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Centerfire Rifles - Semiautomatic or Gas Operated Centerfire rifles, carbines and other gas operated rifles. |
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#43
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These are two different scratches. One was caused when you installed the bolt catch roll pin. the other when you installed the trigger. There is no need to bugger up the inside of your lower with JB Weld just touch it up with a Sharpie if it bothers you.
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Live free or die trying! |
#44
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#45
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Forging (Near Net Shapes) are prone to inclusions and stress cracks. That's why all forged product for the military requires some sort of NDT (Non Destructive Test). They also react poorly to thermals due to uneven stress induced during the forging process, meaning as your weapon heats up the receivers move. |
#46
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I knew someone would open up the Forged vs Billet Pandora's Box...
Syd's Grandpa set the bait and it didn't take long... FWIW, I'm a fan a forged (wheels, lowers, etc)... yes we could go on for days... but we shouldn't |
#47
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I think I can carry they day for billet quickly. Where is the weak point for receivers? And is a forged product or a 7075 t 651 product going to stand up better in that area. This applies to the 308 platform as well. |
#48
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#51
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Next time, put electrical tape around the area before you punch or press the pin in. It prevents these nicks on the outside. Worse case, you jack up the tape with the punch. The job is easier if you have a bolt catch pin punch or a set of starter roll pin punches which holds the pin in place while you try to tap it in.
http://www.brownells.com/gunsmith-to...prod26484.aspx http://www.brownells.com/gunsmith-to...prod20640.aspx Last edited by ShadowX; 03-02-2014 at 12:05 AM.. |
#53
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I'd like to hear it. New topic maybe so this one doesnt get derailed.
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#54
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+1 A little scratch is not going to hurt anything, put a couple on the first lower I assembled as well.
On your next assembly invest in a Brownells lower vice block and bolt catch roll pin punch and you'll be able to do a pro job. |
#55
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OP after you determine if the line is a crack or just a scratch you should definitely get a better camera.
Fwiw. It looks like a scratch from what I can see from the terrible pics. Good luck.
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There are no stupid questions...just stupid people asking questions. |
#56
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I think your fine. Have your mother in law test fire it. I use a set of lineman pliers with tape on jaws to start the pin.
Last edited by edgerly779; 03-02-2014 at 10:01 AM.. |
#57
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That inner scratch now extends to the top of the receiver…I think that makes a crack :face palm:
I didn't know lowers were that weak. All I used was a tiny Craftsman mallet with one side of it being plastic and the other side rubber. |
#58
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That inner scratch now extends to the top of the receiver…I think that makes a crack :face palm:
I didn't know lowers were that weak. All I used was a tiny Craftsman mallet with one side of it being plastic and the other side rubber. |
#59
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Coulda already been there ya just didn't notice or ya just made it worse by bangin' on it.
Try emailing/calling the manufacturer. Perhaps they will do something for ya. Last edited by Sky_DiveR; 03-02-2014 at 10:48 AM.. |
#63
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Highly unlikely it's cracked. Whatever you do, just don't drop it on carpet. It will cause invisible nano-cracks within the micro-structure of the aluminum alloy and also catastropically disrupt subatomic hadron interactions that you can't see without vacuum, laser-assisted radiography with Cesium 137. Last edited by 8200rpm; 03-02-2014 at 11:01 AM.. |
#64
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sharpie works to ease the mind that very moment, but it wont last. first time you clean your rifle, the ink will come off.
Birchwood Casey has an aluminum black touch up. https://www.birchwoodcasey.com/Refin...-Touch-Up.aspx |
#65
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either way looks fine. does it function fine? then its fine.
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Retired Account |
#67
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The small silver scratch located deeper in the fire control area, can be felt. |
#68
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Does look somewhat like a stress crack
Forget the JB weld How about thin CA glue I put a cracked polymer Tec 9 back together with this stuff Last edited by RTE; 03-02-2014 at 1:41 PM.. |
#69
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Seeing that the overall consensus is that the lower is fine and safe to shoot. I'm going to continue on with the build. But I will put some type of adhesive (either JB weld as I have used that stuff before and it's STRONG or some type of extra strength glue) on the inner part of the fire control area for peace of mind. Not a crazy amount, but a small thin film like layer. And after looking online for a bit, I see that several people have fixed cracks, chips and even holes in receivers with different types of epoxies. I guess a crack in the upper receiver is something worse to worry about. Thanks for all the help guys. |
#70
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Spray light penetrating oil on the "crack", KROIL would work well, WD40 should work too. Let the oil sit for a few minutes and then wipe it off very well. Then sprinkle chalk dust on the crack area (you can figure out how to make chalk dust, the finer the better). If the crack line shows up in the chalk dust then you probably have a crack. The crack will allow the oil to penetrate it and the chalk dust will pull oil out and show a "wet" line. This is the cheap version of buying a dye-penetrant kit to look for a crack.
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I'd agree with you but then we'd both be wrong... NRA Certified: Chief Range Safety Officer Instructor: Basic Pistol Shooting Instructor: Personal Protection Inside the Home |
#71
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complete it and function check it... besides if u can manage to jack one up with a small hammer im sure they wouldn't issue the same pattern rifle to our boys.you can go on youtube and watch people put these under a 3 ton press and come out okay..if anything i think u just stress cracked the finish if u jammed it in hard enough that u had to wiggle it free.
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#73
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I looked at your pictures. You would have to whack the hell out of that lower to break it unless it is defective. |
#74
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Looking at it, it looks suspect.
Put a drop of rubbing alcohol on it on one side. If you see the back side get wet, then it's definitely a crack. If you don't see it get wet, then you need to try another test. The chalk method, as mentioned before, will help you see if the back side is getting wet or not. It will wick the moisture, and is also easier to see when it gets wet. This is a really really easy first test. |
#75
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Forged or Billet? This was Grandpa's quote. He believes billet is stronger I disagree.
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"Let me chime in from a manufacturing standpoint. Forging creates a denser metal grain structure when the metal flows under forging pressure and orients surface grain flow to follow the curvature of the features forged into the blank. It increases strength. The same strength gains can be seen in other manufacturing techniques that plastically deforms the material being processed, such as hole mandrelizing, button rifling, thread rolling, cold-form tapping, etc. It's all run-of-the-mill processes used in commercial and aerospace manufacturing. None of it is unique to the firearms industry. You'll find a lot of folks in the automotive hobby tend to have a lot of wild ideas about billet parts too. While not a direct comparison, spun cast aluminum alloy wheels and forged aluminum alloy wheels have a huge weight disparity (and pricing too) because forgings can "do more with less". Machining from a blank is nice because the shape is up to what the engineer and programmer wishes to do on the machining center. You can do smaller runs while keeping reasonable costs-per-unit because you're just investing in additional programming time and not new tooling if you change the design. Forging is a pretty expensive process to set up. Making any changes requires the manufacturing of a new set of forging dies. The accuracy is up to the engineers. Mil-spec receivers are stuck to a specific shape and set of tolerances and cannot add anything extra without falling outside the print dimensions. Billets can be stronger than forgings simply because they can leave more material, can reinforce areas that are prone to deformation, and aren't limited to the blueprint shape of the receivers so it's not really an apples-apples comparison. If you have a forging of identical mass and shape to a billet, it'll be stronger than the billet. Forgings receive further machine work to clean up dimensions, true up holes, and whatnot so any meaningful tolerances in regards to flatness, parallelism, etc, is determined by the print specs and how tight the machinist wants to hold those specs. A tolerance might be -/+ 0.010" so a part held at +.0095" is just as good as a part that measures -0.0003" because it's within print specs. If it takes additional time and effort (which translates to money) to hold smaller tolerances than the print allocation, it makes no financial sense unless the vendor raises the price of the parts and the company is willing to absorb that cost. How a company executes the machining processes used ultimately determines the product. Garbage in, garbage out. Dandy in, dandy out." There are also billet uppers (Vltor MUR) which are machined from forged blocks and these are very strong.
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C'mon man, shouldn't we ban Democracks from Cal-Guns? Or at least send them to re-education camps. Last edited by ScottsBad; 03-06-2014 at 8:16 PM.. |
#76
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#78
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You didn't read the entire thread. The quote by Grandpa is included. The purpose of the quote I included is to try to put the Forged vs. Billet debate to sleep.
Last edited by ScottsBad; 03-03-2014 at 8:09 AM.. |
#79
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Holy Shiet... 2 pages and it can be resolved in 30 seconds...
It is already "blemished" Get a piece of 320 grit sandpaper and lightly sand THE INSIDE of the finish away. If there is a visible line you have a crack. If there isnt you just need to use a lil more sharpie and your headache goes away. I am in Temecula area if you want me to do it.
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#80
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Don't use glue. Check to see if it is a crack with penetrating oil. If it is you can either run it or use it for a paper weight.
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C'mon man, shouldn't we ban Democracks from Cal-Guns? Or at least send them to re-education camps. |
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