Advantages of a 16" bull barrel....

[late08]

I am taking a look at some M4 style rifles. I am not set in choosing the model or manafacturer yet, but I came across this model from DPMS.

http://www.dpmsinc.com/firearms/firearm.aspx?id=12

DPMS Panther Bull sweet 16".

What is the advantage of this gun? I know that a bull barrel can help with accuracy via heat dissapation, etc....but with a 16" barrel how good can this be for target shooting? Is it just a more accurate version of the non-bull version? I also know that its .223 and not 5.56, so thats another question altogether, but I can answer that myself.

I guess what I am trying to get at is, what is this style generally used for, .223 bull barrel....16, 20 or 24"?

Thanks for any insight.

 

[Jake L]

It makes the gun very heavy and eliminates muzzle rise and stainless steel barrels are very accurate. It also looks cool if you’re not into the M4 or Hbar look. I have built many custom guns in this configuration.
If you are really interested contact me and we can put something together.
413 579 1994 also take a look in the dealer area on NES under JDL Sales.

 

[Admin]

20" to 24" is pretty common.

 

[PaulD]

My understanding of the reason for a heavier barrel is that it tunes out harmonics. Harmonics cause the barrel to vibrate and this reduces accuracy. A longer barrel will vibrate more and a lighter barrel will vibrate more. So, in this way a 16" bull barrel makes sense. However, a shorter barrel will give you less muzzle velocity (much in the way a short stroke engine gives less power, all else being equal).

There are compromises. I know Rock River sells an 18" bull barrel AR and the M&P15FT has a 16" heavy barrel that's not quite a full on bull barrel.

JDL Sales can obviously lay out those options better than I can.

 

[Jake L]

The M&P15 has a barrel that is smaller in dia. then the standard M4 barrel it is not a heavy barrel it is only a thread-less barrel that S&W dreamed up for the Mass compliant gun. The non-mass guns all have standard M4 barrels. The Performance Center guns are SS .920 dia. barreled. The Mass. M&P15 barrel is .741 and the standard M4 barrel is .750, the heavy Hbar barrel is tapered from as large as .980 at the start to .700 at the end, a bull barrel is .920 and a light, barrel is .560. Some 12" bull barrels start at .920, however step down to .750 at the gas block through to the end.
A bull barrel does tame the harmonics, however in a 16" barrel it really is the weight of the barrel that makes the difference. That is what tames the recoil "mass" You also must free float a bull barrel.
Once you start thinking about a 600 meter Sub MOA gun it is at least 18" and ideally 24" even 26” Stainless Steel .920 target crowned at the end barrel. This is when concern about harmonics and vibration make a difference.

 

[PaulD]

I don't mean to be argumentative but this barrel:

certainly looks heavier than this one:

Did I miss something? Is the diameter over the whole length important or the weight towards the end? Thanks.

The M&P15 has a barrel that is smaller in dia. then the standard M4 barrel it is not a heavy barrel it is only a thread-less barrel that S&W dreamed up for the Mass compliant gun. The non-mass guns all have standard M4 barrels. The Performance Center guns are SS .920 dia. barreled. The Mass. M&P15 barrel is .741 and the standard M4 barrel is .750, the heavy Hbar barrel is tapered from as large as .980 at the start to .700 at the end, a bull barrel is .920 and a light, barrel is .560. Some 12" bull barrels start at .920, however step down to .750 at the gas block through to the end.
A bull barrel does tame the harmonics, however in a 16" barrel it really is the weight of the barrel that makes the difference. That is what tames the recoil "mass" You also must free float a bull barrel.
Once you start thinking about a 600 meter Sub MOA gun it is at least 18" and ideally 24" even 26” Stainless Steel .920 target crowned at the end barrel. This is when concern about harmonics and vibration make a difference.

 

[Jake L]

closed

 

[Admin]

Does S&W only offer their M&P uppers with a 1/9 twist?

 

[PaulD]

No, the diameter of the M4 barrel is .750 except for the small area turned down for the grenade launcher and at the end. The total profile of the barrel is .750. The S&W barrel is .741. The M4 barrel is also not considered a heavy barrel; however both the S&W barrel and the M4 barrel are heaver then the light barrel. The heavy barrel or Hbar profile can start at .980 and taper to .700 this is what is referred to as a heavy barrel. The next heaver barrel is a Bull Barrel this is .920 some models of the bull barrel can taper at the end.
I hope this will clear this barrel thing up.

Thanks. That does clear it up.

 

[PaulD]

Does S&W only offer their M&P uppers with a 1/9 twist?

They have at least one that has a 1/7 twist.

 

[Jake L]

closed