What will a 6X47L AI do that a .243AI won't?

Rman

Rman

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I am getting a different long range rig, and would like input on these two calibres vs each other. I have shot plenty of .243, and know all I care to, but know very little about the 6X47L. I have read velocities in the 105 grain area are the same, but the Lapua uses less powder to do it, therefore getting longer barrel life. The Lapua case is shorter, which means I can seat my bullets farther out, without magazine issues. The .243AI is hard to beat, but is this the cartridge that does it?
This is not a bench/match rifle, but accuracy is expected.

Thanks.

R.
 
The only difference is in the max velocity you can achieve.

Given similar components, the 243AI will push any bullet faster when run at similar pressures.

NO different then a 308 and 30-06 comparison. The '06 will push the same bullets faster all things being equal.

As for accuracy, both will be very similar.

Jerry
 
If your looking for balls to the wall velocity then stick with the 243AI. No substitute for case capacity except ultra high pressures which will lead you to a bunch of ruined cases or worse yet a ruined action.
The 6X47 Lapua was meant to be easy on the barrel and superb accuracy with bullets in the 100+gr. @3000fps. In both of my 6X47 Lapuas it does the job @ 1000 yards better than I can with my limited experience.
Rc
 
The differences are in the brass. The 6-6.5X47 Lapua uses a small rifle primer. It has far better barrel life than the 243AI, but the velocity will favour the 243.

NOW.... there is a newer wildcat called the "Long-Dasher" which is a 6X47 Lapua improved. This looks very interesting.

I did lots of dabbling with t he 6X47 and to be honest, I found that it was a difficult cartridge to make work well. I know these can be made to work very well, but I took hundreds of rounds to find the right powder and bullet combos. (I did 1:8 and 1:7" twist versions) I spun off the barrels and put them away for another day. I ended up using one as a 6BR later and it bug-holed... wasn't the barrels! Life is too short for a finicky cartridge.

I would also look at the 6XC
 
That speed would be all that I required, the 105 at 3250. If I were to go the lapua route, it would be in AI version as well. How was accuaracy? With the above information, and what you know now, would you try again, or just stick with the .243AI?
Thanks.
R.
 
I have been giving some thought to the 6X47 Improved. Call me a sucker for punishment.

Accuracy was better with the rounds slowed down a bit, but each gun is different.

The 243AI will be much easier to find dies for. That fact alone is huge.

If you are going the 243AI route with 105's go with an 8.5 or 9" twist. You won't need a full 8
 
How do they make a die, once you own the reamer? Does the smith run the reamer into a smaller die? Still may shoot heavier than a 105. Is the 8" to hard on the 105's?
Thanks for the info.

R.
 
Rman said:
How do they make a die, once you own the reamer? Does the smith run the reamer into a smaller die? Still may shoot heavier than a 105. Is the 8" to hard on the 105's?
Thanks for the info.

R.
Click to expand...

typically dies are made from tool steel then heat treated so you will ruin your high speed steel reamer if you try that. your options are pretty much limited to finding one in canada or if im not mistaken dies are not on the ITAR list so you can order them directly from the states

( someone correct me if im wrong )
 
Rman said:
Thanks Jerry.
How fast could a fella run a 105 out of the Lapua, with 105's?
Thanks.
R.
Click to expand...

3000fps would be a comfy level to achieve.

Cartridges can get very finicky when pressures are run really hard. If kept around 60 to 65000psi (magnum pressure ranges), most any popular wildcat can be made to shoot with accuracy.

For dies, look at what is available THEN choose a cartridge to suit. In a wildcat project, dies becomes the single most expensive item that really doesn't need to be.

There are tons of existing chamberings that are only a few thou or degrees different from something "NEW". New wildcat dies can cost a few hundred. Old wildcat, maybe $50 to 100.

Any case shape with a 35 to 40deg shoulder is going to be more tolerant of both pressure and case stretching. Mr Ackley demonstrated this many decades ago. They don't feed from the mag as well as standard shoulders but most of us single feed and the improved shape excels here.

In your example, the 243AI is very common and dies are readily available. However, you can make up your own wildcat using these dies.

Run a 243AI (or 6 Dasher) reamer to headspace off your 6 Lapua case. Now you can use 243AI (or 6 Dasher) dies but have the case capacity to suit. You can cut down the Redding 243AI body die to suit - you may need to expand the bottom to suit the reamer taper but this is an easy job.

Been there done that. I call my version the 6 Mystic (case capacity bigger then either the Lapua or XC). 243AI reamer run to headspace off a 22/250 brass (believe me when I say I am not the first to have done this and there are many variants on this theme). I did splurge and get a custom Lee collet neck die set made cause I really like these dies.

Other then that, off the shelf dies - either 243 or 243AI. Simple.

My 6.5 Mystic was my attempt to stretch the 308 case as much as possible. Works great. Today, I would just as easily get the 260improved. The Mystic will not fit into the 260imp chamber but the other will. The difference is slight and it has not changed my load levels to any significant degree.

260 dies are a no brainer and they all work with the improved version. At least the reamer that Shilen has. So instead of custom dies, the 260imp can use off the rack dirt cheap dies instead.

The only item that is 'custom' is the body die. Here I use the "used to be readily available" Redding 7-08AI body die. This dies is now a custom order part and I have a few coming. Still very inexpensive but you can't grab it off the dist shelf. No biggie....

Look at the chamber drawings in reloading manual and compare them to your new design. Odds are you will find something historic that shares alot of dimensions with your new design. By using or modifying these older chamber dies, you will save a small fortune and get to play in the very interesting and fun world of wildcatting.

Jerry
 
When I hear (or read) about things like the 6.5x47 Lapua AI, I wonder if the water is contaminated with some sort of halucinogen. Does anyone honestly think that a change in shoulder angle, from thirty to forty degrees, is going to have ANY measurable effect on performance? Get together and give your collective heads a good shake! It won't make any difference whatsoever.
Jerry,
I have recently been doing a bit of testing to compare case stretching with a standard VS AI cartridges. Indications are that the so-called "case stretching" is a product of the excessive working of the brass by the dies in standard calibers. The dimensions of the AI dies are much closer to the chamber dimensions and work the brass much less. A standard 30/06 case (Remington brass) loaded 12 times, stretched a total.006" if neck sized. If full length sized, it stretched .006 with each sizing. A custom chamber, cut to be only .002" smaller in diameter in the body than the die, would stretch no more than the neck sized brass. Ackley did a lot of testing which was slanted to validate pre-conceived notions. Regards, Bill.
 
Leeper, it depends on your operating pressures.

I too have done a bunch of testing over the years with various case shapes and have found the 40 deg shoulder offers a substantial benefit to reduce case stretching and brass flow when operating in magnum pressure ranges.

30deg (ie 6 BR) is a nice min if trying to feed from the mag too.

Having spent the last few years playing and abusing the 223, I have found, in several barrels/rifles, case stretching to be very strong at the pressures most competition shooters are going to be playing at.

I had to trim my brass after 3 to 4 firings AND neck turn every 4 to 6 firings. That is alot of brass flow. Yes, the cases did thin in the web and eventually failed/cracked in this area.

Conversely, I have bags of 6.5 Mystic brass from various barrels over a longer period of time that I can say have been run even harder. I have yet to loose a single case to thinning/cracking in the web area. I almost never trim my brass and only need to touch up the necks after 10 to 15 firings. Yes, I do anneal from time to time so the brass is 'soft' enough to flow if it was going to.

I have seen the benefits of the sharp shoulder in my 6 Mystic, 6.5 Mystic, 7 Mystic and 30 GIBBS. All have been run at elevated pressures and all cases have survivied with minimal ongoing case work.

Can't say that for the 223, 308, or 30-06 that I have shot over the years. I don't include belted magnums in this mix as the area around the belt is the weak link and not so easy to deal with

I almost always use the Lee collet neck die so case stretching due to the expander ball is not relevant in these examples. Win brass was used in the 223 and 6.5 mystic examples so we are comparing comparable alloys.

I would expect to hear similar feedback from F class shooters running cases with 'shallower' shoulder angles that they also need to trim quite often.

Jerry
 
Jerry,
My testing load in the 30/06 was 57 grains of 4350 behind a 180 grain bullet. That load might be a lot of things but it isn't low pressure!
The expander ball doesn't stretch case necks. Sizing the body does. If cases thin in the web and separate, the shoulder is probably being set back in sizing.
Back in the late 1970's, I shot a 6x47 in BR competition (this was the real 6x47 not the Lapua latecomer). The shoulder angle is far from sharp in this case and pressures were high enough that expanded primer pockets were a problem. In spite of this, I wore the barrel out without having to trim these cases. I still have some 223 brass I shot in another BR rifle in the early eighties It was also untrimmed in about15 firings and there is no sign of any donut.
Again, brass growth, regardless of shoulder angle seems to be related to sizing die dimension in comparison to the chamber. The expander has nothing to do with it. Very sharp shoulders do seem to resist flowing around the corner in the die; perhaps even enough to produce some linear compression of the case.
By the way, when neck sizing 30/06 brass, the brass would lengthen by about .002" when sized and return to the original length when fired. The sizing was done without the expander. As an AI, the changes were exactly the same.
I have seen some exceptions. A rifle which had a boltface which was far from square was a case stretching fiend.
Another case I work with quite a bit is the 303 British. It has lots of taper and the shoulder angle is shallow. Nonetheless, in the P14 rifle cases have not needed trimming in 12 firings. The loads are stiff with the 174 grain bullets pushed to 2700 fps.
In the Lee Enfield rifles, it's a whole different story. Cases stretch due to the spring in the action. A Lee Enfield rechambered to the Epps Improved stretched cases just the same as when it had the standard chamber.
In short, I am far from convinced that sharp shoulders do much to reduced brass flow and I am quite convinced brass flow upon firing is a largely non-existent problem. On the other hand, I see lots of evidence that sizing operations do cause brass to flow. The sharp should may be of some benefit in preventing brass flow around the corner when sizing but most of the benefit is the result of more compatible die/chamber dimensions. The reason I started testing this in the first place was because I've had very little trouble with case stretching in 45 years of loading and I thought there was maybe something wrong with me! Regards, Bill
 
Well, we are definitely seeing different results.

My cases are sized very little and only a body die is used. At most, the shoulder is bumped a couple of thou and the same procedure is used in the various examples.

Interesting...

Jerry
 
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