6mm rem or 6mmAI
- Thread starter mcseal2
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ReachnOut
Well-Known Member
I use a custom cut to my chamber Redding sizer die and a Wilson seater. Whoever does the chambering on your barrel can supply Redding with the preferred dimensions to match your setup. Using Redding a great deal for custom cuts, I have found the turnaround time to be about 10 days.
Depending upon the barrel length that you prefer, your 'smith may have a short amount of the barrel length in excess material, or a scrap piece to work with. If so, he can make you a chamber gage cut with the same reamer. Invaluable when it comes down to extreme precision in working with headspace and bullet seating. Just a thought, but I like to see, feel and mic the actual fit.
wvcountryboy
Well-Known Member
I am also thinking of building a 6mm ai. I ordered some brass and bullets to make a dummy with. What twist are you guys using for the 70-85 grain bullets? It looks like this case will push the 70 grain 3800 and the 85 3500. Can anyone tell me what kind of velocity you can get with these bullets in a 6-284? I havent completely ruled that one out yet. I would much rather neck down 6.5-284 brass than ai 6mm brass. Also, will both rounds fit in a 700 short action magazine at the saami coal?
Trickymissfit
Well-Known Member
I agree with your thoughts here with the exception of case design itself. An example here is the 6.5/.284 verses the 6.5-06. Both cases are about 120% max capacity for the bore (I'm roughly guessing, but this can be figured out on paper). Both rounds shoot well, but the 6.5/.284 is well known for it short barrel life verses the 6.5-06. The case neck is much too short in the .284 case, but the shoulder angle is acceptable. The same can be seen in a compairison between the 6/.284 and the 6mmAI. Both cases are overbore as we already know. But one case has a much longer neck design putting the hottest part of the flame path well inside the neck. There is another version of the 6/284 that has the shoulder pushed back .100" for nearly a 50% increase in the barrel life with no serious loss in velocity. The difference is in case design. The 6mm has a 26 degree shoulder angle, while the Ackley has a much steeper 40 degree angle. This 40 degree angle does three things well. It tends to seat in the shoulder area a little straiter (ever so slightly). The flame path ends up being further away from the throat much more than the generic 6mm remington case. The chamber pressures tend to direct brass flow strait into the shoulder / neck area. With the narrower angle of the 26 degree shoulder, there is less resistence to brass flow, allowing the brass to flow into the neck. On the otherhand I personally think the 40 degree shoulder angle (35 as well) will creat the dreaded doughnut much easier than the narrower angles do. I can't prove this beyond a doubt, but I'm seeing it. I personally don't think you can go wrong with either case design, but I also think they are at their best with 85 grain and longer bullets
gary
Trickymissfit
Well-Known Member
I think I'd have the gunsmith ream me a sizing die off a Newlon die blank (chrome moly!), and ream a Forster seater sleeve at the same time. That is if you are going with the 6mm Ackley. You can buy a Redding 6mmAI for more money than a custom shop Forster (cut to your cases). Another route is to use Wilson dies with a Redding body die (you will need a way to bump the shoulder back every four firings). And even cheaper route would be to start off with a .257AI bushing die. You might end up shaving a small amount off of the base of the die (maybe .04"), but you'd at least start out in the ball park. This is a standard die set with Forster, thus saving you some money. Remember that with an Ackley (or most any enlargement of the shouder) the case length is going to shrink a few thousandths.
gary
Trickymissfit
Well-Known Member
The way to start out is with a single shot Savage action. The short one will handle the 57mm case length just barely. The Savage is a little longer than the Remington 700 action (I think it's about .150"). The advantage you'll see is in bullet selection, and making them fit. There is no actual SAAMI data on these two cartridges, and using the Remingtion magazine will not do you much good here. Go with a single shot Savage for the slightly longer action length. (also shoots slower giving the barrel a breather)
The 6/.284 is a barrel burner just like the 6.5/.284. The velocity difference between the 6/.284 and the 6mm AI is nill. You can fireform cases with factory loaded 6mm Remington ammunition (you will see a tiny bit of shrinkage). You can't do that with the 6/.284, and necking 6.5/.284 brass down and foreforming will become a chore. I think a 70 grain bullet at 3650 fps out of either one is about it (The 6AI will hit about 3725 fps at about 52K psi in the chamber). There isn't a lot data out there on the 6AI, but Ackley says it will do 3750 using 4064 powder. Huntington claimed 3800+ using 4320 and a 70 grain bullet. I've never known a single person that built a 6/.284 that kept the chambering, but do know a few guys that have shortened the .284 case and been very happy with it.
But of course if you really wanta have a fast 6mm, you can go with a 6mm Vias. This case works very well in a short action Remington and will push a 70 grain bullet in the 4000 fps area
gary
wvcountryboy
Well-Known Member
Gary,
You have me interested in that 6mm vias. I did a google search on it and couldnt find anything on it. Where can I find some info on it? I read in another post of yours that its a necked down improved 6.5x55 swedish mauser. I'd just like to read a little on its accuracy and what kind of powders they shoot in it.
You have me interested in that 6mm vias. I did a google search on it and couldnt find anything on it. Where can I find some info on it? I read in another post of yours that its a necked down improved 6.5x55 swedish mauser. I'd just like to read a little on its accuracy and what kind of powders they shoot in it.
Trickymissfit
Well-Known Member
The round is very similar to a 6.5 Arch or a 6.5x55 Ackley, but necked down to 6mm. It's a high pressure round that was actually developed for the NRA Across The Course competion or maybe F Class. Greanleaf and a couple others were involved. It will shoot a 70 grain bullet as fast (if not a little faster) than a .220 Swift will shoot 50 grain bullets! I've heard that it can be hard on barrels, and 800 rounds is about it (like a 6/.284). The round is accurate, but not quite good enough for F Class
they data for a 60 grain bullet in the 6mm Arch is:
53.5 grains of 4320 @ 4290 fps max load. (I told you it was fast!)
Precision Shooting did two or three articles about this round a few years back (maybe six or seven). I have them in storage, and will try to hunt them up next week.
gary
Trickymissfit
Well-Known Member
There's also a 22 Vias and a 6.5 Vias out there. George Vias has been dead for several years now, but his shop is still open in TX. Look around for the shop that sells the Vias muzzel brakes out of Texas. (the best muzzel brake ever made)
Here's a phone number to try for starting loads
210-479-2803
Here's a phone number to try for starting loads
210-479-2803
Trickymissfit,
I must disagree with your assessment on forming 6 AI from 6mm Rem brass vs making 6mm-284 cases from the 6.5-284 case. There is no fireforming needed when you neck down a case. If the dies are properly made the case is formed with the die and not in the chamber. The 6 AI on the other hand is using the chamber to change the shape of the case.
I suppose one can argue that any case isn't the exact shape of a given chamber till it is fired once and I suppose you could say that is fireforming. It is no chore for me to shoot my rifle and find a great load with virgin brass and use if for a hunt or target shooting. I have been doing so since 1982. Occasionally the rifle will require a slight tweak of the load when switching to once fired brass BUT performance/velocity/accuracy changes quite a bit with an AI before and after.
IMO tedium is tied to forming cases for the AI design and not with necking up or down of a case.
I must disagree with your assessment on forming 6 AI from 6mm Rem brass vs making 6mm-284 cases from the 6.5-284 case. There is no fireforming needed when you neck down a case. If the dies are properly made the case is formed with the die and not in the chamber. The 6 AI on the other hand is using the chamber to change the shape of the case.
I suppose one can argue that any case isn't the exact shape of a given chamber till it is fired once and I suppose you could say that is fireforming. It is no chore for me to shoot my rifle and find a great load with virgin brass and use if for a hunt or target shooting. I have been doing so since 1982. Occasionally the rifle will require a slight tweak of the load when switching to once fired brass BUT performance/velocity/accuracy changes quite a bit with an AI before and after.
IMO tedium is tied to forming cases for the AI design and not with necking up or down of a case.
Trickymissfit
Well-Known Member
interesting! I shoot a few wildcats, and over the years I've owned several more improved chambers. Each one had to fireform the case after initially building it. The main areas were where the neck meets the shoulder and the shoulder itself. Take this and the fact that the case will often shrink on fore forming (won't shrink much in the 6/.284 because your not making a radical choulder change like the 6mmAI. The onething I've notice thru the years is that no matter how well I prep the case in reforming it will need to be retrimmed after foreforming (I always set my cases up on a near max length the chamber will allow). If I were doing a 6/.284, I think I'd partially neck size the brass to make the neck fairly tight in the chamber on foreforming. Guess it's each his own
gary
BountyHunter
Well-Known Member
That smith needs a resize reamer to do that size die, not a chamber reamer so make sure he has one.
BH
BountyHunter
Well-Known Member
Considering the top F class guys are getting 750-1000 and know every barrel made, I think he is about 6800 over on his estimate. No one and I mean no one is getting 2000 rounds out of a 6.5-284 with any kind of accuracy at the end.
BH
