New Bang Stick Build

Well, I decided to build a AR10/M110 SASS weapon after some discussion on here. Bought a stripped lower receiver today from Palmetto State Armory for $79.99 and having it shipped to my FFL.

The finished weapon will have either a 16" or 18" barrel. Haven't decided yet, but leaning heavily toward the 18" for added yardage. Finished weapon will look a lot like this.



Looking forward to shooting it.

Dale

 

To build one, I sell one. Just trying to decide what's going. Choices are a MK12 type AR15 or my M21. Leaning to the MK12 as I can always build another if needed.

Decisions, Decisions...

Dale

 

Fully understand. I have some weapons that will never get sold (MP5, M40, Winchester Model 70, etc.) because I want my kids to have them latter. The rest are commodities.

Dale

 

Dale: That looks sweet. Let us know how it turns out.

My situation is similar with my Nephew being the beneficiary of my " Collection ", which is exactly the term I use. When asked "How many guns do you have?" my response is " the start of a nice collection."

 

I have five long guns: two 10-22's, a bolt-gun in .30-06, an autoloading carbine in 5.56X45, and a 12-gauge slide-action shotgun. Other weapons include a 9 mm autoloading pistol, Martin D-28, and a Gibson RB-250. If I bought another firearm, I'd have to buy more dies for it, and I already am unable to re-load .22LR or 12-ga shotshells.
Besides, look at my signature!

 

Bump...

Assembly begins this week FINALLY!

Dale

 

You are tired of hearing Old Geezer say it: The 9mm and the .308 are not diminished bullet-energy-wise when shorter barrels are utilized (barrel volume / case volume ratio; "Will my barrel burn this powder?").

Loud? OK, so Yes, but hey we're talking about saving your keister, right? Right!

Centuries ago I could have bought an Argentine FAL (yes, metric) for $350; 7.62 NATO. Could kick me arse for not buying it. Reality was that I kept getting the wifer pregnant. My ancestors slapped their knees, pointed, and laughed at me. Never invoke God's sense of humour, for it is pitch black. (If I slip into British, just noticed, God only knows how many Brits and South Africans I've worked with, been around, Holy Christ; how many lives have I led?, lost track).

 

"Give me a sniper rifle and I'll take out platoons."

-Some guy on mysurvivalforum.com

 

OG, I'm not sure what you are talking about as the shorter the barrel the lower the velocity and the lower the velocity the lower the energy on target (Foot/pounds).
If your referring to powder burn within the barrel, that depends more on the type of powder, barometric pressure, air density and weight of projectile being fired. Optimal barrel length for long range target shooting is I think 28 inches, with the 308 Win/7.62mm NATO.

If accuracy could be maintained with shorter barrels in this round the medium weight machineguns (M60, M240) would both have short barrels. The M60 barrel is 22 inches, while the newer and more accurate M240 has a barrel length of 24.8 inches in the basic model and a slightly shorter barrel of 21.7 inches in the B, G and L models. These weapons maintain a 1000 meter range with these barrels. The U.S. Army sniper rifle M24 started with a 24 inch barrel and the latest model of this weapon M24A3 has a 27 inch barrel for added velocity and range. Even the M110 SASS (sniper rifle) has a 20 inch barrel and it was primarily designed for urban sniping environments with fast, multiple target engagements.

If I have not covered what you are referring to, I would love to discuss this with you further.

My choice of a 18 inch barrel allows me to engage targets out to 1000 Yards (915 meters) with the M118LR ammo (175gr BTHP) and keep a killing energy over 500 foot/pounds.



Tomorrow, I paint.

Dale

 

https://www.shootersforum.com/threads/does-all-the-powder-burn-in-the-barrel.35025/

"Expansion Ratio (ER) = (Barrel Volume (Vb) + Case Volume (Vc))) / Case Volume (Vc)"

With this formula, one holds the powder burn rate at a constant.

When taking into consideration powder burn rates and holding the other parameters at fixed value, obviously the faster the burn, the less length of barrel needed. Slower powders require long barrels to burn most of the powder.

When looking at bore volume, the greater the caliber, the greater the volume. When a barrel is bored for a small diameter cartridge then to get the bore volume up (remembering that th larger the bore volume, the greater cubic area within which the powder can be burned) one has to go with a longer barrel.

If you have a large case filled with slow-burning powder and the bullet diameter is small, then one is going to need a longer barrel to burn all of this powder.

Let us compare the burning of the exact same powder in a 7mm-08 vs. the .308. The 7mm is a necked down .308. With powder burn rate kept the same and barrel lengths kept the same. The bore volume of the 7mm will not allow as much powder to be burned as will the bore volume of the larger diameter .308. If one takes the .308 case and necks it down to the .243, then with our barrels kept at the same lengths, the bore volume of the .243 is far less than a .308 barrel. Cutting off two inches of a .308 barrel does not affect the bullet velocity as would the cutting off of two inches of a .243 barrel. The .243 is an overbore cartridge. See link below, it concerns the overbore phenomenon.

https://rifleshooter.com/2016/04/243-winchester-effect-of-barrel-length-on-velocity/
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Sir, your equation is only for expansion ratio of the propellent and is only a part of kinetic energy. Any barrel that is only long enough to allow the propellent to combust fails to utilize the expanding gas in the barrel to it's maximum potential. Where the barrel ends is where the expanding gas ceases to propel the projectile. Which decreases any rounds potential kinetic energy, thus decreasing the rounds velocity and terminal energy.

Please note the above chart on barrel lengths and velocity. The longer the barrel, the greater the muzzle velocity. I am not an engineer so I don't remember all of the calculations for things like kinetic energy, velocity, trajectory and terminal energy. I am a U.S. Army trained sniper and understand what it takes to calculate and place rounds on target, down range.

This article explains it far better than I can. https://gundigest.com/gear-ammo/reloading/bullet-ballistics

Dale

 

"Longer the barrel, the greater the muzzle velocity." Sure, but velocity varies with case volume vs. barrel bore volume, when holding powder burn rate steady."

I am in engineering, and medical technology, and ...

Not trying to be a smart@$$, just that I live in a world of numbers. I made straight A's in calculus. It's how I'm wired. I guess we shouldn't argue over the minutia. When cartridge manufactures and rifle manufacturers are working out the numbers, they must pay attention to the minutia. When working on cartridge / loads, my fellows were all trained in engineering, so we no doubt appeared to be speaking Greek to the other folk at the rifle ranges. Friend of mine designed and build his own circuit board for his chronograph (he was an electronics design engineer, we worked for one of the big internationals).

When out shooting or reloading, one needn't re-invent the wheel.

Friend of mine also went the medical route after leaving our company. His world became a world of seriously advanced physics, however. In meetings, it wasn't just engineering folk who were there. Nope, there were theoretical physicists there. He told me that when they were talking shop, he was totally left in the dirt. He said he might as well had gotten up and gone to get everyone a cup of coffee. I've had friends with IQs that were above 160; often I only marginally keep up with what they were talking about. Everything is relative.

Oh by the way, very intelligent people actually do have a tendency to go bat-sh## crazy. One of my degrees is in psychology, so I pay attention to brain/behavior quirks of the "Beautiful Mind" people. Seen it happen to several men with whom I've worked. Worked with a Harvard PhD., he couldn't stick his finger in his @$$ concerning day-to-day common sense matters and he had a marginal personality ... on a good day. Asperger's Syndrome plays into it heavily. Neurologically, it would appear that one actually does have to rob Peter to pay Paul. Glad I'm not as smart as that crew!
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I was responding to your original post: The 9mm and the .308 are not diminished bullet-energy-wise when shorter barrels are utilized (barrel volume / case volume ratio; "Will my barrel burn this powder?").
It appears that now your comparing different rounds and not one round (308 Win). I agree, different cartridges have different burn times no different than different loadings in the same caliber have different burn times. What specifically are your referring to as bullet energy (i.e. Kinetic energy, peak pressure, terminal energy, ???)

I also stated I wasn't an engineer, not that I don't understand engineering. I raised 2 engineers (aerospace engineer & biomedical engineer) so engineering isn't a foreign concept for me and I also had higher math in college.

Dale

 

Neither the 9mm, nor the .308 are overbore cartridges. If one puts a longer barrel on cartridges such as the 9mm or the .308, the velocity will go up, but not as much as overbore cartridge types such as the .243 Win. Keeping powder burn rates the same, if one cuts 2" off a .308, the result will be a small difference in velocity. Cut 2" off a .243 and you will lose significant velocity. This phenomenon is well known throughout the shooting world.

https://www.shootersforum.com/threads/overbore-whats-that.47361/

https://www.longrangehunting.com/threads/overbore-index-chart-26-nosler.137236/

 

Dale