I still use the 760 in my 243. It really likes it and I load for a hunting buddy of mine and his love it too!! We both shoot the 70gr NozBTs. Did the same as you did and developed a load for winter....
What is the expected barrel life on a 6mmARC???
- Thread starter Raptor
- Start date
The “heat index” of a powder has a lot less to do with barrel life than people imagine. An “index” is a mathematical abstraction.
What matters first is “net calorific value” or lower heating value. Then it’s burn rate because this determines the heat flux (heat release rate) and finally, pressure matters.
Lower heating value does vary but not that much. Nitrocellulose is nitrocellulose. Nitroglycerin is nitroglycerin. 24gr of single base nitrocellulose has the same potential energy as 24gr of any other nitrocellulose.
Burn rate and heat release rate are what people often think of as “flame temperature.” This is where your kernel shape and burn rate inhibitors come in.
Pressure is far more important than people want to believe. Not just the peak pressure but how much time higher pressure is present. Pressure and time are the most significant factors.
What matters first is “net calorific value” or lower heating value. Then it’s burn rate because this determines the heat flux (heat release rate) and finally, pressure matters.
Lower heating value does vary but not that much. Nitrocellulose is nitrocellulose. Nitroglycerin is nitroglycerin. 24gr of single base nitrocellulose has the same potential energy as 24gr of any other nitrocellulose.
Burn rate and heat release rate are what people often think of as “flame temperature.” This is where your kernel shape and burn rate inhibitors come in.
Pressure is far more important than people want to believe. Not just the peak pressure but how much time higher pressure is present. Pressure and time are the most significant factors.
That makes sense.
AckleymanII
Gold $$ Contributor
You had better listen to my post, it is based on actual field experience of shooting 400-600 rounds a day in a single barrel, day after day after day in the 6 PPC and 6 BR with 55-65g bullets...years of repeated experience. I carried a 5 gallon bucket of ammo for each rifle. 223, 6 PPC, 6 BR, 243 AI.
Hence the significantly higher throat wear rate when shooting heavy bullets, also the barrel-life cost of the increased velocities in the Nitrochemie 'EI' powders such as Alliant Re17. Because of their (EI powders') infusion into the kernels the burn rate deterrent life is extended over longer time and bullet movement periods.
I don’t think it’s the heavier bullets per se, but the slower burning powders they tend to require. Run a fast, clean burning powder with a heavy bullet and yes you’ll have poor MV, but less heat in the throat and barrel.
It is actually the heavier bullets. Greater mass = increased inertia = slower acceleration down the barrel = longer concentration of peak pressure/temperature on the throat. if a slower burning powder is also needed, yes that adds another downside factor.
7.62/308 has seen a huge drop in barrel life in a generation with the move from shooting 'as issued' 7.62 milspec with 145gn bullets in the UK to today's F/TR loads with 200s. Yes, pressures are higher in small primer brass, but the primary powder used here is relatively cool burning Viht N150, and it's nothing like as slow burning as burning rates show, charges being only higher than those for H. VarGet. Even the move from 155s to the 185gn Berger Juggernaut in large primer brass at lower pressures saw a noticeable barrel life reduction some years ago.
7.62/308 has seen a huge drop in barrel life in a generation with the move from shooting 'as issued' 7.62 milspec with 145gn bullets in the UK to today's F/TR loads with 200s. Yes, pressures are higher in small primer brass, but the primary powder used here is relatively cool burning Viht N150, and it's nothing like as slow burning as burning rates show, charges being only higher than those for H. VarGet. Even the move from 155s to the 185gn Berger Juggernaut in large primer brass at lower pressures saw a noticeable barrel life reduction some years ago.
Interesting, So we are saying If i were to shoot two different identical rifles in 6mm Arc with a heavy bullet load in one & a light bullet load in the other, barrel life will be notably better with the lighter bullet load every time. Rate of fire being the same in each case & bolt action rifles for each.
For example lets shoot a max lever evolution load under an 85 grain bullet in one barrel. The other barrel may be a 108 grain bullet load pushed again w a max load of Lever evolution. Expecting 32 grains of propellant for the 85's & 31 grains of LVR for the 108 grain load,
For example lets shoot a max lever evolution load under an 85 grain bullet in one barrel. The other barrel may be a 108 grain bullet load pushed again w a max load of Lever evolution. Expecting 32 grains of propellant for the 85's & 31 grains of LVR for the 108 grain load,
Yes, assuming same pressures and peak burn temperatures.
I agree with Laurie, there's no free lunch. More pressure, longer curves and more bearing surface reduces barrel life more than less pressure, shorter curves and less bearing surface.
I picked the 6MM ARC for my general purpose AR rifle because of the performance at lower pressures, I'm looking for long life in the rifle and utility.
I'm working Leverevolution loads to duplicate factory 108 and testing lighter projectiles with the same powder. The 85 and 90 grain have been used to harvest deer for years.
Lkwebb
Gold $$ Contributor
4k rounds and he has 5 thousandths of throat erosion...
Thank you for sharing!! I hope he does one on the AR also......
Lkwebb
Gold $$ Contributor
I'm sure he will , if not I'll ask him
Great video I bilt an Aero Precision AR in 6MM ARC and will post my play time results.
I have one with a Shaw barrel and one with a Proof barrel. Both are solid .5 guns with several bullets. Both have 18" barrels. They are a dream to shoot with a can.....
I've posted this several times but here it is again. I've been waiting nearly 50 years for the AR 15 to be chambered in a general purpose cartridge. By that I mean one that can be used rapid fire in close with less recoil issues than a 30 Carbine and be effective on deer at 250 yards and accurate at 600+ yards.
My AR 15 A2 is ok in close (best with 55 or 62 grain projectiles) but lacks energy at long range as well as being wind sensitive out past 300 yards. The 68 grain helps with accuracy but there's no way to make it a one projectile carry rifle for in close and deer.
My 6MM ARC is a 16" barrel with the Aero standard muzzle brake, recoil management in close and taking game at range seems a possibility with one projectile weight.
I like the concept of one rifle that does 99% of what I may need, shoot it regularly and be good with it, take it where you go. It's a tool.
If I get sub MOA I'm good to go, I want a working rifle, throw it in the Jeep, keep it handy and BE EFFECTIVE.
I'm getting over a bout of cancer and I'm just about strong enough to be range worthy. I didn't go cheap nor did I blow out the bank, I have specialty rifles for dangerous game, varminting and long range work but I'm experienced enough to know that a general purpose rifle gives you what you pay for.
The fit of the Aero upper and lower is perfect, I'm working iron sights (A2 collapsible) until zeroed at 300 and adding a 1 to 4 single lever quick detachable scope. I'm deciding on what brand two point sling.
I added a brass catcher for shoot and scoot range work, damn supplies cost a bit today.
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