129 SP Interbond vs. 140 in 6.5 Creedmoor

C

clockwork65

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My standard deer round is a factory 129 Interbond (I have a ton, so not worried about them being discontinued.) With a SD at .264, 2700-2900 muzzle vel, and excellent weight retention, I think it would also be a solid elk round out to 300 yards or so. So my question is: would it be worth upgrading to a 140 grain, with a slightly higher SD (.287), but probably a loss in velocity and based on what I've read, a loss in weight retention? I've got an invite to go out west next season, so I'd like to figure this out now and practice, practice, practice... especially if it's a new round. My gut tells me to stick with the Interbond and let it do its job on a good broadside organ shot. But I've also never shot an elk before, so I'm interested in real experience, too.

(I'm not interested in the 143 eldx. I've heard too many stories about them having problems at closer range and, in all honesty, I'm not going to be sniping anything at 600 yards... not without an eye transplant, anyway.

Thanks for y'all's help.
 
Thanks for the input. I've lurked on other forums and read through similar elk threads. I posted here because y'all seemed pretty reasonable. Some of the responses to "what do you think of this bullet for elk?" posts on other forums get responses like you asked people to help you burn down Yellowstone or something.

I guess my hangup with the bigger bullets is that they advertise themselves at 60%ish weight retention whereas the Interbonded is much higher (and I've seen the proof). So to me the math in terms of size sort of comes to a wash (85-90% of 129 vs 60-70% of 140). But I'm not sure what a difference the gap in SD makes in real world situations?
 
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If they are accurate in your rifle and you can place the 129 Interbond where you want then there is absolutely no reason why it won't take down an elk.

A 110gr Accubond from a 6.8spc dropped an elk at 235 yards then I don't see a problem with the 6.5 CM.
 
My 6.5x284 Norma thinks the Hornady interlock 129gr & 129gr interbond are the best, sub MOA with bought !!!!
 
Have you noticed any real difference between the lock and bond? I've never used the Interlocks in the 6.5, but have run similar in 300winmag.
 
The InterBond is going to give you the consistent weight retention and penetration you need to kill elk reliably. The Interlock is a far inferior bullet for this application.
 
Hell, I have witnessed people knocking Elk's lights out with a 243 Win. I wouldn't be at all comfortable doing it, but they didn't mind at all.

Last one I got was with a 270 gr in the 375 H&H.
 
The 129's will work, but there is nothing wrong with the 143 ELDX. It will out penetrate the 129's at any range and hit with about 300 ft lbs more energy at 300 yards. Lots of reports of elk kills at 400-500 yards with the 143 ELD-X and it works just fine up close too.

The bullet penetrated almost 2', and matched a 178 gr 308 for penetration in this test.

https://www.youtube.com/watch?v=Dzjei7Hcip8

There is nothing wrong with a bullet that does not exit, in fact they kill quicker most of the time. At some point hunters have been convinced that a complete pass through is necessary. It is not, unless you insist on shooting big game in the butt and expect the bullet to reach vitals.

If you choose to stay with 129's I'd not use it on game bigger than deer at over 200. Those bullets really slow down fast. If you're not comfortable with the ELD-X bullets then try another, tougher 140+ gr bullet for bigger game. The 120 gr Barnes TTSX would probably be even better.
 
Nikon spot on calculator indicates the 129 Interbond sent on its way at 2900 fps, fired at 8000 ft. of elevation will still be packing 1800 ft. lbs. of energy at 350 yards. Considering my total lack of experience hunting elk, maybe I'm full of blarney, but 1800 ft. lbs. with a premium bullet, placed in the vitals should take down elk. Just my humble $0.02
 
Jmr: I hope it didn't read as though I'm completely trashing the eldx. To be more specific, what I've read quite a bit of is that inside 150-175, they're fragmenting quite a bit on impact and not penetrating as they should. It sort of makes sense that a bullet designed for an 800 yard shot might not be perfect for a 100 yarder. If I was ever going to take a 600-700 yard poke in my 6.5, I'd want the eldx. I'm just never going to be doing that.

I'm not super concerned with a through and through in terms of penetration. The extra blood can be nice, especially here in South TX, where a 50 yard death run could be through insane black brush and mesquite. I mostly just meant I wanted something that would definitely gets through an elk's thicker mass and into the vitals. My hunch is that the 129 would do that under reasonable circumstances (300 and in, not taking stupid shots, etc.).

Thanks for all the input. Much appreciated.
 
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It sounds to me like you have a good understanding of the limitations of that cartridge on elk and understand why penetration is important. While the 129 InterBond wouldn’t be my very first choice, it’s a good bullet and will do the job you are asking of it. The extra penetration you’d (probably) get with a 140 Accubond or (definitely) get with a TTSX isn’t ultra important given that you have stated you have reasonable distance and placement expectations.

Is this an optimal elk cartridge? No. Is it a capable cartridge with a solid bullet? Yeah. Sounds like you know why and honestly that’s half the battle because your expectations will be sound. Elk aren’t bulletproof but you do need to hit them well enough to make them die, and they are large animals that carry misplaced shots very very well compared to deer.
 
Weight retention phoey...

People are still dropping elk with the Berger VLD Hunting. Weight retention as close to zero as possible.

Video of one lady dropping an elk in it's tracks with a 243 Win at 683 yards.
 
Mag: afterward did someone ask her why it seemed like a not horrible idea? Obviously it worked. But man. Think about how much could go wrong with any round at 700 yards and then it being even smaller than the 6.5. How do you make a quick follow up shot at that distance if you shoot it in the ass or brisket or leg? Before you know it, it's 800-900 away and you're holding a .243. Yikes.
 
After seeing some questionable results with "tipped anything" bullets, the only bullet I use for elk hunting is Nosler Partition. Do as you like, use what you please but the NP works EVERY TIME.
When you start looking a "retained energy" beyond 350-400 yards, you're making a BIG mistake. Retained energy means nothing if the bullet doesn't expand and that may be a problem with those "tough" bullets designed for "weight retention" at high velocities.
 
I think the OP’s limit of 300 yards for this situation is a reasonable limit to ensure this load will be quite effective on elk.

The Partition works so well because it retains weight and penetrates well at many velocities. Bonded bullets are effective because they do the same thing just by a different process.
 
For a Std. GP/hunting bullet, give the SPEER 140 gr. Grand Slam a look.

Great design. Accurate, sets up well yet holds together and penetrates.

Not as good as a Partition on heavy bone.

But then, it is similar to the Rem Core-Lokt, but $0.28/pop (not counting current 20% rebate) and has a BC of 0.498.


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