Accuracy build help

[wilkup]

Good read.

Maximizing The AR-15: A former military armorer reveals his secrets for cutting AR-15 group sizes in half. - Free Online Library

Free Online Library: Maximizing The AR-15: A former military armorer reveals his secrets for cutting AR-15 group sizes in half.(TECH TOPICS) by "American Gunsmith"; Sports, sporting goods and toys industry Sport, sporting goods and toys industry

www.thefreelibrary.com

After reading through the article several more times, I'm wondering if you've got experience with the "enhanced" bolt systems.
I've done a bit of digging and found Lantec is a well regarded yet affordable option in black nitride or nickel boron.
Side note…
I guess all my research has been flagged somehow I can no longer open that link from my phone.

 

[bamban]

After reading through the article several more times, I'm wondering if you've got experience with the "enhanced" bolt systems.
I've done a bit of digging and found Lantec is a well regarded yet affordable option in black nitride or nickel boron.
Side note…
I guess all my research has been flagged somehow I can no longer open that link from my phone.

Are you referring to carrier anti tilt pads in the article?

 

[wilkup]

Are you referring to carrier anti tilt pads in the article?

Yea. I saw they make specialized bolt for this problem now.

Enhanced E-BCG® Full Auto Style (.223/5.56) | lantac-usa

IN STOCK Read our E-BCG White Paper HERE. LANTAC E-BCG®, Enhanced Bolt Carrier Group.M16 Full Auto Style for increased mass and lock time.Our new BCG is precision machined from 8620 Steel with a shot peened bolt manufactured from Carpenter 158 or 9310 and Magnetically Particle Inspected.The...

www.lantac-usa.com

 

[bamban]

Yea. I saw they make specialized bolt for this problem now.

Enhanced E-BCG® Full Auto Style (.223/5.56) | lantac-usa

IN STOCK Read our E-BCG White Paper HERE. LANTAC E-BCG®, Enhanced Bolt Carrier Group.M16 Full Auto Style for increased mass and lock time.Our new BCG is precision machined from 8620 Steel with a shot peened bolt manufactured from Carpenter 158 or 9310 and Magnetically Particle Inspected.The...

www.lantac-usa.com

That's a better option. Here's my version, I developed the same time Carlos was doing the pads. SS sleeve machined to fit the carrier with about 1/16 clearance for JB Weld to epoxy it to the carrier. I bored out and polished the buffer ID. Polishing was done with brake cylinder hone.

 

[Darryle]

@bamban is that a brass weight added to the rear of the carrier?. Did you have to play with the actual weight to get it to cycle properly? About how deep does it go into the carrier?

 

[bamban]

@bamban is that a brass weight added to the rear of the carrier?. Did you have to play with the actual weight to get it to cycle properly? About how deep does it go into the carrier?

Yes, that's a brass piece, I turned down to press fit on the hydraulic press. I had the Tubb weight for awhile till the holder for the tungsten weight busted.

The length is just flush with the M16 carrier back portion. Did not play with the weight.

 

[budlight]

Full auto heavy bolts is all I use because it reduces the impact against the buffer weight. So you need less buffer tube weights. I have Nickle boron and later switched to chrome nice steel. I also use roller cam pins after waring out hardened pieces.

These are just examples and not what or what I might have bought years ago.

AR-15 BCG, NITRIDE

Full Auto Rated BCG

androcorpind.com

Roller Cam Pin - Patriot Store - POF-USA - Bolt Carrier Upgrades

Our patented Roller Cam Pin is just one more example of how far we will go to reduce friction and drag. Eliminate cam slot wear today!

pof-usa.com

Receiver, Upper, AM-9, No Forward Assist or Dust Cover, Anodized Black

Receiver, Upper, AM-9, No Forward Assist or Dust Cover, Anodized Black

andersonmanufacturing.com

AM-15 Stripped Lower Receiver, Closed Trigger, Uncoated

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andersonmanufacturing.com

 

[budlight]

View attachment 521194

Yes that brass slug is a great fix for short gas tubes like carbine and mid length that cause the bolt to beat the cud out of the buffer tube weights. The real fix is to not create the higher pressure in the first place by having smaller diameter gas ports and or longer gas tubes.

I use the lightest standard buffer tube weights (sub 3 oz) and messed with even taking weights out. Not the H1 or heavier buffer tube weights.

Another thing I played with was the diameter of the hole on the back of the buffer tube. I reasoned that they are cheap, so I drilled the hole bigger. Bigger hole is less air compression resistance to the buffer weights travel back and less resistance to it cycling forward. I also played with springs and spring lengths. The silent flat wound are the best.

ARlife4me did some posts about what is the correct diameter for the gas hole. All my barrels were made with tiny holes down in the .068 - .070 not the monster .090 So I did some research and then thought over about what I'm doing different. The big thing is that I reload to .556 and above to the @60,000 psi level. I never shoot off the shelf 223. If I put in some cheap round from say Scheels I would have ejection problems from being way under gassed.

My advice is to reload to 556 pressure levels, buy barrels with the smallest gas tube hole diameter, and use the longest gas tubes. I've had to call the barrel manufactures and have them drill the smaller holes out at rifle length and +2 inches. I have never had to drill the hole bigger and my only adjustable gas blocks rifles are my piston guns.

 

[wilkup]

Yes that brass slug is a great fix for short gas tubes like carbine and mid length that cause the bolt to beat the cud out of the buffer tube weights. The real fix is to not create the higher pressure in the first place by having smaller diameter gas ports and or longer gas tubes.

I use the lightest standard buffer tube weights (sub 3 oz) and messed with even taking weights out. Not the H1 or heavier buffer tube weights.

Another thing I played with was the diameter of the hole on the back of the buffer tube. I reasoned that they are cheap, so I drilled the hole bigger. Bigger hole is less air compression resistance to the buffer weights travel back and less resistance to it cycling forward. I also played with springs and spring lengths. The silent flat wound are the best.

ARlife4me did some posts about what is the correct diameter for the gas hole. All my barrels were made with tiny holes down in the .068 - .070 not the monster .090 So I did some research and then thought over about what I'm doing different. The big thing is that I reload to .556 and above to the @60,000 psi level. I never shoot off the shelf 223. If I put in some cheap round from say Scheels I would have ejection problems from being way under gassed.

My advice is to reload to 556 pressure levels, buy barrels with the smallest gas tube hole diameter, and use the longest gas tubes. I've had to call the barrel manufactures and have them drill the smaller holes out at rifle length and +2 inches. I have never had to drill the hole bigger and my only adjustable gas blocks rifles are my piston guns.

Mostly went over my head with all your concepts so now I'm gonna have to dig in deeper on buffers, recoil springs, gas tube lengths for 16" barrels, etc.

 

[bamban]

Yes that brass slug is a great fix for short gas tubes like carbine and mid length that cause the bolt to beat the cud out of the buffer tube weights. The real fix is to not create the higher pressure in the first place by having smaller diameter gas ports and or longer gas tubes.

I use the lightest standard buffer tube weights (sub 3 oz) and messed with even taking weights out. Not the H1 or heavier buffer tube weights.

Another thing I played with was the diameter of the hole on the back of the buffer tube. I reasoned that they are cheap, so I drilled the hole bigger. Bigger hole is less air compression resistance to the buffer weights travel back and less resistance to it cycling forward. I also played with springs and spring lengths. The silent flat wound are the best.

ARlife4me did some posts about what is the correct diameter for the gas hole. All my barrels were made with tiny holes down in the .068 - .070 not the monster .090 So I did some research and then thought over about what I'm doing different. The big thing is that I reload to .556 and above to the @60,000 psi level. I never shoot off the shelf 223. If I put in some cheap round from say Scheels I would have ejection problems from being way under gassed.

My advice is to reload to 556 pressure levels, buy barrels with the smallest gas tube hole diameter, and use the longest gas tubes. I've had to call the barrel manufactures and have them drill the smaller holes out at rifle length and +2 inches. I have never had to drill the hole bigger and my only adjustable gas blocks rifles are my piston guns.

The brass was in one of my 20 inch service rifles for NRA/CMP where we shot from 200, 300, 600, and 1000 yards. I used to shoot 10K rounds a year in training and in matches back then. Since I quit shooting in competition, I support the TX JRs (18-24 kids) by cranking their competition barrels from Shilen donated blanks. The top shooters go through a barrel a year.

I had a carbide reamer made for them to accommodate mag length 77s, and long loaded ammo for 600 slow fire shooting 80 class bullets. When they shoot the 6 person team match at Camp Perry it is imperative that their rifles can shoot the team spec ammo to make the coaches' lives easier. Thus, it is imperative that I cut their barrels with the same reamer.

My dedicated 1000 yard service rifles, two to shoot 80 VLDs, the other to shoot 90s have different configuration from my across the course guns.

Service rifle legal by CMP/NRA rules must have 20 or less barrel length (never shot less than 20 in competition myself), 0.750 gas blocks, rifle length or shorter gas system, and no adjustable blocks. No brakes. 4-1/2 pound trigger. Winners get trigger weighed. Trigger fails, you lose


Hey, I was just trying to answer questions posted, not to debate you what works and what does not.

 

[budlight]

Mostly went over my head with all your concepts so now I'm gonna have to dig in deeper on buffers, recoil springs, gas tube lengths for 16" barrels, etc.

Okay. you pull the trigger and the bullet goes down the barrel. Peak powder pressure is achieved in the first few inches of the barrel. As the bullet is going down the barrel you have a few things happening that decrease the pressure. Cooling and an ever increasing volume. So lets say that you start out with 50,000 psi. the pressure has decreased to say 30,000 psi in a a carbine length gas tube and 22,000 in a mid length and 18,000 psi in a rifle length. Just examples.

This 30,000 psi gas goes roaring back in the gas tube and launches the bolt backwards. Using a heavier full auto bolt slows the return speed and because of the slight gap between the bolt and the buffer weight you have a hammering effect. The above brass plug increases the the total size of the bolt surface and doesn't pound a round ring around the face of the buffer weight.

If you have to use a heavy buffer weight which also slows down the cyclic rate it also would increase the hammer effect. Like you can kick a soccer ball, but you can't kick a 16 pound bowling ball.

So the pressure out on the rifle length gas tube is less. Going to a smaller diameter gas hole is less pressure to knock the full auto bolt back. The BCG is going slower and hits the buffer tube weight. The BTW can be made lighter so it's not getting beat up. I have one 20 inch gas gun with who knows 10,000 plus rounds through it and everything looks beatiful other than the nickle boron bolt discoloring from all the carbon and replacing the cam pin because it wore out. I was looking at my friends 16 inch carbine with only a few hundred rounds and the buffer weight was all beat up and the you could shake the rifle and it sounded loose. Yes, it's a cheap off the shelf gun and mine has over a $1000 dollars in parts that I put together without optics.

even with me slowing down the cyclic rate it still might be 10 rounds per second. I bought a trigger polishing kit to improve the Mil Spec heavy trigger. I polished one so well that it didn't always catch for the second shot. Sometimes it would burst fire 2-3 ever time you pulled the trigger and it was so rapid it sounded like one shot almost. I threw it in the garbage and just went to quality drop in triggers. LOL

 

[wilkup]

Okay. you pull the trigger and the bullet goes down the barrel. Peak powder pressure is achieved in the first few inches of the barrel. As the bullet is going down the barrel you have a few things happening that decrease the pressure. Cooling and an ever increasing volume. So lets say that you start out with 50,000 psi. the pressure has decreased to say 30,000 psi in a a carbine length gas tube and 22,000 in a mid length and 18,000 psi in a rifle length. Just examples.

This 30,000 psi gas goes roaring back in the gas tube and launches the bolt backwards. Using a heavier full auto bolt slows the return speed and because of the slight gap between the bolt and the buffer weight you have a hammering effect. The above brass plug increases the the total size of the bolt surface and doesn't pound a round ring around the face of the buffer weight.

If you have to use a heavy buffer weight which also slows down the cyclic rate it also would increase the hammer effect. Like you can kick a soccer ball, but you can't kick a 16 pound bowling ball.

So the pressure out on the rifle length gas tube is less. Going to a smaller diameter gas hole is less pressure to knock the full auto bolt back. The BCG is going slower and hits the buffer tube weight. The BTW can be made lighter so it's not getting beat up. I have one 20 inch gas gun with who knows 10,000 plus rounds through it and everything looks beatiful other than the nickle boron bolt discoloring from all the carbon and replacing the cam pin because it wore out. I was looking at my friends 16 inch carbine with only a few hundred rounds and the buffer weight was all beat up and the you could shake the rifle and it sounded loose. Yes, it's a cheap off the shelf gun and mine has over a $1000 dollars in parts that I put together without optics.

even with me slowing down the cyclic rate it still might be 10 rounds per second. I bought a trigger polishing kit to improve the Mil Spec heavy trigger. I polished one so well that it didn't always catch for the second shot. Sometimes it would burst fire 2-3 ever time you pulled the trigger and it was so rapid it sounded like one shot almost. I threw it in the garbage and just went to quality drop in triggers. LOL

So I've heard several different ways to skin this cat.
- Heavy bolt with lighter buffer/spring combo
(This sounds like it'd smooth out the recoil impulse to me)
- Lightweight bolt with heavier buffer/spring combo
(This is claimed to work like a dead blow hammer and rather than smooth recoil, it sort of eliminates it)
Explaining how the gas effects everything was very helpful.
I'll be picking up a WOA Predator barrel which has the mid length system for a 16" barrel.
Also planning to run that Lantac Enhanced bolt in conjunction with the VLTOR A5 buffer/Geissele Super 42 rifle spring in my new Magpul UBR stock with plug removed.

 

[budlight]

Do you see that Lantac Enhanced bolts are all full Auto bolts. I did competition shoots in 3 gun. So you are around people that money is not the object. High on the list is reliable and accurate. So my home built were patterned after what I had seen and some thinking about how to make things even better.

 

[budlight]

I had a carbide reamer made for them to accommodate mag length 77s, and long loaded ammo for 600 slow fire shooting 80 class bullets. When they shoot the 6 person team match at Camp Perry it is imperative that their rifles can shoot the team spec ammo to make the coaches' lives easier. Thus, it is imperative that I cut their barrels with the same reamer.

My dedicated 1000 yard service rifles, two to shoot 80 VLDs, the other to shoot 90s have different configuration from my across the course guns.

Are the mag length 77's something longer than 2.260. What length were the 80 and 90 gr single shots?