Best copper or bronze mono-metal bullet for expansion?

[JAYgs8163]

I was looking at Lehigh Defense's website, they have a round for 300 win mag in 175gr called the Maximum Expansion. A mono-metal that's designed for soft tissue/lungs and lots of expansion. It's in .308 diameter so I would assume can be loaded for 300 RUM? A non-lead mono-metal that won't zip through. A possible DRT round?

Tipped Maximum Expansion

Lehigh Defense, LLC. - A leading manufacturer of top quality bullets.

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Lehigh Defense Load Data Library | Lehigh Bullets Reloading

Lehigh Defense Load Data Library. Browse a list of Lehigh bullets data for reloading. View the Specifications of all bullets - cartridge, technology, weight, etc

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Yea it can be loaded and shot in a 300RUM. Buy some and test them. I did see they mention this bullet is optimized to work in the "308 Winchester". That leads me to believe it's a mono primarily designed to work at lower velocity with better expansions and shedding at lower velocities.

 

[JAYgs8163]

Here's a quote from another active thread here where a guys working on a 300RUM and 300PRC and trying to decide on a bullet.

"I liked the 181 hammer hunter in 300 rum. H1000 easy shooting load at 3360fps... sub 1/2 moa accuracy. Easiest load development ever. I just loaded to max mag length which functioned properly which was 3.700 in Fierce fury."

Bullet selection. (ELDX/Accubond/Barnes/Hammer/)

Gday dfanonymous On your first bit I got a fair amount of backlash on hammertime for this type of thing occurring now it's only a low % base but one I've been watching the % increase in other's results & my own results & until one looks into hydraulic actuated vrs pneumatically actuated ( I've...

www.longrangehunting.com

 

[FEENIX]

I was looking at Lehigh Defense's website, they have a round for 300 win mag in 175gr called the Maximum Expansion. A mono-metal that's designed for soft tissue/lungs and lots of expansion. It's in .308 diameter so I would assume can be loaded for 300 RUM? A non-lead mono-metal that won't zip through. A possible DRT round?

Tipped Maximum Expansion

Lehigh Defense, LLC. - A leading manufacturer of top quality bullets.

lehighdefense.com

Lehigh Defense Load Data Library | Lehigh Bullets Reloading

Lehigh Defense Load Data Library. Browse a list of Lehigh bullets data for reloading. View the Specifications of all bullets - cartridge, technology, weight, etc

lehighdefense.com

If you like Berger bullets' performance and are considering 175g, DRT's 175 ( https://drtammo.com/drt-technology/ ) offerings are another option.

Instead of a solid copper design, it is a compressed copper powder, and you can practice with a leaded version for nearly a quarter of the price.

It was field-tested by one of the best in the business.







Good luck!

 

[Petey308]

The 240gr CEB Lazer can be stabilized with a 1:7" twist barrel on Berger's Twist Rate Stability Calculator. Should I have gotten my barrel in a 1:7" twist instead of 1:8" ? 1:7" twist also stabilizes the Berger 245gr Elite Hunter.

Here's the results for the 240gr CEB Lazer in a 1:7" twist. The 240gr Lazer needs a stability factor of at least 1.5...

240gr CEB Lazer: 2600 fps = SG 1.57
240gr CEB Lazer: 2800 fps = SG 1.61
240gr CEB Lazer: 3000 fps = SG 1.65
240gr CEB Lazer: 3200 fps = SG 1.69

All the above: "Your bullet is STABLE. Your bullet is flying with full stability. You can expect good groups and your BC is optimized."

What are the positives and negatives with a 1:7" vs the 1:8" twist barrel in 300 RUM other than shooting heavier/longer mono's?

Just fyi, copper monos do not have the same density as lead and grain for grain are longer than their lead core equivalent. Because of this, they require a higher SG to become fully stable- specifically to keep the center of pressure sufficiently spaced ahead of the center of gravity of the bullet while in flight.

The minimum SG for a mono to be considered "fully stable" is 2.0

Good luck with your endeavor. Nothing wrong with continuing to use lead core bullets by the way.

 

[Arken7mm]

Just fyi, copper monos do not have the same density as lead and grain for grain are longer than their lead core equivalent. Because of this, they require a higher SG to become fully stable- specifically to keep the center of pressure sufficiently spaced ahead of the center of gravity of the bullet while in flight.

The minimum SG for a mono to be considered "fully stable" is 2.0

Good luck with your endeavor. Nothing wrong with continuing to use lead core bullets by the way.

I spoke to a rep at CEB through email and they said my barrel's 1:7" twist will support up to the 230gr Lazer bullet.

Berger's ballistics calculator has the SG for the 230gr Lazer at 1.95 at 2,850fps with a 1:7" twist barrel. The ballistics calculator says it's flying with full stability.

The JBM calculator says the same thing, it has the SG 1.951 highlighted in green.

How big of a difference in bullet performance will it make if it's at 1.95 SG and not at least 2.0?

 

[fordy]

Gday Aaron
Longtime no see been a drift myself last 1/2 of 24 but all cool now & hope all is well with you & your family


I noticed below you put "while in flight " do you have information backing that up as I've not seen that sort of numbers published but then again I am somewhat sheltered in that field

Just fyi, copper monos do not have the same density as lead and grain for grain are longer than their lead core equivalent. Because of this, they require a higher SG to become fully stable- specifically to keep the center of pressure sufficiently spaced ahead of the center of gravity of the bullet while in flight.

The minimum SG for a mono to be considered "fully stable" is 2.0

I'll somewhat shift the goalposts a little on "while in flight " to a terminal position which I'll agree in principle that a 2stabilty is a good number to use as it's a great Band-Aid for covering up the lack of ability of some companies to design a well balanced pill

The best pill's definitely don't need this 2 number & can be used extremely effectively on numbers under 1.5 how low I ain't tested to the full limits on those pills as I saw no need to go lower
A few other things need to occur also for the bandaids to come off fully & I see that some companies are lifting the bar on that ability to balance pills terminally on what some pills can do ( still someway to go as no company produces what can be done oh yes I've got some recent tinkering on pills that is pretty cool & I ate crow on this proudly) but I still like a number around 2 or around there as my own personal minimum on most pills but on the odd one I'd happily use a 1.5 as terminally that design is superior but try to find those pills today sadly they aren't made so I hope a company will one day give me the ability to see that type of pill on the shelves

Ps mark fixed his alloy if you haven't heard & even beat one of the best frangibles on the market today on killing efficiency @ low resistance low velocity impact in 6.5 tests I'd done so the bar is getting raised & more to come no doubt

Cheers

 

[FEENIX]

I spoke to a rep at CEB through email and they said my barrel's 1:7" twist will support up to the 230gr Lazer bullet.

Berger's ballistics calculator has the SG for the 230gr Lazer at 1.95 at 2,850fps with a 1:7" twist barrel. The ballistics calculator says it's flying with full stability.

The JBM calculator says the same thing, it has the SG 1.951 highlighted in green.

How big of a difference in bullet performance will it make if it's at 1.95 SG and not at least 2.0?

I don't know how CEB/their ballistician determined the twist rate requirement, but the minimum SG of 2 for mono bullets is relatively new. Twist rate calculators like the Berger and JBM were designed for C&C bullets, and the minimum recommended stability is 1.5 to achieve the maximum BC. I do not think any of them made adjustments to their software. You can still use them, except the SG for C&Cs is >1.5 and for monos >2.

There was an article, video, and podcast with Bryan Litz (IIRC), but I cannot seem to find it at the moment. I am pretty sure @Petey308 has them and more information to share. He's an excellent source on this type of matter. On a side note, I try to get to an SG closer to 2 on my last 3 builds. For instance, below is .257 WBY propelling the 163 Chinchaga out of 22" 1:7" barrel.

Good luck!

 

[Arken7mm]

I don't know how CEB/their ballistician determined the twist rate requirement, but the minimum SG of 2 for mono bullets is relatively new. Twist rate calculators like the Berger and JBM were designed for C&C bullets, and the minimum recommended stability is 1.5 to achieve the maximum BC. I do not think any of them made adjustments to their software. You can still use them, except the SG for C&Cs is >1.5 and for monos >2.

There was an article, video, and podcast with Bryan Litz (IIRC), but I cannot seem to find it at the moment. I am pretty sure @Petey308 has them and more information to share. He's an excellent source on this type of matter. On a side note, I try to get to an SG closer to 2 on my last 3 builds. For instance, below is .257 WBY propelling the 163 Chinchaga out of 22" 1:7" barrel.

View attachment 632171

Good luck!

Are 1:6" twists going to eventually become more common if the industry and market moves more to mono' in order to stabilize long mono's? If I had a 1:6" twist in my 300 RUM I could stabilize the largest mono's in .30 cal.

Any companies make a 1:6" twist?

 

[FEENIX]

Are 1:6" twists going to eventually become more common if the industry and market moves more to mono' in order to stabilize long mono's? If I had a 1:6" twist in my 300 RUM I could stabilize the largest mono's in .30 cal.

Any companies make a 1:6" twist?

That depends on the market; supply and demand.

X-Caliber makes 1:5" and 1:6" in .30 cal.

 

[JAYgs8163]

Are 1:6" twists going to eventually become more common if the industry and market moves more to mono' in order to stabilize long mono's? If I had a 1:6" twist in my 300 RUM I could stabilize the largest mono's in .30 cal.

Any companies make a 1:6" twist?

I don't think so because as we've explained the mass majority will not run as heavy a mono as the cup/core they've run. Some of your monos require significant speed to function properly and open. The one you mention though is stated to work down to 1400fps but it's a single feed only. I'd be curious as to what type of penetration they get at 1400fps. Big and heavy is not necessarily better in Monos. Sacrifice some weight and still get a fantastic BC but increase your speed and killing factor and don't limit yourself to a single shot rifle. If you're just shooting steel then it's meh.

 

[Arken7mm]

For mono's in 308, is around 150gr to 155gr the sweet spot for velocity and penetration? The Cutting Edge bullets in 308 260gr won't achieve a 2.0 SG even with a 1:9" twist. Have any of tried heavier longer mono's in 308 with any success?

 

[JAYgs8163]

Are you asking about a 308 Winchester cartridge or a 308 caliber bullet for your RUM?

Every bullet maker is different. You'll have to look at each bullet.

I run a 130 Mono in my 308 Win at 3150 fps and it's good to 550 yards.

I run a 168 Mono in my 300WSM at 3200 fps.

 

[Arken7mm]

Are you asking about a 308 Winchester cartridge a 308 caliber bullet form your RUM?

Every bullet maker is different. You'll have to look at each bullet.

308 winchester. My Zastava M77 can not stabilize the Barnes 168gr. Am I giving up anything by sticking to 150gr-155gr mono's in 308 win?

 

[JAYgs8163]

308 winchester. My Zastava M77 can not stabilize the Barnes 168gr. Am I giving up anything by sticking to 150gr-155gr mono's in 308 win?

No. Just run them hard and fast. We kill Cow elk with the 130 Barnes TTSX and the load I mentioned above, but we limit shots to 350 with it.

Look at McGuire bullets for your RUM. I'm testing their 168 now in my 300WSM.