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You're talking about filing off nearly one-third of the total weight? MV will definitely go up, although I'm not sure if your calculation is right, or not. The bullet will not be as accurate, even if you do manage to keep the weight fairly well-balanced, as you file them flat. Penetration will go to very little with that flat, soft nose and low velocity, especially if the distance is anywhere near the normal effective range of 50 yards.

Any particular objective in mind, with all of the above?
 

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Discussion Starter #3
Need to reduce the BC of these .22lr type bullets

I want to drastically reduce the ballistic coefficient and hence the theoretical max range!! IIRC the CB Longs (product 0038 M-Vol 730fps BC 0.073) have the potently to travel around 880yards if fired at approx 32deg. I dont intend to fire this distance or at such trajectories but if a bullet glances of a rock or a low lying branch then i could be i trouble with houses close by??

Why not use something else? i hear you say, Well...
I'm living here in Ireland and 22lr ammo types are hard to come by! I was looking for RWS R25 (delivers 20ft/lbs) but can't find it. I also was looking for Aguilar Super colibri (delivers 12 fl/lbs) but only on bloke had it an its all gone now!!!

I'm left with very few option now for low powered shooting close to built up areas except to buy an air rifle:mad: Buying any rifle here in Ireland is an ordeal and best avoided at all cost if possible..

So give me any tips to help bleed of energy from these little round and i try to get them to drop. They only have to be accurate out to about 35-50yard after that i dont care!

I'd imagine that the loss of mass combined with the flat nose will kill off the BC but by how much i dont know. If it worked then some accuracy could be maintained by using an Acu'sizer by paco kelly to resize the width and reform the head to a uniform shape also a SGB tool to gauge the amount of filing in a constant manor!

I know its an unusual cause but its definitely a worthy one

Regards Ivan
 

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Well, filing off 30% of the bullet and leaving a flat point will certainly reduce the maximum range one might travel, but we ARE talking about highly frangible 22 bullets, aren't we? If what you're using has an exposed lead tip, it's not going to ricochet off a rock and travel 500 yards...it's going to come apart in shower of lead and copper fragments. In a nutshell, I think you're going to a great deal of effort when all you really need to do is be sure of your backdrop, which is a rule for every kind of shooting, regardless of bullet size or type.

If you can do what you're proposing, and it works well, more power to ya. ;)
 

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Filing the nose down to a wadcutter shape will reduce the BC a lot. I don't have a direct way to calculate it for the exact shape of the .22 LR, but by stealing an analogy from .32 caliber, I can tell you that averaging the BC's of an 83 and a 90 grain full wadcutter gives a G1 BC for an 86.5 grain wadcutter of 0.0365. There is an H&N High Speed 130 grain round nose in .32, which is very close to 1.5 times heavier than the 86.5 grain wadcutter would be, and is round in the ogive, like a .22 RF. It has a G1 BC of 0.234. Dividing 0.234 by 0.0365 give a ratio of about 6.4:1.

That suggests an approximation for a filed flat .22 round nose at 27 grains, the RA4 BC would be about 6.4 times smaller than a 40 grain round nose. For a 40 grain bullet, If the RA4 BC is about 0.1, then a wadcutter conversion that removes a third of the weight should result in an RA4 BC of about 0.016.

If you are only going for 75% flat meplat your reduction ratio on your 29 grain CB cap will be less. I suppose a factor of 3-5 times smaller than with the round nose might be reasonable, so 1/4 of the 29 grain CB long RA4 BC would be my first estimate. But please note that a wadcutter or a flat nose will not fly with the RA4 drag function shape, so this is all a bunch of SWAG anyway. On the other hand, you are subsonic all the way, so it may be close enough.

The actual muzzle velocity would not be quite as much as you predicted if a powder were propelling the projectile because it would burn less efficiently with the lighter bullet. Primer-only mix, though, should go off right away, so your velocity difference estimate may be about right. You'll have to try it to see?
 

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I have been reading about meplat bullets and the DIY method of filing off of lead bullet noses to create a FN

What effect will this have on Muz-Energy

Ivan from Ireland

Turning the bullet into a flat point will make a more terminaly effective projectile. Enrgy is a meaningless number and an invalid metholigy for determining leathality
 

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Turning the bullet into a flat point will make a more terminaly effective projectile. Enrgy is a meaningless number and an invalid metholigy for determining leathality
I absolutely agree. I shot a bunch of small game a few years ago with round nose CB caps out of my S&W .22 revolver. They never exited and didn't particuarly kill well if I didn't hit CNS. As a handgun hunter, I know how effective flat-nosed hardcasts are on big game, so I took a file to my CB caps and made a nice, large (relatively speaking!) meplat. Keep in mind that my ranges were short. That said, all of my subsequent bullets exited and the effect on the game was considerably better.
 

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Discussion Starter #8
Filing the nose down to a wadcutter shape will reduce the BC a lot. I don't have a direct way to calculate it for the exact shape of the .22 LR, but by stealing an analogy from .32 caliber, I can tell you that averaging the BC's of an 83 and a 90 grain full wadcutter gives a G1 BC for an 86.5 grain wadcutter of 0.0365. There is an H&N High Speed 130 grain round nose in .32, which is very close to 1.5 times heavier than the 86.5 grain wadcutter would be, and is round in the ogive, like a .22 RF. It has a G1 BC of 0.234. Dividing 0.234 by 0.0365 give a ratio of about 6.4:1.

That suggests an approximation for a filed flat .22 round nose at 27 grains, the RA4 BC would be about 6.4 times smaller than a 40 grain round nose. For a 40 grain bullet, If the RA4 BC is about 0.1, then a wadcutter conversion that removes a third of the weight should result in an RA4 BC of about 0.016.

If you are only going for 75% flat meplat your reduction ratio on your 29 grain CB cap will be less. I suppose a factor of 3-5 times smaller than with the round nose might be reasonable, so 1/4 of the 29 grain CB long RA4 BC would be my first estimate. But please note that a wadcutter or a flat nose will not fly with the RA4 drag function shape, so this is all a bunch of SWAG anyway. On the other hand, you are subsonic all the way, so it may be close enough.

The actually muzzle velocity would not be quite as much as you predicted if a powder were propelling the projectile because it would burn less efficiently with the lighter bullet. Primer-only mix, though, should go off right away, so your velocity difference estimate may be about right. You'll have to try it to see?
Cheers for the info- In the end i suppose i'll have to take some auctual measurement to see the ont come.
 

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Discussion Starter #9
Well, filing off 30% of the bullet and leaving a flat point will certainly reduce the maximum range one might travel, but we ARE talking about highly frangible 22 bullets, aren't we? If what you're using has an exposed lead tip, it's not going to ricochet off a rock and travel 500 yards...it's going to come apart in shower of lead and copper fragments. In a nutshell, I think you're going to a great deal of effort when all you really need to do is be sure of your backdrop, which is a rule for every kind of shooting, regardless of bullet size or type.

If you can do what you're proposing, and it works well, more power to ya. ;)
I think you might have got your facts wrong or perhaps we Europeans have a completely different view on the 22lr's ricochet properties! Here in Ireland alot of lads use 22lr subsonics rounds that have great wind avoidance properties in tandem with very high levels of consistency when compared to all other 22lr bullet velocities. Their trajectories are devilish but their real Achilles heel is their susceptibility to ricochet. The high velocity stuff will disintegrate if its still got the velocity but with extended range it soon goes subsonic.
IIRC i dont think 22subs are altogether too popular over the Sea in USA:confused:

Anyway AFAIK the 22 CB Longs are even more prone to the dreaded ricochet.

I do take you point about good back stops and i assure you that safety is top of the list!
ATB Ivan
 

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I took a quick look and didn't find one described by any of the usual suspects. It's odd, because you'd think with all the wadcutters fired at targets, people would want to know what kind of range they actually have? Page 25 of McCoy's Modern Exterior Ballistics has a schlieren photo of a three caliber wadcutter flying through air. I have a couple of programs that will let you create a drag function if you collect enough data. Oh, wouldn't that job be a joy. No sonic crack for microphones and the like. Have to shoot through sky screens at a good distance without causing damage. I wonder if anyone's got a Doppler trace for those bullets somewhere?
 

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Much to-do about nothing, if you ask me. The sub-sonic load has very limited range...truncated flat-nose bullets, less so. You're getting down to the range where you'd be much better off to get a high-quality pellet gun, instead of expending a great deal of time and energy trying to assess the exterior ballistics of a 22 wadcutter. Attach a toothpick to a 5/8" bolt shank and drive tacks with it ? No need to test it out or determine its performance capabilities...it is what it is.
 

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Discussion Starter #13 (Edited)
Much to-do about nothing, if you ask me. The sub-sonic load has very limited range...truncated flat-nose bullets, less so. You're getting down to the range where you'd be much better off to get a high-quality pellet gun, instead of expending a great deal of time and energy trying to assess the exterior ballistics of a 22 wadcutter. Attach a toothpick to a 5/8" bolt shank and drive tacks with it ? No need to test it out or determine its performance capabilities...it is what it is.
Whether or not i buy a pellet gun is irrelevant IMO as its important to understand the possibilities.
The issue of range similarities of the 22subsonic rounds and others mentioned above is like saying a 22hornet is similar to a 22lr high velocity.. I have found a 28grain Short that will only provide a max range of 566yards and that a good bit shorter than the figure of 1700yards for the standard 22lr subsonic... At least i can see 566yards!!! And with a small bit of filing off the nose i could further reduce its existing BC of .049 and also increase its ability to cut and tear soft tissue as opposed to simply pushing it to the side as is the case for all round nose bullets with reduced velocity..
 

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I'd like to hear how the modified shorts/subsonics work out for you in the field, if you get a chance to try them.
 

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Energy is most defininitely NOT misleading or inadequate as a guide. Anyone who's shot rabbits and squirels with both solid lr's and Stinger hp's will tell you that the extra speed and energy makes the stinger obviously a better stopper of such critters. The 223 softpoint and .45ACP ball fmj ammo have the same momentum and the .45 has 4x the frontal area, but animal shootings will quickly show you that the 223''s 4x greater energy is by far more important!. That is, if you know enough to use a bullet that penetrates deeply enough, like the Nosler Partition. Most 223 sp's and hp's are intended to blow up in a prairie dog or a crow, so they don't penetrate adequately in larger animals. The Partition has been the gold standard in terminal performance for 50 years now.
 

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All the different stopping power formulas around prove that nobody has figured out any perfect way to balance the effect of various factors. I find that if you have two bullets of the same shape and caliber that differ only by sectional density, then fire them to have the same momentum, the one with more energy usually is more destructive. But if you fire them with the same energy, the one with more momentum is usually more destructive. And none of that takes nose forms into account. For example, if you give two same-caliber bullets the same weight and give them the same terminal velocities, so energy and momentum at the target are the same, a flat bullet nose is more effective than a pointed FMJ. And then you've got calibers to consider, too. You just gotta take it all into account somehow, and nobody has yet figured out how to juggle that for consistent correct answers. What seems clear is that no one single factor works all the time or covers all the bases, energy included.
 

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Energy is most defininitely NOT misleading or inadequate as a guide. Anyone who's shot rabbits and squirels with both solid lr's and Stinger hp's will tell you that the extra speed and energy makes the stinger obviously a better stopper of such critters. The 223 softpoint and .45ACP ball fmj ammo have the same momentum and the .45 has 4x the frontal area, but animal shootings will quickly show you that the 223''s 4x greater energy is by far more important!. That is, if you know enough to use a bullet that penetrates deeply enough, like the Nosler Partition. Most 223 sp's and hp's are intended to blow up in a prairie dog or a crow, so they don't penetrate adequately in larger animals. The Partition has been the gold standard in terminal performance for 50 years now.
OK, a Partition isn't a FMJ. I think you are confusing "energy" with bullet expansion.

Higher velocities with .22 LR ammo WILL yield greater expansion. That is because the bullets are dead soft to begin with.
 
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