6MM Ackley or 6mm-06 ackly. Doable?

[billy_56081]

  I been thinking about buying a new 243 bull barrel and having it reamed to one of the above. Are they doable in my handi and what are the respective gains in each? Just have a need for speed and something different. The 6mm rem acley would be nice to have the ability to shoot factory in a pinch

[gould]

They are doable and actualy easyer on your fram then the standerd rounds. You should gain about 200 fps with them.

[Cknerr]

Ackley or Ackley Improved where developed to gain better consistancy of muzzle velocity from round to round. THis is done by what happens inside the cartridge case due to the new slope of the shoulder and a few other tricks. It really does make a differance. By using an AI type cartridge, you still retain the ability to load out of a magazine ,not needed with a Handi of course...  and have a cartridge that is superiour to any the regular gun manufacturers can put out. Because store bought ammo is ridiculously expensive and varies too much from round to round (bullet seating deth, OAL cartridge, powder amount to name a few) this type of cartridge is usually for the serious shooter. Hand loading is the only way to get really consistant ammo that the rifle can take advantage of.

Some of the other cartridges in this area are the 6mmPPC, and the 6mmBR. All previously discussed to death in previous threads. If you do a search, getting ready for a lot of reading!

If you are going to use a 6mm and want to reach out, you might want to consider the 6mmBR, it isn't used in competition much. It makes up for a lot by being more forgiving....and it is just the tiniest less accurate then other competition rounds like the PPC.

Good luck,
Chris

[billy_56081]

  Thanks for all that info Cknerr? But what i was asking Was to see if it were possible to ream an exhisting 243 Win barrel on my handi. It cannot be turned into a 6 mm br or ppc. I am looking for a hot rod Coyote gun.

[mitchell]

"a hotrod coyote gun"?? you got one . my 243 can push a 55grain bullet at 4000+  and that makes for one hotrod yote gun even at 400+ yards , if you really what a few more feet per-sec you can go with the 6mm ai from what i read it will clean up a 243's chamber

[billy_56081]

  Thanks the reply. I know my 243 is going pretty fast(about 3950). I've shot quite a few coyotes with it. I.m planning on keeping my 243 I'm just wanting to have another barrel in something different. Just for fun.

[cheatermk3]

It's definately do-able; Daniel Laws has mine I sold it to him a year ago.

[Fred M]

Billy 56081.
What you have to do is find the diameter of the shoulder on the 243, which should be about .454".  The 6mmAI will have the same shoulder diameter but a reamer with a diametre of .459 can also be had if the 243 is larger than .454.

The smith should not use a headspace gauge, but ream the chamber with a standard new 6mm case and have the case come flush with the face of the barrel.
This will best facilitate the fire forming. Reaming should not be done by hand, a slow lathe speed of 56rpm is needed for a good smooth transition into the lands.

Factory ammo may or may not work. That of course should be of no concern since this is handloading cartridge. Case life in a Handi will be about nine uses. Just make sure your 243 shoots well before conversion. The conversion will not improve accuracy.

The 6mmAI is a pretty good one but holds more powder than needed for good 6mm performance. The 250 Sav necked down to 6mm and AI'd is a much better performer accuracy wise, it is also known as the 6mm Iternational in various perversions, but can't be done with a 243 chamber without setting the barrel back.

[shaleetoo]

 i  have  a 6mm-06 a i  am now  getting  4000 out of a  28  in  custom barrel  with 70  grain noslers am not done  w ith  load  development  yet.   still have  room in  case  and  no  pressure  signs   1/2  in.  groups  at  100 yrds.  love  that  speed 

[billy_56081]

 THanks fred I been waiting to hear from you. I'm pretty happy with my 243 but I'm just wanting something a little different. I"m sure a 6mm-06 would be a barrel burner but it won't be shot a whole lot. I'm gonna look into a 6mm rem ackley or a 6mm-06 ackley.

But again thanks for everyone input.

[quickdtoo]

For those interested in rechambering an existing chamber to its improved version in a Handi, this is how I worked with it to resolve the excess headspace issue resulting from the fact that a break-barrel action's barrel can't be set back as done with a threaded barrel.

To insure headspace is correct to prevent dangerous case separation, it will be necessary to create a false shoulder, the following procedure is simple, yet very effective.

I’m showing this being done on a belted mag, but the same procedure applies to any cartridge including rimmed cartridges.

The case on the right is a factory .375H&H case right out of the Remington bag.

The case next to the left is after the it’s been run onto a .408”  neck expander, but any size expander can be used as long as it’s big enough to increase the neck to a size that will form a shoulder to headspace off of, for example, a .308” would work fine for a .270 Winchester or .280 Remington,  the .280 would work for a .25-06, etc.

The next case to the left shows the neck partially full length sized, I did that one just so you can see the shoulder real well, once the shoulder is down near the previous shoulder, it's hard to see.

The case on the left is sized to the appropriate headspace so when the case is chambered, it's flush with the barrel face, or slightly above it, depending on your barrel to frame gap. Ideally, the gap will be minimal because any measurable gap adds to headspace. I like tight on a .002” feeler gauge, snug on .001”

Getting it to this spec is just a matter of adjusting the full length sizing die down in small increments and pushing the shoulder back just a little at a time, then checking the fit in the chamber after each change until the desired fit it achieved.

Once the headspace is dealt with, the brass should be loaded with full pressure start loads to fully fire form the brass to the chamber. After that, work up a good, accurate load!!

Tim

http://www.graybeardoutdoors.com/smf/index.php/topic,97534.msg1098247046.html#msg1098247046

http://www.larrywillis.com/headspace.html

http://www.fulton-armory.com/JPGs/Chamber2.jpg