grain for grain in the 10mm

[krafcheck]

comparing say 155gr. to 180gr.   

please educate me.  155 to 180 gr. ok i get it. One is 25 grains heavier. will 25grains (a very small weight difference) create much difference in momentum.  lets say you have 1500fps (155gr,) to 1300fps (180gr.) .  we may need to take hollow points out of this topic.  grain for grain and speed for speed to me it looks like 155gr. wins straight out when compared to momentum and pure penetration potential. if 180 was faster or 155 slower things would change.

if they were the same speed what will be the power/penetration difference?

i dont think i am asking in the right way but hopefully it makes enough since. 

on paper underwoods 155's look like the best possible choice. fps and ft/lbs (imho).  not considering recoil or current HP's in this discussion.

[The_Shadow]

Well, the energy is not the total answer in any bullet equation...the reason is that if the lighter or heavier faster bullet zips right through the intended target, much of that energy, is then wasted.

Finding a balance of bullet performance/construction...velocity, energy, expansion, penetration, temporary & permanent cavities, does the bullet fragment and does it exit before dumping most all its energy!

Let's step back and look at the 45ACP at 250 grains @ 850 fps and slow as it goes it still carries like a sledge hammer.  It was considered effective for up close and personal!

Personally I like the fact that the heavier bullet carries its energy deeper, not just a surface or shallow energy dump.  But then again the lighter bullet if constructed properly could deliver great performance as well.  So then we have to consider the target, and what the bullets may encounter dealing with the performance...heavy/light clothing, heavy/light body mass and what other things that could play into the mix, shielding and/or distance.

But both of those weight bullets 155 gr and 180 gr as a HST, Gold Dot, Ranger T would still be a defensive bullet! 

[Geeman]

Light bullets loose energy faster.  Light bullets loose integrity faster when they hit things too.  They also penetrate less.  They also tend to be less accurate at longer distance.

I didn't say light was bad.  My home defense round is 135g at high velocity.  I want something that does its damage when it hits and has minimum potential left if it passes through in my home.  Same goes for missed shots.  Bullets blowing up isn't necessarily a bad thing.

If I (heaven forbid) end up in a shoot out outside the home, heavier might be a better option.  If the bad guy is behind an obstruction and popping up letting rounds fly my way, I might be able to get through that obstruction with a heavier bullet and give him something else to think about other than how he's going to deliver his next flurry.

So, as with most things, it depends.

Greg

[4949shooter]

You might want to consider the "cruiser weight" 165 grain bullet. Law enforcement contacts tell me the 165 grain Speer Gold dot in .40 has an excellent record putting down bad guys on the streets. Here is a simtest from TnOutdoors9 on the .40 version:

http://www.youtube.com/watch?v=s8dezgRVqs0

I have no reason to believe a 165 to 170 grain bullet loaded to 1300 fps wouldn't perform exceptionally well on the streets.

[krafcheck]

You might want to consider the "cruiser weight" 165 grain bullet. Law enforcement contacts tell me the 165 grain Speer Gold dot in .40 has an excellent record putting down bad guys on the streets. Here is a simtest from TnOutdoors9 on the .40 version:

http://www.youtube.com/watch?v=s8dezgRVqs0

I have no reason to believe a 165 to 170 grain bullet loaded to 1300 fps wouldn't perform exceptionally well on the streets.

i actually have 165's from Underwood loaded now.  my last 15 of them. as far as losing velocity faster im not too concerned being its a handgun. im sure underwoods 135gr at a 100yards will still have at least 1000fps.  with all this said unless pbr or underwood get some in stock soon i will be stocking up on what they have.  135's and 155's underwood are some rowdy rounds for follow up shots for me.  numbers are sure impressive. i guess i could have some patience and wait for the heavier grains to come in if not in stock in the next couple of weeks.

the youtube video showing i believe 155's vs. 44 mag with steel plate was interesting.

been thinking about going to a junk yard and pick up a car door and shoot it with the different grain hp's to see what they do. 

[harrygunner]

Weight matters when looking at the collision of the bullet with the target. The change in momentum of impacted tissue is nearly proportional to the weight of the bullet. It's not the 25gr difference, rather it's the fact that a 180gr bullet has 16% more mass than the 155gr bullet.

[Dave84]

Krafcheck, UW has 180 grain xtp's back in stock. Haven't seen anything besides 135s and 155s in a long time.