On the heels of a hot 6mm

[Adam in WI]

I have a newer M70 Featherweight in 243 that I'm considering rebarreling for something with a little more guts. I'd limit my bullet weights to 105 grain, and actually most shooting would be done with 85-100 grain stuff. I'd *like* to do a 1-9" twist 24" barrel for decent portability. I know it's not ideal with an overbore 6mm, but my last 6-284 did fine with it.

I have brass for 243, 6mm Remington, and 284 Winchester. Given this scenario, which would you argue is the better hotrod and why?

243 Improved
6mm Improved
6mm-284

I don't see much point myself in 243 improved; not much to be gained.

I like the flexibility the long neck of the 6mm Rem gives. Is there any truth to the notion that the longer neck also preserves the throat?

I like the no-fireform aspect of the 284 case.

I can modify the Winchesters magazine box and bolt stop to allow approximately 3.050" overall length, which appears to be more than enough.

 

[B23]

Love my 6-284! I have many that would go down the road before I let loose of my 6-284.

 

[Adam in WI]

Love my 6-284! I have many that would go down the road before I let loose of my 6-284.

What are some of your better performing loads? No need for specifics, just speeds and weights...

 

[357Mag]

Adam -

Howdy !

Since you already had experience with a 6-284 wildcat, I am wondering just what constitutes " hot/ hotrod 6mm " to your way of thinking ?

A stock .284 Win has 66gr H2O capacity, while a .240 Weatherby Magnum holds 65gr H2O. A notional 6-06 should hold around 65.5gr ( IMHO ). To get any significantly higher case capacities, you'd likely have to use a " Magnum " case, as the parent brass
( whether classic or short / fat case designs ).

Ballistician Homer Powley has told us that one way to compare the internal ballistics efficiency of rifles is to compare their " Expansion Ratios ". Powley gives a simple definition: " Expansion Ratio ( total gun volume divided by case volume ). "
( " Guns and Ammo 1974 Annual - The Powley Papers" ).

Rifles with higher Expansion Ratio numbers are more efficient at converting powder combustion into deliverable bullet energy.

When doing wildcat trade-off studies, consider.....
For a given calibre and barrel length, the way to change Expansion Ratio is by changing volume of the chamber.

For a given calibre and chamber volume, the way to change Expansion Ratio is by changing barrel length.


A regards your question about neck length ( and associated shoulder angle ):
The powder combustion " turbulence point " for a chambering, is something that was brought forth by Savage Arms engineer Robert Greenleaf. The basic notion is that barrel life is aided positively by using a chambering that places the powder combustion
" turbulence point " within the neck. For example, the .243 Win w/ it's shallow shoulder angle has a neck length that places the turbulence point outside of the neck. As you have postulated, the long neck of the 6mm Remington helps by keeping the powder combustion turbulence point inside of the neck.

Hope this helps ?


With regards,
357Mag

 

[Adam in WI]

Adam -

Howdy !

Since you already had experience with a 6-284 wildcat, I am wondering just what constitutes " hot/ hotrod 6mm " to your way of thinking ?

I consider either to be plenty given the confines of a short action .473" bolt face. At this point, my thoughts are the 284 case has the advantage since it doesn't require fire forming and better brass is available. The 6mm I could see potentially feeding better being slightly narrower.

 

[NZ_Fclass]

Don't ignore the 6mmSLR. Easy to form.

 

[357Mag]

I have a newer M70 Featherweight in 243 that I'm considering rebarreling for something with a little more guts. I'd limit my bullet weights to 105 grain, and actually most shooting would be done with 85-100 grain stuff. I'd *like* to do a 1-9" twist 24" barrel for decent portability. I know it's not ideal with an overbore 6mm, but my last 6-284 did fine with it.

I have brass for 243, 6mm Remington, and 284 Winchester. Given this scenario, which would you argue is the better hotrod and why?

243 Improved
6mm Improved
6mm-284

I don't see much point myself in 243 improved; not much to be gained.

I like the flexibility the long neck of the 6mm Rem gives. Is there any truth to the notion that the longer neck also preserves the throat?

I like the no-fireform aspect of the 284 case.

I can modify the Winchesters magazine box and bolt stop to allow approximately 3.050" overall length, which appears to be more than enough.

Adam -

Howdy, again !

I forgot to mention.....

When comparing varying wildcat configurations where the only case changes are the shoulder angle and neck length utilized, shaper shoulder angles will reduce case capacity
( assuming comparison is made with all configurations featuring the neck filled w/ bullet ).

In other words.... with the neck filled w/ bullet and bullet base positioned in the same location for all case configurations compared as above.

For pushing the 6mm envelope, do a search for posts made by " Fredo ", where in he describes his " .240 Redline " . Please also see posts about the " .240 Redline " made by " Snert ".

With regards,
357Mag

 

[1shot]

Don't ignore the 6mmSLR. Easy to form.

I know you said you don't wan't to fireform, but if I was going to have one 6mm it would be the SLR. With an 8 twist, it will shoot "clean" out to 1K with 105 class bullets. If you stay with cooler burning powders, bbl. life is easily north of 2,000 rds. All this while using 43-45 gr. powder and great brass to choose from.
I hope this helps,

Lloyd

 

[B23]

My 6-284 is built on a trued SA Rem 700 with a 12tw Lilja finished at 26 inches. I'm limited on bullet weight due to the twist but I've predominately shot 75gr Vmax with H4350. I'm not pushing if very hard at all and those 75's run 3650. I know I could switch to RL26 and easily pick up another 150fps but the load I have shoots so consistently well I just can't bring myself to eff with it.

I've always like the Rem 6mm and I've shot a 22-6mm my father has a ton but 6mm brass is not only hard to come by but it's quality is mediocre at best. For a hot rod 6mm the 6-284 is just so easy IMO it can barely be called a wildcat and necking down Lapua 6.5-284 brass is a one pass and done deal not to mention it's a pretty good performance gain over the 6mm, 243, or even 243AI.

I don't know if the brass is very good but if someone wanted a super hot rod 6mm on a standard .473 bolt face you could neck down that new 6.5 Weatherby RPM cartridge to 6mm. It's basically a stretched out 284 case that holds 84gr H2O which is a hell of a lot more case capacity but like I said I'm not sure how good the brass is.

 

[Capt. Oblivious]

Don't ignore the 6mmSLR. Easy to form.

6SLR with N560 or Norma MRP will make you double check your crony's batteries and if your not after extreme speed fill the case up with N160 and enjoy the ride

 

[Sniper338]

Id do a 6-284 if that was my prerogative. Not going to gain much with anything else

 

[284winner]

I have a newer M70 Featherweight in 243 that I'm considering rebarreling for something with a little more guts. I'd limit my bullet weights to 105 grain, and actually most shooting would be done with 85-100 grain stuff. I'd *like* to do a 1-9" twist 24" barrel for decent portability. I know it's not ideal with an overbore 6mm, but my last 6-284 did fine with it.

I have brass for 243, 6mm Remington, and 284 Winchester. Given this scenario, which would you argue is the better hotrod and why?

243 Improved
6mm Improved
6mm-284

I don't see much point myself in 243 improved; not much to be gained.

I like the flexibility the long neck of the 6mm Rem gives. Is there any truth to the notion that the longer neck also preserves the throat?

I like the no-fireform aspect of the 284 case.

I can modify the Winchesters magazine box and bolt stop to allow approximately 3.050" overall length, which appears to be more than enough.

I like your thought process. I'd for sure go 284 parent case. You have the reserve case capacity if you didn't want to fill the case and run it cooler. My personal choice would be an 8 twist tho if I built one that way. You could run 85-115s going that route. Again, have it and not need it vs need it and not have it. The faster barrel won't wreck accuracy or have any negative impact. It's just a preference thing.

 

[dstoenner]

Higher expansion ratios are also barrel burners. No free lunch here. It is a balance

for example my 6br got 3000+ rounds out of a barrel while my 6x47L only gets 2000 rounds. BUT i can get more velocity with the 47 thanthe 6br which i need at 1000. I am willing to buy that lunch

David

 

[Liven The Dream]

Built a couple 6mm and 6.5 as you say Hot Rods ! Barrel Burners .......... At the Cost and wait time on Cut Barrels , and there short life Why ?

Look up a Old 60's Song Transfusion !
Speed Kills.

Best of Luck

 

[Adam in WI]

Zero concern with barrel life. Will be lucky to put 500 rounds through it in the next 5 years. Just want a hotrod. Why... Why not?

 

[bullfrog]

I use the 87 gr v-max in my 6/284 with H4831SC powder. 1:10 twist barrel. Could probably go faster with a different powder but it shoots to good to mess with it.

 

[Plumsask]

As I posted before, my 6mm AI with ab26" 8 Twist, 53.0 gr H4831SC and a 90 grain TGK @ 3500 FPS, easy to load for.

 

[75vmax]

243 win and 105s at 3250 how much faster can you push it . Looks like you will need a 40 inch tube to get any more speed

 

[CJ6]

Love the 6-284. I've been using a 12 TW with 87 V-Max and 88 Bergers. The barrel I have coming is in 9 TW. Reason being my friends 240 Weath. is in 10 TW and he uses 105-108 gr weights and stabilize just fine . I want to try the heavier weights to see how heavy I can go 115 and up if possible. This will be in a 31" bbl.

 

[searcher]

Since no concern for barrel wear, Weatherby Magnum