Fancy 6mm’s vs the .243

[ajdemar215]

There is a lot of 6mm’s leaving benchrest rifles and going to prs rifles now. From the 6br, the bra, brx, GT, xc, 6mmLGBTQRX123. Why are we going this route over the .243? What benefits do the cases have over the win? Brass for the .243 is everywhere. Can be made relatively easy. Feeds well from a magazine and has a standard case head. If barrel life is the concern, why couldn’t you just load to 6BR velocities? Just seems excessive to me with these super short cases that need mag spacers and tuning and specialty brass manufacturers. Or maybe I’m just a stupid dumb idiot. What gives?

 

[spife7980]

They are shorter so you can stick the bullets really far out in the longer necks to create additional case volume without running out of room inside of the mag. Have steeper shoulders for a more efficient powder burn and less brass migration. The longer necks and steeper shoulders also help to mitigate torching of the throat. They also use less powder. All of those play into better barrel life as well.

The 243 is a mouse trap that still works just fine, its just there are newer shinier better mouse traps now.

 

[Sixfivesavage]

It's too basic bitch to be used by most trendy gamers.

 

[b6graham]

They are shorter so you can stick the bullets really far out in the longer necks to create additional case volume without running out of room inside of the mag. Have steeper shoulders for a more efficient powder burn and less brass migration. The longer necks and steeper shoulders also help to mitigate torching of the throat. They also use less powder. All of those play into better barrel life as well.

The 243 is a mouse trap that still works just fine, its just there are newer shinier better mouse traps now.

like those sticky pads that trap their feet

he's right. shoulder angle. long neck. less taper on case. better barrel life. downloading means shit case fill.

30gr powder versus 43

 

[264win]

It's biggest downfall is that it lacks cool factor, And companies developing new cartridges have financial motivation to play up the shiny new round. There isn't really much it can't do as well or better than many of the new 6mms.

 

[b6graham]

It's biggest downfall is that it lacks cool factor, And companies developing new cartridges have financial motivation to play up the shiny new round. There isn't really much it can't do as well or better than many of the new 6mms.

243 and 260 didnt capitalize on fast twist heavy bullets in factory offerings and are longer cases

the creedmoor take advantage of this fact

the BR /dasher pushes fast enough with 12 grains less powder. big advantage in positional shooting

 

[Rust]

It's tailoring the cartridge to a specific purpose. The .243 was developed off the .308 case so you could say what was wrong with the .308 that the newer shinier .243 was needed. Looking back a lot of years the .243 prospered and the 6mm Rem did not simply because for years no one offered a rifle in 6mm Rem with a fast enough twist barrel to run heavier hunting bullets. It never took off.

As far as the 6mm Br goes, it was developed as a reply to the 6mm Swiss more or less for 300 meter shooting in Europe. Ruag was neve interested in sending the Swiss to export markets. Turns out the 6 BR was excellent at 600 and 1,000 to, and the variants with slightly more powder capacity were slightly better at 1,000 plus some folks like to tinker.

Lapua developed the 6.5 X 47 for 600 meter shooting, it will shoot to 1,000 too but not quite as well as the 6 BR variants. Necked down to 6mm though it works and less recoil than in 6.5.

The Creedmore was designed to work in large frame AR platforms, long neck to keep the bullet out of the engine room and still mag. It got necked down to 6mm too with less recoil

I think the 6.5 X 47 and the Creedmore were both in development at about the same time and the 6.5 X 47 made it out of the gate first.

Anyway, all of those were designed for a specific purpose and then modified to better suite a little different purpose. The .243 is a good general purpose case, has been for years, but because of that it's not as well suited for some specific applications. That and for a few people it's not shiny new enough.

 

[Sheldon N]

From the 6br, the bra, brx, GT, xc, 6mmLGBTQRX123. Why are we going this route over the .243? What benefits do the cases have over the win?

Looking at the newer popular cases they tend to have longer neck, steeper shoulder, less powder burned for velocity. All those contribute towards longer barrel life, plus less powder burned equates to less recoil and less muzzle blast/overpressure.

Not to mention that the small 6mm's are much more consistent and accurate generally. With any round on the BR case it's super easy to get SD's in the low single digits and to have a load that shoots a very tight waterline at distance.

Complaints of feeding issues are overblown, and a mag spacer is a pretty simple device. Lapua brass is readily available in both 243 or 6BR at the same price so that's a non-issue.

So the answer is because the smaller 6's are better, at least for the PRS game.

 

[ajdemar215]

I seen some one mentioned shitty case fill if you De-load the .243 to BR velocities. Will that cause sub par SD’s?

 

[flyer]

Since you can't fit long bullets in a .243 easily, the throats are cut for short bullets and the barrel twist usually isn't fast enough for what people want to do for long distance.

If you're going to change that stuff to try to make .243 work, you might as well try to get every other advantage you can get with an improved chambering.

It is messy and somewhat redundant in the 6mm flavors but eventually the cream will rise to the top.

 

[RogueTanker]

Almost all PRS shooters use custom barrels with their choice of twist and chamberings. To bring that up that I would argue is a moot point.

The 243 SAMMI might have a short throat but most places offer more freebore and get past this.

The pros of the 243 are definitely the availability of components. Brass is everywhere and you can use the same bullets as everyone else.

When paired with h1000 from what I've seen with mine you should come up on 2k barrel life easily, equivalent to other 6mms. My barrel is touching 900 rounds and the lands have barely moved( started at 2.680 and I'm at 2.777 now). I can load them out to 2.96, so I've got miles of lands to chase.

I'm running the DTAC at 2980 with h1000. From 46.0 to 46.4gr, 3x per .2gr, the entire spread was 28fps. Easily the most accurate and easy to tune caliber I've ran yet. And if you hate your barrel, rl26 can get you 3100.

 

[Bandit320]

Almost all PRS shooters use custom barrels with their choice of twist and chamberings. To bring that up that I would argue is a moot point.

The 243 SAMMI might have a short throat but most places offer more freebore and get past this.

The pros of the 243 are definitely the availability of components. Brass is everywhere and you can use the same bullets as everyone else.

When paired with h1000 from what I've seen with mine you should come up on 2k barrel life easily, equivalent to other 6mms. My barrel is touching 900 rounds and the lands have barely moved( started at 2.680 and I'm at 2.777 now). I can load them out to 2.96, so I've got miles of lands to chase.

I'm running the DTAC at 2980 with h1000. From 46.0 to 46.4gr, 3x per .2gr, the entire spread was 28fps. Easily the most accurate and easy to tune caliber I've ran yet. And if you hate your barrel, rl26 can get you 3100.

I’ve been using RL26 with 105RDFs in my 243 and have been happy with it so far. Is RL26 hard on the barrels because of burn temperature / other ignition characteristic, or because you can push it so far. If H1000 is easier on the bore when loaded to similar velocities I wouldn’t mind trying it instead. Thanks for any input.

Mike

 

[Sheldon N]

My barrel is touching 900 rounds and the lands have barely moved( started at 2.680 and I'm at 2.777 now

I wouldn't call 100 thou of throat erosion in 900 rounds "barely moved". For context my Dasher barrel had the lands erode like 40-50 thou in 2k rounds and my 6BRA moved maybe 0.035 in 2k rounds.

 

[jasent]

I love the 243. It’s not the cool kid but I’ve taken mine out to a mile so far. 1:7 28” shooting 105’s at 3230fps(mag fed)I don’t shoot comps. I’ve never seen a 243 that didn’t shoot great. Components are every where, one of my 243’s has almost 3000 rds through it and still holds moa. Most of my barrels have gone 1200-1400 so I’m about half way through my current barrel
Barrels are like tires, you’ll go through more with a hot rod.

 

[Bandit320]

Jasent, What powder and load are you using? I’ve been using 46.2 grs of RL26 with 205 RDFs out of a 26” and getting 3160. Thanks.

 

[Milo 2.5]

I wouldn't call 100 thou of throat erosion in 900 rounds "barely moved". For context my Dasher barrel had the lands erode like 40-50 thou in 2k rounds and my 6BRA moved maybe 0.035 in 2k rounds.

Lol, .100" in 900 is getting after it. It is funny how some barrels, or powders, or bullets, blah blah can handle erosion, others cannot. I had to pull a comp match barrel at 1200 rds, with .027" erosion, nothing I did could bring it back. I'm talking 2" at 100 yards bad.

To the OP, all these 6mm's work and will shoot, I've about ran all of them, the most fun and was easy to do was the 6 SLR. But the brass I used sucked, and 2-3 firings was all I got from it. Pick one and have some fun, learn as you go, every case has it's pluses, and minuses.

 

[jasent]

Jasent, What powder and load are you using? I’ve been using 46.2 grs of RL26 with 205 RDFs out of a 26” and getting 3160. Thanks.

43gr h4350 and 105gr hunting vld
Es/10 for ten shots. Norma brass. Work up as it’s on the hot side. Went up to 45.0 but started loosing primer pockets fast @3320fps

 

[300ATT]

I shoot a .243 and 6x47 for PRS matches. The .243 is in an AI AT and the 6x47 is a custom MileHigh gun. Both shoot better than 1/4 moa. The 6x47 shoots berger 105's at 3,090 fps, the .243 shoots them at 3,180 fps but will start to blow primers when the barrel warms up in 14+ shot strings. In terms of performance on steel any advantage is only in my mind but I give it to the .243. The biggest difference is the 6x47 is cool and the small primer pockets are the bomb. If you are a brass whore ... go with the new cool 6mm's. If you are speed whore go for the .243 which also doubles as a nice long-range prairie dog round.