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Old October 25, 2013, 07:27 PM   #1
Colorado Redneck
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Skinny barrel vs. heavy varmint barrel

I am getting all het up to buy another prairie dog rifle in .204 Ruger. Have looked at the Howa Classic Varminter and Ruger Hawkeye Predator. Then I got to thinking about a "Ruger M77 Hawkeye Standard Rifle" and maybe restocking it with an after market unit. I have a Ruger MK77 in 25-06 and it is a tack driver with Nosler Accubond, so that is an interesting alternative.

The question: Is a Skinny Factory Barrel at a disadvantage compared to a Heavy Varmint Barrel for shooting 30-50 rounds per hour?

I have read various opinions, and some believe the heavy barrel will heat slower, and the POI will walk around less than a skinny barrel. My CZ American in .222 Remington will walk some if fired too rapidly---say a round every 30-45 seconds like a guy sometimes shoots in the heat of a prairie rat massacre. If it is allowed to cool a couple of minutes between rounds I can shoot the thing for hours with no cleaning or cool off.

Looking forward to reading your opinions!
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Old October 25, 2013, 08:19 PM   #2
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Skinny barrel vs. heavy varmint barrel

It's really quite simple. Skinny barrel means less distance between the hot bore surface and the exterior outside diameter. So heat will cross that thermal mass more quickly than a thick bull barrel. Sure it will heat up faster but also cool more quickly. The bull barrel will take longer to heat up so there will be less heat to dissipate. Bull barrel also has more surface area to dissipate heat from.

So like I said, Its really pretty simple

Cliff notes: They don't call it a varmint barrel for nothing.
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Old October 25, 2013, 09:10 PM   #3
Art Eatman
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The heavier barrel will do better, overall, for not having a change in the point of impact during long strings of fire.

No matter how thick the barrel is, the leade is the critical "hot spot" with such shooting. This particularly holds for such cartridges as the .204, .220 Swift and the .22-250.

I've used a light sporter barrel in prairie dogging with a .223. I'd shoot three or four times and then take a break and watch my buddy shoot while my barrel cooled a bit. Never had any particular problem with change in the point of impact, as near as I could tell.
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Old October 25, 2013, 09:10 PM   #4
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A skinny barrel will heat faster and cool faster. The rate you are guessing at ( 30 to 50 ) per hour. That's every 1 to 2 minutes. Your skinny barrel is going to heat up,but you will be fine for a while. That ( every 2 minutes) is a pretty slow fire rate. The walking of the bullets would be my last concern ( only considering what you are shooting at ). My concern is the damage you could do to your barrel by heating it up to much. ( got 2 rifles ). No sense in damaging a barrel over a dog.
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Old October 26, 2013, 06:04 AM   #5
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The smaller bores in a standard weight barrel have somewhat similar effect as a heavy barrel with a bigger bore. I have a HB 223 but really don't need it for anything except PD shooting. It does "hold" nicer than the standard weight barrel and allows seeing the hits. My 17's are standard weight and have basically the same barrel thickness as my 308 HB.
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Old October 26, 2013, 07:22 AM   #6
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My normal barrel is a No 7 contour for competition. For about everything else it was a 5A contour but now I have two barrels in Palma Medium Contour and though they are long they are a pleasure to carry.

Thusly from now on I will be getting Palma Medium contours.

Pull up the Douglas barrel website for a chart of these dimensions.

All three of them will take cutting off the barrel threads at say 2500 rounds and rechambering several times for increased barrel life.

It will really pay you in the long run to invest in a custom reamer so your brass will last longer.

You just take a new factory round of your favorite caliber and measure the base dimension .200 up from the rim and add .002" for the reamer. Same for the neck dimension. Have it headspaced to snug on a GO GAGE and you are sent for a long case life as nothing moves over .002" on firing. I call it the 222 principle.
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Old October 26, 2013, 07:45 AM   #7
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Barrel heating up is all interesting theory, but I think accuracy will depend more on the quality of the barrel, quality of the build and overall weight.

First, barrels do heat the throat/leade mostly. A skinny barrel is requiring mostly convective heat transfer off the outer surface....think slow to reduce temp of throat. A heavy barrel has a larger thermal mass. It is conducting heat away from the throat and then slowly using convection to return to ambient. The conduction is a fairly rapid heat transfer away from the throat. This helps a lot with throat temp when you are shooting 10 in 2 min and the wait 15 min for the dust to settle and the varmints to pop up again. Also, keeping the barrel temp down should reduce barrel movement fro heating up.

That said, a cheap barrel with lots of stress will move more with heat. A properly stress relieved barrel, skinny or fat will move less.

Weight....A factory varmint rifle gains the most accuracy by adding weight to the front rest. From prone, bench or any good rest, the heavier gun it better.

From position shooting like Palma or hunting, balance is more important as it is all about getting sights on target.

So, the heavy barrel is better, unless it is too heavy to shoot kneeling, standing or unless the bedding can't support it.
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Old October 26, 2013, 02:57 PM   #8
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Good comments---much appreciated!

So, after reading your thoughts and comments, I ordered a Ruger Varmint with heavy barrel today. Be here Friday---hope the weather is good next weekend so it can be fired and broken in. Depending--may do a range report. Or if it takes some work to get a good load (the 222 Rem in CZ took a hundred rounds or so to get it right) then later on.
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Old October 26, 2013, 03:25 PM   #9
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A heavy barrel will generally shoot better longer because the steel absorbs the heat more slowly. But a friend once had a .308 on a Mauser action with a 22" Herter's barrel he picked up cheap when they went out of business. That was, I think, the thinnest .30 barrel I have ever seen, not even 1/2" at the muzzle.

With GI match ammo, it shot MOA and would do it all day, group after group. Go figure.

(FWIW, the term "bull barrel" has nothing to do with the animal; Freeman Bull, Chief Armorer at Springfield Armory, was a pioneer in the use of heavy barrels for accuracy.)

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Old October 26, 2013, 06:25 PM   #10
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Interesting bit of trivia James

Barrel heating is another of those subjects that seems to draw differing opinions.

I have a Savage 12 in 22-250 with heavy varmint barrel. Always used the load data for COL depending on the data source and got good accuracy. Recently did the routine where a bullet is seated way long in a fired case that has three cuts in the neck and the bullet is colored with a marker, then insert the case/bullet into the chamber, close the bolt gently, then eject the combo very slowly so as not to dislodge the bullet from the case. There is some free bore (won't call it throat erosion as I have no baseline data) but it isn't a great deal. The standard COL for use with the Hornady 50 V-max is 2.350 inches. Using the technique it appears to be that the 50 V-max would be at 2.430 to touch the lands. I personally have put more than 2000 rounds down the tube of that Savage, so given the number of rounds, the free bore isn't extreme IMO. Now the good part--on various occasions that gun has been shot till it was so hot you couldn't touch the barrel for longer than about a second or two, and the original composite stock (cheesy darn thing) would start to smell from the heat. Never kept count, but probably 30-40 rounds in 30 minutes and the temperature in the sun was likely well over 90 degrees.

The gun is still very accurate. So my experience doesn't indicate a lot to worry about overheating a barrel. I will add that since then other guns have been added to the armory and they don't get used that way.
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Old October 26, 2013, 07:31 PM   #11
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In shooting my own longer, whipper barrels and shorter, stiffer ones, as well as observing those of many others, none changed point of impact as they heated up. Going from ambient temperatures to upwards of 150 to 170 degrees firing one shot every 15 to 20 seconds for 20 to 30 shots or two 10 shot strings in 60 seconds fired back to back, no change in zero was observed. Even standard weight barrels in M1's and M14's (both are fairly skinny out past the reinforce) shot 24 times in 50 seconds starting out cold do not change point of impact tested for accuracy at 200, 300, 500 and 600 yards. But these had something in common others that do change point of impact when they heat up.

Those "others" were different in that their barrel shoulder only contacted hard at one point around them to the receiver face. The receiver was not squared up on its front end with the tenon shoulder square with the chamber axis. As both the barrel and receiver heated up, contact at that point became harder creating a stress line at that point. The stress line down the barrel increased as it heated up and the metals expanded. That made the barrel whip more in that axis as it got hot.

Solution? Square up the front of the receiver by facing if off .005" or so then put a shim washer of the same thickness between it and the barrel so the barrel clocks back in the same to maintain the same heaspace. When the barrel and receiver expand from heat, its uniform all the way around the barrel shoulder against the receiver.

Barrel steel has to go way over 200 degrees F before its metalurgy structure changes make it bend as it gets hot. I've never seen bolt action barrels shot so hot rain drops boiled on them.

The only other cause of a barrel walking shot impact as it heats up is twofold. One's poor metalurgy and not stress relieved properly. Even these will bend as the heat up when perfectly fit to receivers. The other's an epoxy bedding pad under the chamber area of the barrel. As the barrel expands from heat, it bears harder against the epoxy and vertical shot stringing starts. With either cause, once the barrel heat's stabilized at one point, the group center usually stays at one place.

The answer to your question; no, if they're both well made and properly fit. Few factory barrels are properly fit, hence their tendency to walk impact as they heat up.
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Last edited by Bart B.; October 26, 2013 at 08:29 PM.
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Old October 26, 2013, 07:53 PM   #12
Brian Pfleuger
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Skinny barrel vs. heavy varmint barrel

My M77 MkII in .204 is the most accurate rifle I've ever shot. My hand loads routinely shoot under 1/2" at 100.
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Old October 26, 2013, 09:06 PM   #13
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Have you shot sustained strings from your MK77 II ? Like 25 in a row over a few minutes?

Last edited by Colorado Redneck; October 26, 2013 at 09:07 PM. Reason: Correction
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Old October 26, 2013, 09:40 PM   #14
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Skinny barrel vs. heavy varmint barrel

Not quite like that. I've fired 3, 3 shots groups in a few minutes time with full power loads and I fired 25 fire forming rounds with Trail Boss at about 2,250fps in just a couple minutes. Never cared/needed to shoot more.
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