Loading for correct seal

[spitballer]

Have a question about loading with the correct pressure for a positive seal.

(Rem 700 Varmint in .223)

Here's the situation: When I load with too little pressure, I get fouling on the lands and blow-by in the grooves. As I begin to add pressure (higher charge) to my bullets, I start to get more fouling (wear) on the high-pressure (right)side of the lands and wear (fouling) begins to show up in the center of the grooves.

Still more pressure, and I get wear evenly on both sides of the lands and the wear in the grooves starts to ease. Any further pressure only extends wear from the base of the lands. This may be because my barrel is worn more in the grooves than it is around the base of the lands - makes sense.

When should I stop increasing the pressure? The wear pattern with my last batch of ammo extends out uniformly from both high and low-pressure sides of the lands , and I seem to be in close contact with about 1/3 of the bore surface at this point. At some point I'll want to stop adding pressure and work on a glaze by shooting with a consistent pressure. Should I limit the close bullet-bore contact (wear pattern) to the area immediately at the base of the lands and count on a heavy glaze for the majority of the surface of the more deeply worn grooves?

Yes, I have another barrel on order, but I'm cheap and I want to get as much use as I can out of this one and yes, maybe learn a thing or two while I'm at it, so any constructive comments appreciated.

 

[Laphroaig]

Apparently you have a borescope. I've never seen or heard of an evaluation of loads such as yours. Most people look for best accuracy and/or pressure signs as the point to stop when shooting jacketed bullets, not barrel condition. I assume you're talking jacketed bullets, .223 varmint and all. Lead is another story.

I have a question though, why do you refer to fouling as "wear" and visa versa? Fouling can generally be removed from the steel back to an unfouled condition. Wear is just what it says, barrel steel being eroded.

Laphroaig

 

[smokey262]

Without data that describes the accuracy you are getting as well as what accuracy you want or find acceptable it is pretty hard to comment

I would rather have a barrel that shot lights out for 3000 rounds than one that shot crappy, but lasted forever because I loaded it to prevent wear

 

[Sam1911]

Are you able to make these pressure changes with no positive or negative effects on your accuracy?

If so, great.

If not, then there's no point. The barrel is a wear item. Work up to best accuracy and then shoot it until it wears out.

Or am I oversimplifying somehow?

 

[rcmodel]

Fouling is not wear.

It is a perfectly normal occurrence when any round is fired.

Some loads foul less the others.
But that should not be a consideration when searching for the most accurate load.

rc

 

[witchhunter]

Since you said it is a Remington .223 Varmint barrel, I think we are all assuming that your goal is for it to be accurate. I wouldn't worry about barrel life too much with that cartridge. It should last a long time. I would concentrate on accuracy loads. If they are not too hot you should shoot it for years. Then order a quality barrel, look at it with a borescope! You will be amazed at the difference.

 

[spitballer]

Nope, Laphroaig, no borescope just eyeballing from the muzzle. By fouling/wear, I mean the areas where the bullet makes the most contact and ultimately produces the most wear. Generally I clean any copper fouling down to the metal after every shoot and subsequent shoots will abrade the same spots until fouling starts to cover them. Obviously the lands receive the brunt of this wear/fouling, but under pressure the lower areas will, too. Thanks for your input.

 

[spitballer]

Smokey262 for the longest time I shot 1/2 MOA with a 55 grain bullet loaded with 24.5-25 grains of IMR 3031. In the last year or so my groups have opened up, probably from good old-fashioned barrel wear, but as stated earlier I'm a cheapskate and I'm looking for a strategy to extend the life of this barrel and perhaps more importantly, the next one. Good point about loading for long barrel life and well taken. Thanks for comment.

 

[spitballer]

Sam1911 You are right on the money, barrel being a wear item. Mine has lasted several years and many thousands of rounds and it's probably just time to let it go. In fact I'm finalizing a Pac-Nor barrel change even as I write. Maybe with a little luck and good advice I can make the next barrel last even longer.

 

[AABEN]

Winchester 748 is a very good powder for the 223 it is very easy on the barrel. Look it up.

 

[Laphroaig]

I'd guess that the major cause of your groups opening up is throat erosion and not wear to the lands and grooves. Possible solutions might be to increase your COL to get closer to the end of your enlarged throat and thereby decrease bullet jump and also maybe try and polish out some of the roughness with some JB bore paste or lapping compound. It will probably never be what it was when new and only you can say what is acceptable to you.

If you can't live with your decreased accuracy it might be time to strap on that new barrel. The cost of barrel life per shot is far less than the cost of a round of ammo.

Laphroaig

 

[spitballer]

AABEN I tried 748 and actually still have a little bit left in my powder bin, but I found that it didn't seem to burn very clean with my reloads. Admittedly I used the CCI 400 primers and NOT the magnum (#450) primers. I understand that magnum primers are recommended for the ball powders.

 

[788Ham]

You might also try IMR 4198 powder,thats a very good powder for the .223 using 55g bullets. I have a Remington 788 in .223 thats a very accurate rifle, using that powder has made a very accurate round.

 

[FROGO207]

I also like IMR4198 the best with my 55 grain FMJ projectiles. I have had long barrel life so far (30k+ rounds) in 3 different 223/5.56 rifles without detectable barrel accuracy issues. A barrel with slower twist rate will last longer and stabilize heavier bullets from what I am told as well. A thought when replacing the barrel.

Had an uncle that used only surplus tracer propellant for 223 loading and his barrel life was dismal. He always was at max or a bit above as well so take this as you will.

 

[spitballer]

Thanks, guys. I had considered 4198 at one point but I wasn't sure if maybe it wasn't a little too fast. I always seemed to get a lot of muzzle blast and upset with the slower powders and had better luck with the 3031, but I thought I was pushing the limit with it. I will try the 4198.

I also took advantage of the opportunity to try the poly rifling on this next barrel. Anyone have experience with poly rifling in .223?