# 6mm Ideas...Anyone?



## longbow (Mar 31, 2009)

[attachment=0:71l2z2qp]DSC00354.JPG[/attachment:71l2z2qp]
I'm staring at a box of 6mm parts. I just got a Stiller Predator V, right bolt, left port action and a Bertlein F-class 6mm barrel. I had an idea to build a 1000yd .308 to shoot 175 VLDs. But I found a 6mm Bertlein for only $250! :mrgreen:
So now I'm thinking about a 6mm Ackley Improved. I want to keep it above the transonic stage at 1000. I had trouble with some 100gr Barnes going squirrely about the time they got to the target. I plugged in the numbers and with either the 105 A-Max or the 105 Berger I have plenty of poop left to stay ultrasonic past 1000. This won't be a competition gun so I'm not dead-set on the caliber but I have to stay with 6mm based cartridges. Sooooo... any idea? I haven't bought my reamer yet so I'm wide open for suggestions.


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## Al Hansen (Sep 7, 2007)

Nice. I shoot the Amax 105's in a .243 Custom build Remington. ( Uhhh, I don't own any guns, just borrow them. :roll: ) It was suppose to be a 600-700 yard gun. Best I've been able to do is about 400 and some change. Strictly P-dogs. Is the barrell already got a twist in it ? The one I shoot has a 8.5 twist. I wish I had gone a different route.


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## longbow (Mar 31, 2009)

It has a 1 in 8 twist.


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## chet (Sep 7, 2007)

Longbow, you got too much stress...... let me take them parts off your hands and relieve you a little....

Here's my thoughts: the problem with 105's and 6mm-rem(ai or not) is the OAL . Going at it single shot helps (no mag to limit OAL) I can't tell from the pic if your action is long or short, but if it's short you might have some issue feeding the longer case. Also the throat location of the reamer will change things up a bit, and you could end up taking up too much powder space with the 105's and not getting the velocities that you're expecting. (I know you've thought all this through, but just in case). That throat length can make or break your set-up.

A 243AI will take care of all the OAL issues..... but will it stay ultrasonic? what about the 95 grainers?

I was on the same train of thought as you a few months ago...... but I decided on 260AI, then I changed my mind to 338 fed, then I thought about 358 win for a few hours, then I was on a 243 kick for a few days, now I'm back onto 6.5 stuff........... at least fate has decided a bore size for you, hahahahahaha good snag bud!


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## Narient (Jan 9, 2011)

How about a 6mm JDJ? Just a thought.


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## BPturkeys (Sep 13, 2007)

The Ackley Improved sure makes life simple.


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## chet (Sep 7, 2007)

> How about a 6mm JDJ? Just a thought.


Although very interesting and just plain cool, WAY too slow for what he's trying to accomplish.


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## longbow (Mar 31, 2009)

Good thinking Chet. I must add that I saw this on KSL and it was such a good price that I snapped it up before it got away. I got the barrel and the action for just $975. I just figured I'd think about the build later so that's why I'm not settled on the caliber. Usually I'd have all the details in order.
[attachment=0:3j45otrl]DSC00357.JPG[/attachment:3j45otrl]
Here's a picture of a 6mm Rem loaded with a 95 VLD. It's loaded long because that's what shoots good out of my gun. The closest shell is a factory .243 for Lisa's gun. I'm thinking Chet's right, I may have to go .243AI instead, which is fine. The ejection port just isn't big enough.
95gr VLDs are definately a consideration. They shoot REALLY well out of my other 6mm.
Does anyone know anything about the 6x47 Lapua or any other suggestion?


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## chet (Sep 7, 2007)

a 243ai will out-perform the 6x47...... 
feeding the cartridge will be the easy part, ejection is where case length might cause problems.
See if that action will spit out an empty 284win case with ease, If it does then a 6-284 is your huckleberry!
Bang the gavil! discussion over! no more thought neccesary! over! finished! gone! done! out!

case lengths:
6mmAI 2.233"
243AI 2.045"
6-284 2.170"

those are basically the three different lengths you'll be working with. 
6-284, 105 berger @ 3200+ sounds like a winner, don't ya think?


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## Loke (Sep 7, 2007)

Before I make a suggestion, what size case head will fit the bolt face?


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## longbow (Mar 31, 2009)

Al Hansen said:


> Nice. I shoot the Amax 105's in a .243 Custom build Remington. ( Uhhh, I don't own any guns, just borrow them. :roll: ) It was suppose to be a 600-700 yard gun. Best I've been able to do is about 400 and some change. Strictly P-dogs. Is the barrell already got a twist in it ? The one I shoot has a 8.5 twist. I wish I had gone a different route.


What velocities are you getting out of that combo Al?


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## longbow (Mar 31, 2009)

Loke said:


> Before I make a suggestion, what size case head will fit the bolt face?


Loke, it's a .470 boltface. So cases could include 225Win, 22-250, 6mm BR, 243 Win, 250 Sav, 260 Rem, 6.5x284, 7mm-08, 284 Win, 300 Sav, 308 Win, 338 Fed, 35 Rem, 358 Win. Those are some of the calibers that are on a boltface cheatsheet I have. I'm sure there's a lot more.


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## longbow (Mar 31, 2009)

[attachment=0:2bcd61us]I-m-So-Confused---Mantled-Howler-Monkey-1.jpg[/attachment:2bcd61us]
What to do????
Planning a build is part of the fun.


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## longbow (Mar 31, 2009)

chet said:


> case lengths:
> 6mmAI 2.233"
> 243AI 2.045"
> 6-284 2.170"
> ...


At only .125 longer case I think there's a possibility it might work. Boy, if I can get the 6x284 to work I'll be loving that.


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## Loke (Sep 7, 2007)

If opening up the bolt face is an option, a 243 WSM (not WSSM) could be interesting..........


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## Al Hansen (Sep 7, 2007)

I do not know the velocities of my .243. I don't own a crony. I was shooting for groups. It does ok but nothing spectacular like I was expecting from an expensive custom gun. I have done a few more things to it this winter and hope it brings it in tighter. 

I was watching the military channel yesterday and there is a new sniper round from lapua that is shorter than the 7.62x51 (.308) but goes further and hits harder. I know it's not their .338 it's smaller. That might be worth looking into.


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## Loke (Sep 7, 2007)

That is a 6.5. Checking the specs, I don't see much difference between it and the 260 Remington. Neck it to 6mm and you get a cross between the 243 Winchester and the 6mm Bench Rest.


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## Al Hansen (Sep 7, 2007)

Loke said:


> That is a 6.5. Checking the specs, I don't see much difference between it and the 260 Remington. Neck it to 6mm and you get a cross between the 243 Winchester and the 6mm Bench Rest.


Just did a Google search. Yes a 6.5 X 47 is it. Less recoil than a .308.


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## Loke (Sep 7, 2007)

I'm curious how that 6.5 bullet is not subject to the effects of gravity, yet the 308 bullet starts dropping as soon as it exits the barrel? And Newton's law that for every action there is an equal but opposite reaction doesn't apply to the latest and greatest most powerful new cartridge that has no recoil? I just can't understand that "more powerful with less recoil" concept. It sounds like a light beer commercial to me.


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## Bax* (Dec 14, 2008)

Al Hansen said:


> Loke said:
> 
> 
> > That is a 6.5. Checking the specs, I don't see much difference between it and the 260 Remington. Neck it to 6mm and you get a cross between the 243 Winchester and the 6mm Bench Rest.
> ...


Al this is the round that I am interested in building a custom gun around. But I gotta man up and fork some cash out to get started... Longbow is well ahead of me on getting parts. I cant even decide what action I want!


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## Bax* (Dec 14, 2008)

Loke said:


> I'm curious how that 6.5 bullet is not subject to the effects of gravity, yet the 308 bullet starts dropping as soon as it exits the barrel? And Newton's law that for every action there is an equal but opposite reaction doesn't apply to the latest and greatest most powerful new cartridge that has no recoil? I just can't understand that "more powerful with less recoil" concept. It sounds like a light beer commercial to me.


Thats one of those questions that I have yet to have explained in a manner that makes sense to me Loke. But when you look at your reloading manual with a list of all the BCs for various calibers, the .264 does have a higher BC than the .308 and that seems to be a huge appeal for competitive shooters. I gotta learn to shoot better at a distance before I start toying with this stuff anyways


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## longbow (Mar 31, 2009)

Bax* said:


> Thats one of those questions that I have yet to have explained in a manner that makes sense to me Loke. But when you look at your reloading manual with a list of all the BCs for various calibers, the .264 does have a higher BC than the .308 and that seems to be a huge appeal for competitive shooters. I gotta learn to shoot better at a distance before I start toying with this stuff anyways


Your right about a lower BC being an attractive quality in bullets. It's not so much the trajectory as the improved ability to buck wind. Distance is something I can measure exactly and will stay constant. I can control my vertical dispersion by tightening my extreem velocity spread. Wind, on the other hand, varies every second and at different distances. I have noticed a difference in horizonal dispersion with different BCs. Below is results of changing the BC of a couple of my favorite 6.5 target bullets in a 10mph, 9-oclock wind. The top bullet has a .595 bc and the bottom is .313. With the .595 BC I gain about 153 inches less winddrift at 1000 yards.

Range	Speed	Energy	Drop	Path	Windage
yards	fps	ft.lb	inches	inches	Inches
1000 1841 790 260.64 -226.66	147.37 
MOA 21 3/4	-6 
Mils 6.29	-1.74
NPR2 Bars 10 8/10	- 6/10
Clicks 87	-24

Range	Speed	Energy	Drop	Path	Windage
yards	fps	ft.lb	inches	inches	Inches
1000 1060 262 402.55 -368.01	300.10 
MOA 35 1/4	-14 1/4
Mils 10.22	-4.12
NPR2 Bars 17 6/10	-2 7/10
Clicks 141	-57


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## longbow (Mar 31, 2009)

I've got it narrowed to a 6x284 or a 6x47. Maybe I'll improve the 6x284 shoulder. I have a benchrest buddy that's going to help me design a reamer as soon as I decide.


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## Loke (Sep 7, 2007)

What the ammuntion advertisers don't want you to know.
Ballistic coeffecient is a measure of how well a bullet overcomes the effects of wind resistance, not gravity. The flattened trajectories of these wonder rounds are a result of higher muzzle velocities, and bullets that fly more effeciently. This results in a shorther time of flight, so that gravity (and the wind) have less time to act on the bullet. 

There, I feel better now.


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## Al Hansen (Sep 7, 2007)

I have talked to and read that the 6-284 gets about 1000 rounds down the tube and it's done. If your a machinest that's no big deal. Cut an inch and rechamber and screw it back in (easy version). But if your like me it's going to cost ya some $$$$$$$. For that reason I would look at a different caliber.


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## longbow (Mar 31, 2009)

Al Hansen said:


> I have talked to and read that the 6-284 gets about 1000 rounds down the tube and it's done. If your a machinest that's no big deal. Cut an inch and rechamber and screw it back in (easy version). But if your like me it's going to cost ya some $$$$$$$. For that reason I would look at a different caliber.


Good point Al. Thanks for making my decision harder. :mrgreen:


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## longbow (Mar 31, 2009)

Loke said:


> What the ammuntion advertisers don't want you to know.
> Ballistic coeffecient is a measure of how well a bullet overcomes the effects of wind resistance, not gravity. The flattened trajectories of these wonder rounds are a result of higher muzzle velocities, and bullets that fly more effeciently. This results in a shorther time of flight, so that gravity (and the wind) have less time to act on the bullet.
> 
> There, I feel better now.


That's spot-on Loke.
Here's another advantage to speed that for the life of me I can't explain, but with the same bullet, the faster you drive it the higher the balistic coeficiant is. Sierra actually publishes a couple different BCs for the same bullet at different speeds. :shock: 
The more I learn the less I find out I know.


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## Loke (Sep 7, 2007)

A buddy of mine had a 6-284. He said he was getting 4300 fps from a 75 grain bullet. He also claimed to be able to hit p-dogs at 1800 yards with it. I also think his cronogpraph measured the same 20 inch yard that his range finder did. I don't remember that it killed them any deader than my 243 Winchester.


Oh, and don't forget that altitude and temperature also affect air density, which also have a huge influence on balistic coeffecient. And how well your rifle stabilizes that particular bullet will also change the BC. The numbers published by manufactures should only be used to compare bullets from the same manufacture, since each manufacturer's calculations can differ from the others based on how they collect their data.
If you want to know the actual BC of your load, you need to measure the velocity of each shot twice (at the muzzle and again at 100 yards), then you can calculate the actual BC of your load in your gun, at that particular altitude, temperature, and barometric pressure. Simple, isn't it?


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## longbow (Mar 31, 2009)

I agree. Except for Berger, I find most published BCs are inflated. I use the published BCs to get me in the ballpark then change my BCs in my programs to match the real-world trajectories.


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## Loke (Sep 7, 2007)

Finally, someone who actually knows how to shoot!!


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## Bax* (Dec 14, 2008)

longbow said:


> Sierra actually publishes a couple different BCs for the same bullet at different speeds. :shock:
> The more I learn the less I find out I know.


Boy you hit it on the nose there Longbow! I feel like I am starting to get a good grasp on these concepts, and then a wrench is thrown in that makes me re-evaluate my preconceptions.

Someday I may ask you to take me out and teach me a thing or two in person :lol:


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## Al Hansen (Sep 7, 2007)

Bax* said:


> longbow said:
> 
> 
> > Sierra actually publishes a couple different BCs for the same bullet at different speeds. :shock:
> ...


 Me2, I wanna go, please please please.


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## Al Hansen (Sep 7, 2007)

Actually years ago, about 30, my neighbor and I would get together and go out to where Eagle Mountain is now. We would set up a sheet of plywood and shoot 100,200,300, 400 all the way out to 800 yards. I had a 3x5 card taped on the stock with the clicks for the scope adjustments out to the set distances. He was shooting a 6mm Remington with a 20 power Unertle scope. At 800 he could pretty consistently put them in a paper plate. We would stand out there way off the target with a hand held CB and binoculars and call the shots so the adjustments would be done immediately. The 6mm did a pretty good job. My Remington 788 .243 w/ a 18.5 inch barrell, well lets just say I could occasionally hit the plywood.

2 points to this rambling and walk through yesteryear. 1. The 6mm is not that bad out to 800 yards. and 2. The only way to tell your ballistics and bullet drop is to shoot the dang thing at those long targets. Now as Lee Remey would say " carry on men".


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## Loke (Sep 7, 2007)

Who is lee remey?


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## Al Hansen (Sep 7, 2007)

Lee is the retired Marine Master Sargent. Had the Show on the History Channel about weapons, makes commercials (Jack Wagon ) and was in a movie about Viet Nam.


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## Loke (Sep 7, 2007)

Wasn't he in a movie where he kissed a guy?


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## Narient (Jan 9, 2011)

He was also in "Saving Silverman" as the gay gym teacher. 

"You know what makes ME sad? YOU, ya jack wagon!"


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## lehi (Sep 13, 2007)

You dudes are talking about R. Lee Ermey. Full Metal Jacket, and he also played a Helicopter Pilot in Apocalypse Now.


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## Al Hansen (Sep 7, 2007)

OK back on task here. 6mm remember.


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## Bax* (Dec 14, 2008)

I have to agree with the .243 AI, even though it is a barrel burner it really has some appeal.

Another that has my interest is a 6.17 Spitfire from Lazzeroni (still a 6mm chambering). You gain about 200 Fps over the .243 AI, but barrel life cant be that amazing and brass would have to be ordered in as opposed to the AI where you could just fire form


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## Loke (Sep 7, 2007)

It would be even funner to chamber for a standard round, then design a 6mm bullet with a BC in the 1.00 range.


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## Bax* (Dec 14, 2008)

Loke said:


> It would be even funner to chamber for a standard round, then design a 6mm bullet with a BC in the 1.00 range.


I cant think of more than one bullet with even a close BC to 1.00, the .408 Cheytac's bullet (made by Woodleigh if I remember right) has a BC of near 0.92

But that would be insanely awesome to have a high BC bullet for a .243 chambering


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## Loke (Sep 7, 2007)

The Barnes 800 grain solid for the 50 BMG is listed as having a BC of 1.095. I believe that several of the target/match bullets for the 50 are over 1.00 as well, like the AMax, and others.

I'm just guessing, but I would imagine that a 6mm with a BC close to 1.000 would have to weigh close to 180 grains. It would be tough to get the velocity needed to make it fly efficiently. It may need to be fin stabilized.


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## Bax* (Dec 14, 2008)

Loke said:


> I'm just guessing, but I would imagine that a 6mm with a BC close to 1.000 would have to weigh close to 180 grains. It would be tough to get the velocity needed to make it fly efficiently. It may need to be fin stabilized.


Maybe we could neck down a 338 Wby case to 6mm, and steepen the shoulder slightly.... should create the velocity needed.... we could call it the 6mm O My Gosh This Barrel is Going to Last 500 Rounds, or the 6 OMG for short :lol:


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## Loke (Sep 7, 2007)

You should be able to do it with the WSM case, a really long throat, and ceramic coated bore. That should get about 3000fps. A dual diameter bullet to shorten the bearing surface, and gain-twist rifling to reduce the pressure spike. It could work.


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## longbow (Mar 31, 2009)

6mm update. Thanks to you guy's I finaly decided on a 6mm Ackley Improved for my build rifle. I just got it back from the gun plumber, Dean Parker, an avid benchrest shooter and gunsmith from Wellsville, Utah. Sweet!
[attachment=1:1ku2g27y]163.JPG[/attachment:1ku2g27y]
I made a pin transfer punch at work last night and installed the Timmney trigger this morning. I set the trigger at 1.75 lbs. Now I'm waiting for my Stiller bottom metal and my Stocky's Electric Blue thumbhole stock. Cain't wait. I'll bed the action and take step by step pictures of the bedding if your interested. It's slowly coming together.

And as usual with some of my KSL ads and some of my posts, for your viewing pleasure, I've included a picture of my dog Kimber.
[attachment=0:1ku2g27y]167.JPG[/attachment:1ku2g27y]


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## lehi (Sep 13, 2007)

Wow thats awesome! Should be an awesome shooter. Can't wait for more pics. 

Great pic of the "hound" btw.


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## Bax* (Dec 14, 2008)

I look forward to the step by step pictures. I'm in need of some good gun porn


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