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most people i have talked to sugest 180 gr for 40S&W but i found that 155 gr has higher ftlbs whats the deal

im new to this so keep it simple
 

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180 gr is a bigger bullet so to speak. I usually un 165 gr to get the best of both worlds
 

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Personal choice. I would go with the heavier bullet for deeper penetration.
 

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Has anyone done a good conclusive study here comparing different bullet type and weight for penetration in the 40 s&W. The difference in kinetic energy is really not to much, only 25% less between the hottest load I could find, the Cor-bon 135 grain power-ball load (526ft-lbs) compared to 180 grain WWB (391ft-lbs). The difference in momentum is nearly negligible at only ~6% less for the WWB compared to the power-ball. Certainly heavier bullets are generally tougher and less prone to fragmenting on impact but I would be interested in some 'box O-truth' style tests to really see if the 180 grain bullets actually penetrate better.

My guess is that they may be more reliable in real world situation and penetrate better in a larger variety of situation but I would bet that with just a good old block of ballistic goo the lighter hot loads are going to penetrate deeper as long as the bullet does not fall apart.

Given that fact that the bullet mass only varies by 25% I would guess that in a ballistic gelatin test KE is going to be a pretty good indication of penetration. But as we all know a lab test is only valid for the lab situation and real world situation rarely look like a lab.

Rambling
mcb
 

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MCB,

Your conclusion that there is not much difference in penetration is correct...there really isn't. However, your conlcusion that the 180gr would penetrate less is incorrect. Other things being equal if you have two of the same round but in two different weights the heavier will penetrate deeper in gel. I've seen visual evidence of this. Between 165 and 180 gr the difference is small but it's there and it's pretty consistent.

I think either 165 or 180 are fine. Just select a good, proven round.

brad cook
 

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I did not say the heavy bullet would nor would not penetrate better.

Me earlier: "Given that fact that the bullet mass only varies by 25% I would guess that in a ballistic gelatin test KE is going to be a pretty good indication of penetration."

My point was that if were are talking about the range of possible 40S&W loads which seems to be about 135 grain to 180 grains (lighter and heaver do exist but are had to find in factory ammo) then kinetic energy is going to be better indicator than bullet weight when it comes to which will penetrate more in a lab like testing situation like ballistic gelatin.

The link agalindo provided gives a little support to my assumptions.

The Winchester 155 grain load with 400ft-lbs of energy average 12 inches of bare gelitane and 4 of 5 got over 18+ inches of penetration in denim covered gelatin. The 180 grain load that had 327ft-lbs (18.25% less) had 11.2 inches of penetration on bare gelatin and with the denim in place averaged only 13 inches.

Just for completeness the momentum of the two loads was 155 grain load had .881 slug-ft/sec and the 180 grain load had .858 slug-ft/sec (2.6% less). It seem that momentum in this case is nearly as bad an indicator as bullet mass.

To rehash, I believe that kinetic energy is going to be a good indicator of possible penetration when comparing 40S&W loads. The higher the kinetic energy a bullet has the better the penetrations; I believe this will be nearly independent of bullet weight when looking at the range possible in 40 S&W loads. Given the propensity of lighter bullets to structurally fail in real world situations I would opt for the slightly lower kinetic energy of the heavier bullets for the reliability they bring in real world situations.

Again a rambling JMHO :)
mcb
 

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From what I read of the FBI ammunition tests, heavier weight bullets maintained much better penetration than lighter weight especially when they had to go through a barrier, like cloth, denim, leather, or even a glass window, etc. If you look at the FBI approved ammunition, almost all of them are 180 grain, in .40 caliber.

Scott
 

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mcb said:
The Winchester 155 grain load with 400ft-lbs of energy average 12 inches of bare gelitane and 4 of 5 got over 18+ inches of penetration in denim covered gelatin. The 180 grain load that had 327ft-lbs (18.25% less) had 11.2 inches of penetration on bare gelatin and with the denim in place averaged only 13 inches.
You cannot compare the penetration of those two rounds because they are completely different rounds and even a cursory look at the pictures shows that the 180gr Ranger loads had more robust and consistent expansion through denim. In fact it appears that the 155gr silvertips probably went out the other side of the gel block because they did not expand at all. This is a much more likely and logically sound explanation than the one you presented. If you shoot a winchester white box 165gr FMJ into gel it will probably go out the other side, if you shoot a Ranger T 165gr JHP into gel it probably won't simply because it expanded. Look at the picture of the 155gr silvertips. The one bullet that they were able to recover through denim appears to have little expansion. In fact probably the only reason it stopped in the gel was because it shed it's jacket.

Now look at the 180gr Ranger bullets. Every one of them appears to be fully and consistently expanded through denim.

Either way though you cannot compare apples to oranges and base your assessment of bullet weights off of it. The comparison is invalid if using two different bullets.

Here's a picture of Federal HST bullets shot into gel from various calibers and in various weights:



As you can see in both 9mm and in .40 S&W if you have the same bullet of different weights the heavier one will penetrate slightly MORE than the lighter bullet. This holds true with any bullet...Gold Dot, Ranger etc... That's just how it works.

brad cook
 

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Fair enough I did compare apples to oranges but weight alone is not enough. For example I don't think you would expect a 180 grain bullet from a 40S&W to out perform the same bullet design in say a 165 grain version fired from a 10mm, assuming both were load to max pressure. Or say a 240 grain bullet fired in a 44 Magnum compared to the same bullet design in 180 grain fired from a 444 Marlin if both were loaded to max pressure. Sufficient kinetic energy will allow a lighter bullet to out penetrate the heavier bullet of the same design (assuming the lighter bullet can maintain integrity). Weight of the projectile alone is not enough info just as kinetic energy or momentum alone is not enough info.

Given the fact that many of the heavier 40 S&W cartridge seem to be loaded down from the maximum potential makes this even more of a problem. In the example you showed of the Federal HTS bullets the heavier bullets appeared to not be loaded down and had nearly the same KE (less than 10% less KE then the lighter bullets). This simple shows that bullets of similar energy the heavier is going to penetrate better. I can accept this.

I agree with you in general I usually favor bullets that are heavy for the caliber over lighter bullets (exploding groundhog cartridges being an exception here, light and fast makes then go pop) but none the less I think you have to look at more than bullet weight. Just because the bullet is heavier does not guarantee better penetration unless the kinetic energy is there to do the work.

mcb
 

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mcb said:
Fair enough I did compare apples to oranges but weight alone is not enough. For example I don't think you would expect a 180 grain bullet from a 40S&W to out perform the same bullet design in say a 165 grain version fired from a 10mm, assuming both were load to max pressure. Or say a 240 grain bullet fired in a 44 Magnum compared to the same bullet design in 180 grain fired from a 444 Marlin if both were loaded to max pressure. Sufficient kinetic energy will allow a lighter bullet to out penetrate the heavier bullet of the same design (assuming the lighter bullet can maintain integrity). Weight of the projectile alone is not enough info just as kinetic energy or momentum alone is not enough info.
Of course. My whole point is based on comparing the same bullet and caliber just in two different weights. Looking back I probably didn't make that clear. Sorry about that. I agree with you that there are more things to take into account than weight. However, you can usually say with pretty good accuracy that a slightly heavier loading of the the same round will penetrate a bit more than the lighter load.

brad cook
 

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You may need to search the internet to confirm this, but I read a report of a worker in a morgue giving his opinion on heavier bullets that may have traveled slower then lighter bullets but penetrated bone better then lighter bullets, he felt this was consistent enough to form his opinion. Ballistic test on gelatin is good for showing expansion and penetration because it has preditable consistency, unlike the human body with bone, muscle, and for some of us....alot of fat...lol.
 
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