What are the primary factors for short barrel life?

[geo]

Other then my shooting habits and barrel care. What factors affect barrel life? I'm sure heat would be the primary contributor to short barrel life. And this can come from a number of different ways. Like the interval between shots, and the velocity of a round? At what velocity does this become an issue? Does powder charge have an effect?
I can control some of these factors by picking loads that minimize these things but there are limits to what I can do.
I'm not in the market for a rifle right now but if I were looking for a new rifle that I could shoot often and have good barrel life what would I look for? My first guess would be any caliber called a magnum would have a shorter barrel life? But would that always be true?
One more question. What does the term OVERBORE mean?

 

[JD338]

geo

Welcome to the forum.

Heat is enemy number one for short barrel like.
Large amounts of powder in small calibers, known as over bore, will reduce barrel like. It is important to keep the barrel cool when shooting and to also keep it clean and free of fouling will help prolong life of the barrel.

I had a 30-06 that I had shot out the barrel on. The throat was gone and accuracy fell off but I also had over 5000 rounds down the pipe. Some of the over bore rounds may only have a 1500 round like but it is really going to come down to keeping the barrel cool and clean.

JD338

 

[DrMike]

geo,

JD338 is correct in noting that heat is the primary source of throat erosion in a barrel. Some rifles show clear evidence of erosion and degradation of accuracy after as few as 400 rounds (think WSSM that is shot hot and neglected). Overbore cartridges, especially with small bores (think 257 STW, etc.) can be degraded very quickly. I have seen them trashed in as few as 1000 rounds. On the other hand, I have friends who have the precise calibre who have several thousand rounds through it and it still shoots acceptably. They are careful not to engage in rapid fire, and they keep the chamber/bore clean. Recently, I saw a couple of custom rifles chambered for Lazzeroni cartridges that had accuracy degraded and severe throat erosion after less than 400 rounds. It was obvious that the owners had tried to fire multiple rounds very quickly and did not wish to be bothered with cleaning. The cost? A couple of very expensive rifles that were trashed.

 

[Desert Fox]

As JD said, Heat is the number one factor in reducing barrel life. Others factors are secondary. Keep the barrel cool and clean and you'll be able extend that barrel life.

 

[old #7]

Overbore is when you have a very large case compared to the bore.
Lets say you took a 300 rem ultra mag and necked it down to a .223.
All the pressure and heat generated in the case eats the throat as the gasses excape the small neck of the case. The heat and pressure in the case gets restricted at the mouth.

 

[Ridge_Runner]

alot can be done to prolong barrel life, I shoot some pretty overbore cartridges. My 7mm Allen Mag is a monster in the 284 world, all the things mentioned above can help, and so can shooting ball powders, seems though they burn more violently they have a lower flame temp than extruded powders due to the addition of nitrocellulose into they're composition. don't take my word for it make your own test as I did.

In my 7mm STW I normaly run an overmax charge of H-1000 that is 2 gr under pressure signs in my rifle, after 3 shots the barrel is too hot to comfortably hold. MV was 3550 fps

Now at the time the only ball powder on hand was WC872, a very slow ball powder made for the 50 BMG and the 20 MM vulcan cannon.
I worked up a max load (with zero pressure signs) with the WC872 and a 160 gr nosler. fired 3 shots and the barrel was just warm, less heat has to help! The MV for that load was 3340 fps, smoking for a STW/160.

My 7mm AM has 470 rounds downrange and throat erosion is between .002-.003" not bad for a .284 cal that has 122 gr of H2o capacity.
RR

 

[JD338]

geo,

Examples of over bore cartridges are 257 Wby, 264 Win Mag, 7mm STW, 7mm RUM, 300 RUM.
As already noted, keep the barrel cool and clean to obtain maximum barrel life. Its difficult to give an actual number because there are too many varibles. Powder burn rate used, amount of powder, barrel temp, and frequency of cleaning all play a role. I think it is safe to say though that you should be able to get 1500+ rounds out of a over bore caliber before accuracy starts to go away.

JD338

 

[geo]

Thanks for all your replys. I take pride in the care I give my rifles. But I have been doing alot of shooting these days and I would hate to ruin my favorite rifle.
I just started shooting the Nosler 150gr E-Tip in a 280AI and they shoot great.

 

[cloverleaf]

welcome to the fun. More knowlege here already than I can bring to bear. However, I will pass along some wisdom from an Uncle. "Most folks dont shoot a rifle enough in a life time to wear it out...they are usually so fouled its no wonder they wont shoot up to there potential. People get frustrated and sell 'em before they wear them out." Get yourself a can of "Wipe Out", a bore guide and a good coated rod and dont shoot it hot and you may be surprised how long she lasts. Just my .02 CL

ps. The guys on this board will tell you, I have been on the verge of selling my favorite rifle several times in the last few years and it always turs out to be some other factor that is messing with my groups. So little patience and less faith in my equiptment. There is also the "brain to trigger interface" that needs work.

 

[JD338]

I just started shooting the Nosler 150gr E-Tip in a 280AI and they shoot great.

I have tested the 150 gr E-Tip in my 280AI and accuracy was excellent.
http://noslerreloading.com/phpBB2/viewt ... t=7mm+etip

What is your load?

JD338

 

[geo]

I have started with 47 grs of RL17 (recomended by Alliant) and fired 4 set of 3 shot each. After 2 fouling shot the first group was .100 off the land and each set .005 longer. The .95 look good and I will start increasing the powder charge next to see how that effects the groups. I do not know the velocity yet.
Here is a picture from my log. I have only shot at 50 yards. I wish I could say it was at 100 but I can't. I hope I can do some test at a longer range soon. [/img]

Again I wish to say thanks for your feed back.

 

[JD338]

geo,

Good results for sure. If you do not get the velocity you desire, give RL 22 a try. This powder has been exceptional with 140 gr and 160 gr AB's. I am also using Federal GM215M primers,

JD338

 

[woods]

The reason overbore cases like the 264 win mag are noted for burning out barrels is that they work best with very slow powders. The old saying with the 264 is "What powder are you using? It doesn't matter anyway, that's not slow enough!"

So when you use a very slow powder like H870 in an ovebore like the 264 or H1000 in the 257 Wtby then you are busy burning your throat out.

 

[30-338]

I have started with 47 grs of RL17 (recomended by Alliant) and fired 4 set of 3 shot each. After 2 fouling shot the first group was .100 off the land and each set .005 longer. The .95 look good and I will start increasing the powder charge next to see how that effects the groups. I do not know the velocity yet.
Here is a picture from my log. I have only shot at 50 yards. I wish I could say it was at 100 but I can't. I hope I can do some test at a longer range soon.

You had better luck with Alliant than I did. I'm having 280AI build and very interested in using R-17 so I "ASK THE EXPERTS" per their site and here is the answer I got back.

"I can only recommend that you use the standard 280 data as a place to
start. The improved version should allow you to get approx another 3
grs in the case. Work your way up slowly and watch your pressure signs.
Let me know how it works out."

Ben Amonette
Consumer Service Manager
Alliant Powder Company

 

[JD338]

I have started with 47 grs of RL17 (recomended by Alliant) and fired 4 set of 3 shot each. After 2 fouling shot the first group was .100 off the land and each set .005 longer. The .95 look good and I will start increasing the powder charge next to see how that effects the groups. I do not know the velocity yet.
Here is a picture from my log. I have only shot at 50 yards. I wish I could say it was at 100 but I can't. I hope I can do some test at a longer range soon.

You had better luck with Alliant than I did. I'm having 280AI build and very interested in using R-17 so I "ASK THE EXPERTS" per their site and here is the answer I got back.

"I can only recommend that you use the standard 280 data as a place to
start. The improved version should allow you to get approx another 3
grs in the case. Work your way up slowly and watch your pressure signs.
Let me know how it works out."

Ben Amonette
Consumer Service Manager
Alliant Powder Company

Not much of an answer from the experts.

JD338

 

[geo]

I'm getting a good education from you guys. That was an interesting chart Woods. The nice part about reloading is we can pick our components to obtain each of our own objectives. I’m turning 49 and this is the only new rifle I have ever owned. I want to do what I can to make it last.

 

[geo]

I have started with 47 grs of RL17 (recomended by Alliant) and fired 4 set of 3 shot each. After 2 fouling shot the first group was .100 off the land and each set .005 longer. The .95 look good and I will start increasing the powder charge next to see how that effects the groups. I do not know the velocity yet.
Here is a picture from my log. I have only shot at 50 yards. I wish I could say it was at 100 but I can't. I hope I can do some test at a longer range soon.

You had better luck with Alliant than I did. I'm having 280AI build and very interested in using R-17 so I "ASK THE EXPERTS" per their site and here is the answer I got back.

"I can only recommend that you use the standard 280 data as a place to
start. The improved version should allow you to get approx another 3
grs in the case. Work your way up slowly and watch your pressure signs.
Let me know how it works out."

Ben Amonette
Consumer Service Manager
Alliant Powder Company

I hope that after enough request that Alliant will post some test data for the 280AI. I received my reply from the same guy. I’ll paste it here maybe someone could use the info.

“Nosler says the etip bullet require about 2 grs less powder and should be seated from .050 to .100 off the lands. This seems to put the charge wts into the standard 280 Rem area. I suggest you use the data on our website for the 160 gr Speer BTSP. Start with 47 grs and the max should be close to 51 or 52 grs. Thanks for your note and keep me posted.

Ben Amonette
Consumer Service Manager
Alliant Powder Company

 

[wingnut]

Back on subject, please pay close attention to Dr. Ken Howell, gun nut, cartridge designer, long time interior ballistics expert, in the below thread. His answers are contrary to some above.

http://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/48608/1

 

[30-338]

Back on subject, please pay close attention to Dr. Ken Howell, gun nut, cartridge designer, long time interior ballistics expert, in the below thread. His answers are contrary to some above.

http://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/48608/1

I don't disagree but here is a clip from Broughton barrels on the 5C
"***Shooters are reporting more velocity, great accuracy, longer barrel life, reduced bolt pressure and ease in cleanability with the Broughton "5C ®"

The post you found was from 2002 alot has happen in selecting barrel rifling in 8 yrs. Krieger,Bartlein,Rock,Obermeyer,Broungton all make 5r barrels. Broughton first used the 5r on his barrel but forget to get Obermeyer OK so he used 5c (cant) instead and Rock set up Rem for their 5r barrels.

Shilen has a Ratchet twist only (cant) on one side and thats a great barrel. I'm shooting one in 30-06 and I had one on the 30x280AI.

 

[wingnut]

Higher pressures thus higher temps will stress barrel metal more than lower pressures and temps no matter which era the barrel is made. Just a matter of degree (pun intended) with better metallurgy.

Are there any calibrated/scientific data points comparing the newer barrels to older ones. Or, comparing high pressures in 1 5C barrel to another 5C using lower pressures. As you have seen above "shooters" and scientists can differ.