Ruger American Compact/Predator Loads .308 Help

[bj426]

This is bound to get long... so thanks for hearing me out.


SO... It all started when my oldest decided he wanted to start hunting. Any excuse is a good excuse to get a new gun! I decided on a set of consecutive serial numbered Ruger American Compacts in .308 for him and his little brother when he got old enough. Figured since I reload I could download to appropriate recoil and he'll never outgrow it. Well we had great success with finding a load that worked and he tagged his first deer on our second day out. Couldn't have been prouder. I'm hoping that one day he'll be able to claim to have only harvested game with cartridges he made.

Fast forward to a few weeks ago, Cabela's is running a deal on the new RA Predator in 308 and I just so happen to have enough Cabela's bucks to get it free and clear. (which is also how I got the boys') Now I've got essentially the same gun that's just enough different that there is no mistaking "Dads".

I've long been a fan of the .308 and am looking forward to trying a number of different rounds including the reduced recoil rounds that I made for jr. but I start thinking about the nightmare of having to re-sight-in every time I want to use a different round.

It dawned on me that (in a perfect world) I might be able to develop rounds that would have the same ballistic path. So I popped open a Hornady reloading manual, fired up the internets, a reloading program or two and started chugging numbers.

SO: (all examples are for illustration purposes only) Starting with the assumption that the largest load brings the most challenges, I tried to identify what speeds the other loads would need to be at to match this path. THEN, accepting that I live in MN and would rarely get a shot beyond 150yd I also identified a zero that maintained a flat +/-1" trajectory for each load.

I would however like to use this occasionally at longer "moderate" ranges out to 300yd primarily for hunting purposes. For that reason, I listed holdovers, and the yardages that the energy dropped below 1000ftlb as well as the velocity falling below 1900fps. (Obviously subjective numbers, but lets just humor me for now...) Just for fun, I included some relative recoil numbers.

It looks like "in theory" (and I know each barrel/load combination is going to like whatever speed it likes...) I could get a 130Gr Reduced recoil, a 150Gr, a 165Gr and a 180Gr to all shoot to the same point of aim, zero'ed at 140yd and staying within a 2" range (+1": 85yd, -1": 160yd).

So the question is: Will it work? Has anyone tried this? If so is there a name for it? I'd love to be able to have recipes for 4-5 particular loads that all work with the same scope setting or at least within a few clicks. Maybe have the turrets set to zero for the 165gr and have a chart for the minor adjustments for the others if I HAD to?

I've tried to attach the chart I worked up. Hopefully that works so that it illustrates a bit better what I'm going for. I figure with three guns in the house it'd be a fun longer term experiment for the boys and I. However, if I'm going to be chasing rabbits down a bunny hole, I'd rather hear it now.

Also, yes I'm aware that my predator has a different contour barrel than the compact, but its the same length and twist, so for now I'm ignoring that fact.

Any thoughts you can share would be MOST helpful.


Supporting info:
*Reduced Recoil (H4895: 41Gr)
**Sub-Sonic (IMR Trail Boss: 10gr)

Muzzle Velocity "Achievability" Verified with Hogdon .308 Pistol Data (15" Barrel)
http://www.hodgdonreloading.com/data/pistol

Short Barrels don't reduce accuracy:
http://www.tacticaloperations.com/SWATbarrel/

 

[jmr40]

You are over thinking this.

I load for 308, 30-06 and 300 WSM. At 300 yards there isn't enough difference in trajectory to matter. With a 100 yard zero I can still hold on hair and make hits on deer size game with any of them. If you and your rifle are capable of shooting 1/2" groups at 300 yards you might actually notice the difference. Otherwise a typical 3-4" 300 yard group will be far greater than the tiny difference in trajectory.

The 300 WSM drops the least at about 9", the 308 about 12" with 30-06 10". I can hold on the top edge of a deers back and put a bullet in the kill zone with any of them. At longer ranges it starts to add up.

 

[bj426]

Hunting would just be one of my intended purposes though. I agree the vital area is large enough that as long as loads don't inherently fall left or right it, I could find a combination to hunt ethically. However, when introducing a level of accuracy in target shooting, I'm more curious HOW close I can get and if that ballistic path can't be darn near identical. The math works... but how much fooling around will there be. Again, I'm CERTAIN that it will all depend on what load my gun likes the best. It would be foolish to choose a load that matches muzzle velocity but doesn't provide optimum accuracy.

 

[Snyper]

I'm more curious HOW close I can get and if that ballistic path can't be darn near identical.

Any ballistics calculator can give you a general idea, but matching trajectories won't insure the loads will be accurate in each gun.

I agree that you're overthinking it all.

98% of big game is killed at 200 yds or less, with about 80% at 100 or less

Find an accurate load for each gun and don't worry about fractions of an inch trajectory variations

Also keep in mind that even if trajectories are indentical, the POI can change with each load

 

[Peakbagger46]

H4895 youth loads with a 130g soft point is sub moa in my wife's 308 and has been very effective on mule deer.

 

[MartinS]

Sounds like trying to stick to the theory could make things complicated enough to get in the way of learning how to shoot.