6BR vs. 243

[BoilerUP]

I'm thinking about building a Savage-based rig to sling the 105 AMax, 107 SMK or 115 DTAC, and have pretty much narrowed my candidates down to 6BR and 243 (don't want to mess with Dasher or Ackley case forming). Purpose would be paper punching & steel ringing from 100-600yd, and likely built into a tactical-style rifle (though I'm not 100% set on that yet).

I like that, compared to the 243, 6mmBR Lapua brass is a bit cheaper, its uses less powder, has less recoil (though both are mild) and Varget seems to be fairly popular, which I also use in my 223. Not sure how well this will load from a blind mag or DBM setup, however.

I like that, compared to the BR, I can use Win brass for the 243, and it has more "horsepower" if I ever wanted to shoot long range (though I understand the BR gives up nothing in accuracy), and is a proven competitor in tactical/practical matches.

I'm also curious about barrel life with both the 243 and BR, given I realistically hope to drive those 105-115gr bullets at 2850-3050fps.

I've got a 260 that hasn't reached its full potential yet so I probably shouldn't dive into another project...but I'm curious what others who have been down this road before decided, and why.

 

[MinorDamage]

Re: 6BR vs. 243

There have been successful attempts to get the 6mmbr case to feed from a repeater but they are few and far between. It is just too short, fat, and has such a sharp shoulder angle. The 6br seem to be fine for what you intend, but the 243 is going to be superior in most respects beyond about 300 yards simply due to muzzle velocity differences. Also, you are going to want to ensure your rifle will handle the small rifle primers without piercing them. Having the FP hole bushed alleviates this, but most factory actions aren't set up that way. Military rifles like the AIs and TRGs have issues with the small primers, so that isn't really an option for me, personally. Good luck

 

[427Cobra]

Re: 6BR vs. 243

6XC will feed fine from a mag, perfermance is very good with 115's capable of going faster than 3k, brass is excellent.

 

[darrenk75b]

Re: 6BR vs. 243

The 6br will beat out the typical 243 accuracy wise, no doubt. However, I wouldn't think about the 115 DTACs in it. The 105/107 class of bullets is about max for it.

The 243 will feed reliably, whereas the 6br is finicky at best due to the case geometry. There are some methods developed out there to help address this issue, but they do not always work perfectly. I've seen some AICS mags modified for the 6br, and that seems to be a good option so long as you only intend to shoot longer bullets.

Due to the case capacity, the 6br will have much better barrel life than the 243.

If you are only shooting to 600 yards, I don't think that you need to consider the DTACs. The 105 AMAX or Berger bullets or even the 95 Bergers should get you there well enough in either chambering.

Personally, if I was building a rifle like you are considering and reliable feeding was a mandate, as was no fireforming, I would look past the two calibers you note and consider the 6XC or the 6x47L.

The 6XC has formed brass available, or you can create it yourself from 22-250 brass. I guess this would be considered fireforming, but it's not the same as fireforming 243AI or Dasher brass. The forming is basically performed by the reloading die and the firing just smooths things up.

The 6x47L is formed just by running 6.5x47L brass through the FL die.

Both of these options burn less powder than a 243, which should result in increased barrel life, and are very accurate out of the gate. Either will feed well as they are not hampered by the case issues the 6br has.

 

[DMann]

Re: 6BR vs. 243

Just to muddy the waters a bit more, let me suggest the 6mm Super LR - it is a 243 case with the shoulder set back to the same angle as the 6XC, yielding a longer neck and better case life. There is also some evidence that it will erode the throat much less than the 243.

Link: http://www.6mmar.com/Super_LR.html

A little more ass than a 6XC and a little less blast (on the throat) than the 243.

 

[gme]

Re: 6BR vs. 243

on balance I dont think theres a better cartridge than the 6br for punching paper out to 600 yards, it feeds fine through a system designed for it.
http://www.youtube.com/watch?v=ZtMJwLQSRfI

 

[steve123]

Re: 6BR vs. 243

I've owned both.

The main reason I've stayed away from the 6br as a tactical repeater is the having to mod mags.Otherwise it's a very efficient round and has many wins to it's credit in long range benchrest.

243 is a great round.Trading some efficiency for power and speed.It does well also cept for throat life.Standard brass is easy to come by and not to expensive.

I settled on 6x47L which has been a stellar round.All you have to do is one pass of 6.5x47L brass into a 6x47L sizer and commence as normal.It does not need foreforming.Is efficient and accurate.The brass is uniform,super tough and seems to last forever.I'm still using my original batch from 4 years ago.

There's one problem with it.The brass can withstand extremely high pressures so what happens is it gets overloaded easily.You can either drop the load back a bit to reduce primer flow and use CCI 450's,Rem 7 1/2's or get your bolt bushed.I'm about to get my 3rd 6x47 barrel back any day now which I had melonited this time.I plan on reducing the velocity from 3070 fps with 115's to the lowest node which should be low 2900's.I'm hoping to get 4000-5000 rounds out of this barrel.Fingers crossed

 

[BoilerUP]

Re: 6BR vs. 243

Hmmm....never thought about the 6x47 or the 6XC. I think I could live with forming Lapua brass with a single pass through a FL die, though it looks like Norma 6XC brass is much cheaper if sourced from Superior Shooting Systems.

Will both the x47 and XC feed from AICS-style mags? What powder do folks like to use with them...seems maybe H4350/RL17 from what I've found on the net?

It would appear that 3000fps with a 107 SMK is doable from either the x47 or XC, which should outperform the 6.5 123gr AMax/SMK from my 260...what could one expect for barrel life from either cartridge at that velocity?

And to put my barrel life questions into perspective, I would have to work pretty hard to send more than 500 rounds downrange a year...so if I got 5 or more years of life from a consumable barrel that'd be reasonable to me.

I really appreciate the insight!

 

[GUNNER75]

Re: 6BR vs. 243

8 twist 243

 

[D_TROS]

Re: 6BR vs. 243

http://www.6mmbr.com/243Win.html

here a good read. Pesonally, I would go with the 243, but thats due to it being double use as a hunting rifle...dont need the inherent accuracy of the 6br over the dominate energy of the 243 downrange. That being said, Im building a 260

Regards,
DT

 

[Engine 22]

Re: 6BR vs. 243

Considering your comment on total rounds fired per year, just roll with a 7.5 twist in the .243. Plenty of data, powder options, brass suppliers, no issue feeding, yada, yada, yada.

 

[Rob01]

Re: 6BR vs. 243

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Engine22</div><div class="ubbcode-body">Considering your comment on total rounds fired per year, just roll with a 7.5 twist in the .243. Plenty of data, powder options, brass suppliers, no issue feeding, yada, yada, yada. </div></div>

Good idea although if you plan on using the lighter bullets as well as the 115s I would go with an 8 twist. The 7.5 can tear apart the lighter bullets at higher speeds. Don't ask how I know that

Get some Win brass and a .243 and it's all you will need. Inexpensive and accurate. I have almost 2000 rounds through mine sending the 115s out at about 2990fps and it's still very accurate.

 

[sobrbiker883]

Re: 6BR vs. 243

Would a 243 AI be worth it over a standard 243? Everyone here's going 6XC, but they're a lot of work...

 

[Rob01]

Re: 6BR vs. 243

I don't like fireforming so no for me. The standard feeds fine and gives plenty of accuracy for me.

 

[sobrbiker883]

Re: 6BR vs. 243

Same here, I guess the CM will have to do for a while.....

 

[5RWill]

Re: 6BR vs. 243

Have friend with the .243 AI and his fireform groups are producing 5 shot close to 1 hole groups. But he hasn't gotten the same out of his AI loads, they're still Sub-MOA but still it's kinda weird. I've already got plans to build a 6XC so that would be my choice/median between the 6mmbr and .243. But if i had to choose between the two, .243 all the way maybe even .243 AI depending on the barrel length. Like Rob said winchester brass is inexpensive and plenty good.

 

[steve123]

Re: 6BR vs. 243

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BoilerUP</div><div class="ubbcode-body">Hmmm....never thought about the 6x47 or the 6XC. I think I could live with forming Lapua brass with a single pass through a FL die, though it looks like Norma 6XC brass is much cheaper if sourced from Superior Shooting Systems.

Will both the x47 and XC feed from AICS-style mags? What powder do folks like to use with them...seems maybe H4350/RL17 from what I've found on the net?

It would appear that 3000fps with a 107 SMK is doable from either the x47 or XC, which should outperform the 6.5 123gr AMax/SMK from my 260...what could one expect for barrel life from either cartridge at that velocity?

And to put my barrel life questions into perspective, I would have to work pretty hard to send more than 500 rounds downrange a year...so if I got 5 or more years of life from a consumable barrel that'd be reasonable to me.

I really appreciate the insight! </div></div>

I learned the hard way about R-17 and warm loads.I only got 1500 rounds out of the last barrel.The first barrel lasted 2400 rounds but only the last 1000 were with R-17.I'll be switching to a slow single based powder.Probably H-4831 or H1000.

3000 fps with 107's is a medium load with 6x47L and it feeds perfectly out of AI mags.

I've never owned a 6XC so I won't comment on it.

Honestly I'm not sure you will notice much of a gain over 260 with 243 cal going at medium speeds??? I had a 6-284 once.It was launching 75's at 3800 fps.I'd imagine you could get 3400 fps with a longer barrel with 105's.In your case it would last 2-3 years probably.

 

[Mike]

Re: 6BR vs. 243

243 with Win brass and 115s DTAC will smoke others at longer >600 yard ranges.

6.5 mil 1K
1.7mil 10mph FV @ 90*

Just about every GAP barreled 243 has done this.

 

[9H_Cracka]

Re: 6BR vs. 243

If you are willing to trade 15 grs of powder every time you pull the trigger and 3x barrel life for 150 or so FPS, by all means pop for the 243.

It goes to 11.

http://www.youtube.com/watch?v=EbVKWCpNFhY

 

[Mike]

Re: 6BR vs. 243

Leo, I don't know if I'm on board with "3x the barrel life". Most 243s are easily getting to 2K + rounds with virtually no loss of accuracy (for tactical operations).

 

[Engine 22]

Re: 6BR vs. 243

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Engine22</div><div class="ubbcode-body">Considering your comment on total rounds fired per year, just roll with a 7.5 twist in the .243. Plenty of data, powder options, brass suppliers, no issue feeding, yada, yada, yada. </div></div>

Good idea although if you plan on using the lighter bullets as well as the 115s I would go with an 8 twist. The 7.5 can tear apart the lighter bullets at higher speeds. Don't ask how I know that

Get some Win brass and a .243 and it's all you will need. Inexpensive and accurate. I have almost 2000 rounds through mine sending the 115s out at about 2990fps and it's still very accurate. </div></div>

Sorry, I figured after he sees what the 115DTAC does at distance out of a .243win, he'd forget about the other bullets.

 

[scotharr]

Re: 6BR vs. 243

From a pure accuracy standpoint, 6BR has to get the nod and out to 600 yards the match results I've seen effectively bear this out...and I"m a 243WIN shooter.

But, it's only a tiny difference we are talking about. Beyond 600 yards, 243WIN clearly gets the nod and I would not even consider a 6BR for magazine-feeding.

Regarding the supposed superiority of the 115DTACs over the 105/107s, I'll simply point out that the current long-range champion (& 3-peater) uses a 243WIN with 105 Berger VLDs. This is for a prone rifle where recoil and rifle weight are important considerations. The 7mm short magnums seem to be the current top dogs for long-range bench rest/F-Class comps.

 

[BoilerUP]

Re: 6BR vs. 243

I now find myself vacillating between the 6BR and 6XC.

I figure since 600yd is really all I have available to shoot, I don't really NEED the extra oomph of the 243...and I'm not sure I'd need the extra velocity the XC offers over the BR at that range, either. I'm also attracted to the BR's very low recoil and thriftiness with powder...and that prefit Savage barrels are stocked while the XC would have a 2-3 month lead time.

Lapua brass for the BR, Norma brass for the XC. The XC reportedly feeds reliably from an AICS mag, while the BR would need some mag modifications...something to consider for a mag-based tactical build.

Decisions, decisions...

 

[cjgemm]

Re: 6BR vs. 243

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">Would a 243 AI be worth it over a standard 243? Everyone here's going 6XC, but they're a lot of work... </div></div>

What kind of work?

 

[WhiskeyWebber]

Re: 6BR vs. 243

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mike</div><div class="ubbcode-body">Leo, I don't know if I'm on board with "3x the barrel life". Most 243s are easily getting to 2K + rounds with virtually no loss of accuracy (for tactical operations). </div></div>

I have heard 2-3K all the way down to 600-700 for barrel life on the .243. Why do you think there is such variation in barrel life for the .243?

I'm designing my next build now an I'm leaning towards 6XC for feeding, accuracy, barrel life, and it can still get the 115s up to 3020fps. I think recoil on any 6mm round is a non-issue.

 

[Mike]

Re: 6BR vs. 243

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: WhiskeyWebber</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mike</div><div class="ubbcode-body">Leo, I don't know if I'm on board with "3x the barrel life". Most 243s are easily getting to 2K + rounds with virtually no loss of accuracy (for tactical operations). </div></div>

I have heard 2-3K all the way down to 600-700 for barrel life on the .243. Why do you think there is such variation in barrel life for the .243?

I'm designing my next build now an I'm leaning towards 6XC for feeding, accuracy, barrel life, and it can still get the 115s up to 3020fps. I think recoil on any 6mm round is a non-issue.</div></div>

Two things. First, you'll find the actual tactical shooters who compete with the 243 will quote the 2K-3K barrel life as that's what they've seen personally. As I had said I personally saw Moon from GAP shoot a 243 at RO with 3K+ round and it still shot >1moa.

The people who claim ridiculously low barrel life are either parroting what they've read and really have no experience with it or are overly anal BR guys who have unreal expectations and whose requirements aren't necessarily relevant to our style of shooting.

On another note, I have yet to see a 6XC match a 243 pushing 115 DTACs. 6XC shooters will "claim" they can, but at all the events I attend, the 6XC shooters tell me they're seeing pressure before that velocity.

 

[WhiskeyWebber]

Re: 6BR vs. 243

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mike</div><div class="ubbcode-body"> are overly anal BR guys who have unreal expectations and whose requirements aren't necessarily relevant to our style of shooting. </div></div>

I think you're correct. Now that I think about it, both of the smith's that I talked to about .243 that mentioned below 1k barrel life were BR types.

 

[cjgemm]

Re: 6BR vs. 243

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mike</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: WhiskeyWebber</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mike</div><div class="ubbcode-body">Leo, I don't know if I'm on board with "3x the barrel life". Most 243s are easily getting to 2K + rounds with virtually no loss of accuracy (for tactical operations). </div></div>

I have heard 2-3K all the way down to 600-700 for barrel life on the .243. Why do you think there is such variation in barrel life for the .243?

I'm designing my next build now an I'm leaning towards 6XC for feeding, accuracy, barrel life, and it can still get the 115s up to 3020fps. I think recoil on any 6mm round is a non-issue.</div></div>

Two things. First, you'll find the actual tactical shooters who compete with the 243 will quote the 2K-3K barrel life as that's what they've seen personally. As I had said I personally saw Moon from GAP shoot a 243 at RO with 3K+ round and it still shot >1moa.

The people who claim ridiculously low barrel life are either parroting what they've read and really have no experience with it or are overly anal BR guys who have unreal expectations and whose requirements aren't necessarily relevant to our style of shooting.

On another note, I have yet to see a 6XC match a 243 pushing 115 DTACs. 6XC shooters will "claim" they can, but at all the events I attend, the 6XC shooters tell me they're seeing pressure before that velocity. </div></div>


> greater than
< Less than

assuming you meant the latter.

 

[Mike]

Re: 6BR vs. 243

Yes, fat finger syndrome. Great for chicks, not so much for typing.

 

[BgBmBoo]

Re: 6BR vs. 243

I own a .243 (Surgeon Scalpel) and juts sold a 6XC to a fellow Hide member. This was my 2nd 6XC.

I REALLY like the 6XC. When I shoot out the .243 barrel it will be re-chambered in 6XC. It pretty much gives up very little to the .243. They are very close in velocity...I was running the XC at 2925 fps and I run the .243 at 2975 fps. I am using 107 SMK's and H4350 powder.

The 6XC feeds flawlessly from AI mags. I used Norma brass with very little case work.

Both of the 6XC I owned where EXTREMELY accurate. Right before I sold the rifle I shot it in a 600 yard BR match and won small group with a 1.925" five shot group...and this is from a tactical type rifle going head to head with full blown BR guns.

If you like a .243....my feelings and opinion is you will love the XC.

Take care,Stan

PS...video of XC I just sold shooting steel at 1000 yards.

<object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/_KV8JhG0BOY"></param> <param name="wmode" value="transparent"></param> <embed src="http://www.youtube.com/v/_KV8JhG0BOY" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"> </embed></object>

And Targets from the 6oo yard BR match mentioned above:

 

[shooter65]

Re: 6BR vs. 243

Simple - If you are only going to punch paper or ring steel, go with the 6br. The 6br will be much cheaper to shoot and is more accurate.

If you are going to shoot tactical matches go with the 243. Tough to be the 243 in a tactical match.

Or go with the 6.5x47 and shoot 123's. You will have accuracy and efficiency.


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BoilerUP</div><div class="ubbcode-body">I'm thinking about building a Savage-based rig to sling the 105 AMax, 107 SMK or 115 DTAC, and have pretty much narrowed my candidates down to 6BR and 243 (don't want to mess with Dasher or Ackley case forming). Purpose would be paper punching & steel ringing from 100-600yd, and likely built into a tactical-style rifle (though I'm not 100% set on that yet).

I like that, compared to the 243, 6mmBR Lapua brass is a bit cheaper, its uses less powder, has less recoil (though both are mild) and Varget seems to be fairly popular, which I also use in my 223. Not sure how well this will load from a blind mag or DBM setup, however.

I like that, compared to the BR, I can use Win brass for the 243, and it has more "horsepower" if I ever wanted to shoot long range (though I understand the BR gives up nothing in accuracy), and is a proven competitor in tactical/practical matches.

I'm also curious about barrel life with both the 243 and BR, given I realistically hope to drive those 105-115gr bullets at 2850-3050fps.

I've got a 260 that hasn't reached its full potential yet so I probably shouldn't dive into another project...but I'm curious what others who have been down this road before decided, and why. </div></div>

 

[rpk762]

Re: 6BR vs. 243

All of the post above are good posts. I have a 6mm Norma BR in a Eliso R5 kit. I used it for high power for a little bit until I stopped competing now it is a PD rifle. There are a few mods that can be done to get a BR to shoot from a mag. If you just want to single load the only real choice is the BR. If you need to load from a mag then the 243 is your round.

I would like a better mag on the Eliso than what they currently use but it will feed those 5 rds just fine.

 

[Rmkeyjr]

Re: 6BR vs. 243

There have been successful attempts to get the 6mmbr case to feed from a repeater but they are few and far between. It is just too short, fat, and has such a sharp shoulder angle. The 6br seem to be fine for what you intend, but the 243 is going to be superior in most respects beyond about 300 yards simply due to muzzle velocity differences. Also, you are going to want to ensure your rifle will handle the small rifle primers without piercing them. Having the FP hole bushed alleviates this, but most factory actions aren't set up that way. Military rifles like the AIs and TRGs have issues with the small primers, so that isn't really an option for me, personally. Good luck

Mags are no problem-1 shot one kill

 

[Olen_4504]

Mags are no problem-1 shot one kill

this thread is 8 years old ....so maybe in 2011 that was that case....

 

[6brshooter]

Re: 6BR vs. 243

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mike</div><div class="ubbcode-body">Leo, I don't know if I'm on board with "3x the barrel life". Most 243s are easily getting to 2K + rounds with virtually no loss of accuracy (for tactical operations). </div></div>

I have heard 2-3K all the way down to 600-700 for barrel life on the .243. Why do you think there is such variation in barrel life for the .243?

I'm designing my next build now an I'm leaning towards 6XC for feeding, accuracy, barrel life, and it can still get the 115s up to 3020fps. I think recoil on any 6mm round is a non-issue.

Mainly people regurgitate what they see on the interweb about 243 barrel life, without actual due diligence. I've had several 243 and 6br barrels. The 6br can be ran at 2925, I've done it in 2 26" criterion prefits. 105 hybrids or 107smk and 29-29.8gr h4895 will do it. I've got a 18" 6br that runs 2750 with those 2 bullets. I've never had issues feeding 6br in m700, tikka, or savage. The only issue I have saw was in ejection. That short fat case tends to get slung out against action, from too strong ejector spring, and gets lose from extractor. A sako extractor handles it better than rem or savage.

My 243s have been very good for me, 42-43 gr of h4350 and a 105-112 bullet will roll at 3120+fps. I had a criterion remage 243 8tw that hammered in the low .2s with 107 at 3125. I shot it a lot, but never in a mad minute type stage. It still shot .5moa at 2500 or 2600rds, but speed had dropped to 3000fps.
I really like 243ai, fireform loads in 2 barrels were 105/107 class bullets at 3050 and 3090, shot in the .3-.4 range. Full power loads were 3175, in a tikka, saving barrel life and cost to rebarrel. The other was in a remage, ran it at 3320 fps with hybrids. That criterion would shoot in the .1-.2s and has several 2-3" groups at 800, still going good at 1200rds, but has slowed to 3190. I've got a tl3 with a 243 7.5tw, it hammers 110smk at 3090, when barrel is toast it will be a 243ai. Keep loads at 3150 area, never trim brass and should be easier on throat with its 40° shoulders, plus 243ai look badass.

 

[Hawkwood]

Mainly people regurgitate what they see on the interweb about 243 barrel life, without actual due diligence. I've had several 243 and 6br barrels. The 6br can be ran at 2925, I've done it in 2 26" criterion prefits. 105 hybrids or 107smk and 29-29.8gr h4895 will do it. I've got a 18" 6br that runs 2750 with those 2 bullets. I've never had issues feeding 6br in m700, tikka, or savage. The only issue I have saw was in ejection. That short fat case tends to get slung out against action, from too strong ejector spring, and gets lose from extractor. A sako extractor handles it better than rem or savage.

My 243s have been very good for me, 42-43 gr of h4350 and a 105-112 bullet will roll at 3120+fps. I had a criterion remage 243 8tw that hammered in the low .2s with 107 at 3125. I shot it a lot, but never in a mad minute type stage. It still shot .5moa at 2500 or 2600rds, but speed had dropped to 3000fps.
I really like 243ai, fireform loads in 2 barrels were 105/107 class bullets at 3050 and 3090, shot in the .3-.4 range. Full power loads were 3175, in a tikka, saving barrel life and cost to rebarrel. The other was in a remage, ran it at 3320 fps with hybrids. That criterion would shoot in the .1-.2s and has several 2-3" groups at 800, still going good at 1200rds, but has slowed to 3190. I've got a tl3 with a 243 7.5tw, it hammers 110smk at 3090, when barrel is toast it will be a 243ai. Keep loads at 3150 area, never trim brass and should be easier on throat with its 40° shoulders, plus 243ai look badass.

6brshooter, This might be an ignorant question... I’m Looking for the most accuracy from my 6mm Creedmoor Ruger Precision Rifle. What do you and others figure is an expected gain in accuracy from rebarrel with a Criterion, Patriot Valley, LRI, Hawk Hill or other first cabin barrel? Or is there any improvement?

 

[mattwaage1]

Holy back from the dead

 

[6brshooter]

I had a 6creed rpr, just to try the rpr and 6creed. Factory barrel was so-so, it shot some .5" groups during load development, but after that 5/8-3/4 would be more realistic ave. I replaced factory barrel with a criterion prefit from brownells. After load work, I could get 105 hybrids or 107smk to shoot in the .3s. The criterion was faster by 100fps/same charge weight, than for rpr factory pipe. It also cleaned easier. I sold that rifle because it didn't do anything my 243 or 243ai couldn't do better. I'm also not a fan of how chassis feel.

 

[ilmonster]

Would simply downloading a .243 or 6mm Creedmoor with a powder like H4895 to 6mmBR levels get you 6mmBR performance from a case that feeds reliably? Hodgdon's website says you can use H4895 down to 60% of max charges safely. So if you're shooting a .243 with 107 gr. Sierra's, 60% of max. charge of 32.5 gr. would be 19.5 gr. You could certainly get a load around 30 gr. which is what a 6mmBR might use.

 

[6brshooter]

The problem with 60% case fill is that the es/ sd will probably be ugly.

 

[ilmonster]

That certainly makes sense at 20 gr. of H4895, but do you think the ES/SD would be too high if one downloaded to 80% - 90% of max, say 30.0 gr. would give around 2,600 fps extrapolating from Hodgdon's website? That would strike me as a very 6mmBR type load that I would imagine would give good barrel life, good velocity to 600yds, low recoil and reliable feeding in a 6mm CM.

 

[6brshooter]

6br feeds fine, if you want 6br performance just get a 6br. The case size/shape is what makes 6br stupid accurate, not 2850fps. If you want speed, than do a 243/6creed, if you want crazy accuracy then do a 6br. 6x47 would be a good compromise.

 

[6brshooter]

I would actually look at slower powder in the 243 than h4895. I load 40.8 gr of h4895 with 70gr varmint bullets for 3450fps from a 20" barrel. I would try h4831sc or h1000 in a 243 for sub 3000fps. I used to use 43.0gr h4831sc in a 243 with 105s, it ran 2998fps in 28", that was 10 or 12 yrs ago. That slow powder would fill ur case and be more like 2950ish in a 24-26" barrel.

 

[DGD6MM]

My .243 28" Criterion started at 3153 with H1000. Now after 1200 rounds it's down to 3130fps. Waiting on a 7.5 twist Criterion 6Br prefit now.