Normal throat erosion?

22-250 is a "barrel burner" because of the velocities and the shoulder/neck in the case. Hight velocity "blast furnace" in the throat.

Same thing with the 6.5 - 284, because it's pushing a small bore bullet fast behind a large charge.

308 Win. is not so bad. Depends on the barrel though, what it's made of, how it's chambered, throated, leade, materials, even how it's rifled.
 
Normal throat erosion

jaybic said:
Hey guys,

I have a 22-250 and shoot a 50gr vmax thru it fairly close to maxed out with H4895. When it was brand new on 08Sep06 and had never been shot, it measured 2.080 to touch the rifling using a stoney point measuring tool and comparetor(sp?) and a Lyman dial caliper.

Today, it measures 2.115 to touch the rifling with the exact same bullet I used then for the dummy round. Has the throat of my rifle eroded that much and is that about normal for maybe 1500-2000 rounds? I this enough erosion to start seeing signs of eratic accuracy?

I dont know if thats alot or a little erosion.

Thanks all,


Jamie
Click to expand...


That sounds about right to me; .035 of throat erosion for 1500-2000 near max. loads. I have several .22-250 A.I.'s in different twists that are shot at max. Ackley load and have monitored throat erosion along the way and kept records for each barrel. What you are witnessing is a normal part of the shooting game. Just load your bullets further out to chase your throat; the barrels will still shoot very accurately. When you get into the overbore calibers, you'll quickly find that barrels are an expendable commodity and that's just part of the game.

Lou Baccino
 
Is a 22-250 considered an "overbore" cartridge? To be honest, I really dont know exactly what the term means.:eek:

This is a 20 inch barrel and a 1:14 twist. As stated, I would like to shoot a 50 gr Vmax but if the throat is getting long, should I go to a bullet with more "bearing surface" like a 55gr bullet or maybe that slow twist and long throat would favor a 40gr Vmax? What is the optimum barrel lenght for a 22-250 to get complete powder burn and max velocity anyway?

Sorry for the dumb questions but I honestly dont know.

Any ideas on this?

Jaybic
 
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I have several 220 Swifts (similar to the 22/250) and none have barrels less than 26 inches. I wouldn't put a barrel less than 24 inches on a 22/250. With some powders you won't lose a lot of velocity with shorter barrels but with other powders you do.

If you have throat erosion experiment with various bullets. Let the rifle tell you what it likes--you may be surprised.

The 22/250 is not overbore. Overbore cartridges have a case with powder capacity too large to permit efficient burning of powder for the bore diameter. A good example is the 264 Winchester Magnum.
 
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I have a factory Savage 22=250 Varminter that came from the factory with a 26 inch barrel. Longest barrel I have out of about eight centerfire rifles. And it's fine with me.

I don't see any benefit to a short barrel in this sort of gun. The argument for short barrels is made for hunting rifles, such as -- "long barrels may catch on brush", etc. Or, "makes the rifle lighter if you carry it all day."

Well, there's no brush to catch on at the shooting range.
And . . . varminter style rifles are generally much too heavy to carry all day, esp. with the added weight of a big scope.
 
jaybic said:
Is a 22-250 considered an "overbore" cartridge? To be honest, I really dont know exactly what the term means.:eek:

This is a 20 inch barrel and a 1:14 twist. As stated, I would like to shoot a 50 gr Vmax but if the throat is getting long, should I go to a bullet with more "bearing surface" like a 55gr bullet or maybe that slow twist and long throat would favor a 40gr Vmax? What is the optimum barrel lenght for a 22-250 to get complete powder burn and max velocity anyway?

Sorry for the dumb questions but I honestly dont know.

Any ideas on this?

Jaybic
Click to expand...

Jay,

The term "overbore" is not really defined, it's like the term "hot" or "fast" or "skinny" or "fat" in that it describes a condition as contrasted against an ill-defined "norm." "Overbore" means that the case capacity is larger than the bore can comfortably handle.

Every now and then some gunwriter makes an attempt at quantifying cartridges in terms of "efficiency" or powder charge to bore ratio and showing how some rounds use their capacity more efficiently than others. Generally the writers do a good job. Some reloading manuals have similar comparison charts......the 22-250 definitely falls into the inefficient or overbore camp. It IS a barrel burner. A 22BR is much more efficient and will run to within 5% of the 22-250's velocity while using 30% less powder.

Same with the .30 cal's ..... for comparison a .308 will almost keep up to the 30-06 which will ALMOST keep up to the 300Win Mag but for each jump of 100fps velocity you must cram in a BUNCH more powder. This is called "the law of diminishing returns."

From an accuracy standpoint it's simple fact that the more efficient rounds are more inherently accurate. A 22BR will ALWAYS beat a 22-250 and a .308 Win is the most accurate factory .30 of the three choices presented. In fact the real knowledgeable folks will drop to the .300 Savage for accuracy in .308cal....This isn't speculation. There are solid reasons why efficient cartridges are more accurate, it's pure-dee fact that an "overbore" round like the 22-250 will not win any BR competitions.

For your situation,

A 20" bbl is short for a 22-250. Fast powder and small bullets will be the order of the day for you. IMO barrel length for the 22-250 should be 24-26" for loose twist (14") and 28-30" for the 8" twisters.

There is no rule about which bullet will shoot for you. Just try different bullets and see if they shoot different.


BTW Montana Pete From Wisconsin, the 2-groove barrels were built to be some of the most accurate barrels of their time. Why the laughter? I guess I don't get it.

al
 
BTW Montana Pete From Wisconsin, the 2-groove barrels were built to be some of the most accurate barrels of their time. Why the laughter? I guess I don't get it.


Because we were all in love with Star gaged barrels back then.

What Pete saw was exactly what I saw with the two groove barrels, they all shot vary well indeed. I used to wonder if they were the first of the button rifled barrels made by Remington? I do know that Remington during WW II was the first to do button barrels. There are still a lot of people that decry the two groove barrels. That's just foolish.

I'll bet that none of our top barrel makers today would make one however, I think the prejudice is still to strong against them.
 
As to the definition of overbore capacity, ACKLEY darn sure defined what he meant by the term. You can find the definition in his first volume.
 
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