243 AI-Any Input?

[pods8 (Rugged Stitching)]

What’s your barrel length?

I’m really liking the results

He reamed a 20" tikka barrel.

 

[PathFinder]

It's a 20" factory Tikka barrel

Sent from my SM-S901U using Tapatalk

 

[pods8 (Rugged Stitching)]

2900 fps, which is ideal for quick drop at the DA range I typically hunt.

Naïve question I expect but how is that a good match? I assume you're hunting CO based on being in the front range wouldn't the drops be something like this:
300 = 1mil
400 = 1.7mil
500 = 2.5mil
600 = 3.3mil

I thought ideal quick drop matchups was more 1:1 IE 400yd = 2mil, 500yd = 3mil

My guns don't match up well with what I assume to be "ideal" so I'm genuinely curious how you are applying it as it could be useful to me.

 

[PathFinder]

Naïve question I expect but how is that a good match? I assume you're hunting CO based on being in the front range wouldn't the drops be something like this:
300 = 1mil
400 = 1.7mil
500 = 2.5mil
600 = 3.3mil

I thought ideal quick drop matchups was more 1:1 IE 400yd = 2mil, 500yd = 3mil

My guns don't match up well with what I assume to be "ideal" so I'm genuinely curious how you are applying it as it could be useful to me.

In this case, it starts to line up at 600. Not sure if that's how it usually works, but when I noticed that dropping to 2900 would make that work, it seemed worth a try. The following is for a NR DTAC (G7 .295) at 8000 DA:

• 200: .35
• 300: 1
• 400: 1.6 (memorized as 1.5 for simplicity)
• 500: 2.3 (2.5 for simplicity if in a hurry)
• 600: 3.1
• 700: 4
• 800: 5
• 900: 5.92 9 (Basically 6)
• 1000: 7

They aren't perfect, but in a hurry they're all close enough to kill beyond 600. Not having to mess around with the app is really nice, especially for fall bear. It's a 9mph load out to 700 yards as well. Moving forward, my plan is to utilize this correlation with as short and light a rifle as possible.

 

[AZ_Hunter]

Naïve question I expect but how is that a good match? I assume you're hunting CO based on being in the front range wouldn't the drops be something like this:
300 = 1mil
400 = 1.7mil
500 = 2.5mil
600 = 3.3mil

I thought ideal quick drop matchups was more 1:1 IE 400yd = 2mil, 500yd = 3mil

My guns don't match up well with what I assume to be "ideal" so I'm genuinely curious how you are applying it as it could be useful to me.

You can adjust your zero range to line the numbers up better. My buddy’s 16” 308 for example with 155TMK. We sighted in 1” high at 100 which allows him to use the formula:
First number of yardage minus two = mil hold.

300 yards: 3-2=1mil etc with a +/- .1mil tolerance. Worked out really well at his DA up to 600 yards.

 

[pods8 (Rugged Stitching)]

You can adjust your zero range to line the numbers up better. My buddy’s 16” 308 for example with 155TMK. We sighted in 1” high at 100 which allows him to use the formula:
First number of yardage minus two = mil hold.

300 yards: 3-2=1mil etc with a +/- .1mil tolerance. Worked out really well at his DA up to 600 yards.

If the change between 100yds is ~.7mil I don't think adjusting the zero range would line up things, it would just change which one was lined up. If the 100yd mil difference is .9 to 1.1mil I can see that working though.

 

[AZ_Hunter]

Please keep posting on your development. I have been analyzing every pro and con on my next rifle project and a 20” 243AI with an Airlock can is what I’m really leaning towards.

 

[pods8 (Rugged Stitching)]

In this case, it starts to line up at 600. Not sure if that's how it usually works, but when I noticed that dropping to 2900 would make that work, it seemed worth a try. The following is for a NR DTAC (G7 .295) at 8000 DA:

• 200: .35
• 300: 1
• 400: 1.6 (memorized as 1.5 for simplicity)
• 500: 2.3 (2.5 for simplicity if in a hurry)
• 600: 3.1
• 700: 4
• 800: 5
• 900: 5.92 9 (Basically 6)
• 1000: 7

They aren't perfect, but in a hurry they're all close enough to kill beyond 600. Not having to mess around with the app is really nice, especially for fall bear. It's a 9mph load out to 700 yards as well. Moving forward, my plan is to utilize this correlation with as short and light a rifle as possible.

I believe in an ideal world your bullet BC and velocity (slower is required) would line up 300-600yd with the minus 2 formula. 350yd = 1.5mil, 480yd = 2.8mil, etc.

Past 600yd I wouldn't be using quick drop for anything other than follow up shots on a wounded animal imho.

Anyways, that's a discussion for another thread no need to derail further on this one, I was just wondering if I was missing a trick.

 

[pods8 (Rugged Stitching)]

Please keep posting on your development.

This.

As much as I have in the past said "just go 6cm if starting from scratch" I impulse acquired some 20" threaded tikka 243 1:8 and 243ai (vs leaving alone, punching to 6-284) keeps fighting back into my fore front of tinkering thoughts. I got a 1:10 243 that probably has 500rds on it, I have the thought creeping in I should send out that and those other barrels and have them all chambered at once to the same headspace/reamer. Use the 1:10 for fireforming brass.

Or leave them alone... or 6-284... round and round the thoughts go.

 

[PathFinder]

This.

As much as I have in the past said "just go 6cm if starting from scratch" I impulse acquired some 20" threaded tikka 243 1:8 and 243ai (vs leaving alone, punching to 6-284) keeps fighting back into my fore front of tinkering thoughts. I got a 1:10 243 that probably has 500rds on it, I have the thought creeping in I should send out that and those other barrels and have them all chambered at once to the same headspace/reamer. Use the 1:10 for fireforming brass.

Or leave them alone... or 6-284... round and round the thoughts go.

There are a lot of good options for mid-capacity 6mms. Reality is, that especially with Alpha brass, the 6 Creedmoor and standard 243 can get really close to the higher capacity cartridges. Especially for this version of a quick drop load, if that can be done in a 16" barrel then the scenarios where more velocity would be an advantage are few and far between.
That's my thinking for now, but I tend to let my thoughts go round and round back to the drawing board every couple of years Maybe some scenario will push me back to a 6 UM again.

 

[pods8 (Rugged Stitching)]

That's my thinking for now, but I tend to let my thoughts go round and round back to the drawing board

I know the feeling haha.

 

[AZ_Hunter]

What I don’t like about std 243 is the case flow. My experience with the 243 is always having to trim. I like the idea of AI because that issue would be mitigated, while gaining some performance, and at the same time being able to shoot factory 243 in a pinch.

 

[pods8 (Rugged Stitching)]

What I don’t like about std 243 is the case flow. My experience with the 243 is always having to trim. I like the idea of AI because that issue would be mitigated, while gaining some performance, and at the same time being able to shoot factory 243 in a pinch.

Right, but I didn’t like the loss of barrel life and fire forming involved from the perspective of one barrel. But if having multiple cut at the same time from same reamer and headspace opens up more potential in my view. Esp when the first one is one I wouldn’t care about babying.

 

[wind gypsy]

There are a lot of good options for mid-capacity 6mms. Reality is, that especially with Alpha brass, the 6 Creedmoor and standard 243 can get really close to the higher capacity cartridges. Especially for this version of a quick drop load, if that can be done in a 16" barrel then the scenarios where more velocity would be an advantage are few and far between.
That's my thinking for now, but I tend to let my thoughts go round and round back to the drawing board every couple of years Maybe some scenario will push me back to a 6 UM again.

Did you move away from 6 UM?

 

[PathFinder]

Did you move away from 6 UM?

Sort of for now. I still have mine and everything for it, but scavenged its stock, scope, and mounts for the 243 AI short term. Mine is a 24" 3b, so the way I had it set up it's 11.5 lbs all together, no suppressor. The 243 AI will be around 8.5lbs ready to hunt this year. My 6 UM is also 1.5 MOA or so, which is fine but not great. There will probably be some situation on a hunt this year that makes me wish I had it, but burning 66 grains of powder and killing barrels every 600 rounds was getting old.

 

[ACHILLES]

For a true all around cartridge “on paper” it’s hard to beat the balance of the 243winAI ,257/260remAI, and 260remAI variants. In reality though Hornady has made the 22,6,6.5creed,6.5prc the easy button. That being said I have a new tikka 20” 243win 8” take off in the shop I’ve been wanting to AI and run h1000 with myself. Thanks for posting data.

Then again if we were all smart we’d just buy $650 tikka 6.5prcs chop them to 20” and save thousands.

Glad to see the wildcats and ppl willing to try 6UM +p’s n shit too

 

[pods8 (Rugged Stitching)]

Pretty much. But eventually rifles need new barrels (even that stock PRC eventually) and this is where the devil starts justifying itself.

 

[pods8 (Rugged Stitching)]

That being said I have a new tikka 20” 243win 8” take off in the shop I’ve been wanting to AI

group buy project!

 

[BigDog00]

@PathFinder how has this been working out? I've got a 243 barrel I'm trying to talk myself out of doing (or into it) this as well.

 

[PathFinder]

@PathFinder how has this been working out? I've got a 243 barrel I'm trying to talk myself out of doing (or into it) this as well.

Overall, at least on paper, I'm happy with the gun. It's shooting 10 shot groups under 1" at 100 yards with the 115 DTAC and H1000 at 2900 fps. The Alpha brass is holding up great. Neck diameter ended up with .004-.005 of clearance with no neck turning. It wants to have clickers, but the body die is able to push everything back to where that isn't an issue. The Redding neck die won't allow the case to get deep enough to size the entire neck, so I've been neck sizing in a 6 UM die, then body sizing with the 243 AI die. Probably need to chuck it up and run a reamer deeper into the insert of the die. The micrometer neck sizing set is probably good overall for the AI version, it's extremely useful for setting up the false shoulder. Having easy extraction and ejection (compared to 6 UM) and perfect function from factory mags is great.
There have been some really odd issues with the gun/loads/bullets/can though. Haven't been able to diagnose it yet. On an antelope hunt, had some strange misses and no visible impact from 880 and 550. Then a straight airball at 270 yards prone with a bipod and rear bag. I had been shooting shallow cut DTACS on paper/target, then deep cuts for hunting. Finally got the goat with shallow cuts at 280 the next day.
Testing on paper, the deep cuts were stringing vertically 1.5 MOA or more. Shallow cuts exhibited no such behavior. Thought it was just the deep cuts, although I'd never seen that in the 6 UM previously. Shot on steel at 400, 600, 800, and 1000 with no issues making hits. However, the data at 600 and 800 was .5 mil less correction than calculated, which was a lot. That may have been due to extreme mirage. Not sure yet. Testing in the mountains had impacts right back where they should have been.
Had a couple more rodeos on a deer/elk hunt. Shots with no visible impact on wide open dirt hills. Shots that went 1+ mils high at 800-900 yards. Just strange behavior that I've never seen before, especially with solid mounts, optic, and a rifle that shoots so well on paper. I still need to get out and diagnose the issue in the next couple of weeks. I did check zero and it was spot on.
Whatever the issue is, I don't think it's related to the Improved chamber cut. I'll update this thread with more details when I finally have a clear answer.
Was it worth it? For the case geometry and no trimming, probably. To be able to better accommodate H1000? Certainly. Could a standard 243 probably run almost the same load and velocity? Almost certainly in Alpha or Lapua brass.
Moving forward, I have a lathe now so there's more experimenting to come. The plan is to jump back in to the 6 UM as well, and use it to target 3100 fps in the shortest barrel possible with H1000. If the 6 UM can do that, and have 1k+ rounds of barrel life with H1000, that will probably be my go to. That will also be contingent on brass going more than 5 firings with mild loads. If that doesn't work out, I'll probably go back to the 243 AI once the issues are sorted out. Having access to Alpha brass, standard case diameter (less bolt thrust, easier extraction, factory Tikka mags feed perfectly), and greater barrel life are big pluses to the 243 AI over the 6 UM. The Tikka factory barrel was definitely a good move. All of my most accurate barrels now have been factory Tikkas. This one runs circles around the only Bartlein I've owned.

To summarize:
The good:

• Case geometry works great. All dimensions with Alpha brass work with no neck turning.
• Load with H1000 worked well
• Throated ideally for 115 bullets
• Fire forming worked really well with Alpha brass
• Feeds perfectly from both M+ and long action standard Tikka mags
• Very accurate on paper
• Tikka factory barrels are excellent. Definitely my preference.

Bad/Unknown:

• Fire forming is annoying. I'll probably whip up a fire form barrel to use the no projectile method if I decide to stick with the 243 Improved and buy a bunch more brass.
• Something weird going on with this setup. Could be a can, bullets, etc. No idea yet.

Future plans:

• Test the 6 UM with H1000. Goal is 20" or shorter barrel, 3100 fps with 115s, 1k+ barrel life. Will be chopping/threading and setting my current Bartlein back to test.
• Figure out why this 243 Improved barrel is doing weird stuff. Isolate whatever the issue is.
• Maybe test different powders. Grand, N160/170, N560, etc. Could be some velocity to be gained at reasonable pressure, though it would defeat the point of greater barrel life with H1000.
• I have a Kimber that may become an experiment too. The outcome of the above will influence what it ends up chambered for. Tempted to play with the current 6.5 barrel as I have a 260 AI reamer now...