How quickly do thin barrels start walking?

T

targetterror

Sergeant
Full Member
Minuteman
Sep 16, 2008
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Boston, MA
#1
I recently picked up a Stevens 200 in 7mm-08 for hunting. I grabbed a Boyds featherweight thumbhole sporter and dropped the action in (no pillar or bedding of any sort). She shoots ok with my handloads, ~1 moa out to 200 with some Nosler 120 grain Ballistic tips, at least for the first 5 or 6 shots. Then things start opening up. Same with some milder 140 grain Sierra loads I worked up.

The barrel on the Stevens is obviously very thin and the whole rig is clearly best suited for hunting, but I was still surprised how quickly the groups opened up at the range and to what extent (probably opened up to 3 moa or so). Is this normal behavior for this/any uberthin barrel? Would bedding help? (I would think not since its floated, but I'm not sure)
 
#3
Re: How quickly do thin barrels start walking?

Bedding the action to the stock will likely help at least a little bit in terms of preventing any flexing, stress, etc. from the stock impacting the action.

However, a thin, "pencil" barrel on any rifle will begin to throw rounds the hotter they get. The thinner they are, the faster they will heat up and the faster accuracy will deteriorate. Not a whole lot you can do about it other than make sure that the barrel is, in fact, completely free-floated. You should check this with both a cold barrel and a hot barrel. Depending on how much relief you have between the barrel and the stock on a cold barrel, when you heat things up, you may get some interference.
 
#4
Re: How quickly do thin barrels start walking?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ORD</div><div class="ubbcode-body">However, a thin, "pencil" barrel on any rifle will begin to throw rounds the hotter they get. The thinner they are, the faster they will heat up and the faster accuracy will deteriorate. Not a whole lot you can do about it other than make sure that the barrel is, in fact, completely free-floated. You should check this with both a cold barrel and a hot barrel. Depending on how much relief you have between the barrel and the stock on a cold barrel, when you heat things up, you may get some interference. </div></div>

Yea I ran a dollar bill under the barrel after ~10 rounds and it was still floated.
 
#5
Re: How quickly do thin barrels start walking?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TargetTerror</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ORD</div><div class="ubbcode-body">However, a thin, "pencil" barrel on any rifle will begin to throw rounds the hotter they get. The thinner they are, the faster they will heat up and the faster accuracy will deteriorate. Not a whole lot you can do about it other than make sure that the barrel is, in fact, completely free-floated. You should check this with both a cold barrel and a hot barrel. Depending on how much relief you have between the barrel and the stock on a cold barrel, when you heat things up, you may get some interference. </div></div>

Yea I ran a dollar bill under the barrel after ~10 rounds and it was still floated. </div></div>

That being the case...not much more you can do. Definitely get your action properly bedded in the stock. That will give you an edge over the unbedded setup you are running now. Probably won't help much once your barrel gets hot, but it couldn't hurt things that is for sure. It most certainly will help your accuracy before you get the barrel hot as you'll have the rifle in a much more rigid setup.
 
#6
Re: How quickly do thin barrels start walking?

Folks are quick to fixate contours,because that is a visual response,though it matters little.

The heart of any barrel is it's interior and just as importantly it's stress relief. A good barrel of modest contour,will reliably hang tough,because they aren't bound with stress.

A dollar bill is a faux float,by at least 5 bucks.
 
#7
Re: How quickly do thin barrels start walking?

It really depends on rifle, caliber and powder used. i had a 700 in 25-06 that i could shoot til the barrel was SOKING HOT and groups didn't open up. My kimber Montana in 260 opened up groups after 2 shots!
 
#11
Re: How quickly do thin barrels start walking?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: OilyOwl</div><div class="ubbcode-body">I've a 25-06AI KS that'll brand cattle and track. </div></div>

My 243AI with #3 cont. is the same way, havent got it hot enough to brand, but have put 20 down the pipe pretty fast in 100 + temps[ to hot to touch]. On the 850 yrd target still held moa easy. No bedding and damn sure isnt floated.
234ai043.jpg
 
#12
Re: How quickly do thin barrels start walking?

I've a herd of #1 contours that reliably do shit that can't be done,according to conventional "wisdom".
 
#13
Re: How quickly do thin barrels start walking?

Ran brads MR cont pretty hard while he was here to. I think to 700yrd line it was hotter than hell and still held well better than moa..Smaller cont. than the rifle above...
 
#16
Re: How quickly do thin barrels start walking?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: donovan</div><div class="ubbcode-body">Ran brads MR cont pretty hard while he was here to. I think to 700yrd line it was hotter than hell and still held well better than moa..Smaller cont. than the rifle above... </div></div>

It hasn't been mentioned yet, but a light trigger in a light rifle really brings it to life. I'm running a R'Basix in mine at 11ounces.

DSC_3492-1.jpg
 
#19
Re: How quickly do thin barrels start walking?

I've yet to have a barrel that was too accurate or a trigger that was too good,though I eagerly await both afflictions.
 
#20
Re: How quickly do thin barrels start walking?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Brad Arnett</div><div class="ubbcode-body">
It hasn't been mentioned yet, but a light trigger in a light rifle really brings it to life. I'm running a R'Basix in mine at 11ounces.
</div></div>

I got it used with a Timney trigger. Not the best trigger I have felt, but just over 2 pounds and entirely useable.
 
#22
Re: How quickly do thin barrels start walking?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Brad Arnett</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: donovan</div><div class="ubbcode-body">Ran brads MR cont pretty hard while he was here to. I think to 700yrd line it was hotter than hell and still held well better than moa..Smaller cont. than the rifle above... </div></div>

It hasn't been mentioned yet, but a light trigger in a light rifle really brings it to life. I'm running a R'Basix in mine at 11ounces.

DSC_3492-1.jpg
</div></div>

Your gonna scare everything away with that blue stock!.....laffin!!
 
#26
Re: How quickly do thin barrels start walking?

My next build is going to toned down a little bit and not so bright.

I picked up a Stainless PacNor .257" 1-10"twist 3-grv in Mountain Rifle contour. It'll be chambered in 25-284 @ 22"s and is going in an Edge Mountain Rifle stock. I have a feeling that it might turn in to another favorite when its done.

I was planning on just rebarreling the blue/white 243 but it just shoots too damn good to tear it apart.
 
#27
Re: How quickly do thin barrels start walking?

Just to make sure I understand correctly the wealth of wisdom being dispensed in this thread: are you highly experienced gentlemen saying that the barrel thickness is secondary in a well made barrel, with the quality of the barrel being numero uno?

The conventional wisdom, of course, is that the thickness is at least equally important to quality of rifling, bore, etc. And also that I'd need to have a 26" heavy barrel on my .308 to reach past 600 yards. I have recently learned that the long barrel necessity is a myth and that <span style="font-style: italic">most </span>of the work in a 308 is going to be finished within 22" or less ... and now the thickness? This is good to hear from professionals because I am trying to choose a profile for a poor-boy 308 build and the thought of carrying a 12 pound rifle in the woods was making me ill.
frown.gif


So, might I be generally OK to 600 yards with a good quality 22" #3 (.700") contour - assuming the rest of the weapon is up to snuff, of course? The build will be a Marlin XS action fully bedded on a laminate thumbole stock.
 
#28
Re: How quickly do thin barrels start walking?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Snakum</div><div class="ubbcode-body">Just to make sure I understand correctly the wealth of wisdom being dispensed in this thread: are you highly experienced gentlemen saying that the barrel thickness is secondary in a well made barrel, with the quality of the barrel being numero uno?

The conventional wisdom, of course, is that the thickness is at least equally important to quality of rifling, bore, etc. And also that I'd need to have a 26" heavy barrel on my .308 to reach past 600 yards. I have recently learned that the long barrel necessity is a myth and that <span style="font-style: italic">most </span>of the work in a 308 is going to be finished within 22" or less ... and now the thickness? This is good to hear from professionals because I am trying to choose a profile for a poor-boy 308 build and the thought of carrying a 12 pound rifle in the woods was making me ill.
frown.gif


So, might I be generally OK to 600 yards with a good quality 22" #3 (.700") contour - assuming the rest of the weapon is up to snuff, of course? The build will be a Marlin XS action fully bedded on a laminate thumbole stock.</div></div>

Do you see that rifle with a bright blue stock about 6 posts above? it is a 243 with a thin barrel and Brad ran that dude to 700 yards with a 3-9x40 Leupy. It was still MOA or better. So yes these guys know what they are talking about.<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: donovan</div><div class="ubbcode-body">
234ai043.jpg
</div></div>

This one has been run to 850 with the 75gr Vmax and is a #3 contour.
 
#29
Re: How quickly do thin barrels start walking?

I'm running a 1" 3.5-10x40 Leupold on the blue rifle.....that 1 extra X makes a difference.
grin.gif


I'll work up a 105Amax load for that little rifle and run it to 1000 here shortly. Even with just the Talley LW's I still have about 30MOA of erector travel available so it'll work out just fine.
 
#30
Re: How quickly do thin barrels start walking?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Brad Arnett</div><div class="ubbcode-body">I'm running a 1" 3.5-10x40 Leupold on the blue rifle.....that 1 extra X makes a difference.
grin.gif

</div></div>

My bad, didn't mean to hate on your glass...
grin.gif
 
#31
Re: How quickly do thin barrels start walking?

Shot at an F-Class practice in Jan next to a guy with a Browning A-Bolt in .308. It had the no-slot Boss and was around 24" all in. Shot great through sighters and first 10 rounds, then went to making an upside down banana shaped pattern from 9 o'clock through 12 and down to 3 o'clock. Zero prediction of where in that pattern the next shot would land. When the rifle cooled off, back to 10 ring. This was a new guy just getting his feet wet, but he was able to learn that that particular barrel wasn't good for the 22 shots usually needed. For its intended purpose as a hunting rifle it was very impressive, though. AG
 
#32
Re: How quickly do thin barrels start walking?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TargetTerror</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ORD</div><div class="ubbcode-body">However, a thin, "pencil" barrel on any rifle will begin to throw rounds the hotter they get. The thinner they are, the faster they will heat up and the faster accuracy will deteriorate. Not a whole lot you can do about it other than make sure that the barrel is, in fact, completely free-floated. You should check this with both a cold barrel and a hot barrel. Depending on how much relief you have between the barrel and the stock on a cold barrel, when you heat things up, you may get some interference. </div></div>

Yea I ran a dollar bill under the barrel after ~10 rounds and it was still floated. </div></div>

That's only 1/2 the test. Put the same pressure you use to shoot, then try the dollar bill test. Sometimes a stock will be fine until pressure is put on it from underneath (from a bipod or bags for instance) which causes it to flex upwards and create contact with the barrel.
 
#33
Re: How quickly do thin barrels start walking?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: eleaf</div><div class="ubbcode-body">That's only 1/2 the test. Put the same pressure you use to shoot, then try the dollar bill test. Sometimes a stock will be fine until pressure is put on it from underneath (from a bipod or bags for instance) which causes it to flex upwards and create contact with the barrel. </div></div>

So I don't quite get how the presence of a bipod or bag affects things. If the first 1/2 (if you will) is where it touches completely free floating in space (so no pressure anywhere), then do you mean the pressure exerted from resting the stock in position? I did the dollar bill test with the front and rear of the rifle on sandbags, but of course the only weight pushing down was the weight of the barreled action itself (which is minimal b/c this is a thin pencil barrel.
 
#34
Re: How quickly do thin barrels start walking?

I was able to strengthen and free float my M70 so that I could use a bipod effectively, and I liked not having to buy a heavy tactical stock since I'm hunting with it. But before that, even with the barrel floated, the recoil with a bipod caused the forearm to contact the barrel ... sprayed like a shotgun. I think that's what he's talking about. Floating alone is not a cure-all. I like to make sure there is <span style="font-style: italic">plenty </span>of clearance and that the forearm is strong.

I'm doing the same thing to my Marlin XS7. I bedded an aluminum rod into the Marlin's forearm and am applying Devon in the open channel beneath the barrel, and actually bedding the first inch or inch and a half of the barrel along with the recoil lug. The rest of the barrel will be floated. I want to see what I can do with a lightweight stock and sporter barrel before swapping to a heavy barrel and aftermarket stock. Or before buying a heavy-barreled 10FCP or 700 SPS-V.
 
#35
Re: How quickly do thin barrels start walking?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TargetTerror</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: eleaf</div><div class="ubbcode-body">That's only 1/2 the test. Put the same pressure you use to shoot, then try the dollar bill test. Sometimes a stock will be fine until pressure is put on it from underneath (from a bipod or bags for instance) which causes it to flex upwards and create contact with the barrel. </div></div>

So I don't quite get how the presence of a bipod or bag affects things. If the first 1/2 (if you will) is where it touches completely free floating in space (so no pressure anywhere), then do you mean the pressure exerted from resting the stock in position? I did the dollar bill test with the front and rear of the rifle on sandbags, but of course the only weight pushing down was the weight of the barreled action itself (which is minimal b/c this is a thin pencil barrel. </div></div>

When a bipod is mounted and then properly loaded, some stocks will flex causing the stock to contact an otherwise free-floated barrel. The idea is to get your rifle shouldered and load the bipod and then have someone run the dollar bill test to ensure that your barrel is still free-floated with the additional weight/force added to the stock. Same for the use of bags, etc. all of which can exert forces on the stock and possibly cause an otherwise free-floated barrel to make contact with the stock.
 
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