speed

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speed

Postby overtheir » Mon Jan 07, 2019 6:56 pm

How do u detrmine the proper speed of a projectale to perforum the task at hand , I would like one thats moa at 100yrds and still peforme they way it should not act like a grenade . I understand finding the sweet spot for accuracy but if that creates a speed that it fails what it was desingned to do then why do it other than to see that BUG HOLE.
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Re: speed

Postby Hoot » Mon Jan 07, 2019 7:39 pm

Once you reach the velocity that creates enough RPM to stabilize the particular bullet, there will be accuracy nodes that reoccur every xxx increase in velocity beyond that point. I've seen three accuracy nodes come and go as the velocity went up using the 225 FTX myself. There is a crucial role that the barrel has in accuracy depending upon its length but lets not muddy the water by including that. I don't know if there is a calculation that precisely determines the minimum velocity that the bullet stabilizes at but I know its a function of bullet length and barrel twist. Beyond that minimum stabilizing velocity, there will be a velocity where the bullet develops enough energy so as to "do what it was designed to do" but its probably a compromise over what kind of animal you want it to act upon and precisely where you intend the bullet to impact. I'm sure a lot of combatants have been dispatched by 230 FMJ hardball traveling 800fps but would the same experience exist with a 180lb buck with one heck of a will to survive? I've seen little 55gr 223 bullets do the job and I've seen 20ga slugs not. Its hard to quantify an experience with so many contributing variables into a steadfast rule of thumb.

If a bullet is designed to stabilize out of a handgun and expand properly at a given velocity, chances are its going to be a grenade at 2-3x that speed out of a rifle. I had the opportunity to shoot some Lehigh Defense Xtreme Penetrators. Range Report They are a solid chunk of copper or brass with some unique nose geometry designed do damage by creating cavitation as opposed to opening up and possibly disintegrating like most hollow point bullets. The 245gr ones are creepy accurate out of my 20" 1:24 twist AR 450b. Actually there is also the Xtreme Defense bullet which is intended to create even more cavitation at slightly less velocity but the bottom line is that both are designed to not distort or come apart as the encounter tissue and bone. If you want to hedge your bet, get some of them. Sadly, they are not cheap but neither is a deer hunt.

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Re: speed

Postby overtheir » Wed Jan 09, 2019 7:50 pm

Hoot thanks for the reply I also read your range report very great info look like Ill have to do some water jug test in the spring. TheI other bullets u mention we will probally never see them here in canada unless someone importas them . Ill contact them and see if they have a dealer up here.
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Re: speed

Postby Al in Mi » Thu Jan 10, 2019 7:02 am

most manufactures will have a FPS operating range for their bullets, if not published, just ask them for it. I know a couple guys here have asked Barnes and Hornady for theirs, but I can't find it at the moment.

what I do is try and match the bullet for what animal and where I'm hunting, 90% of the time its deer and hunting from a blind on my place, which 200yds be my top shot with most being 100-120yds ish. I love to shoot bughole groups like anybody else, shows what you and your equipment are capable off the bench but rarely matches field conditions. Also try some 200yd shooting and see what your groups and real world drops are, with my aging eyes 9x its a challenge anymore :o :shock: :(

I've been hunting with the bolt guns last 4yrs of years, can throttle them up a bit and will trade some accuracy for the extra power and performance. For how I hunt, bullet selection for me is either a Barnes or a bonded Fury or maybe a bonded Shockwave, all will hold together on a close shot and expand on my longest shot.
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Re: speed

Postby Hoot » Thu Jan 10, 2019 3:28 pm

I sure fell dumb for wasting all those blue tip (Shockwave) bullets I got from Midway a few years back, on the cheap, as an analog for Hornady 250 FTX bullets in a couple of experiments. I didn't realize they were bonded. Image

Should have used up the yellow tips first. Those days of ridiculously cheap blems from midway are history now. :roll:

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Re: speed

Postby Thom28 » Thu Jan 10, 2019 6:11 pm

Al in Mi wrote:most manufactures will have a FPS operating range for their bullets, if not published, just ask them for it. I know a couple guys here have asked Barnes and Hornady for theirs, but I can't find it at the moment.

Al,
Is this what you were looking for?

Minimum impact velocity for expansion is as follows-
TMZ 250gr catalog# 30589- 1100 fps
XPB 200gr catalog# 30554 – 1700 fps
XPB 275gr catalog# 30548 – 1400 fps
TSX 275gr catalog# 30628 – 1200 fps
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Re: speed

Postby CJP1 » Tue Jan 15, 2019 10:47 am

I got ahold of both Barnes and Hornady to find out what the max velocity is for their XPB and XTP Mag bullets. Barnes said that there was no max velocity for their XPB bullets even out of a 450BM bolt or single shot rifle. Case capacity and high pressures would be the limiting factors. Hornady said that their 240gr and 300gr XTP Mag bullets have a max muzzle velocity of 2200 FPS.
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Re: speed

Postby KenMI » Wed Jan 16, 2019 6:08 pm

The FTX are made for 1800-2000 fps, but they didn't want to make a new bullet, so they called it good enough.
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