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Bolt carrier groups


Powerman

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Ya, the silent spring sounds nice. I'm going to pull the trigger on a JP adjustable block to do what I want.

But the silent spring is just the spring right? That is how I took it. You still need the buffer weight right. If that replaces everything, i just might do it.

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Ya, the silent spring sounds nice. I'm going to pull the trigger on a JP adjustable block to do what I want.

But the silent spring is just the spring right? That is how I took it. You still need the buffer weight right. If that replaces everything, i just might do it.

If I understand correctly, JP's silent spring assembly serves to replace both the spring and buffer as a single captured unit.

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Is it "silent". Does it "feel" better. That actually sounds pretty cool.

I have no experience with it. But if JP said "silent" then they do mean no audible sound, to us humans, is produced by it, either directly or indirectly. If you have seen the design then you would know why. I do want one.

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Matt, I sure hope you can make that happen with the locals - that would be an invaluable connection and asset, in the not-so-distant future.  Count me in for several.  <thumbsup>

Thanks! I need to get a good strategy laid out for myself, right now everything is just rattling around in that big vacuous space between my ears.

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NEW QUESTION:

I managed to secure a striped carrier. It was new, but raw steel. Guy had it parkerized. It has FA serrations, and it is DPMS pattern. Does anyone know who would make that carrier? It does nt have any markings, and I am puzzled that a new carrier would come with no coating of some sort. Just trying to get some piece of mind.

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Maybe those more knowledgable could educate me on this. I'm trying to figure out how much punishment the carrier actually takes. When the gun is fired, I thought that the gas impulse on the carrier key is what causes the BCG to begin it's rearward travel. I thought that when the gas pressure goes from the end of the gas tube into the gas key, it exerts pressure which enters the cavity in the carrier behind the bolt. I thought that this pressure trys to seperate the bolt and carrier, and that is what drives the carrier rearward, until the holes on the side of the carrier are exposed, and then the pressure bleeds off, but since the carrier is traveling rearward (against the resistance of the buffer spring) it eventually acts on the cam and unlocks the bolt. The reason I ask this, is because I'm trying to get an idea of just how tough the carrier needs to be? I know the bolt needs to be tough so that the lugs can handle the load of the cartridge ignition without sheering, but I'm thinking that since there is nothing holding the end of the gas tube into the gas key, the gas tube would rupture long before the bolt carrier would fail. Any opinions on this? I'm not sure why the carrier would need to be as strong as the bolt needs to be. So maybe this IS  a part that could be manufactured by the average shop, as long as all of the dimensions were maintained?

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Well ,lets see, the BC is there for a few reasons , weight ( will explain below ) , alinement of components (BCG) & there mechanisms for bolt extraction & ejection , harnessing the gas impulse from the propellent gases ( some say its a piston ).

The weight is used in some ways as a timing thing for case cool down prior to extraction( this is also why there is travel in the bolt, with in the BC, when unlocking ) , if the case was still tightly adhered to the chamber walls (ignition pressure ), you would get a lot of cases stuck in the chamber & no extraction or ripped up case rims .

The carrier key helps alien it all & redirect the propellent gases to the BCG.

You can lighten the weight , but you have to do other things to compensate for this weight loss , adj. gas block , heaver buffer / spring .

The CUP or pressure of these firearms are quite substantial & that in its self is a good reason to have a robust BCG.

I tried to keep it simple & probably missed some . <dontknow>

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Hey guys,

I'm an Mechanical engineer for a large, electrical stamping manufacturer and am the manager for all design & tooling operations.

My point? I'm looking for a blue print of the LR.308 bolt and I'm going to make some of these myself, or have one of the tool makers make them after hours.

I have the Fulton carrier, but like everyone is saying "there are no bolts to be found" If I even had a worn out one I could reverse engineer it, but the closest I've come to a .308 bolt is a photo.

I would also be willing to make some extras for interested parties. I would guestimate the price to be around $60-80.

But I first need a print.

tucson308

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@Tucson308,

I have an extra bolt (stripped). We should talk. I was just about to install the springs/extractor, but it'd be a lot easier to reverse engineer while it was stripped.

The bolt is LR308 patterned with a NiB coating. It is shot peened stainless steel. Made by SI Defense, out of northern MT.

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That Youngs .308 carrier sure is a good looking part, just like their 5.56 carriers that i run. I waited for over six month for one of them, kept being told that they'd be avaliable in another month, before I finally gave up and picked up an Armalite recently,in order to finish my current build. I wonder if they'll ever be a stock item from them.

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Just got my DPMS style, .308 carrier from Fulton Armory. It is an A+ part. Bores and outside are smooth and a great chrome finish. Dimensions are rite on.

They have more in stock, but they shut down there website, again, to catch up on orders. They will be up and running in a few days. Fulton has done this shut down two times since Christmas. Hopefully my 22", .308 AR barrel gets shipped during this "catch up period".

They also have AR15 carriers as of yesterday. This place must be huge, they always seem to have almost everything and for the most part they have good pricing.

There Criterion barrels are awesome and very reasonably priced ($200-$300) depending on options. I've built 5 AR"s with there barrels and everyone will shoot under 1 MOA out to 300. I have not done any serious shooting with them past 300, yet, but everything points too good groupings way beyond 300 with good quality ammo.

Now I will have to machine a bolt. Luckily a super nice guy on this site is loaning me his bolt  to reverse engineer it. Ordered some 9310 today and will be making several.

Yes, Shot peen and MPI tested as well and went out for a quote on Nickel Boron plating. My normal job involves manufacturing of various precious metal, electrical contacts as well as medical parts. We have millions of parts plated with silver, gold and other plating every year, so our plater said he will see if he can just fit it in and not worry about it as far as a formal quote.

GS

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YEP! My upper and 20" SS Hvy barrel shipped today. I ordered a chrome carrier and key a week ago, so I should have it in a  couple of weeks. The only ridiculous thing I did was buy a JP Ent. Enhanced bolt off Gun broker. New, $320... ouch. I felt pretty silly about that until a DPMS plain phosphate bolt went for the same amount.  :cookoo:

No bolts anywhere. I also bought that stripped carrier off Arms list for a reasonable price. I will sell it when I get he FA carrier in.

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