7.5" to 10" SBR - Barrel Life Expectancy?

[MarcSpaz]

Guys and Gals,
Help me here... I have been interested in an SBR for some time now. I was blessed to experience several different types thanks to a member of this forum. I was able to make some better choices based on his knowledge and actually firing those weapons.

I was going to buy an AR pistol with a 7.5" barrel in 5.56. My thought was to register it with ATF as an SBR. This would allow me to own the weapon and have it in my possession (as a pistol) while I waited for my tax stamp to come in the mail. So, I headed off to the store to make a purchase today and the sale guy said something I flat out don't believe is true. So, I left empty handed.

We were having a bit of chit chat when I asked about barrel life. He said it was only good for about 1,000-1,500 round before they get shot out. I asked him if he meant 15,000 and he reiterated 1,000 to 1,500.

Well, I go through 1,500 round in 5 or 6 trips to the range. I figured I would be buying $250-$350 barrels ever 3 months. I didn't want to insult the guy by asking for the manager, so I just left.

So, what is the truth? Did the guy talk me out of an AR pistol because he is right or because he has no idea what he is talking about?

Thanks,
Spaz

[MarcSpaz]

Forgot to mention. He said a 10.5" will go about 5,000 rounds. I was considering the 10.5" because of the lower noise/pressure and flash levels when the projectile leaves the barrel.

I guess I am having trouble believing it because 16" chrome lined AR barrels are good for 20,000 rounds if kept cool (so I have heard. LOL). I am missing why the barrel length would impact the life.

[Palladin]

Hmmm I have no experience with this, and no idea what the answer is.

My gut says if it's erosion affecting accuracy not function, get two barrels, one for tacks and one for hosing.

stuff to read while waiting for jd to give you the scoop...

http://www.thetruthaboutguns.com/2013/1 ... -accuracy/
http://www.sadefensejournal.com/wp/?p=1093
http://www.shootingvoodoo.com/index.php ... __the_bar/

disclaimer: these articles don't help

[RO73]

The guy is obviously an operator swat green beret seal. I would shop elsewhere if I were you. I have a 7.5" and a 10.5". The 7.5" has over 6K rounds and no issues. The 10.5" is fairly new but will easily go 20K +. Get a quality barrel and you won't have to worry about it. Having shot both, I would go with a 10.5 instead of 7.5. You will get much higher velocity out of the 10.5" and should you ever want to suppress it, the 7.5" is not an ideal host.

[jdonovan]

We were having a bit of chit chat when I asked about barrel life. He said it was only good for about 1,000-1,500 round before they get shot out. I asked him if he meant 15,000 and he reiterated 1,000 to 1,500.

So first you need to define shot-out.

If this is my .308 match rifle, when my .25 MOA groups open up to .75MOA my barrel is shot out. I'm not sure the off the rack AR starts at .75MOA, so is it shot out the day it leaves the factory?

If your goal is soda cans at 20 yds on the 4-5th shot, you can probably be happy with about 10 MOA. You would probably get 100,000 rounds of life out of the barrel.

So, what is the truth? Did the guy talk me out of an AR pistol because he is right or because he has no idea what he is talking about?

Was this the same shop that sold you that ar 10?

So lets think what happens inside the barrel.

I take a 16" ar-15 and fire it--- thats baseline for this next discussion
Now I walk inside the shop and take the saws-all to the barrel and make it 7" long.
I go back outside and fire it again.

Can the chamber/case/throat/barrel/bullet tell the difference during the first 6.999999" of travel? no

So why do SBR's have a reputation for wearing out barrels faster? Because people shoot them more, and faster.

The FASTER is the key. What wears out barrells is powder/projectiles rubbing as they go down the bore. If you get the steel hotter it gets softer. Rub the now softer steel and that next burst of powder and copper will take off a bit more barrel. Get it hotter yet, and the problem gets worse.

See if you can find the manager of the store, and tell him you didn't buy this gun because of the sales guy, and won't be buying it from them. That should help get the sales guy back to a job that involves french fries.

[Reverenddel]

"So why do SBR's have a reputation for wearing out barrels faster? Because people shoot them more, and faster."- JD

This...

No difference in the mechanisms, metals, or make. SBR's are smaller, easier to carry, and a helluva lotta fun to shoot.

Otherwise? That "MallNinja" is full of "PamperProduce"

[0ne5hot]

I believe that the mass of the barrel is also at play here too; Objects with more mass require more energy to heat them to the same temp as an object with less mass. A 16" barrel has more the double the mass of a 7.5" with the same profile and material composition. So the 7.5" barrel will get hot quicker then a 16" barrel, with all other variables being the same.

[MarcSpaz]

My gut says if it's erosion affecting accuracy not function, get two barrels, one for tacks and one for hosing.

I thought about getting 2 separate uppers for my M4. One to bump fire and one for precession. I just can't seem to convince myself to add a Slidfire stock to any of my guns.

The guy is obviously an operator swat green beret seal. I would shop elsewhere if I were you. I have a 7.5" and a 10.5". The 7.5" has over 6K rounds and no issues. The 10.5" is fairly new but will easily go 20K +. Get a quality barrel and you won't have to worry about it. Having shot both, I would go with a 10.5 instead of 7.5. You will get much higher velocity out of the 10.5" and should you ever want to suppress it, the 7.5" is not an ideal host.

That good info. Thanks a bunch. I am actually wanting to get (and almost bought) the Sig P516 with the 10" barrel. That is the one I will likely end up with. Sig seems to have great quality products.

So first you need to define shot-out.

If this is my .308 match rifle, when my .25 MOA groups open up to .75MOA my barrel is shot out. I'm not sure the off the rack AR starts at .75MOA, so is it shot out the day it leaves the factory?

If your goal is soda cans at 20 yds on the 4-5th shot, you can probably be happy with about 10 MOA. You would probably get 100,000 rounds of life out of the barrel.

So, you and I have talked about this a few times and you know what I want to do, but I'll share with the class so everyone knows what I am thinking.

We talk about preparedness all the time. Poking holes in paper and ringing the metal gong is a lot of fun and will be the primary purpose. However, if we have an L.A. Riot or Katrina type situation or worse, my goal is to keep my family safe. I don't need to hammer nails at 1,000 meters; just stop the bad guys from a safe(r) distance. I think I can do that with a weapon that is a 1 to 1.5 MOA out of the box with relative comfort. If it blows out to 4 MOA, that is still a 1" group at 25 yards.

In a building, the M4 is doable, but I don't feel like it is ideal for me. That is what brought me on this magical adventure. LOL If while using an SBR, I can reliably hit a man-size target from 30 to 60 feet away... that's a win.

Was this the same shop that sold you that ar 10?

OMG no! hahahaha I'll never go there again. That whole experience was a bad dream that I never woke up from.

It was at a shop I regularly go to. Most of they folks there seem to have a clue and the owner is pretty cool. I had never worked with this guy before and I'll likely never work with him again.

See if you can find the manager of the store, and tell him you didn't buy this gun because of the sales guy, and won't be buying it from them. That should help get the sales guy back to a job that involves french fries.

That is funny! I'm friendly with the owner I'm sure if I mention it, he won't be too happy.

Thanks for all the info.

Otherwise? That "MallNinja" is full of "PamperProduce"

That is awesome! Can I use that one?

I believe that the mass of the barrel is also at play here too; Objects with more mass require more energy to heat them to the same temp as an object with less mass. A 16" barrel has more the double the mass of a 7.5" with the same profile and material composition. So the 7.5" barrel will get hot quicker then a 16" barrel, with all other variables being the same.

All that makes sense. Thanks for the info guys.

I'm going to head over there in a few minutes. I'll let you know how it goes.

[MarcSpaz]

Damn it! Both AR pistols are gone. All they have are already registered as SBR's with ATF.

They were slammed when I got there and there was only 30 minutes to closing time. The owner was busy doing background checks, so I didn't get to talk to him. I have to go buy some 40 S&W before Wednesday so I can head to the range. I'll go back Monday or Tuesday and talk to him. Hopefully They can order the p556 for me.

I did pickup my 44-40 rounds though.

[cwfunrider]

I have a 7.5 pistol that I built. I wish I would have built as a 10.5. The 7.5 is just a tad to short. So eventually I'll rebuild my upper to a 10.5.

I have no plans to SBR it. It will stay a pistol. I am going to add one of those Sig forearm braces though.

[MarcSpaz]

I'm wondering ,if I do the Sig brace, Is the stock really needed? I was going to buy the model that comes with the brace. I might run it like that for a few weeks before I make a decision.

One good thing about keeping it registered as a pistol... you have a full-blown AR you can legally conceal carry if you have a CHP. Might be worth keeping it a pistol for that reason alone.

[cwfunrider]

With the brace you will get what you want and get to keep your 200 bucks.

Win win.

[MarcSpaz]

Okay... I have a quick question. For those who have the 7" to 8" barrels; a couple folks said they would rather have gone with the 10"+. Why?

I ask because my local shop has a used AR pistol in .223 Wylde with a 7.5" barrel for $1,200. I was kinda bummed because I missed buying one of the new ones a few days ago. I can save at least $500 over a new one. I just need to know where the regrets are.

Thanks.
Spaz

[cwfunrider]

For me its a noise and percussion thing. The 7.5 is really close to your face when it is shouldered which is how I normally shoot it.

I have a all forward muzzle break on it but you can still feel it when it goes off.

if you ever think you want to suppress it the 10 is also much better for that.

[jdonovan]

[quote="MarcSpaz"]Okay... I have a quick question. For those who have the 7" to 8" barrels; a couple folks said they would rather have gone with the 10"+. Why?/quote]

my personal feeling is suppression on a short 5.56 is of limited purpose. If I want short and quiet, 5.56 is not my go-to choice. Also most, if not all supressor makers don't guarantee a suppressor on < 10" bbls.

But knowing you want to use this for your indoor mall-clearing ninja jobs, then you want all the short you can get.

Just remember to put the sound suppressors on your ears before you touch it off indoors.

[RO73]

MarcSpaz, I agree with the posts above but let me add one more thing. Having shot both on the same range outing, the 10.5 produced much better results at 100 yards vs the 7.5". The bullet drop on the 7.5" requires a pretty big adjustment vs the 10.5". If I were to use either for a shtf scenario, it would be my 10.5" hands down.

[MarcSpaz]

JD, how long was the barrel on that 300? That seemed like a good length and suppressed without hearing protection was good, even with the rounds that were not sub-sonic.

I was looking at this too... http://www.sigsauer.com/CatalogProductD ... 00blk.aspx

Should I just build my own in a 10" in 300 blackout?

[jdonovan]

9" by AAC in 300 blk.

you can't compare the 300 and the 5.56 the pressures they have at the muzzle are quite different even at the same barrel length, and that is what is making the noise.

short range, suppressed.. its hard to beat a 300 blk.

BUT for what its worth... speed + weight = energy.

900 FPS 220gr 300 blk vs 900 FPS 45 ACP... same energy.

Don't discount the viability of a pistol caliber upper.

[Reverenddel]

I know from experience that a 12" bbl will be a bit more accurate, and you drop accuracy as you shrink the barrel.

A 10.5" bbl is a good length.

As to it wearing out the barrel, I'm still not convinced that a SHORTER barrel would... Maybe the FREQUENCY of shooting would validate that, but if you shot 1000 rounds out of a standard bbl, and then 1000 out of a shorter bbl...

The Shorter bbl would have less "bullet time", and "Powder time". So heating up would probably be a touch less. Not "comfortably put your hand on it.", but less in regards to the BT/PT situation.

And as to .300 Blackout, I love the round, but the Military SOCOM is using 6.8 cal as a standard in most cases. I'm thinking of ease in obtaining rounds.

[MarcSpaz]

9" by AAC in 300 blk.

you can't compare the 300 and the 5.56 the pressures they have at the muzzle are quite different even at the same barrel length, and that is what is making the noise.

short range, suppressed.. its hard to beat a 300 blk.

BUT for what its worth... speed + weight = energy.

900 FPS 220gr 300 blk vs 900 FPS 45 ACP... same energy.

Don't discount the viability of a pistol caliber upper.

The 45 was awesome to shoot. Low recoil, suppressed it was very quiet, and the weight and length were good. The problem is, I'm note sure I can afford a quality .45 SBR. And I wouldn't even have the slightest clue where to start with finding and buying a quality .45 ACP AR style pistol. Well, maybe except for asking here.

Anyone know if such a creature exists? Something that looks like a .45 SBR, but is a pistol? Is that something I should build?

AND... as bad ass as the 45 was... the 300 blackout was the top contender out of all the weapons I tried. I was giving in to the 5.56 pistol because I had cash and it was there, but I still prefer the 300.

It's funny... two days ago, I thought I knew what I wanted.

I know from experience that a 12" bbl will be a bit more accurate, and you drop accuracy as you shrink the barrel.

A 10.5" bbl is a good length.

As to it wearing out the barrel, I'm still not convinced that a SHORTER barrel would... Maybe the FREQUENCY of shooting would validate that, but if you shot 1000 rounds out of a standard bbl, and then 1000 out of a shorter bbl...

The Shorter bbl would have less "bullet time", and "Powder time". So heating up would probably be a touch less. Not "comfortably put your hand on it.", but less in regards to the BT/PT situation.

And as to .300 Blackout, I love the round, but the Military SOCOM is using 6.8 cal as a standard in most cases. I'm thinking of ease in obtaining rounds.

12" and 14" barrels just wont get me where I want to be. I am trying to keep the barrel as short as possible while still being affective and quiet. For the most part, my M4 with the 16" barrel isn't bad. It has an overall length of 32" with the stock collapsed... but if I stick a 5" to 7" can on it, now its just way to long for in a house.

So, I really was thinking that I would get an AR that was long enough to have good accuracy and work well with a can, but be at or under 32" overall once the can is on it. That leaves me with very few options. I figured an SBR or AR pistol with a 10" barrel with a 5 inch can would put me right at 32" overall.

As far as the life of the short barrels go, Based on everything you guys are telling me... the guy at the shop had no idea what he was saying. I don't mind replacing a $200-$300 barrel every year or two. But monthly was not happening. LOL

I always thought 300 blackout was popular. Granted, not a NATO round, but enough of it is around, no? I just don't know. Haven't looked into it yet.

I would assume if we get to the point of worrying about pickup ammo, there are going to be some pickup weapons too.