Ok boys. I am 850 rounds into my last build competition rifle. I knew the risk of running a fast 6mm but this is crazy. This barrel has curbed 200 fps in the last month. I built the gun with a Rock Creek barrel, rem vmt countour, stainless. I have only run 115 DTAC coated bullets. Ran Tubbs TMS bullets through every 200 rounds. The barrel shot awesome and still does but I have gone from 3050 fps to 2850. Load is 42.2 H4350. I have been running 41.2 for about half of the barrel life because of a speed limit on a match I shot last fall. Is there a secret? Other than fit three barrels at a time? Chrome moly or button cut maybe? Any smiths have any insight?
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Gunsmithing What is the secret to making a 243 barrel last
- Thread starter 2Shots
- Start date
The only way to make a 243 Win barrel last is to not shoot it. Not trying to be a smart ass but that is the reality. Some use slow burning powders like H 1000 and it does help. I run a 6mm Competition Match and use H 1000 exclusively and the barrels do last quite a bit longer.
After this, I would look at a new load. If you're going to run H4350 with the 115s, I would try to keep it at or under 3050. If you want to run the 115s faster, try RL-25 and don't believe the hype about "temperature sensitivity". You should easily get 2000 rounds, especially if you go with the 3050 load.
Nobody ever replied to this thread about a chrome moly barrel vs stainless. Or maybe a coated barrel? Has anybody shot a 243 barrel beyond 2000 rounds with good accuracy and velocity? If so give me your barrel specs.
Yes. There have been many who have shot past 2K rounds in the 243. Moon of Crescent Customs had a 243 with over 3k down the tube and it was still a sub moa gun. There's no magic in the barrel as just about any custom will do well. If you're looking for a guarantee you're not going to find it. But those of us that have shot barrels out did so way beyond the 1500 internet number.
Great, I guess. I'm just trying to decide what to do next. Looks like I'm not one of the lucky ones that got that kind of mileage. Thanks for the help.
Turning down the velocity helps a ton. My first barrel I ran the 115dtac with H4350 at 3075fps and barrel was toast in about 1800 rounds. I cut the speed to 2925-2950fps and the second barrel ran over 3000 rounds. The loss in velocity showed a minimal impact on elevation or windage calls and I really cannot say it ever cost me any points at all. If I read the wind well the hits were there, the extra 100fps would not have saved me.
What about salt bath nitrocaburizing ? I dont have any personal experience with it but I have read some positive things. Look Here
http://bulletin.accurateshooter.com...face-treatment-for-barrels-bolts-and-actions/
http://bulletin.accurateshooter.com...face-treatment-for-barrels-bolts-and-actions/
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I probably have half of the rounds through that barrel in that 2940 to 2975 range, not that many pushing the speed limit.
I have 1200 rounds of 105 Amaxs @2970-3000 FPS with H1000 and the throat has barely moved (about .040). The barrel is a Brux 1-8 twist heavy varmint and still shoots sub MOA. This barrel hasn't been treated like a queen either. I usually put 50 rounds through it in about an hour when I shoot it so it gets plenty hot. I'm not saying this is typical but so far the H1000 seems to be a pretty decent .243 powder. Definitely not the fastest load but gets the job done.
6CM here pushing the 115Dtac with H1000 and I am over the 2000 mark now. I believe the key is to keep velocity reasonable and use the slow powders to do it. No reason the barrel cant go 2500-3000 or even more.
2Shots,
Moly bullets, VV N-560 or N-170, no lapping or TMS bullets until 1k rounds down the barrel. Don't shoot more than 20 rounds at a time without letting it cool. Got 2-2.5k rounds through the one I wore out even though it got hot fairly often and velocities were between 2900 and 3150 out of a 30" barrel. I'm willing to let the extra barrel length do the work to get velocity up.
HTH,
DocB
Moly bullets, VV N-560 or N-170, no lapping or TMS bullets until 1k rounds down the barrel. Don't shoot more than 20 rounds at a time without letting it cool. Got 2-2.5k rounds through the one I wore out even though it got hot fairly often and velocities were between 2900 and 3150 out of a 30" barrel. I'm willing to let the extra barrel length do the work to get velocity up.
HTH,
DocB
This can be hard on throats: "Ran Tubbs TMS bullets through every 200 rounds."
^^^this. You don't need to lap the barrel again once you've run it in by shooting it. It's a Rock Creek barrel - which is hand-lapped by Mr Rock and Co before it gets shipped out. All that TMS stuff has done is increase wear. The only time you should use that stuff is in a factory tube that has a bore like 10 miles of bad road..
Next time around, shoot slower powders and maybe look at one of the 6mms with a slightly steeper shoulder angle.
In the meantime, shoot the shit out of it and enjoy the ride
Next time around, shoot slower powders and maybe look at one of the 6mms with a slightly steeper shoulder angle.
In the meantime, shoot the shit out of it and enjoy the ride
Isn't the 30 degree shoulder a 6cm? And what length barrel do you need to burn the slow powders? 28" min?
Sharper shoulder, longer throat, and slower powders are good options.
I'm thinking about a 40 degree version of this, if I can find dies: http://6mmar.com/Super_LR.html
I'm thinking about a 40 degree version of this, if I can find dies: http://6mmar.com/Super_LR.html
Some random thoughts.....stay away from double based powders. They will burn the barrel faster. Moly coated bullets don't do anything to help barrel life. Don't fire lap anything unless the barrel is on it's last legs and or more of a factory barrel that is very rough. Cut rifled barrels on average last a little longer then button rifled. I would lean towards the Melonite treatment helping the barrel to last longer. I got my first Melonited treated barrel on a rifle. Not a lot of rounds thru it at this point (.260rem.) but so far no complaints. I lean towards a c.m. steel barrel lasting longer than a s.s. barrel. The steel can vary from lot to lot. It is possible the steel your barrel was made out of might not be helping you. Hard to tell though. .243win. is a barrel burner. When we do testing here that is the caliber we choose to use. Ammunition makers don't like the round as well. When the test barrels start getting close to the 1000 round mark the test barrels start giving them fits. Pressure becomes erratic and the barrels start to become unreliable as far as the data goes. Longer bearing surface bullets work against barrel life as well. .055" of throat wear in 850 rounds sounds kinda high. Backing off of your loads will help but you give up other stuff.
Best you can do is chase your throat with your seating depth and adjust your loads like was mentioned.
My first across the course match rifle I did in 6mm Rem. Why? It's easier on the barrels then the .243win. With newer rounds out like the 6x47 Lapua, 6XC, 6CM, 6 Creedmoor (which I'm building right now) I feel you have better choices out there than the .243win.
I don't know what barrel length you are running but my 6x47 Lapua (30" palma contour/just sold the rifle) I was getting 3030fps with only 39.0gr. of powder. Even if that barrel was cut down to 26" I bet you I could still hit 2900fps and guess what? I use less powder than the .243win. I would say on average about 10% less. Less powder also means longer barrel life.
Later, Frank
Bartlein Barrels
Best you can do is chase your throat with your seating depth and adjust your loads like was mentioned.
My first across the course match rifle I did in 6mm Rem. Why? It's easier on the barrels then the .243win. With newer rounds out like the 6x47 Lapua, 6XC, 6CM, 6 Creedmoor (which I'm building right now) I feel you have better choices out there than the .243win.
I don't know what barrel length you are running but my 6x47 Lapua (30" palma contour/just sold the rifle) I was getting 3030fps with only 39.0gr. of powder. Even if that barrel was cut down to 26" I bet you I could still hit 2900fps and guess what? I use less powder than the .243win. I would say on average about 10% less. Less powder also means longer barrel life.
Later, Frank
Bartlein Barrels
Thanks Frank, It looks like the 243 is a crap shoot. When compared to my other guns it's a damn laser to shoot, hard to put it down. A friend of mine just built a 6 x 47 and loves it, he is getting the same velocity I was when my barrel was new and using 3 grains less powder, we'll see how long it lasts but it looks promising. I just bumped my oal .040" and am going to see what they do hoping for the best. It kinda irritates me when I call Tubb on the lapping thing and they want you to start firing his throat maintenance bullets right off the get go on a custom barrel. I know next build I will change several things. Hey Frank, got an extra 6mm tube laying around in rem var? I'll do some testing for you!!!?? Just kidding. Thanks for the insight.
When you say burners you mean barrel burners? Or just fast? What kind of barrel life you getting?
Both. Wouldn't agg under .25moa after 1,300 rounds, set the barrel back and got another 700. Running 3,055FPS with Berger 105 Hybrids.
6 Dasher accuracy is hard to beat so I accept the trade-off.
Everybody will think I've been snorting powder or something but I loaded my normal loads .030" longer and test fired at 500 yds. I guess the velocity came back (I never thought load length or jump to lands could make a velocity difference) but my dope went from 2.8mil at 500 to 2.4, where it should be. Is this possible? I have witnesses to this dope. Can a bullet curb that much velocity with .055" of throat wear?
Agreed on the double base powders and H1000 to retumbo. Also next time around try to run with the slowest twist you can get ahold of for the bullet weight you want. Some guys think that helps. Personally I run 7.75tw 5R for everything in my 6mm remington.
Chris
Benchmark Barrels
Chris
Benchmark Barrels
Chamber it to 243AI with the 40 degree shoulder and turn the fps down a notch of two...your reloading anyway...
Sounds like atmospheric conditions more than velocity. Gave you confirmed your speeds with a chronograph, or are you just guessing based off of your come ups on a given day? That would be a very large velocity swing, like 175 FPS.
Frank, you've mirrored exactly what has been my experience with 6x47L.
With 1st barrel, the rifle being bought used with approx 500 rounds through it, with R-17 "double based powder", shot out at 2400 rounds, 115's at 3080 fps.
2cnd barrel with R-17, shot out at 1500 rounds, 115's at 3020 fps- soft steel or ???
3rd barrel, Melonited, H-4831SC, between 2925 and 3000fps-"long story"- .025 throat wear at almost 2300 rounds and shot a .28" 5er at 100Y last time out. Hoping for close to 4000 rounds barrel life and looks like it's possible at this point.
Or scope not tracking correctly. Op did you open up a new jug of H4350 or change primers?
I don't think that's too bad of a trade off with the Dasher and would still consider not a barrel burner. It is does run at crazy high pressures but doesn't really generate that much barrel heat with the 10ish less grains of powder than the 243. I think the standard 6BR has some accuracy lose at 1,300 rounds. I take it your are running straight benchrest comp where you need that sub .25 agg. You must teach me your ways though, I can be holding a brand new tac ops and hope to agg in the .4-.5 range. I need to lay off the caffeine. This is why I stick to Fclass and not the benchrest competition, it is so much more forgiving. IE-Dasher competitive at 2500 rounds at midrange match.
Agreed. I associate barrel life with gas mileage. Your vehicle may do great at 55 mph, but get on the freeway to 70 mph and that last 15 mph really drags down your mileage. RL-25 or H1000 at 3000fps would give up very little to 3050 or 3100fps and save that barrel!
I have to post this on SH every two years, the life of a thread.
1992 Bart Bobbitt's forumula for barrel life
https://groups.google.com/forum/?fromgroups=#!topic/rec.guns/iC-CoKQCeW8
Bart Bobbitt
11/4/92
I finally completed my research on a way to calculate how many rounds
a rifle barrel can be expected to deliver its accuracy level. By that,
I mean the barrel can be expected to have an average group size for
so many rounds before that average group size starts to get larger.
First, the rule-of-thumb formula I derived will produce a barrel accuracy
life of about 3000 rounds.
Second, if a lot of rapid fire (one shot every 5 to 10 seconds) is done,
the accuracy life will be less.
Third, if full-auto or very fast fire (a few shots per second, or one shot
every second) is done, accuracy life will be much less.
Fourth, the accuracy levels are for ranges through 600 yards. Once the
barrel life calculated limit is reached, groups will probably start to
get bigger at the longer ranges before they are noticeably bigger at the
shorter ranges.
My formula, or rule-of-thumb process, is:
1. Calculate the bore area in square millimeters.
2. Use one grain of powder for each square millimeter. This is what
I call the reference, or base powder charge.
Example: .30 caliber bore = 45.6 square millimeters.
Base powder charge for .30 caliber is 45.6 grains.
A .30 cal. cartridge that burns 45.6 grains of powder should give a
barrel life of about 3000 rounds of good accuracy.
3. If a larger cartridge is used and it burns more powder, the
accuracy life in rounds for that bore size is reduced. The amount
of reduction is determined by
a. Divide the increased charge by the base charge, then square
the answer.
b. Divide that answer into 3000.
Example: .28 caliber bore has a base charge of 38.5 grains.
Cartridge burns 57.8 grains of powder.
(57.8/38.5) squared is 2.25.
3000 divided by 2.25 is 1,333 rounds.
If anyone can shoot a hole through this theory, I welcome that shot. This
is more or less an emperical process based on accurate barrel life in
several calibers as reported to me by lots of folks. All I did was study
the data and determine what math would give a best-fit formula.
And if someone has a better method, I'd like to know what it is. My
formulas may not be the best.
1992 Bart Bobbitt's forumula for barrel life
https://groups.google.com/forum/?fromgroups=#!topic/rec.guns/iC-CoKQCeW8
Bart Bobbitt
11/4/92
I finally completed my research on a way to calculate how many rounds
a rifle barrel can be expected to deliver its accuracy level. By that,
I mean the barrel can be expected to have an average group size for
so many rounds before that average group size starts to get larger.
First, the rule-of-thumb formula I derived will produce a barrel accuracy
life of about 3000 rounds.
Second, if a lot of rapid fire (one shot every 5 to 10 seconds) is done,
the accuracy life will be less.
Third, if full-auto or very fast fire (a few shots per second, or one shot
every second) is done, accuracy life will be much less.
Fourth, the accuracy levels are for ranges through 600 yards. Once the
barrel life calculated limit is reached, groups will probably start to
get bigger at the longer ranges before they are noticeably bigger at the
shorter ranges.
My formula, or rule-of-thumb process, is:
1. Calculate the bore area in square millimeters.
2. Use one grain of powder for each square millimeter. This is what
I call the reference, or base powder charge.
Example: .30 caliber bore = 45.6 square millimeters.
Base powder charge for .30 caliber is 45.6 grains.
A .30 cal. cartridge that burns 45.6 grains of powder should give a
barrel life of about 3000 rounds of good accuracy.
3. If a larger cartridge is used and it burns more powder, the
accuracy life in rounds for that bore size is reduced. The amount
of reduction is determined by
a. Divide the increased charge by the base charge, then square
the answer.
b. Divide that answer into 3000.
Example: .28 caliber bore has a base charge of 38.5 grains.
Cartridge burns 57.8 grains of powder.
(57.8/38.5) squared is 2.25.
3000 divided by 2.25 is 1,333 rounds.
If anyone can shoot a hole through this theory, I welcome that shot. This
is more or less an emperical process based on accurate barrel life in
several calibers as reported to me by lots of folks. All I did was study
the data and determine what math would give a best-fit formula.
And if someone has a better method, I'd like to know what it is. My
formulas may not be the best.
All these powders mentioned have a high flame temperature. BALL POWDER(R) Propellant has a much lower average flame temperature, and as such, gas cutting and bore erosion are much less. I used to compete with VV powders with my 6mm BR, and my barrel life was around 1200 rounds. I switched to 748. My accuracy was 2" or better at 300 meters, and my barrel now has over 1500 rounds on it. Showing no signs of giving up. I have not shot the 6 BR in a few years, but I'm thinking of trying 2000 MR and CFE223 in it. If I still had a 243, I'd definitely try either CFE223 or 2000 MR. When I try these powders, I'll be looking for a full case, at max pressure.
I just saw this last post, thanks guys for all this data. I will definately change some things on the next barrel, slower powders, longer length maybe melonite. Thanks
Damn, this sure is making me think... I've been running RE 17 in my 6XC almost exclusively at around 3100 fps. 27" 7.5 twist Bartlein, coated 115 DTAC's. I've only have to chase the lands .010" after 650 rds, but now I'm thinking of maybe switching back to H4350 and giving up the extra 120 fps? Are double based powders really that bad on barrel life? Can someone give me some more info on that? I would hate to stop shooting my RE 17, but if I'm gonna gain 30% more barrel life I think the trade off would be worth it. Anybody had good barrel life numbers with RE 17 or any other double based powder?
1. Presently building an AR10 in 243 just for fun.
2. Haven't ever competed; never will.
3. What are you guys in this thread calling "shot out"? Would a barrel that would be "shot out" for competition last a good many more rounds for a recreational shooter? How many, given conservative loading with slow, single base powders?
4. Once again, using conservative handloading, would a 243AI last significantly longer?
5. Of note, I have never "dumped a mag", and never will unless a T-Rex is hot on my heels...
Thanks for advise/info. I've never had a 243 before, but always wanted one, so I'm excited about this build!
Vettepilot
2. Haven't ever competed; never will.
3. What are you guys in this thread calling "shot out"? Would a barrel that would be "shot out" for competition last a good many more rounds for a recreational shooter? How many, given conservative loading with slow, single base powders?
4. Once again, using conservative handloading, would a 243AI last significantly longer?
5. Of note, I have never "dumped a mag", and never will unless a T-Rex is hot on my heels...
Thanks for advise/info. I've never had a 243 before, but always wanted one, so I'm excited about this build!
Vettepilot
Sounds like a cool project and the .243 is a nice cartridge. Great all-around round for everything from varmints to deer. And a nice shooter....
But realistically, one of the early posts said "Best answer is to not shoot it..." But this is not what you are looking to hear and not the point of building a cool rifle!
If you are looking for a gun to shoot recreationally, the .243 will last a long time. I have a Pre-64 Model 70 featherweight in .243 that is now about 70 years old... and is perfect. Shoots great. I bet that in hunting and sighting-in for decades.... it hasn't seen more than 500 factory Win/Rem/Fed hunting rounds through it. It will probably last forever! It shoots minute of deer every time... I don't even know what it groups. It groups minute of white-tail.
If your thoughts are to build a .243 that you are going to shoot 300 - 400 round recreationally every month or so (which is not unreasonable for a fun range gun) then your barrel isn't going to last more than a few years or even months. But what does that matter? It's an AR-10. Changing barrels is not hard, nor does it damage the value like, say, changing out a pre-64 barrel.
So instead of trying to conservatively load and take away from the whole purpose of an awesome cartridge... why not order 2 -3 extra barrels with your AR-10 and be ready to swap them out when they wear out. AR-10 barrels are not bank breakers. So get a couple of extra barrels made and fitted when you do your build and then shoot the cartridge to its potential!
Sounds like a cool build. And don't let the necrothread thing bother you. It's only un-cool when people do it with stupid questions or to bump a post count. And this is an intriguing set of questions and interesting sounding project! Go for it!
Cheers,
Sirhr
Thanks for the response and info. Just to build something different, I bought a Boyd's laminated stock for it, along with numerous other goodies. I have a BCA 22" barrel for it, (guaranteed 1 MOA or better, and I've had good luck with their barrels). I paid 260$ for that a month ago, and now the price is up to almost 400$!!!
That's pricey for a "play gun" barrel from my personal financial perspective, but you are quite right; it would really take away from the fun factor to down-load it. That's not why I chose a 243!
As far as "necro-threads", on the opposite side, when you create a new thread, everyone says, "This has been discussed many times, do a dam search!!"
Vettepilot
That's pricey for a "play gun" barrel from my personal financial perspective, but you are quite right; it would really take away from the fun factor to down-load it. That's not why I chose a 243!
As far as "necro-threads", on the opposite side, when you create a new thread, everyone says, "This has been discussed many times, do a dam search!!"
Vettepilot
A 115 at 3050 is asking a lot I think. 4350 I suppose that as well.
my last 8tw.25” 243 barrel got pulled at 15-1600rds. All with 105’s at 3030 with H4831. Still 25 minutes to 1000 at sea level, 80 degrees. Did not throw that barrel out. Just changed it.
my last 8tw.25” 243 barrel got pulled at 15-1600rds. All with 105’s at 3030 with H4831. Still 25 minutes to 1000 at sea level, 80 degrees. Did not throw that barrel out. Just changed it.
