308kiwi

I do like Vihtavuori powders, they are so consistent and clean, my 10mm just loves N350 and the wifes 9mm Carbine loves 3n37 BUT they are so ridiculously expensive and just when you get a load sorted it's out of stock and the next shipment isn't due until next year. So I've just given up on it as a powder, nothing wrong with the product, just the clowns that import it can't get their shitt together. We have ADI, (who make a lot of powders you guys are familiar with, especially in the Hodgdon range), next door to us, supply is so much more consistent and the exchange rate between AUS and NZ is almost $ for $ so cost is realistic. So we just buy 'local' now except the odd time that Winchester Autocomp or WSF are in stock, both great pistol powders.

I've been using ADI AR2205, sold in the USA as Hodgdon H4227, same burn rate as H110 but being an extruded powder it's super clean and seems to be a lot less offensive, in your face, when running suppressed, also use it in 9x25 Dillon loads.

I've been living with this, almost, exact system since 1990, 28 years, pretty much a whole generation, of literal freedom to "walk in and grab stuff of the shelf", yes, just because I have the permit, (license) to do so. And yes, the tin foil milliners went right off when it was introduced, "next step is full registration then confiscation", "they're going to take all your guns" blah blah blah, well that just didn't happen, if anything it worked in our favour, opened up a whole new world to us, as it would to you guys as it would, as far as I can deduce, pretty much nullify your NFA Act. And yes I may not be a US citizen nor live in the USA and have no vested interest in this discussion, I simply offer from experience how it does/can work.

Agree 110%. Here it's a legal requirement that your firearms are secured in approved storage if not in your immediate possession/control. All bolt actions and pump actions must be locked in a secure cabinet separate to any ammunition, all semi auto's, hand guns and full auto must be secured in an approved safe, minimum construction 1/4" steel plate. We have a 'strong room' built in the centre of our house, inside that is a steel safe secured to the reinforced concrete walls and floor, the whole lot is protected by an internal alarm and IR camera's that record straight to the 'cloud', then we have the normal house alarm system that is linked the gun room cameras and alarm and both of our cellphones, and just in case that's not enough our local police have our cell numbers and address 'flagged' so if we call, even under duress, from either of our phones they know who and where they are going to and that firearms are present at the address. Does this all sound like a lot of over the top ridiculousness?, maybe, but we are happy to leave our home with the knowledge that if some dirtbag wants to break in he's going to be in for a tough time taking anything more that our 10 year old TV and the chances of any of our firearms being used in a crime or worst still to take an innocent life are almost zero.

........................and you may just be surprised at how quickly and quietly it could happen. I remember quite clearly what happened in Australia after the Port Arthur mass shooting, legislation was written and put in place so damn quick that it left heads spinning, if one was susceptible to conspiracy theories one would say it was already drafted and simply sitting waiting for an appropriate event to happen. There was the expected uproar and standard rhetoric from the firearms groups and individuals, "you'll never take our guns", "from my cold dead hands", "not one more inch" but once the 'buy back' began and the trucks were rolling on the road, stopping town to town the ques formed in an orderly fashion and the sheep handed in their firearms and pocketed the compensation cheques, not a single shot fired, not a single firearm pried from any cold dead hands, it was a pathetic and sad sight. And this was in a country with a population of 25 million, a country that had fought in 2 world wars as well as every conflict since, a country where firearm ownership was considered a right of passage, where hunting is a huge pass time. We watched this happen to our shooting brother and sisters across the 'ditch' (Australia is separated from NZ by the Tasman Sea, we call it 'the ditch') with mouths agape, but but but why aren't they standing up for their rights?, why aren't they doing something about this? It just happened, no significant protest, was it lethargy?, was it the money they offered in compensation? , was it overwhelming odds against any 'stand' being successful? If you want a modern example of how a government can peacefully disarm an entire country take a long hard look at how EASILY it was done in Australia.

I'd try it with the heavier spring first, JP make a 'tune kit' of springs for their captured thingy ma jig, try the heaviest spring. Could well be that the BCG just isn't being driven into battery with enough momentum. It's the last little bit of travel that requires the most energy, when the BCG has to overcome the extractor and the ejector.

WTF is going on over there?

Stainless tends to gall, pick up on itself, very easily, especially when screwed into an unlike material, add to that it being in a location exposed to high temp gases composed of who knows what and who knows how corrosive, stainless is only what it's name suggests, it stains less, it still oxidises just as carbon steel does, just not as much and not as quickly. Sure carbon steel screws in the same environment are exposed to the same gases and temperatures but two like materials in contact with each other tend to be more chemically stable than two unlike metals. I spend some of my spare time threading barrels for suppressors for a local gunshop, carbon steel barrels take a thread SO much easier than stainless ones, cutting threads in stainless takes considerably more care and more precise feed rates for a nice finish, galling is a big problem, the material you are removing with the threading cutter tends to gall onto the tool. Aluminium does the same, threading aluminium I use a specific cutting fluid designed for aluminium and make twice as many passes with the tool otherwise it just picks up and makes a mess. I also have to advance the cutting tool on every pass so that it is only cutting on the front face where as with carbon steel the tool can cut both faces of the thread at the same time without issue. Stainless, and aluminium for that matter, is a freakin PITA.

Agree completely, seems like every man and his dog are making barrels and all other manner of neato AR go fast bits, like you've said so many times, there aint no std on the large frame AR's, seems like the specs/std's are slowly being shifted further and further +/- on every front and on every sized AR, extraction/ejection issues are not limited to the 308's, there are plenty of posts on the 'other' forums re the same issues with the smaller family of AR's. OH and I concur, don't go buying stainless set screws etc, recipe for disaster.

?well you could consider the gas port as a Thermal Expansion Orifice, or a 'TX' valve, the key component to any air conditioning system. Interesting that so many unrelated things, an AR', your AC and your beer fridge, work on the same principle don't you think?

And if you really want some bedtime reading that's guaranteed to put you to sleep have a read of the info on the linked page, it deals with calculating pressure/flow/volume/velocity drops across orifices. (it deals with fluid flow but the same calculations can be extrapolated to get an idea of the drops through a gas port). And when you get your head around all the info, then bear in mind that by fitting an adjustable gas block you are compounding the calculations as you now have 2 orifices to deal with, the gas port in the barrel and the adjustment screw in the gas block, not to mention the leakage via the gas block/gas tube junction, the gas tube/carrier key junction etc etc etc. So, is the diameter of the gas port in the barrel just some random diameter hole that we, armed with our trusty Black and Decker and a cheap drill set, should be playing with.? https://neutrium.net/fluid_flow/calculation-of-flow-through-nozzles-and-orifices/

Ditto to what 98Z5V said. I would go as far as to say that unless some component involved in the initial extraction of the case from the chamber, eg extractor, has failed then your extraction issues are due to the bolt groups initial unlocking/extraction being too violent. Adding extra weight into the system, heavy buffer, simply delays the rearward travel of the BCG by a few milliseconds allowing the case to relieve itself from the chamber a little more and the gas pressures to decrease ever so slightly, it is a solution but you need to fix the cause, not the symptom. Sort your gas system first and you'll likely find your problems will go away.

If I can add my 2c worth, don't go polishing your chamber unless there is a reason to, IE a visible burr etc. On firing the brass expands and grips the chamber walls, a considerable amount of the rearward thrust created by the expanding gas and the equal/opposite reaction forces of the projectile being pushed down the barrel is counteracted by the case gripping the chamber, if you polish it mirror smooth you will increase the amount of thrust being applied to the bolt and locking lugs, not a good thing to be doing. Whenever I chamber a barrel I always 'rough' the chamber surface with '0' steel wool wrapped around a small piece of dowel.

I have seen a LOT of change over the last couple of decades here, we used to struggle to get anything, the very thought, dream, of owning a brand new AR15 was just that, a dream, but slowly things changed, a few individuals put in the hard yards and with much effort things opened up, most of us now work WITH the authorities and we have spent a long time building relationships between us that work for all involved, a lot of trust has been developed and nurtured to the point that I can now apply for import permits for almost anything and they are granted. BUT we still have the obstinate twats that won't get with the program, they're constantly poking the bear and cause so many problems it's not funny, they are so damn set in their ways and beliefs that they will never change, they just can't see the light. It's incredibly frustrating when the very people that should be helping are being purposely obstructive because they won't "give one inch", I've been verbally abused and personally threatened by some of these guys, in their eye's I am a traitor to the shooting community for no other reason than I get along with and work with my local Police Armourer, ( my first point of contact with anything firearm related) and the various Govt Departments, Customs etc, that are also involved with owning and importing firearms related things.

My very first AR started as an ejector, ejector roll pin and ejector spring, it was a 'test' order I placed with Creedmoor Sports, the only place I could find nearly 20 years ago that would ship small parts out of the USA, as soon as they arrived the mission became full on. AR15's used to be like rocking horse excrement over here and if you could find one for sale it would set you back close to $10K, (no crap), and chances were it was an ex chopper gun that had had 50K rounds through it and was knackered. Only part I couldn't manage to get was a stripped lower, no one was exporting them back then, so I machined one up out of some 7075 toolplate, still have it but it's a paperweight now that sits in my workshop to remind me of what had to be done to fulfil the 'need'

Add to that, most 'drop in' cartridge type AR triggers don't use the hammer and trigger springs to retain the pins like std triggers do, anti walk/rotation pins solve this issue. I've seen a few hammer pins break through the middle groove and start walking out of the lower, like 98Z5V said, 9mm carbines are good at this. As an aside, Glocks are capable of doing this as well, the top pin has a groove machined in it that locks into the slide catch spring, have seen two of them break through the groove and walk out of the frame on high round guns. Machine a groove in anything and you've created a weak point, same reason toilet paper always tears at the perforations

So here's a perspective from a system based on individual firearms licenses for citizens.... We don't have a 2nd Amendment to protect us in NZ, owning firearms here is considered a privilege rather than a right although you can argue that the definition of privilege extends to it being a right, but that's not what I'm here posting about. What I can tell you is the pro's and con's of a system based on individuals having a 'firearms license' because that's exactly what we have had here for decades and it works pretty well. Obtaining a FAL, (FireArms License) here is a matter of applying to the police, they do a thorough background check on you, interview your referee's and visit your home to check that you have adequate security for storage of firearms, once that's all done you're issued your FAL, it lasts for ten years before needing renewal, (a simple process). So now you have your FAL, (std FAL covers all your bolt actions, pump actions and semi autos up to 7 round capacity), then you can apply for individual endorsements to go onto your FAL, (adding endorsements does require upgraded security for storage), a "B" endorsement allows you to buy handguns with a minimum barrel length of 4", a "C" endorsement allows you to buy anything full auto, belt feds etc and sub compact pistols, no 'tax stamps' or the like, I can buy a belt fed or an M16 or an Uzi same day if I so desire, a "D" endorsement allows you to deal in and manufacture firearms including full auto, a bit like your 'FFL', an "E" endorsement allows you to buy all your semi auto stuff, AR's etc etc with unlimited mag capacity. (all B, C and E firearms are recorded to your FAL and if you sell them the 'ownership' is recorded to the new owners FAL) That's a very basic run down, but what it pretty much means is I can go to any gun shop or buy any firearm from any other dealer or private citizen and have it sent to me direct, no farting around with having it shipped to a dealer, no questions asked, no extra background checks, I've already been vetted to hell and back and been deemed 'fit and proper', simple as that, for B, C and E sales all I need do is fill out the procurement forms that you can download online and e-mail to the local police and they 'rubber stamp' it, normally immediately or at worst the same/next day. So the con's are that the govt has all my info, ummm, so when did they not?, they already know everything about me through my tax info, my medical records, my drivers license, etc etc, they have a record of all my B, C and E firearms, do I care?, nope, is it a pathway to confiscation?, well it's been in place for decades here and we're still doing OK, although the tin foil milliners will have you believe otherwise. One other point, we don't have a State/Federal system here, it's one system that covers the entire country so is probably a little easier to implement than what it would be in the US.

Swapping barrel extensions is an extremely difficult job, you have so many factors to consider, 1...the distance from the breech face of the barrel to the front face of the locking lugs, (the length of the tenon on the barrel that sets your bolts locking lug clearance and/or the depth of the barrel extension), will need to be the same or if not the barrel will need to be set back and this clearance corrected. 2.....head space, especially if you have had to set the barrel back to get your lock up distance correct, this is actually the easy one as you can re-set your head space by simply running a chamber reamer in and re-cutting the chamber the appropriate amount deeper. 3....now this is the tricky one, timing the gas port, the chances of the thread in your new barrel extension starting in exactly the same place as your existing barrel extension are so remote it's not funny, where the thread starts will determine were the gas port ends up when the extension is torqued up, the only way to fix this if it doesn't time up, (and I almost guarantee it won't), is to keep setting the barrel back a few thou at a time until it does, a time consuming job. I'm not trying to discourage you, but these are the things you need to consider and if you're paying someone to do this for you it could well run well over buying a complete barrel assembly that is to the spec you are trying to achieve.

So true, I've been around for a while, have barrelled countless bolt rifles, some of which have won national and international long range titles, does this make me "a world class gunsmith", pfffft, not even close & I aint that vain. My day job is a Heavy Diesel Mechanic for a major brand of tractors and combine harvesters, been doing it for 35 years, still learn new things on a daily basis and one thing I constantly hammer home to our apprentices as they come through is don't ever think you know all there is to know cause it'll bite you right on the ass.

The numbers I talked were from measurements made, the .120" over travel I had was from nothing else but a combination of the internal length of the buffer tube vs the length of the buffer and bolt group, I made the buffer myself, it's OA length was determined from what I had read on here and other searches around the net, consensus is that the DPMS 308 carbine buffer is 2.500" long, (mine is 2.530" long as the rubber squishy bit is .030 longer than I allowed for), had I made it 2.610 long then I would have had my .040" over travel that I have now, making a spacer up took 5 minutes, making a whole new buffer would take an hour or so, simple choice was made. How did I come up with the thickness of the spacer I made?, .080", trust me, nothing any more technical than plucking a number out of the air, .120" divides easily by 3, I thought I may have to make several different thickness spacers to try as I was unsure that I would have enough 'dwell' time with the BCG at full rear and for the mag follower to react on the catch and have time to place the catch in front of the bolt face, turns out my first guess works just fine. One of the most important lessons I have learnt since getting into the 308 AR 's is what the guys on here keep saying, "there aint nothing standard".

Thanks 98Z5V, it's your posts that have hammered this home to me Yes, I've seen the same with PCC's, have seen several 9mm PCC's over here that have broken hammers through the narrow section of the hammer, I put it down to the same, very high initial bolt speed. Same happened to a .223 AR I saw once, that had a Ceiner 22lr kit fitted to it, broke a RRA 2 stage match hammer neatly in half after about 3K rounds. Ran 100rnds through my M5 today, locked open at each mag empty, even with only .040" of over travel, which sorta surprised me, I wasn't sure that I had left enough travel in it.

I hope so, was thinking of an adjustable gas block to tame it down a little more but really don't want to be trying to fix something that doesn't need fixed or can be fixed in a different manner, eg spacing the buffer and spring slightly further forward. There are so few of these, 308 AR's, over here that the knowledge base for issues is equally tiny, hence why I am here, you guys have been around these things a long time and know your poop.

So I managed to break the bolt catch on my Aero M5 last week, (Aero bolt catch that came with the lower), ordered a couple of DPMS 308 catches from Brownells which turned up in the mail this morning, fitted with a lot less for/aft float in the slot in the lower. After reading some of the info on here I thought I'd measure my bolt over travel, bolt face measured at .120" rear of the back face of the bolt catch when bottomed out in the buffer tube, so I machined up a .080 Delrin spacer to drop down the end of the buffer tube, now I have a .040" gap between he bolt face and the catch. Buffer tube is a AR15 carbine, Buffer is a stainless steel unit I machined up with a couple of tungsten ar15 weights in it, 6.5 oz and 2.530" long, as for the spring it is a LBE 308 Rifle spring that I shortened to 27 coils, wire dia is .070" Any other suggestions from you guru's on what else I should look for as to the cause of my original failure.

Damn straight. Living at the bottom of the world forces you to 'self help' sometimes