Lead vs copper.

[marcos0901]

I started looking into some cutting edge bullets for my 308 and started wondering if I wanted to go with the same grain I am shooting now or go a little lighter. I shoot a 1/10 26 inch heavy barrel. Usually anything lighter then 160 in 1/10 doesn't shoot the best. But will the extra length of the copper bullet stabilize like a 168 lead bullet?

 

[Varmint Hunter]

Almost without exception, monos shoot better at a lighter weight than cup & core bullets, at least IMO. But as long as you match the mono's twist requirements to your barrel you shouldn't have an issue.

 

[Reelamin]

I'm old and stubborn. Twist rates have gone nuts over the internet with all kinds of must should have to junk. It has gotten so ridiculous people are blaming bullet failure because of wrong twist rate.

If you want to try heavier lighter or the same load it up and you will find what it likes. You will read about 1000 rifles that had r. Wrong billet for twist rate. Almost never read how the wrong bullet for twist rate and it shoots the best. I know there are just as many on both sides of that situation.

 

[marcos0901]

I'm old and stubborn. Twist rates have gone nuts over the internet with all kinds of must should have to junk. It has gotten so ridiculous people are blaming bullet failure because of wrong twist rate.

If you want to try heavier lighter or the same load it up and you will find what it likes. You will read about 1000 rifles that had r. Wrong billet for twist rate. Almost never read how the wrong bullet for twist rate and it shoots the best. I know there are just as many on both sides of that situation.

I was taught by old school people so I am more of just a good cored bullet person. My rifle loves 168 hornady bthps it doesn't like anything lighter. I was just curious if the length of a lighter copper bullet would shoot about the same at a little heavier cored bullet.

 

[marcos0901]

Almost without exception, monos shoot better at a lighter weight than cup & core bullets, at least IMO. But as long as you match the mono's twist requirements to your barrel you shouldn't have an issue.

Thanks I will have to try them and see.

 

[HARPERC]

https://www.google.com/search?q=jbm+ballistics+stability+calculator&oq=j&aqs=chrome.1.69i57j35i39j69i59j46i131i433j46i199i291i433i512l2j69i60l2.2441j0j7&sourceid=chrome&ie=UTF-8

Pretty easy free calculator to give you an idea where your stability is.

Berger also has one.

 

[Hugnot]

I ran some Sg's on my spread sheet & came up with this:

This stuff shows the 165 Cutting Edge Lazer's Sg is sort of adequate at lower temps like when shooting deers & other. I would go for the shorter Cutting-Edge bullets. I selected the 168 Hornady ELDM as a sample comparison bullet because it is a cup/core, weighs 168 grains & has a plastic tip. A Sg of 1.4 has been defined as minimum for stability in Miller method Sg calculations. Berger might go higher at 1.5 for complete stability. The Berger Sg program does not make provisions for tipped bullets & uses altitude instead of actual pressure, the last time I ran it. Altitude values may not indicate actual atmospheric pressure. 2650 fps seems like a nice MV for a 168 out of a .308. Various manuals show MV's in the mid 2700 fps range for 165-168 bullets. This velocity increase would only show a tiny Sg increase as indicated by -(M375/2800) in the math, M375 being the velocity. This spread sheet calculation matches that of JBM's and if corrected for altitude matches Berger's.

If you have Apache Open Office software (free) on your computer this stuff can be duplicated. The math is shown on the top line. Lots of "( ), & exponential shown by "^". Picky but simple math.

 

[marcos0901]

I ran some Sg's on my spread sheet & came up with this:

View attachment 323459


This stuff shows the 165 Cutting Edge Lazer's Sg is sort of adequate at lower temps like when shooting deers & other. I would go for the shorter Cutting-Edge bullets. I selected the 168 Hornady ELDM as a sample comparison bullet because it is a cup/core, weighs 168 grains & has a plastic tip. A Sg of 1.4 has been defined as minimum for stability in Miller method Sg calculations. Berger might go higher at 1.5 for complete stability. The Berger Sg program does not make provisions for tipped bullets & uses altitude instead of actual pressure, the last time I ran it. Altitude values may not indicate actual atmospheric pressure. 2650 fps seems like a nice MV for a 168 out of a .308. Various manuals show MV's in the mid 2700 fps range for 165-168 bullets. This velocity increase would only show a tiny Sg increase as indicated by -(M375/2800) in the math, M375 being the velocity. This spread sheet calculation matches that of JBM's and if corrected for altitude matches Berger's.

If you have Apache Open Office software (free) on your computer this stuff can be duplicated. The math is shown on the top line. Lots of "( ), & exponential shown by "^". Picky but simple math.

Awesome thank you for that! Sadly i don't have a computer so I may see if I can find an app that does about the same.

 

[marcos0901]

https://www.google.com/search?q=jbm+ballistics+stability+calculator&oq=j&aqs=chrome.1.69i57j35i39j69i59j46i131i433j46i199i291i433i512l2j69i60l2.2441j0j7&sourceid=chrome&ie=UTF-8

Pretty easy free calculator to give you an idea where your stability is.

Berger also has one.

Thank you!

 

[Texis]

Our rifles are similar, 308, 1-10, 26" Varmint barrel.. mine loves 168 Barnes TTSX. They fly very well! (.3 MOA) Also, the only round I've found that matches the output on Ballistic AE dead on. Every other round I have to "true" the ballistics.
Try some solid copper. you'll like um

 

[Texis]

And yes.. they kill large critters VERY well.

 

[Bucklowery]

My 308 20" 1:10 twist loves the 168g too. It will shoot the 150 and the 175 but it loves the 168g. I have always been a cup and core guy and like the bullet to expend all its energy in target, so I have usually shot ballistic tip type Bullets on our small deer here in Florida. I wanted a bit tougher bullet for my hunt out west this year. I set up my 300 wsm with hammer bullet and I love them now. They are the best of both worlds

Thanks

Buck

 

[WildRose]

I started looking into some cutting edge bullets for my 308 and started wondering if I wanted to go with the same grain I am shooting now or go a little lighter. I shoot a 1/10 26 inch heavy barrel. Usually anything lighter then 160 in 1/10 doesn't shoot the best. But will the extra length of the copper bullet stabilize like a 168 lead bullet?

Monos will generally shoot like a lead bullet 10-12% heavier as a rule using the same twist.

As most of us have learned here over the years your mileage may very but that's been a pretty good rule for me in everything from 7mm-.375 so far.