I was wondering if any of you guys with a lot more experience than me (and anyone with the technology to test it) could tell me what the relative value of a lighter bullet is for flatter trajectories.

Conventionally, I'd think that a 300g bullet would drop less at 300 yards than a 400g, presumably because it weighs less, but it also has less momentum since it has less mass, and that is the kicker...

Somewhere, there has to be a trade-off between momentum and less gravity pulling down on the lighter bullet. I mean, you can originally get a 300g bullet going faster with less powder/preasure (depending on the powder), but ultimately, that bullet starts to slow down at a faster rate than the heavier bullet (i.e. it wont fly as long). Since the only thing that really keeps bullets flying is a ton of momentum, there has to be an optimal weight of bullet that will have the least drop when it gets out to 300 yards. I'm guessing it isnt the 250g or the 300g either, but maybe something that was getting closer to 400g (Maybe 375?). Now I know that this all depends on loads, but there has to be one powder that produces the minimum preasure at the most velocity for one of these weights of bullets, and if those two cartrige combos were put head to head, who would drop the most at 300 yards?

What made me think of asking this besides a physics flashback? Well, I have a pellet gun that fires as fast as a 22 rimfire...thing is, it will never have the range of a bullet since a pellet just doesnt weigh enough to keep going. Also, I heard that the old military 45-70 guys used to get longer range out of a 500g than a 405g (But I'm guessing it was not with a flatter trajectory). :)

Please inform, and thanks,
JH

Without a detailed analysis I can only say that your query is directly related to the ballistic coefficient of the projectile, which is determined to be a function of bullet mass, diameter and drag coefficient and that bullet's velocity. While you have correctly surmised that there is a threshold at which the lighter bullet no longer has sufficient momentum to achieve the least drop at 300 yards, a simple look at ballistic calculations would reveal that a 300 grain bullet would exhibit the least drop compared to a 400 grain bullet, given they are loaded to their potential in the Marlin 1895 45-70 and are of similar construction and configuration. I would think that given the 300 yard range that the bullet weight threshold you seek is going to be below 300 grains. A comparison of the 250 grain Barnes XFN and 300 grain Barnes XFN does not get one closer to the answer as the 300 grain is so long it limits the case capacity of its loadings. And there are not the cup and core bullets of similar construction and configuration below 300 grains to easily make the comparison.

I think you also have to qualify your discussion with whether or not you are talking about bullets of different weight be driven to their potential. A 300 grain bullet may indeed have more momentum than the heavier bullet due to its being driven at greater velocity. Because of the relative ballistic coefficients of the bullets the light bullet should lose that momentum faster, but perhaps not fast enough to drop less at 300 yards.

If I remember my physics right, you are definitely right about the ballistic coefficiencies of the bullets...I'm just wondering how much more drag a 400g with a .300 meplat will have over a 250g with a .300 meplat....I'm just guessing the front part of the bullets produces the most drag.

And I guess I'm thinking about relatively safe presures (under 40,000 cup).
For argument sake, how fast you could get a 300g bullet using Varget, H4064, or H4895 loaded as clos to 40,000cup as possible.

Would that bullet out perform a 400g also using a lower preasure powder...getting as close as can be to 40,000cup...if they both had the same meplats?




I think you also have to qualify your discussion with whether or not you are talking about bullets of different weight be driven to their potential. A 300 grain bullet may indeed have more momentum than the heavier bullet due to its being driven at greater velocity. Because of the relative ballistic coefficients of the bullets the light bullet should lose that momentum faster, but perhaps not fast enough to drop less at 300 yards.

So, I found the following ballistics table from on Conley Pricision Cartridge's website concering their 45-70 ammo. I know it's just a handfull of bullets and loads, but the Barnes Original 400g seems to beat out the Barnes Original 300g. I don't know what kind of powder their using, and what kind of preasure their hitting (aside from the fact that it's within the specs for modern 45-70 levers), but it does add a little to my curriosity...that's 400g at 1900fps...what about 2000fps?
Also makes you wonder what the stats would be with a premium cast bullet?

http://www.cpcartridge.com/45-70marlin-B.htm

By the way, I'm in New York City for the next 6 months, so maybe I'm just trying to live vicariously through you all since my guns are thousands of miles away. :) (Yes, sadly this means that I will miss this year's deer hunt).

Take care you all, and have a blast.

JH

The Conley Barnes 300 grain load is not loaded to the potential of the Marlin lever action achieving only 2664 fpe compared to the 400 grain at 3206 fpe. The 300 grain Barnes Original can be driven 2355 fps in a 22" barrel which again then would give it the edge in trajectory at 300 yards. You would be hard pressed to drive a 400 grain Barnes 2000 fps in a 22" barreled Marlin with 1989 fps being about tops. Here is an example of these bullets driven to their potential in the Marlin:

300 grain Barnes Original
Range Velocity Drop Energy
0 2355 0 3695
100 1994 3.78 2649
200 1676 16.43 1871
300 1401 41.62 1308

400 grain Barnes Original
Range Velocity Drop Energy
0 1989 0 3514
100 1743 5.13 2698
200 1525 21.81 2698
300 1337 53.55 1588

Thanks for running the math jackfish. :)
Looks pretty much like a victory for the 300G.

Have a great weekend,
JH

The Conley Barnes 300 grain load is not loaded to the potential of the Marlin lever action achieving only 2664 fpe compared to the 400 grain at 3206 fpe. The 300 grain Barnes Original can be driven 2355 fps in a 22" barrel which again then would give it the edge in trajectory at 300 yards. You would be hard pressed to drive a 400 grain Barnes 2000 fps in a 22" barreled Marlin with 1989 fps being about tops. Here is an example of these bullets driven to their potential in the Marlin:

300 grain Barnes Original
Range Velocity Drop Energy
0 2355 0 3695
100 1994 3.78 2649
200 1676 16.43 1871
300 1401 41.62 1308

400 grain Barnes Original
Range Velocity Drop Energy
0 1989 0 3514
100 1743 5.13 2698
200 1525 21.81 2698
300 1337 53.55 1588