6mm br 100-108 gr bullet. long guns are 2900-3200 fps i think. what is the barrel life if you do not over heat it? now for the same barrel but only 15" and same bullet but only 2300 fps what would the barrel life be? # of rds it will shoot before group starts to open up fron it's 1/2 " thanks
barrel life
- Thread starter 686
- Start date
Way too many variables ( and "I think" type questions) for a fixed number type answer. Keep an accurate record of number of rounds fired, load combinations, etc., get a "Hawkeye" borescope, and you can watch the life of the barrel as it really progresses, then your answer will be based on fact, not on conjecture. I can relate from personal experience my barrels had to be replaced at: 1450 rds. with several 243 chamberings. 2350 rds. with several 22-250's. 3500 to 4000 with several 223's. A 204 Ruger (Hart) showed the beginning of some serious fire-cracking at 550 rds. A Shilen 6BR looks as new with 1020 rds. fired. And I could go on and on. My numbers are based on keeping accurate barrel counts and using my "Hawkeye". Some will claim and get a higher round count, but that may depend on their willingness to accept an occassional flyer from an otherwise excellent group of 5, and the heavier copper fouling (and cleaning required), both indications of a barrel nearing the "end-of-life". Just my experience with record keeping and using my "Hawkeye". Additional note: Am in the process of replacing a shot-out 6ppc barrel, as "we speak", that has 2410 rds. fired. Groups opening up & no longer competitive, and more difficult copper removal. Just another example. 
Alf hit the nail on the head!
Hey Frank,
I'd call it 1200-1500 rounds at best, based on the 1/2 MOA figure mentioned earlier. That's about the point that I expected to see accuracy drop off with SMK 107s from our test barrels, and I was actually running loads a bit slower than those cited here. The problem here isn't so much one of capacity or speed, but bullet weight; heavier bullets wash out throats faster than do the lighter bullets at higher velocities.
Another thing to consider here is what's required of the rifle itself. In my testing, when a rifle wouldn't hold .5 MOA consistently, each and every ten-round group, it wasn't worth my keeping it around any longer. If the standards are opened up to an inch, obviously, barrel life will be "better" simply because the rifle is still capable of meeting that specification. All a matter of what's required by the shooter in question.
Kevin Thomas
Lapua USA
I'd call it 1200-1500 rounds at best, based on the 1/2 MOA figure mentioned earlier. That's about the point that I expected to see accuracy drop off with SMK 107s from our test barrels, and I was actually running loads a bit slower than those cited here. The problem here isn't so much one of capacity or speed, but bullet weight; heavier bullets wash out throats faster than do the lighter bullets at higher velocities.
Another thing to consider here is what's required of the rifle itself. In my testing, when a rifle wouldn't hold .5 MOA consistently, each and every ten-round group, it wasn't worth my keeping it around any longer. If the standards are opened up to an inch, obviously, barrel life will be "better" simply because the rifle is still capable of meeting that specification. All a matter of what's required by the shooter in question.
Kevin Thomas
Lapua USA
Kevin: Great, first hand info from someone who has the "hands-on" experience. Your statement about heavy weight bullets washing out a throat faster than lightweight is the main reason I'm using the 95 gr. Berger VLD, and Sierra 95 gr. #1537 as my maximum weights for 500 yd, my limits on distance, dictated by range availability within a reasonable driving distance. They both get the job done, so why use anything heavier? Same holds true for my other ctgs. as well. Still keep a copy of your PS article "17224 Rounds---", and enjoy re-reading it. Thanks for sharing.
Kevin,
I'll bow to your experience with testing at Sierra Bullets, but that figure surprised (not to say worried!) me. My 6mm BR Norma has racked up just over 2,000 rounds (Border Barrels 1-8" twist four-groove cut rifled) and still performs, although whether it is losing its edge is maybe an issue.
That 2,000 total covers a lot of bullet weights from 55gn to 108gn, although it's mostly 105s in competition, and I've backed my match load off quite a lot in recent times so I'm only seeing 2,730 fps out of a 28" barrel, so the pressures will be very moderate.
Anyway, I have a winter 600yd BR season with 105s and several hundred test rounds with 55-85gn varmint rounds to go with this barrel and we'll see if I 'get away with it'.
The question then, is what to rebarrel it with, which looks like it may be a little sooner than I'd been thinking before I read your post. Straight 6BR? 6BRX? 6 Dasher? - but that's another subject for another thread!
Laurie,
York, England
My 6BR Krieger was never a great barrel, But, I noticed duplex grouping at about 2,500 rounds. Many NRA Prone shooters go 3500 or so before changing barrels and use 105-108's. Mine has some erosian patches on the center of the lands and in the middle of the groves. The all the edges look good, I'm going to put some TMS bullets down it and see if that helps.
Mike
Mike
Laurie,
please bear in mind that that was for that particular application, and it was strictly a business approach to accuracy. When I started getting the occasional flyers that blew an otherwise 1/2 MOA group, that was a real problem for me. Since everything was fired via machine rest, I saw these things pretty plainly, without the doubts of human element thrown in. There was also a steady que of guys lined up drooling over my "scrap" barrels. Many of those went on to live long, happy lives as hunting or varmint barrels in their "retirement afterlife" of being test barrels. It's all a matter of standards.
That said, I'll tell you that Marksmen's and Sharpshooter's barrels last far longer than those of High Masters. Nothing to do with the barrels themselves, just that the High Masters will much more quickly toss a barrel when things aren't "on call." I've seen Mid Tompkins and David Tubb both fire shots that came up on target somewhere other than where they called them. They both have the confidence in their own shooting ability to call a flyer when it happens. Lower levels of shooter will heistate, and blame or question their shooting, and hence hang on to a barrel a lot longer. I've heard lots of guys talking about 7-8,000 round barrel life out of an M1A, and that's fine. I wouldn't use a barrel with anywhere near that many rounds through it, but if they're happy with it, that's their business, more power to 'em. In the end, it really is a personal call.
Hope that helps clarify this a bit,
Sincerely,
Kevin Thomas
Lapua USA
please bear in mind that that was for that particular application, and it was strictly a business approach to accuracy. When I started getting the occasional flyers that blew an otherwise 1/2 MOA group, that was a real problem for me. Since everything was fired via machine rest, I saw these things pretty plainly, without the doubts of human element thrown in. There was also a steady que of guys lined up drooling over my "scrap" barrels. Many of those went on to live long, happy lives as hunting or varmint barrels in their "retirement afterlife" of being test barrels. It's all a matter of standards.
That said, I'll tell you that Marksmen's and Sharpshooter's barrels last far longer than those of High Masters. Nothing to do with the barrels themselves, just that the High Masters will much more quickly toss a barrel when things aren't "on call." I've seen Mid Tompkins and David Tubb both fire shots that came up on target somewhere other than where they called them. They both have the confidence in their own shooting ability to call a flyer when it happens. Lower levels of shooter will heistate, and blame or question their shooting, and hence hang on to a barrel a lot longer. I've heard lots of guys talking about 7-8,000 round barrel life out of an M1A, and that's fine. I wouldn't use a barrel with anywhere near that many rounds through it, but if they're happy with it, that's their business, more power to 'em. In the end, it really is a personal call.
Hope that helps clarify this a bit,
Sincerely,
Kevin Thomas
Lapua USA
Kevin,
thanks for the update. I'll be looking to rebarrel this rifle during 2010 in any event. As I said, the question is: "To what?" - almost certainly a member of the 6BR 'family' again, as it is such a good little number, and so well suited to 600yd precision shooting.
I have another 'six' being built, a 6XC 'Light Gun' which will be throated for your 'old' 107s. The word is 6XC barrels 'die' dramatically at the 2,000 round mark, so I imagine performance drops off well below that, so I'll have to be rather more sparing in the use I put this rifle to!
Bests wishes from [Old] York,
Laurie
thanks for the update. I'll be looking to rebarrel this rifle during 2010 in any event. As I said, the question is: "To what?" - almost certainly a member of the 6BR 'family' again, as it is such a good little number, and so well suited to 600yd precision shooting.
I have another 'six' being built, a 6XC 'Light Gun' which will be throated for your 'old' 107s. The word is 6XC barrels 'die' dramatically at the 2,000 round mark, so I imagine performance drops off well below that, so I'll have to be rather more sparing in the use I put this rifle to!
Bests wishes from [Old] York,
Laurie
Octopus
NRA Instructor NRA CRSO NRA RSO
How long does a barrel last? Why are some calibers better than others?
These questions have a lot of answers. And, not all the answers agree. The 264 Win Mag is know as a “barrel burner”. Back in the early 60s there were many stories about barrels being “shot-out” with 500 or less rounds. On the other side there were stories about the 218 Bee and 222 with barrels that last forever. The following are the observations of several shooter that I have noted over many years of shooting.
These items result in shorter barrel life:
1. Burn more powder
2. Big case capacity with smaller diameter bullet
3. The heavier the bullet the faster the barrel washes out
4. Use slower burning powders
5. Very high velocity (Usually goes along with the three items above)
6. Very high pressures
7. Rapid fire
8. Hot barrels
Today with the new powders and better quality barrels there are still issues about barrel life and “barrel burner cartages. How long a barrel last depends a lot on what you expect in the way of accuracy. If you happy with 1” @100 yards say 1.0 MOA, barrels last a long time. If you except “hunter accuracy about 3” @ 100 yards barrel life is not usually an issue. Hunting rifle barrels usually go bad from rust, i.e. the lack of cleaning and oiling. But, if you expect precision and demand the very best in the way of accuracy barrel life is a big issue.
My standards are: (@100 yards from stable bench 5 shot group aggs.)
Benchrest Competition Rifles 0.100
Benchrest Practice Rifles 0.200
Live Varmint Field Rifles 0.375
Long Range Hunting Rifles 0.500
Hunting Rifles 1.000
Muzzle Loaders 2.000
If a rifle (Barrel) does not meet these standards it will not find a home in my safe unless it is very old.
I have experienced some powders produce more heat into the barrel than others. For example the IMR powders heat the barrel more than the VV single base powders for the same velocity shot. I do not think this makes much difference overall.
Barrel life is very dependant on one’s accuracy requirement. I want my BR barrels to agg 0.100 or better but I tend to live with a larger agg. At 0.250 the barrel is done by all BR standards but would still be very acceptable for P dogs and other shooting sports. The differences in acceptable accuracy confuses the issue of barrel life reports.
I think there is a slight barrel life advantage shooting moly bullets. I also think the single point cut barrels last a little longer. How well the barrel is cleaned makes a big difference. Barrels that are kept clean seem to last longer. Some cleaning techniques can shorten barrel life. (I use only JP bore paste and Koil. I never use a metal brush or any harsh chemical cleaners in any of my BR barrels. I bore scope my barrels very often. My cleaning procedures are based on the bore scope and what works for accuracy. There are chemical cleaning procedures that work fine and do not damage the barrels. As long as a workable cleaning procedure is use this should not have a significant impact on barrel life. Corrosion is a barrel killer.
My recorded experience is a follows:
222 1 barrel SST 1-14 Agg std 0.200 over 10,000 rounds and still shooting. Last forever I guess.
243 1 barrel CM 1-10 Agg std 0.750 Under 2,000 rounds Failure throat and lands erosion
25-06 2 barrels SST 1-10 Agg std 0.375 2,000 to 2,500 rounds Failure throat and lands erosion
30-06 2 barrels CM 1-10 Agg std 0.75 2,000 + rounds Failure corrosion pits near the muzzle. FL humidly.
308 1 barrel CM 1-10 Agg std 0.50 2,000 + rounds Failure throat and lands erosion.
6BR 1 barrel SST 1-14 Agg std 0.200 1,800 to 2,200 rounds Failure throat and lands erosion
6PPC 2 barrels SST 1-14 Agg std 0.200 2,000 to 2,200 rounds Failure throat and lands erosion
I would very much appreciate any knowledge and data that you can add to this subject.
To make the data more usable please always include the acceptable accuracy standard.
For the Agg I use the average of five shot groups. My experience is when the barrels start to go by throat erosion the bullet has to be set almost out of the case to reach the lands. Flyers start to show up. When there are pits in the barrel near the muzzle, usually caused by my poor care, the barrel will group for only three to five shots after cleaning then it opens ups. (As a point of reference the majority of all the rifle barrels I have inspected at gun shows with the bore scope had corrosion pits within five inches of the muzzle.)
My experiences with 22-250 and 25-06 are these calibers burn the barrels out of acceptable accuracy in about 2,000 rounds shooting a mix of 75% below velocity rounds and 25% maximum velocity rounds. The more powder you burn the shorter the barrel life. The barrel is usually best from 300-800 rounds down the tube.
A long range shooter using a 6.5 X 284 shooting slow burning powders and heavy VLD bullets may only get 700 to 1,000 rounds before the barrel’s accuracy drops off. Shooting rapid fire with a hot barrel does shorten barrel life. Shooting the same rifle and load slow where the barrel never gets hot will make the barrel last longer. 1.5 times or more longer. And there is a difference in powders. Some brands of powders burn barrel throats faster than others. If you take the 6.5 X 284 and shoot it for fun keeping the barrel cool using lighter bullets and only shot max velocity loads when needed the barrels will last over 2,000 rounds and still hold accuracy.
The 218 Bee and the 222 barrels will shoot almost forever. These barrels use little powder per shot and rarely get very warm. My friend Capt. Bob’s Ugly Gun with a 222 tight neck barrel has over 20,000 rounds down the tube that we have counted. And the gun and barrel was used when he got it. We think this is a Douglas barrel. It will still shoot aggs under 0.200 and sometimes better.
The Savage factory stainless steel 223 target barrels are quite good. I have seen two of these shoot below 0.500 all the time, below 0.375 some of the time and even better once and a while. These barrel seem to hold hunter accuracy for 4,000 shots or more. But they usually open up after 2,000 rounds or so. For the price the Savage rifles and barrels are a good value.
Some shooters say barrels with single point cut rifling last longer, I think there is some truth to this.
It is important to understand that one must be shooting off a very stable bench, with a very stable 20-40 power scope, a tuned or custom rifle and a very light trigger to obtain the higher levels of accuracy. The bench and the rest gear must be benchrest quality. Most days at least 4 wind flags are needed for 100 yard shooting.
Calibers such as the 6.5X55 and 308 will often go over 4,000 rounds if the right powders and primes are used and if they are not loaded to hot. The 30 BR will go several thousand rounds and still hold precision.
Calibers such as the 220 Swift, 243, 7 mm Rem Ultra Mag and 300 Win Mag will have shorter barrel life. These cases hold more powder and have smaller neck diameters, which focuses the heat in a smaller area, which makes it more intense. Kind of like the difference between a cigarette lighter flame and a miniature torch flame. They both have a flame but the torch is focus with higher temperature and more heat energy.
The first thing to go in a barrel is usually the throat area and the first few inches in front of the throat. This area can burn out fast. However, accuracy will often hold good when the throat area looks gone. A lot depends on your demand for accuracy.
As said by others smarter than I: “The process most responsible for eating away the steel in the throat is called ablation. Ablation is actual vaporization of the steel from heat as opposed to abrasion, which could be likened to "sandblasting". Much of the talk about sandblasting, abrasion, shoulder angles VS neck length (Turbulence Point Theory) etc is subject to question. Ablation is the result of hot gas impinging upon the steel surface for a sufficient time to melt some steel and carry it away. This is exacerbated by slow-burning powders coupled with large chambers and long barrels. Longer barrels hold the heat and the pressure longer.
Some powders burn hotter that others. Some knowledgeable people feel the "hotter" powder is lesser important than the duration of the event. Keep the heat concentrated on the steel's surface LONGER and you get more heat transfer and gasification of the steel.
These are know to be true:
• Using MORE powder, burning hotter over a LONGER period of time will always decrease barrel life.
• Rapid fire heats the barrel more and barrel burn is much faster.
• Keep your barrel cool and it last longer.
Most of the new calibers have came about not because they are need but because new calibers sell new guns. Look at the Ultra Mag series. Most of all the new calibers have an over bore powder capacity. That is the volume of the case is greater than is needed for the bore diameter. Accuracy does not sell rifles. Velocity sales rifles. When you loose sight of direction make up for it with speed.
Calibers with over bore capacity use lots more powder to gain only slightly more velocity. Recoil and muzzle blast noise go up faster than velocity.
With today’s new and better powders the 308 case has more capacity than needed for the 30 caliber bore. I have yet to see any of the 300 Mags, Ultra Mags or Short Mags better the tested and proven 308 at short or medium ranges. 200 fps never replaces bullet placement.
With today’s powders and premium bullets the Benchrest cases are making a come back. The 6 MM BR is a short version of the 243. It has and continues to win matches out to 1,000 yards. When you shoot a match lots of shots are fired. Recoil is a real issue as is barrel life. The 6 BR betters the 243 in regards to accuracy, recoil, barrel life and is very close in velocity.
For most calibers there is a wildcat version called the Ackley Improved, i.e. the 243 AI, the 25-06 AI and etc. These are the same as the original with the case shoulder mover forward, shorter neck and steeper neck angle. Usually the AI version will produce 200 fps more velocity. The AI versions with the steeper shoulder angles seem to have about the same barrel life. But accuracy is usually slightly less. This may be due to the shorter neck lengths, which make neck tension more difficult to keep constant.
Keeping the barrel clean and oiled is critical to barrel life. Lack of oil will kill a barrel over time. Barrels do not shoot good with rust and pits in the bore. Calibers with larger powder capacity seem to be more subject to rust and pitting damage. Barrels need to be cleaned from the chamber end and not the muzzle. Cleaning from the muzzle with out a muzzle guide will damage the bore and the muzzle.
These questions have a lot of answers. And, not all the answers agree. The 264 Win Mag is know as a “barrel burner”. Back in the early 60s there were many stories about barrels being “shot-out” with 500 or less rounds. On the other side there were stories about the 218 Bee and 222 with barrels that last forever. The following are the observations of several shooter that I have noted over many years of shooting.
These items result in shorter barrel life:
1. Burn more powder
2. Big case capacity with smaller diameter bullet
3. The heavier the bullet the faster the barrel washes out
4. Use slower burning powders
5. Very high velocity (Usually goes along with the three items above)
6. Very high pressures
7. Rapid fire
8. Hot barrels
Today with the new powders and better quality barrels there are still issues about barrel life and “barrel burner cartages. How long a barrel last depends a lot on what you expect in the way of accuracy. If you happy with 1” @100 yards say 1.0 MOA, barrels last a long time. If you except “hunter accuracy about 3” @ 100 yards barrel life is not usually an issue. Hunting rifle barrels usually go bad from rust, i.e. the lack of cleaning and oiling. But, if you expect precision and demand the very best in the way of accuracy barrel life is a big issue.
My standards are: (@100 yards from stable bench 5 shot group aggs.)
Benchrest Competition Rifles 0.100
Benchrest Practice Rifles 0.200
Live Varmint Field Rifles 0.375
Long Range Hunting Rifles 0.500
Hunting Rifles 1.000
Muzzle Loaders 2.000
If a rifle (Barrel) does not meet these standards it will not find a home in my safe unless it is very old.
I have experienced some powders produce more heat into the barrel than others. For example the IMR powders heat the barrel more than the VV single base powders for the same velocity shot. I do not think this makes much difference overall.
Barrel life is very dependant on one’s accuracy requirement. I want my BR barrels to agg 0.100 or better but I tend to live with a larger agg. At 0.250 the barrel is done by all BR standards but would still be very acceptable for P dogs and other shooting sports. The differences in acceptable accuracy confuses the issue of barrel life reports.
I think there is a slight barrel life advantage shooting moly bullets. I also think the single point cut barrels last a little longer. How well the barrel is cleaned makes a big difference. Barrels that are kept clean seem to last longer. Some cleaning techniques can shorten barrel life. (I use only JP bore paste and Koil. I never use a metal brush or any harsh chemical cleaners in any of my BR barrels. I bore scope my barrels very often. My cleaning procedures are based on the bore scope and what works for accuracy. There are chemical cleaning procedures that work fine and do not damage the barrels. As long as a workable cleaning procedure is use this should not have a significant impact on barrel life. Corrosion is a barrel killer.
My recorded experience is a follows:
222 1 barrel SST 1-14 Agg std 0.200 over 10,000 rounds and still shooting. Last forever I guess.
243 1 barrel CM 1-10 Agg std 0.750 Under 2,000 rounds Failure throat and lands erosion
25-06 2 barrels SST 1-10 Agg std 0.375 2,000 to 2,500 rounds Failure throat and lands erosion
30-06 2 barrels CM 1-10 Agg std 0.75 2,000 + rounds Failure corrosion pits near the muzzle. FL humidly.
308 1 barrel CM 1-10 Agg std 0.50 2,000 + rounds Failure throat and lands erosion.
6BR 1 barrel SST 1-14 Agg std 0.200 1,800 to 2,200 rounds Failure throat and lands erosion
6PPC 2 barrels SST 1-14 Agg std 0.200 2,000 to 2,200 rounds Failure throat and lands erosion
I would very much appreciate any knowledge and data that you can add to this subject.
To make the data more usable please always include the acceptable accuracy standard.
For the Agg I use the average of five shot groups. My experience is when the barrels start to go by throat erosion the bullet has to be set almost out of the case to reach the lands. Flyers start to show up. When there are pits in the barrel near the muzzle, usually caused by my poor care, the barrel will group for only three to five shots after cleaning then it opens ups. (As a point of reference the majority of all the rifle barrels I have inspected at gun shows with the bore scope had corrosion pits within five inches of the muzzle.)
My experiences with 22-250 and 25-06 are these calibers burn the barrels out of acceptable accuracy in about 2,000 rounds shooting a mix of 75% below velocity rounds and 25% maximum velocity rounds. The more powder you burn the shorter the barrel life. The barrel is usually best from 300-800 rounds down the tube.
A long range shooter using a 6.5 X 284 shooting slow burning powders and heavy VLD bullets may only get 700 to 1,000 rounds before the barrel’s accuracy drops off. Shooting rapid fire with a hot barrel does shorten barrel life. Shooting the same rifle and load slow where the barrel never gets hot will make the barrel last longer. 1.5 times or more longer. And there is a difference in powders. Some brands of powders burn barrel throats faster than others. If you take the 6.5 X 284 and shoot it for fun keeping the barrel cool using lighter bullets and only shot max velocity loads when needed the barrels will last over 2,000 rounds and still hold accuracy.
The 218 Bee and the 222 barrels will shoot almost forever. These barrels use little powder per shot and rarely get very warm. My friend Capt. Bob’s Ugly Gun with a 222 tight neck barrel has over 20,000 rounds down the tube that we have counted. And the gun and barrel was used when he got it. We think this is a Douglas barrel. It will still shoot aggs under 0.200 and sometimes better.
The Savage factory stainless steel 223 target barrels are quite good. I have seen two of these shoot below 0.500 all the time, below 0.375 some of the time and even better once and a while. These barrel seem to hold hunter accuracy for 4,000 shots or more. But they usually open up after 2,000 rounds or so. For the price the Savage rifles and barrels are a good value.
Some shooters say barrels with single point cut rifling last longer, I think there is some truth to this.
It is important to understand that one must be shooting off a very stable bench, with a very stable 20-40 power scope, a tuned or custom rifle and a very light trigger to obtain the higher levels of accuracy. The bench and the rest gear must be benchrest quality. Most days at least 4 wind flags are needed for 100 yard shooting.
Calibers such as the 6.5X55 and 308 will often go over 4,000 rounds if the right powders and primes are used and if they are not loaded to hot. The 30 BR will go several thousand rounds and still hold precision.
Calibers such as the 220 Swift, 243, 7 mm Rem Ultra Mag and 300 Win Mag will have shorter barrel life. These cases hold more powder and have smaller neck diameters, which focuses the heat in a smaller area, which makes it more intense. Kind of like the difference between a cigarette lighter flame and a miniature torch flame. They both have a flame but the torch is focus with higher temperature and more heat energy.
The first thing to go in a barrel is usually the throat area and the first few inches in front of the throat. This area can burn out fast. However, accuracy will often hold good when the throat area looks gone. A lot depends on your demand for accuracy.
As said by others smarter than I: “The process most responsible for eating away the steel in the throat is called ablation. Ablation is actual vaporization of the steel from heat as opposed to abrasion, which could be likened to "sandblasting". Much of the talk about sandblasting, abrasion, shoulder angles VS neck length (Turbulence Point Theory) etc is subject to question. Ablation is the result of hot gas impinging upon the steel surface for a sufficient time to melt some steel and carry it away. This is exacerbated by slow-burning powders coupled with large chambers and long barrels. Longer barrels hold the heat and the pressure longer.
Some powders burn hotter that others. Some knowledgeable people feel the "hotter" powder is lesser important than the duration of the event. Keep the heat concentrated on the steel's surface LONGER and you get more heat transfer and gasification of the steel.
These are know to be true:
• Using MORE powder, burning hotter over a LONGER period of time will always decrease barrel life.
• Rapid fire heats the barrel more and barrel burn is much faster.
• Keep your barrel cool and it last longer.
Most of the new calibers have came about not because they are need but because new calibers sell new guns. Look at the Ultra Mag series. Most of all the new calibers have an over bore powder capacity. That is the volume of the case is greater than is needed for the bore diameter. Accuracy does not sell rifles. Velocity sales rifles. When you loose sight of direction make up for it with speed.
Calibers with over bore capacity use lots more powder to gain only slightly more velocity. Recoil and muzzle blast noise go up faster than velocity.
With today’s new and better powders the 308 case has more capacity than needed for the 30 caliber bore. I have yet to see any of the 300 Mags, Ultra Mags or Short Mags better the tested and proven 308 at short or medium ranges. 200 fps never replaces bullet placement.
With today’s powders and premium bullets the Benchrest cases are making a come back. The 6 MM BR is a short version of the 243. It has and continues to win matches out to 1,000 yards. When you shoot a match lots of shots are fired. Recoil is a real issue as is barrel life. The 6 BR betters the 243 in regards to accuracy, recoil, barrel life and is very close in velocity.
For most calibers there is a wildcat version called the Ackley Improved, i.e. the 243 AI, the 25-06 AI and etc. These are the same as the original with the case shoulder mover forward, shorter neck and steeper neck angle. Usually the AI version will produce 200 fps more velocity. The AI versions with the steeper shoulder angles seem to have about the same barrel life. But accuracy is usually slightly less. This may be due to the shorter neck lengths, which make neck tension more difficult to keep constant.
Keeping the barrel clean and oiled is critical to barrel life. Lack of oil will kill a barrel over time. Barrels do not shoot good with rust and pits in the bore. Calibers with larger powder capacity seem to be more subject to rust and pitting damage. Barrels need to be cleaned from the chamber end and not the muzzle. Cleaning from the muzzle with out a muzzle guide will damage the bore and the muzzle.
Kevin,
an off-topic question about your Sierra experiences - if you don't object.
When the Sierra relaoding manual recommends its 'Accuracy Load' (and 'Hunting Load' too for that matter), what criteria are these based on?
(I've always assumed 'accuracy' is based on a small velocity / chamber pressure spread, but never seen anybody actually confirm or correct this.)
Thanks,
Laurie
an off-topic question about your Sierra experiences - if you don't object.
When the Sierra relaoding manual recommends its 'Accuracy Load' (and 'Hunting Load' too for that matter), what criteria are these based on?
(I've always assumed 'accuracy' is based on a small velocity / chamber pressure spread, but never seen anybody actually confirm or correct this.)
Thanks,
Laurie
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.