16 inch Barrel Comparison - 22CM, 6CM, 6UM

[mxgsfmdpx]

I tried it once, and got frustrated. I went back to AB and haven’t tried anything else…

Strelok, Revic, and Shooter all seem to be pretty reliable solutions (likely working off the same base engine).

 

[Formidilosus]

I’m not sure you are getting 3000fps out of a 16” 6cm with 95tmks. Is that someone’s real number or speculation?


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18” 6cm, 95gr TMK.

 

[mxgsfmdpx]

I’m not sure you are getting 3000fps out of a 16” 6cm with 95tmks. Is that someone’s real number or speculation?


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My previous 7.5 twist on one of my 6 creeds, a 16” barrel, had them JUST under 3,000 with a safe hunting load.

 

[WyoWild]

I have always felt that the tipped cup & core bullets performed best with impacts in the 2000-2800 fps range. That being said I have killed most my animals with 308, 6.5 Creed and now 6 Creed so dont have any personal experience with real high velocity impacts. For those shooting 6UM and 22 Creed are you seeing extreme fragmentation with close range impacts over 2900-3000fps? Does that lead to decreased penetration on bigger animals? Just curious how these bullets perform in that hyper velocity range. Thanks!

 

[Formidilosus]

For those shooting 6UM and 22 Creed are you seeing extreme fragmentation with close range impacts over 2900-3000fps?

Yes.

Does that lead to decreased penetration on bigger animals?

No. They die emphatically

Just curious how these bullets perform in that hyper velocity range. Thanks!

With the right heavy for caliber bullets, they kill exceptionally well.

 

[z987k]

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I don’t know if anyone wants this, but I spent a lot of time thinking on it and decided to write it up.

I wanted to compare bullet options across the 22 Creedmoor, 6 Creedmoor, and 6UM for my preference for a 16 inch barrel. Categories that interested me were range at 1800 fps, wind number, recoil, and danger zone. I found the concept of recoil efficiency from solarshooter really interesting, and I included his awesome chart.

To start, I pulled the book max for each round with the expected velocity from a 24 inch barrel. I subtracted 30 per inch for the estimation for a 16 inch barrel. I then combed through rokslide looking for load data for 16 inch barrels with measured MV.

I ran ballistic calculators off the loads I found on rokslide rather than the ideal from book max as it seemed the actual speeds were generally lower (especially in the 22CM). I first did this in Hornady 4DOF at 5000 feet. I then did JBM Calculator which also provided danger space on a 10 inch target at 500 yards.

The results were drastically different making me think I did something wrong in JBM, and I’d love to see if someone can pick up my mistake. If nothing else, the results were proportional throughout the calibers, so still useful as a comparison.

Finally, I ran recoil numbers using an 8lb gun and charge weights based on what I found on rokslide.

I’m intrigued by the concept of the 22UM so I included the possibilities if Form gets close to his goal of 3500fps from a 20 inch barrel.

I started this expecting to see that the 88 ELDM from a 22 creedmoor would provide the optimal combination, but I was somewhat surprised to see that the 95TMK from a 6 creedmoor had a very slight increase in recoil with the same wind number and (depending on calculator) a better terminal range. I may even be underestimating the 95 TMK’s capabilities given that someone reported 3137 out of an 18 inch barrel which could mean that 3050fps+ is even possible. It was the only bullet where I found reports of an increase over book max - 240fps.

This mainly came down to the difference between book ideal and actual results with a 16 inch 22 creedmoor for the 88 ELDM. I included mwoolsey5’s chart on powders and pressures for 16 inch barrels in a 22 creedmoor which was another source I leaned on. I assume a cartridge this overbore suffers more as length decreases. This seems to apply to the 6UM as well.

I’m curious if anyone has seen better results than I found with a 16 inch 22CM. Otherwise, my conclusion would be to say that the 95TMK in a 6 creedmoor is ideal for 0-600yd hunting in a 16 inch barrel.

The 22UM feels like the Holy Grail if it even comes close to the goal. That said, with how much the 22CM seems to suffers from decrease in length, I would guess that the 22UM would be even more dramatic.

Final caveat: I’ve read a whole lot more than I’ve shot or reloaded. This is almost entirely theoretical. Any of these weapon systems would outperform my abilities. I’m hoping at the S2HU course this summer, I can start to bring my capability a little closer to taking advantage of any of this.

Without seeing the inputs for the 4DOF it's hard to say where one or the other is going wrong.

I'm not familiar enough with the JBM to know, but I noticed the atmos pressure is 24.90 and the altitude is 5000ft. Did it set that? Because 24.90 is what you'd expect at 5000ft (standard lapse rate is basically 1 inch per 1000ft.), but if those are both inputs, does it assume you mean station corrected pressure of 24.90 at 5000ft on a standard day? Which would be the same as 10k ft pressure altitude. Which would be less drag, less slowing of the bullet, and a longer distance to 1800fps as you are showing in your data.

Edit: I went and played with JBM and that's exactly where your error is. You put altitude and a pressure that would be the non-station corrected pressure for that altitude, so it's effectively adding 2 pressure altitudes together. Effectively your JBM data is for 10kft Pressure altitude.
Set 24.92inHg and 0ft OR put 5000ft and 29.92in Not both. Or look up the local station pressure and put that in. Like right now Denver for example would be 30.03, or if you prefer millibars, the SLP122 means 1012.2mb/hPa.
So you'd put Denver elevation, 5434ft and 30.03in.


Or, there's a box under the altitude & pressure there for JBM that says pressure is corrected. If you uncheck that, you could put 24.92 AND 5000ft because those are the same thing.