"It shoots flatter" 308 discussion

[Antlion]

Going back to a discussion I had with a rep at Huntex, specifically telling me why a 150gr mono makes sense in a 308. The usual points about penetration, less risk of failure etc were mentioned. But one point I would like to hear opinions on, as its shot faster , it has less drop out to around 300m. Any merit in this? Some quick calculations on JBM ballistics show the difference is not that great when comparing to the heavies, more so with a 200m zero.

[A-R]

A salesman you say? Why would he even consider giving you a balanced opinion on the relative merits of his product?

Do your own research and compare apples to apples.

Starting with the bullet choice. If your 308 has the typical 1:12" twist barrel, a 150gn expanding copper mono bullet will likely be marginally stabilized and a poor choice for the application.

Generally speaking, copper mono's will usually retain a bigger % of initial weight than a cup-core type. You have to choose a lighter mono bullet to stabilize as well as cup-core type, so it should be able to be shot faster and drop less than a cup-core bullet of equal length. Monos are also not always easy to get accurate and some rifles flatly refuse to shoot them into acceptable groups. There is more. It is a somewhat complex equation with complex answers.

Don't let the rep over-simplify the matter. Next time ask him some informed questions and see how he backpedals...

[Dale SH]

Slightly off topic here AR but I have never battled to achieve accuracy with a mono.
Simply because they are CNC machined to exact tolerances in terms of length, weight and BTO measurements.

[Messor]

Ok, so the long range guys they all try and shoot the heaviest bullet, and here we don’t read it as heaviest bullet we read it as highest BC bullet, because in product lines that is generally the norm.
This is all to try and beat the wind, because wind is something you must anticipate, drop is something you just calculate and dial.

Normal cup and core bullets have terrible BC’s which looses speed easily and are very much affected by wind.

However, in product lines when comparing modern bullets of general overall high BC’s, under 300m the effect is very little. For example one day I compared an 180gr sst shot at 2450ft/s to a 150gmx shot at 2800ft/s. When zeroed at 200m the drop difference at 300m was about 7cm, with almost equal wind bucking ability. And bear in mind I literally did this, shot the 180gr SST slow to see how it performs, and I can tell you it performed outstanding out to 500m.

In reality, at 300m, a 7cm difference is a terribly small difference, you can call it insignificant. Most people cannot even shoot that accurate at 300m from field positions.

However, and this is a big however, seeing as the impact velocities are more or less the same, about 2200ft/s, I’d take the 180SST over the GMX. Why, well I can guarantee proper expansion from the SST but only perhaps on paper for the GMX. Weight retention at 300m is a non issue, cup and core stay together at such low speeds.

The “it shoots flatter” argument swings both ways, I can for example provide a scenario in which I’d rather have the mono. Understanding all the variables are much more important.

[A-R]

Slightly off topic here AR but I have never battled to achieve accuracy with a mono.
Simply because they are CNC machined to exact tolerances in terms of length, weight and BTO measurements.

Me neither, but some users I have spoken to claim to have struggled and given up. Wheither they used an unsuitable bullet or their rifle's barrel was out of spec will likely never be known.

Conventional cup-core bullets are softer and can be squeezed down a little or bumped (obturate) up to fit a particular bore. Monos are not as forgiving. Does not bother me, seems my rifle barrels are built to spec.

[414gates]

It depends on the range, the bullet, and the muzzle velocity.

As the range gets longer, a lighter bullet at higher velocity loses out to a slower, higher BC.

If the scope has enough elevation in it, it won't matter much which way you go.

IMO, heavy bullets with high BC are over-rated in 308 , 155gr Nosler Custom Comps do just fine on targets to 1000 meters.

And if you're going to hunt, use 130gr HV from GS Custom.

[A-R]

... Understanding all the variables is much more important.

This ^^^

[Dale SH]

Me neither, but some users I have spoken to claim to have struggled and given up. Wheither they used an unsuitable bullet or their rifle's barrel was out of spec will likely never be known.

Conventional cup-core bullets are softer and can be squeezed down a little or bumped (obturate) up to fit a particular bore. Monos are not as forgiving. Does not bother me, seems my rifle barrels are built to spec.

Yip.
Probably substituted conventional bullet weight for a mono and the bullet wasn't stabilized.

[A-R]

Yip.
Probably substituted conventional bullet weight for a mono and the bullet wasn't stabilized.

Common mistake. And some bullet makers seem not to care either.

[Messor]

I bet correct and often practice beats bullet choices every day of the week.