Just looking for help ending a argument that has been going on at the local gun store. From your personal experiance what is the true barrel life of the 300 win mag 300 ultra mag and my beloved 308 winchester. according to some of the wanna be gun guru's that frequent the shop barrel life of the ultra mag should be in the 4500+ range as longe as the gun is not shot hot all the time I disagree also according to this so called know everything fella the barrel life of the 300 win mag is the exact same as the ultra i also disagree but !!!! [img]/ubbthreads/images/graemlins/tongue.gif[/img]
Well I dont know exactly how many rounds are down my 300 RUM, but Its around 600-700. I could tell my accuracy was starting to drop off around 500. It's still not bad accuracy, just not the 1/3MOA factory rifle it was in the beginning. I have heard the barrel life to be around 1000 rounds.
Apparently your "know it all" has been eating bad rice crispies....what's working on maybe his brain! Anytime you start putting vast amounts of powder aka flame and gas through a bore....throat erosion starts right from day one!! The way most shoot the large capacity cases.....FAST....HOT....I'd say that if one were able to sustain accuracy levels to 700 rounds...they would be extremely lucky!
On the other hand I have .308 Winchester barrels that are accurate up to and beyond 7000 rounds! Mild loads=EXTENDED BARREL LIFE!! [img]/ubbthreads/images/graemlins/grin.gif[/img]
I've been monitoring barrel life that competitive shooters get for years. So I came up with a rule of thumb that has worked very well.
But it depends on how good of a shot you are. An excellent marksman will notice accuracy degradation before a duffer will. A competitor on a US international team will rebarrel his .308 Win. at about 3000 rounds while a military combatant will rebarrel his M14 at about 10,000 rounds. And rapid fire erodes 'em faster than slow firing.
What I've learned is most centerfire barrels shoot the best for about 3000 rounds when the powder charge equals 1 grain for each square millimeter of the bore's cross sectional area. Double the powder charge for a given bore diameter and barrel life drops to 750 rounds.
I had this discussion with one of the bullet techs at Sierra. Here is what he had to say: We used the .300 RUM as an example, it seems to be a favorite barrel burner. If you fire a 190 grain SMK bullet Vs a 240 grain SMK you will get longer barrel life with the 190 SMK we are talking 300 RUM here. Take a lighter bullet in a 300 RUM and the barrel life will be longer even though the bullet is moving faster. Will a .300 RUM last as long firing a 110 grain bullet as a .308 Win firing a heavy bullet? NO!!!!!
My first question was why? His answer was dwell time, it takes the heavier bullet longer to leave the chamber, and the flame has more time to erode the throat. Its like holding a hot torch to metal for a longer time. Rapid fire accelerates wear, allowing longer cooling time definitely extends barrel life. There are also certain powders that are more barrel friendly than others. Its not the barrel that wears out, its the throat.
Cartridges like the .308 Win are known for longer barrel life because they use less powder, and with a lighter bullet they will also last longer than with a heavier bullet. It's not the speed of the bullet its the time and intensity the flame has to erode the throat that kills them. More powder equals more heat, the faster the bullet exits, the less heat on the throat.
I am sure there are people who will say this is not the case, but he claims it took several years to prove, and it was not easy to prove.
Hope I explained this correctly, its been a while since the conversation.
If a 300 Rum has 4500 fullhouse loads with 180+ gr rounds down the tube, time to rechamber it to 28 guage because all it is doing is shooting "patterns" anyway.
A 300 win Mag with 190-210s will normally loose its top accuracy at 1200-1400 rds tops. Same for Weatherbys, 300 Ack Imp etc. Some of the improved 30 cal mags are loosing top accuracy at 800 rds.
Trimming brass to fit the chamber correctly seems to help barrel life instead of leaving them .050 short because of what is written somewhere. Depends on how the reamer was set up!!
The only mag that seems to beat that number right now is the 300 WSM. Mine went 2300, took top 10 in the Nationals but groups were starting to open up. That seems to be pretty normal for the WSMS, 4 of us shooting them and all running double barrel life at least compared to other mags.