AR Sponsor
Posted: 9/9/2005 1:49:11 PM EDT
|
Can someone please explain the differences in the production of each. I'm familiar with metal casting, and forging of knives. Maybe direct me to a web site. I ask this because the local "gun gurus" told me the other day "There's no difference in any of the recievers 'cause their all cast and all by the same place".. "The're all Mil-Spec"..."You can't forge Aluminum". I was at a loss to explain the technical process. Any help would be appreciated. |
|
Forging uses intense heat and pressure to transform a solid slug of alloy material into the final shape of a receiver. Forged aluminum is about 300 per cent stronger than cast aluminum, yet less material is needed to produce the same "cast receiver", which results in a stronger but lighter product. Casting is a relatively inexpensive way to produce a fairly strong receiver. There are two methods used. One, system is known as gravity casting... whereby the molten material is poured into a mold and allowed to cool. The mold of the receiver is generally made on a CNC machine. This is usually the preferred method for casting the AR15 receiver. The other, and better system used, is the low pressure or negative pressure casting. Here instead of pouring the molten material into the mold, the molten alloy is drawn up into the mold using a high-pressure vacuum. This eliminates much of the trapped air found in gravity casting process. ~NewbieDave |
|
Casting has gone a long way since the technique first came to be, but that's not saying much. On that note I will say in my opinion casting should be limited to steel, not aluminum. There are a lot of cast parts on your car that will probably never break, but on a rifle, be sure it's a good company, like Springfield Armory, before you go the cast route. I have never seen a quality AR-15 cast receiver, at least not one that i would trust in combat. |
The only HAMMER Forged lowers are Colt SP1s. |
Back in olden times Essential Arms sold tons of cast receivers. They are of apparently good quality and I have never heard of one breaking. I have one, but I have never really used it. |
| I owned a cast lower, by Essential Arms that had over 8000 rounds per year put through it for over ten years. When I got it, it was still in excellent shape, excepting the near complete lack of finish. Any person who states that all cast lowers are junk does not really know what he is talking about. I would stake my life on an EA Cast receiver. |
Yeah like I'm giving a lower away  -at the last gunshow I tried to sell a dpms mutt lower (a very nice mutt lower) at one point I tried to trade a guy the assembled lower for two stripped ones ie watch me turn one lower I don't need into two lowers I don't need |
|
I bought several DPMS cast lowers (pre-ban) during the ban.... was one of the few ways to get them in quantity. Though they may not be "combat" proven as a previous poster said... none that I've built from them has given me any troubles. Future buys would be spec'd forged... but, as they say, dance with the one who brung ya |
Like wood, metal has a "grain" when formed under pressure. Aluminum billet is just a chunk of forged aluminum, and will have a grain running lengthwise, similar to a 2x4. And just like if you were carving a lower from a wooden 2x4, a machined lower is going to have "end-grain" exposed on many of the curved surfaces, and it will be weakest at those points. Overall, it will be stronger than a cast lower (which has no grain, and has a much looser molecular structure), but not as strong as a machined forging. The reason for this is because the forging process (pounding heated metal between two die halves by a huge hydraulic hammer) causes the grain to be "wrapped around" and formed to the outside shape of the part. This gives the shaped forging the greatest strength possible for the material. It's the same reason why, when building, say, a boat hull with wood, you bend the wooden planks instead of cutting a curved plank out of a larger piece of lumber. If you cut a curved plank, you would be cutting across the grain, and the plank would be far weaker. -Troy |
|
I owned a cast lower, by Essential Arms that had over 8000 rounds per year put through it for over ten years. When I got it, it was still in excellent shape, excepting the near complete lack of finish. Any person who states that all cast lowers are junk does not really know what he is talking about. I would stake my life on an EA Cast receiver. +1 I had an EA J-15 for a number of years, an excellent lower. I have never seen a problem with an AR-15 that could be blamed on the EA lower. I also know a number of police officers with Ar's built on EA lowers. No, not all cast are the same. I understand Oly cast lowers had problems, as did a few others. Early Bushmaster rifles used Essential Arms lowers, as did some other manufacturers. I have no hesitation about using an Essential Arms lower. |
|
First off, tell your local gun gurus, they're idiots. Forged aluminum is used for not only firearms, but pistons, connecting rods, and engine blocks made of forged aluminum are all used in automotive applications regularly. Newbie Dave had an excellent post that addresses the biggest problems of gravity castings. Gravity castings are horrible when it comes to molecular bonding, and they retain air pockets that cause extremely weak points in the object cast. However, a good casting should be fine for most AR15 lower receivers. While it is not optimal, the lower is not usually subjected to the kind of force it takes to cause structural damage to a good casting. The problem is, that most castings are very inconsistent, especially compared to forgings. The way I see it, is why bother with castings when the forged receivers are very little more. Companies like Essential Arms, Olympic Arms, and DPMS all used to offer cast receivers, but now I don't believe any of them do. |
Your gun "guru" is a fucking dumbass. |
| Some one mentioned springfield Armory.Their M1a receivers are cast.Entreprise and LRB make a true forged original recipe 8620 alloy steel hammer forged 12lb receiver block that the reciver is then CNC machined from.Tolerances probaly kept to an even more exact standard than 50 years ago. |
Entreprise arms supposedly makes their receivers out of billets, but it makes no difference when their specs are out of wack. |
Essential Arms is back in the business of making investment cast lowers. Essential Arms |
Yeah I called down there when someone got stuck with a new production lower that he thought was pre-ban. The new lowers are marked "J-15-2" Seemed like nice guys from the brief conversation I had with them. |
That kind of confusion is likely to happen since I've seen several web pages online that are based on old info that say all EA lowers are pre-ban because EA sold their tooling to DPMS in 1994 and got out of the business until recently. You are correct about their new production lowers being marked J-15-2. The other obvious difference is the old production ones don't have the extra reinforcement around the buffer tube area. And I will agree with others that say that EA receivers work damned well and seem to hold up just fine, which makes me skeptical of all the people who say all cast receivers are junk. Simply doesn't seem to be true. |
| To DARKEST I have an entreprise receiver and yes it starts out as a billet and is then heated and hammer forged into shape.The winchester M14 parts kit it was assembled with fit fine and it has been real reliable in the 7000 rounds so far through it.My receiver was no way out of spec,If it was it would have gone back for the $700 I paid for it.Whats your experience that you got one out of spec?My smith is a former marine corp armorer from back in the late 60s early 70s.He didint have to modify anything to get the GI parts to fit.I also have a chineese M14s.Even that receiver is better than the springfield one,it just has to be heat treated harder and receiver modified to take a GI bolt,but it is forged as well. |
|
WOW! Thanks for all the input. I love this site. I bought a Grizzly lower last year from them. After that barage of BS I don't think I'll be dealing with that shop in the future. Can anyone recommend a shop in the Mid-Hudson area with staff that knows what the're talking about? |
And because so many of them broke, they now use a forged receiver and call it the super plinker, or something like that. 
|
|
Please tell you gun store guy he is passing on bad info. Serious, dont be an ass about it, but tell him. I work in a gun shop and hear guys where I work give bad info and if no one tells them its bad, they will continue to think its correct. Telling more people etc. Just tell them MOST AR receivers are forged and that the forged are much better than cast. If he doesnt believe you, just tell him to look it up. He should care enough about what he's telling people to look it up (just like you did). Here is a pic of a cast reciever a guy came into our shop with. He did not get the rifle from us, but we did help him get it replaced with a new forged one from DPMS. They were very good about replacing it. This gun was dropped about two feet from the ground, fell on the stock. The casting was so week, the threaded are broke, but the plastic stock that took the brunt of the impact was 100% fine. Just say no to cast receivers. 
|
| Put me down as another satisfied Essential Arms owner. I prefer forged, but after over 15 years my EA lower is in its 3rd incarnation & still going strong. It is perfect for retro builds as it is "A1" type.Forged is stronger but proper castings work great. Regarding cast engine parts, aluminum blocks in cars & motorcycles are cast. Also 95% of pistons are cast,forged being used for high performance applications(even a lot of hi-po builds use cast).Pistons take a hell of a pounding,at high heat ,up to several thousand times per second. |
AR Sponsor