284 win ackley improved

[762 ULTRAMAGA]

I'm having an 18" 284 win barrel made up for my tikka for a suppressed hunting rifle, I want to send a 175 elite hunter around 2700-2750.
I know there's a shehane version available but I like the idea of going to a 40 degree shoulder.
Any thoughts about doing a 284 ai?

 

[B23]

Short of just having something different and a 284 with a 40° shoulder there isn't really much to be gained by improving the 284. The 284 is already a pretty straight case and comes with a 35° shoulder so I'm not sure it would be worth the extra time and money to blow it out to a 40.

I'd think throated properly and with the right powder, RL26 maybe, you'd be able to reach 2700 or more with just a straight 284.

You'd have to either replace the bolt or have it opened up but if you wanted more velocity than a straight 284 will give you I think you'd be money ahead to go 7 SAUM or WSM. Maybe even a 7-6.5PRC.

 

[jamesmc8]

What is the length of the suppressor? Could you get by extending the barrel to 20" for more velocity?

 

[fightthenoise]

Just a data point, not trying to sway you one way or another but I have a 20” 7 SAUM sending 180 ELD-M’s at 2780 with a charge of RL23 that was on the low end of my ladder, so a ways off from pressure. I’m not sure how the powder capacities compare between the two though. I ladder’d RL26 as well and velocities were appreciably higher. All that to say that your goal seems reasonable especially if you can find good brass. I know Lapua makes 284. I’ve pondered a 284 myself, seems like the Tikka actions were made for it.

 

[762 ULTRAMAGA]

Short of just having something different and a 284 with a 40° shoulder there isn't really much to be gained by improving the 284. The 284 is already a pretty straight case and comes with a 35° shoulder so I'm not sure it would be worth the extra time and money to blow it out to a 40.

I'd think throated properly and with the right powder, RL26 maybe, you'd be able to reach 2700 or more with just a straight 284.

You'd have to either replace the bolt or have it opened up but if you wanted more velocity than a straight 284 will give you I think you'd be money ahead to go 7 SAUM or WSM. Maybe even a 7-6.5PRC.

Definitely some good points but the saum is out because I have a 6.5 version already, plus I'm not a fan of the shoulder angle. I have to trim mine every 2-3 firings.
The wsm is awesome but brass does make it tough, plus it's more than I need with an 18" barrel.

I've done a bunch of reading on the 284 Shehane and it looks like there's a 2 grain usable powder increase just blowing out some of the taper. Looks like people are getting 75ish fps velocity gain over the straight 284.
By going with an ai version I'm thinking I could blow the shoulder out a bit and remove all case taper for a 4 grain increase??
I know that's not a ton but it has me intrigued, I'm going with the 284 case either way so it's just a matter of dealing with custom dies.
And the more I think about it the more I like the idea of having dies cut to my chamber

 

[B23]

I don't 100% remember but I think, some time back, Shawn Carlock w/Defensive Edge did a 6.5-284 Improved. It's been some time since I talked to him about it but if I recall he came to the conclusion the small gain wasn't worth the extra work and cost. For me, even if you gained 100fps, and at equal pressure that'd probably be stretching it, it wouldn't be worth it. That extra gain by improving a 284 case would be about exactly equal to what a 7-6.5PRC would be and that would be a whole lot easier way to go.

Don't get me wrong, I'm a big 284 fan. My 6-284 and 6.5-284 are two of my most favorite rifles but I've had my fill of "improved" cartridges and unless I can get formed brass from the smith that built it or there's a big gain by improving it like there is with say a 338 Lapua Improved it's just not worth the extra work. But that's just me and we all like and see things differently.

 

[Trogon]

284win was basically AI’d from factory. With already straight walls your gains from 5 extra degrees on the shoulder seem very small.

280ai vs 284 win:

 

[762 ULTRAMAGA]

I don't 100% remember but I think, some time back, Shawn Carlock w/Defensive Edge did a 6.5-284 Improved. It's been some time since I talked to him about it but if I recall he came to the conclusion the small gain wasn't worth the extra work and cost. For me, even if you gained 100fps, and at equal pressure that'd probably be stretching it, it wouldn't be worth it. That extra gain by improving a 284 case would be about exactly equal to what a 7-6.5PRC would be and that would be a whole lot easier way to go.

Don't get me wrong, I'm a big 284 fan. My 6-284 and 6.5-284 are two of my most favorite rifles but I've had my fill of "improved" cartridges and unless I can get formed brass from the smith that built it or there's a big gain by improving it like there is with say a 338 Lapua Improved it's just not worth the extra work. But that's just me and we all like and see things differently.

I can't argue with you
Maybe I'd be smarter just selling my standard boltfaced tikka and getting a magnum to go 7-prc.
Another issue with that plan besides scraping what I've got is that 6.5 prc lapua brass is completely unobtainable.
It might be worth it though in the long run considering I could use a 6.5 prc bushing die vs waiting 4 months for expensive customs..
See what you did?
Now I'm trying to talk myself out of the 284
Edit:
I see the 6.5 prc holds 68 grains of h20
I measured a few 284 lapua cases tonight and they were right at 67 grains
That definitely makes me lean towards doing a blown out 40 degree 284

 

[B23]

Neck up the 6.5 PRC brass to .284 and that 68 number will go up a little. Are you looking for some Lapua 6.5PRC brass? I recently saw 200pcs for sale.

 

[762 ULTRAMAGA]

Neck up the 6.5 PRC brass to .284 and that 68 number will go up a little. Are you looking for some Lapua 6.5PRC brass? I recently saw 200pcs for sale.

Possibly
I'm definitely considering it
Let me know if you come across some

 

[HighUintas]

Possibly
I'm definitely considering it
Let me know if you come across some

I think your idea of going 40 shoulder and blowing the wall out (basically 40 degree shehane) is awesome.

I've got a 30-284 and was considering getting a reamer made for a 30-284 shehane ai... But I'd have to call it something else.

The only thing that has stopped me needing to use a hydroform die and having to get completely custom resize dies made. And I think doing that has the potential to shorten the neck a lot. I bet it wouldn't be an issue for a 284 though.

Do it!!

 

[jjohnsonElknewbie]

@762 ULTRAMAGA where did you land on this build? I know this thread is old, but I'm curious and in the same boat as you were. Forster now sells .284 Shehane FL sizing dies and Whidden sells .284 Shehane micrometer seating dies. 284 brass is available from Peterson and Lapua, and standard .284 loads can be very accurate in the Shehane chamber when fireforming.

Thank you in advance!

 

[HighUintas]

@762 ULTRAMAGA where did you land on this build? I know this thread is old, but I'm curious and in the same boat as you were. Forster now sells .284 Shehane FL sizing dies and Whidden sells .284 Shehane micrometer seating dies. 284 brass is available from Peterson and Lapua, and standard .284 loads can be very accurate in the Shehane chamber when fireforming.

Thank you in advance!

I did it in a 30cal version. Basically a 30-284 AI. I had Manson make me a custom finish reamer and resized reamer.

It shoots phenomenally, but unfortunately the "smith" I had do the work didn't cut either the chamber or the die very well and so I've got sizing issues due to the chamber and sizing die not being cut to correct dimensions. Manson checked my reamers and verified they're in spec.

Now I'm looking to get out of it due to requirement of fireforming, the cost of having the work redone, etc.

I'd say a 284 shehane would be sweet though, considering the options available now for off the shelf high quality dies. The 35-40* shoulder change gets you very little, unless you were to push the shoulder back far enough to increase neck length.... Then you'd absolutely have to neck turn though.

 

[jjohnsonElknewbie]

I did it in a 30cal version. Basically a 30-284 AI. I had Manson make me a custom finish reamer and resized reamer.

It shoots phenomenally, but unfortunately the "smith" I had do the work didn't cut either the chamber or the die very well and so I've got sizing issues due to the chamber and sizing die not being cut to correct dimensions. Manson checked my reamers and verified they're in spec.

Now I'm looking to get out of it due to requirement of fireforming, the cost of having the work redone, etc.

I'd say a 284 shehane would be sweet though, considering the options available now for off the shelf high quality dies. The 35-40* shoulder change gets you very little, unless you were to push the shoulder back far enough to increase neck length.... Then you'd absolutely have to neck turn though.

Thank you for the information, and from what I've read, the shoulder and lack of body taper is supposed to gain 3 grains of capacity in the Shehane with 2 grains typically "usable". I would also think you'd have less trimming with the shoulder improvement. I have a 22" OEM 7-08 Tikka superlite that I'm thinking of having rechambered. I already have a 7-08, and it's awesome, but I like to push and tinker as well.

 

[solarshooter]

I'm a big fan of the 284 case. In my opinion it's the best designed, highest capacity case for a standard bolt face, and generally matches about the most recoil I want to tolerate. I have a 26" straight 284 pushing a Berger 175 at 2820fps with 55.5gr of H4831SC. I think IMR7828SSC is a touch more optimal, and I could probably squeeze another 50-75fps out of it if I really wanted to. I've heard RL23 is pretty awesome too, but I've always had trouble finding it. But, it will be an 8mph gun either way so why bother?

If anything I'm thinking about chopping it to 20" and having it threaded so I can shoot suppressed. In which case I would be in a very similar boat to you. Using the 25fps/in rule, I expect I'd be right around 2700fps with my current load at that barrel length, which drops it to a 7mph gun. BUT, if I were to switch to the 162 ELDM, which has about the same BC as the 175 EH, I could likely get back into the 8mph bracket. Accuracy wasn't there last time I tested but I might be willing to try again.

I bought straight 284 brass from Lapua and am currently on my 4th firing of it, it has been great. Easy and consistent resizing, no clickers or anything weird, no fireforming or necking up/down required. I'm a fan. Standard Redding FL dies.

When this gun needs a rebarrel, I'm thinking hard about an 18-20" 6-284 or 25-284.

 

[jjohnsonElknewbie]

If anything I'm thinking about chopping it to 20" and having it threaded so I can shoot suppressed. In which case I would be in a very similar boat to you. Using the 25fps/in rule, I expect I'd be right around 2700fps with my current load at that barrel length, which drops it to a 7mph gun. BUT, if I were to switch to the 162 ELDM, which has about the same BC as the 175 EH, I could likely get back into the 8mph bracket. Accuracy wasn't there last time I tested but I might be willing to try again.

My daughter's 18" 7-08 load is 46.5 grains of SB 6.5 under hte 162 ELDX at 2628 MV. I love the compact handling of this rifle, and with my 7" can it's still only 25". This load shoots 10 shot 1-1.25 MOA groups consistently at 100 and 200 yards, and my daughter one-shot killed a magnum cow elk with it at 185 yards a couple weeks ago. Assuming roughly 25% recoil reduction with the can, and it's around 10.5 ft. lbs. Sweet little shooter.

My 22" 25-284 is hitting around 2828 MV with 54.5grains of H1000 under the 134 ELDM. The #3 McGowen is barrel heavy, and I may get it fluted to improve the balance. I'm also going to experiment with some N560 this spring to see if I can get it to 2900+. However, my ideal .25 would be a 18-20" barrel shooting the 130s around 2900-3000. For that though, a guy has to step up to a magnum bolt face and more recoil.

Short barrels, high velocity, and .6+ BCs are really fun to imagine, but achieving your goals with acceptable recoil and without too many extra steps at the bench are always the challenges. It's all overkill at the end of the day, but it's fun to experiment.

 

[pods8 (Rugged Stitching)]

I wouldn't bother with it imho. Its very little gain over the straight 284win which is plug and play.

One thing to be aware of with these flatter shoulders is they are weaker against vertical force when sizing and seating (IE make sure things are lubed and chamfered properly). I've collapsed 280AI shoulders in the past and accidentally just did it to a 284win regular too. If the walls get much straighter you may have chance at a stickier chamber. Don't make it more complicated imho.

 

[SloppyJ]

If you can stand a little longer throw, the 280ai has you covered with no sweat.

 

[jjohnsonElknewbie]

If you can stand a little longer throw, the 280ai has you covered with no sweat.

That was the next thing I was going to look at and thank you.

I was also just thinking about the 6-284. I'm not sure if a guy could get away with one pass on a 6-284 FL die with 6.5-284 brass or if you'd need to step down with 25-284 first. I'm guessing a guy could get those 115 DTACs as well as the other 103-109 humming pretty fast with the 284 case without a magnum bolt face.

 

[pods8 (Rugged Stitching)]

That was the next thing I was going to look at and thank you.

I have a 280ai also, I run the 145LRX in that one and its loaded longer than a T3 mag would fit (its built on a M695). 284win is a nicer fit in the T3 imho. I gotta assume a 162eldm or something else heavier with high BC is also going to run into that issue, I can go mock up a 280AI case with a 162eldm into a T3 mag if you'd like.