Remington 700 Break in? Shot it hot

[SniperJon]

So I brought my brand new 700 SPS out yesterday to sight it in for hunting next weekend. It's chambered in .300 Rem Ultra Mag. I didn't do any research on break in procedures and got excited to shoot it when I got out there. I went through 20 rounds in less than an hour, let it cool a little but some shots were right after the other. After some research after the fact, I'm worried I may have caused damage to the barrel. What kind of conditions are these barrels built to withstand and after cleaning it good should I have peace of mind that it's fine?

 

[Fremmer]

Your barrel will be fine. Your shoulder, on the other hand.....lol.

 

[a-sheepdog]

I don't think that you did any harm to your barrel unless it got so hot that it warped, and that seems unlikely. The main thing is to get the copper out of the barrel. Clean it good and get the bore and barrel clean and you should be fine. On a hunting rifle I don't think that the shoot one and clean procedures are near as important as with a DMR. Don't worry, your 700 will still shoot just fine. Good luck on your hunt.

 

[Horsemany]

20 shots in an hour wont hurt anything. In the future shoot 3 shot groups leaving a minute or two between shots. Cool for 5 min. between groups. Never shoot a barrel you can't keep your hand on comfortably.

 

[dakotasin]

concur w/ these guys - you did no damage.

how did the gun shoot w/ the hot barrel? if your poi shifted, free float the barrel...

in my sporting rifle competitions i routinely run 40 - 50 rounds thru the gun in about 15 - 25 minutes. and then do it again the next week...

 

[Dr. Tad Hussein Winslow]

Breakin, schmake-in, keep shootin.

 

[Big_E]

I wouldn't worry about it, I felt the same way when I got my first centerfire.

I shot a bunch of rounds and it got hot. But it still shoots great, even after the 2nd time I put about 40 rounds through it in 1 1/2 hours. If the barrel isn't starting to turn orange I think you're not going to cause serious damage to it.

 

[MCMXI]

Never shoot a barrel you can't keep your hand on comfortably.

Why not? Are you concerned with a loss of accuracy or increased wear. I'd be interested in seeing some theory to back up that claim.

I calculated the increase in bore size of a stainless steel .308 barrel at the following temperatures ... assuming 0.3080" at 80°F.

100°F > 0.3080"
200°F > 0.3083"
300°F > 0.3085"
400°F > 0.3087"
600°F > 0.3092"
800°F > 0.3096"
1000°F > 0.3100"
1200°F > 0.3105"

Now consider that the melting temperature of steel and/or stainless steel is around 2500°F and that high temp creep doesn't occur until the lower critical temperature for the solid solution phase at around 1300°F (approximately half the melting temperature) I'm left wondering how you came up with that recommendation. I won't pretend to know what the critical temperature is for a barrel in terms of accuracy and longevity, but I'll bet it's a lot higher than "a barrel you can't keep your hand on comfortably" which is most likely less than around 120°F. I regularly shoot rapid fire stages in our matches which are 10 rounds in 60 seconds (200 yards) or 70 seconds (300 yards) and the barrel is WAY too hot to touch at the end of the string with no adverse affect on accuracy. I haven't taken any measurements but I'd guess that the barrel could reach temperatures in excess of 350°F but so what.

 

[Horsemany]

Why not? Are you concerned with a loss of accuracy or increased wear. I'd be interested in seeing some theory to back up that claim.

Throat erosion. It's just the gauge I use. I picked it up years ago when I got serious about benchrest shooting. If you believe metals get softer when they get hot then my technique protects the throat from flame cutting by not shooting the barrel hot. I'm sure my recommendation is overkill to some degree. I changed out M60 barrels for Uncle Sam that were cherry red. We used them again after they cooled but it's hard to determine accuracy or throat erosion with them.

Remember the temperature of the top of your barrel is a lot less than the inside of your bore. Especially the first 10"-12". Like I said, it may be overkill but I'll never shoot out a throat by shooting too hot.

Go to any benchrest match and watch what lengths we go to keep barrels cool. Mini fans and alcohol soaked rags are used. Heat affects accuracy without question. The less internal stresses on the barrel and bedding the less heat effects accuracy IME. This is why benchrest matches are timed events. Shooting inside the allowed time is the challenge. It's about how you manage barrel heat and wind conditions.

 

[HOUNDDAWG]

Horsemany wrote:

"Remember the temperature of the top of your barrel is a lot less than the inside of your bore. Especially the first 10"-12". Like I said, it may be overkill but I'll never shoot out a throat by shooting too hot."

It takes only seconds for the heat sink effect to draw those "chicken fryin' temps" away and into cooler metal. This wasn't possible with sustained M 60 fire when Charlie was overrunning our positions which is why the cutting torch effect was a factor with our belt-fed squad weapons, but not with our favorite rifles.

The main reason for allowing the barrel to cool between shots (while still working with a warm barrel) is the universal goal of one ragged hole consistency.

 

[MCMXI]

Heat affects accuracy without question.

I'd change that to INCONSISTENT heat affects accuracy which is basically what HOUNDDAWG just said. It's much easier to maintain a barrel at ambient temperature (by cooling with various methods) than it is to maintain a barrel at a specific elevated temperature such as 100°F, 200°F, 300°F, 400°F etc and I believe this why all of you benchrest shooters go to great lengths to cool the barrel.

For all practical purposes, I'm still not convinced that throat erosion is much more severe with a hot barrel versus a cool or cold barrel but if anyone has some data they'd like to share rather than speculation and intuition then I'm all eyes and ears. If you look at Young's Modulus for instance, it doesn't change that much with temperature i.e from 70°F to 500°F or even 1000°F. Hardness and Young's Modulus are related so I have my doubts that there's a significant difference in throat erosion between barrels at 100°F or 500°F.

 

[Horsemany]

Since you have all the data of Young's modulus maybe you could tell me what the flame temperature is of a 7mm Rem Mag round. That way I don't have to rely on "speculation and intuition" like the rest of the folks who use the hand method. What temperature is the throat area after 10 rounds rapid fire?

I've taken my infrared temp. gun to matches but have not always trusted the data. It's hard to get accurate reads on round things. I use it to keep temps consistent but dont' trust the actual numbers.

Even if you don't believe heat can speed throat erosion surely you cannot deny better groups with a cooler barrel on factory sporting rifles. I have A LOT of rifles. Not one shoots better with a hot barrel. That's not "intuition or speculation".

 

[MCMXI]

Even if you don't believe heat can speed throat erosion surely you cannot deny better groups with a cooler barrel on factory sporting rifles. I have A LOT of rifles. Not one shoots better with a hot barrel. That's not "intuition or speculation".

I think you missed my point earlier but I'll state it again in a different way. All flow (flux) requires a gradient be it temperature, pressure, elevation, concentration etc. If you plot the flux or flow of heat from a hot barrel, you don't get a linear function, what you get is exponential decay. So the rate of change of the temperature of a very hot barrel is a lot faster than a moderately hot barrel which is a lot faster than a cool barrel. In other words, for thermal stability, either shoot very fast or very slow.

If you believe that the coefficient of kinetic friction changes as a function of temperature, then it's reasonable to assume that bullets leaving barrels with different temperatures will have different velocities (everything else being equal). So my point is, IF you could maintain a barrel at 100°F and shoot 10 rounds, then at 200°F and shoot another 10 rounds, then at 300°F and shoot another 10 rounds etc, what affect will each increase in temperature have on precision AND accuracy? I bet it's not much if anything at all. Also, if you shoot fast enough, there's a much better chance that the barrel temperature is relatively constant.

I have no idea what "the flame temperature is of a 7mm Rem Mag round" so you're on your own with that one. Your "experience" that you draw upon isn't even close to a scientific method so let's keep things in perspective.

 

[Horsemany]

Your "experience" that you draw upon isn't even close to a scientific method so let's keep things in perspective.

I guess I missed the OP's request for scientific data on the issue. I was simply giving some advice based on how I and others I shoot with assess acceptable barrel temperatures in general. If you don't agree with my advice that's fine I'm not losing sleep over it. Do you have anything to add to the OP's question? How do you determine proper barrel temps? We'd all like to here the algebraic equation and bring our calculators to the range. Gotta go find my pocket protector.


Another thread full of shooters who use the same unscientific method I do.

http://http://www.24hourcampfire.com/ubbthreads/ubbthreads.php/ubb/showflat/Number/3402081/gonew/1/7mm_remington_mag_hard_on_bbl_#UNREAD

 

[MCMXI]

Do you have anything to add to the OP's question?

Yep ...

1. Disregard Horsemany's "Never shoot a barrel you can't keep your hand on comfortably" axiom. I don't know about you, but I can't keep my hand "comfortably" on a barrel that's 140°F.

2. If you're concerned about throat wear, try to find data on throat wear at elevated temperatures rather than listen to unsubstantiated anecdotal evidence. Also, try to find a comparison in throat and barrel life between a barrel shot hot to very hot and one shot cold. Good luck with that.

3. If you're concerned with accuracy and precision, try to keep as many of the variables as constant as possible. For rapid fire stages, the barrel will be close to steady state so practical accuracy will NOT be an issue. If you want proof of that, I can PM you numerous targets shot in 30-shot strings in under 3 minutes in sunny 90°F ambient temperatures. Let me assure you, the barrel was MUCH hotter than 300°F and probably closer to 400°F and yet accuracy was easily under MOA and in many cases under 0.5 MOA and that's for 5-shot groups. I'm not talking about neat little benchrest targets with convenient aiming points either, I'm talking realistic, real world targets i.e. human faces.

4. Good luck with whatever you decide to do.

 

[Horsemany]

1. Disregard Horsemany's "Never shoot a barrel you can't keep your hand on comfortably"

That's not just my guideline. It's used by THOUSANDS of shooters. Methinks someone doesn't want to admit they've been toasting the throat on their barrel.

 

[MCMXI]

That's not just my guideline. It's used by THOUSANDS of shooters. Methinks someone doesn't want to admit they've been toasting the throat on their barrel.

Thousands of shooters don't use a bore guide. Thousands of shooters clean the barrel from the muzzle. Thousands of shooters have their scope sitting too high above the bore. Thousands of shooters don't have their scopes mounted with the proper eye relief. Thousands of shooters don't lap their scope rings. Thousands of shooters break in a new barrel. Thousands of shooters don't break in a new barrel. Thousands of shooters don't wear safety glasses. Thousands of shooters don't wear hearing protection. Thousands of shooters only shoot from a bench. Thousands of shooters only shoot 3-shot groups. Thousands of shooters single load every round. Should I go on?

Try thinking for yourself ... you might like it!!

I have no interest in benchrest shooting since it won't help me protect myself of those that I care about. I'm still not convinced that accelerated throat wear is an issue with rapid fire drills, but let's say it is for the sake of argument. I'd still rather spend $300 every 3000 rounds to have my chamber recut rather than every 5000 rounds if that's the price to pay to acquire the skill of putting 10 shots in a sub MOA group in under 60 seconds on targets anywhere from 100 yards to 1000 yards.

 

[Horsemany]

Thousands of shooters don't use a bore guide. Thousands of shooters clean the barrel from the muzzle. Thousands of shooters have their scope sitting too high above the bore. Thousands of shooters don't lap their scope rings. Thousands of shooters break in a new barrel. Thousands of shooters don't break in a new barrel. Thousands of shooters don't wear safety glasses. Thousands of shooters don't wear hearing protection. Thousands of shooters only shoot from a bench. Thousands of shooters only shoot 3-shot groups. Thousands of shooters single load every round. Should I go on?

No thanks. One key difference here. Not shooting your barrel hot has can hurt NOTHING. Your examples all have negative consequences which is the difference.

 

[MCMXI]

Moderators, Horsemany and I have agreed to a truce via PM. We apologize to the OP for the direction that this thread has taken but hope that some good has come out of it. We'll be on our best behavior from now on.

My apologies to all and no malice or disrespect was intended in my replies to you Horsemany.

 

[Evenflo76]

Try this

http://www.youtube.com/watch?v=TRRahHX9Zkg

 

[RoostRider]

Wow... all the guy asked was if we thought he wrecked his barrel.... let's find the common ground here, which happens to be the subject of the thread (not barrel temps and theories/facts on accuracy)

Universally we agree.... no, you did not wreck your barrel....

And don't forget to wear your hearing protection and clean the barrel from the chamber side...

 

[Average Joe]

As long as it didn't turn cherry red, like my M-60 used to, its OK...

 

[mljdeckard]

I would not be concerned at all.

There are those who talk about 'breaking in' precision barrels, but I have found little difference between barrels I have run 100 rounds through, not letting it hit full temp, 10 rounds, or none at all.

The idea of breaking in a barrel is that you are burnishing the bore, lapping off the microscopic burrs left over from the process of cutting the rifling. IF this is a significant factor, I think most of the problem is solved with the first ten rounds. I also think that modern barrels are made to a higher standard, and this process is not as necessary as it was, say, 20 years ago. These days competition has made it so that pretty much any brand-name rifle is good for 1 MOA or better out of the box. (That rifle is probably more like 1/2 with match ammo.) As for the temperature, if that kind of fire ruins a barrel, I've probably destroyed a dozen or so SAW barrels over the years.

 

[Offfhand]

Your rifle is fine, worry not. But some of the responses to your question prove once again that thanks to the internet some dumb old shooting myths are alive and well and being spread faster than ever.

 

[Uncle Mike]

While these guys debate over heat and accuracy...you'd better send me your SPS...chances are you have trashed your barrel and I wouldn't want you to be disappointed thereafter. hehehehe

I'll even pay the shipping....!


Your barrel is Fine and dandy...yes, I did say dandy!

Probably did it some good...! Shoot away, have fun!