Looking for smaller caliber "Ballistic twin"

[2rocky]

I'm intrigued with the idea of a pair of rifles in different calibers that could allow someone to practice with a lower recoil rifle but still get the experience with wind drift and drop akin to the larger caliber rifle.

Ron Spomer wrote about it Here:

In a brief search there doesn't seem to be an online database of calibers and loads by Muzzle velocity and Ballistic Coefficient.

So what matches with a .300 Win Mag shooting 165 gr. Hornady GMX's BC of .447? at 3260 at the muzzle?
as far as MV goes,

25-06 looks good...as does a 55gr .223 but within the GMX line the Ballistic coefficient falls off below .300. So I have to look for higher BC bullets.

 

[BuzzH]

Lots of good choices...a heavier .243/6mm in the 95-105 grain with a MV of 3k would be close.

7mm-08 with 120 BT or 140 BT would be close.

260 Rem. with a 120 BT.

Etc. Etc.

 

[rwc101]

I've thought about this as well. I'm leaning towards the .243. With hand loads it should be relatively easy to approximate a number of larger cartridges.

 

[338 win mag]

The .223 may work to move up to a 62gr or a little higher even though velocity will fall off a bit, but bc may be closer

 

[std7mag]

I'm thinking you may not be too sucessful ballistic matching up to your rifle/load.

Example 140gr SST with G1 BC of 0.487, with MV of 2,800 fps, the 7mm-08 isn't going to match you trajectories from your 300 Win Mag.

While easier on recoil, and a good all round hunting cartridge, the biggest benefit is going to be trigger time.

 

[ImBillT]

Anything with a similar BC and MV.

95gr VLD in a .243Win
130gr VLD in a .270Win
75-80gr VLD in a long barreled custom 22-250 with a tight twist.

You can use other bullets, just pick one with a BC that is close, and match it to a cartridge that will deliver that weight bullet at roughly the same MV as the one you’re trying to match.

 

[Doublecluck]

6mm w 105’s

 

[6mm Remington]

280 AI - 140 gr. Nosler Partition .434 BC. 3230 fps out of my Winchester Model 70 - 280 AI
- 140 gr. Nosler Accubond .485 BC 3186 fps

6mm Remington - 90 gr. E-Tip .403 BC 3200 fps

 

[std7mag]

Hmmm, seems like the winner would be the 280AI.
Slightly higher BC, but with slightly lower MV.
If your looking for trigger time, i'd probably use the Hornady SST, not quite as accurate (but accurate enough) and easier on the wallet. POI same as the Accubond and Ballistic Tips but about half the price.

The 6mm Rem would be out due to lower BC, and MV.

 

[BAKPAKR]

How about a 1:8” twist Tikka 22-250 with 77 gr Sierra TMKs or 75 gr Hornady ELD-Ms? I am pretty sure the TMKs could be loaded to fit the magazine but I am not sure about the ELD-Ms.

 

[noharleyyet]

Lots of good choices...a heavier .243/6mm in the 95-105 grain with a MV of 3k would be close.

7mm-08 with 120 BT or 140 BT would be close.

260 Rem. with a 120 BT.

Etc. Etc.

Been meaning to project a .243 for years. Zeroed a buddy's a while back as he was gifting to a grandchild...a nice little Winchester with a clear VX2 3x9...fun and accurate. But my attention deficit dialed up a 45-70....gotta fix that.

 

[Jbotto]

I remember reading this article when Spomer first put it out. It makes a ton of sense to me but I don’t deal much with long range stuff. I keep it old fashioned as I zero everything for 200 and then learn my drops from there. From that point as long as you do your drops from past 200, the skill in measuring or dialing remains the same. It’s just the numbers that are different. Spomer relies on the MPBR method of sighting in and I could see why this matches up with the two rifles theory of matched velocities and BC’s.

I like having two matched rifles in terms of a “lower powered” option along side as the big game rifles we all use and rely on, but instead of matching ballistics I’m more concerned about safeties, triggers, actions, scope reticles, and feel. It’s nice to have all of those things match no matter what rifle I pickup. I’ve bought into this instead and I’m likely to change at some point as it has got me to the point that all my rifles are the same brand and model. Though boring, and self-limits my new rifle purchases, it works for me....for now.

 

[Taxed in Maine]

I have a 7mmRem Mag paired with a 25-06.

 

[CubSlayer]

I've gone through a similar exercise motivated by cost, not recoil. In my .308s, the cheap 150-grain Core Lokts perform almost identically to the 150-grain Trophy Copper (I can't explain this). The 180-grain Fusions fly like the 165-grain Trophy copper. In .243, the 100-grain Core-Lokts are ballistic twins to the 95-grain Partitions. In the .338s, the 200-grain Fusions fly just like the 200-grain VitalShok rounds. What sucks is the .338 Trophy Copper, which I'd really like to try, groups well, but doesn't fly like anything else. Don't want to practice with these all year.