ar15performance

Cold(Jansen) also owns 68forums.com and maybe 458 Socom forums, seems like there was a third firearm related forum.

Just seein' if I missed something. Isn't this 265PF? I thought this died a year ago, Thats not a MPF load just a quick one. The 130gr Sierra will make it to 2500 and only needs 2462fps. Gentleman Jim, ever finish your receivers? Vltor just started forging theirs and they are now loose at the barrel extension area.

Was talking about rails on a YHM in the OP. Light carriers and fast carrier speeds damage AR bolts in every shooting sport but, you could tame it with an adjustable gas block. I see that the carriers are just TI coated so it is for friction and that cool gold cold huh? NO not tacticool BS!!!....real TI...6al-4v Sorry...your comment on hand guards ...made me think you ment the Vtac. In our game we sometimes beat our equipment pretty hard ...to gain an edge. Jim Are you making these TI carriers? YM has changed their match carriers and I am looking for a better carrier and hopefully one that is .002-.004 larger in dia. than a standard carrier. I was going through 10-20 uppers and carriers to match up that correct fit and it gets worse every year.

Was talking about rails on a YHM in the OP. Light carriers and fast carrier speeds damage AR bolts in every shooting sport but, you could tame it with an adjustable gas block. I see that the carriers are just TI coated so it is for friction and that cool gold cold huh?

Sorry, Jim, I'd advise a carbon fiber handguard. I got tired of wearing a glove. The carbon fiber handguard doesn't get hot, well not very quickly. Certainly not as fast as aluminum. But, then, I'm not a "Tacticool" kind of guy. I like carbon too, Pri's has a heat sheild inside but, it is high dollar. The 4 rail tubes are good for hanging up on everything. Most people are adding carrier weights so why pay twice as much for a Ti carrier and then add more weight? I haven't had a carrier break in 15 years so I don't think strength is an issue.

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Very good and one of few that offer MPI bolts, the receivers are white etched T marked and have M4 feed ramps.

AA's loading data is conservative to say the least but, when they started they had bolt breakage issues and lowered the pressure to save the bolts. I use LWRCs 6.8 "AC bolt" opened up to the Grendel rim size and have purposely shot 65-70000 psi loads to test the strength of the bolt. In the last 6 months I've shot about 400 rounds in the 60k psi range, The Lapua brass will handle it and the bolt looks good so far but the long term test will continue. Try 10X with bullets in the 100gr and lighter range.

There are a lot of people out there who read magazine articles and believe every word, afterall you couldn't print it if it wasn't true right? Someone once said RE7 was way to fast for the 6.8 and 10x was way to fast for the grendel in print. RE7 will push a 90gr TNT 2950fps from a 18" 6.8 and I've been doing it for almost a year and I'm not talking 20 shots a week either. Same with the Grendel and 10x. Most people don't get in and dig for the real info and test loads, slow twist VS fast twist and different chamber specs and try powders that aren' t listed in the latest reloading manual. Some of us do so if someone is way off base I throw out a little shadow so they'll think about it or check into it before making the decision. How many here knew about PRI mags and being able to load them to 2.31" The LWRC super bolt? I think that whole article zipped right over everyones head at the speed of light. 320pf, I'm sure you're the same one that posts on arfcom and I don't mind a bit if people shoot slow loads but, I like flat shooting cartridges. Why should I care if someone buys a mag that you have to work on before it will function or buys a hyped up caliber just to find out in a month it was all hype, it's not my money so why should I care? Who cares if the guy next to you is shooting at half the velocity you are? Why do people answer post on forums when someone else asks a question? some people just post to be a jackass and some post to help. Chills, did I say I try to shoot major? did I say you should? my short range 3gun is a 223, my long range 3gun is a 5.56x42 and yes there is a reason. Very first post, simple "don't make the mistake of buying a Grendel blindly" read up to see if the bolts break or if they have mags that work and does it really ballistically beat the other cartridges as everyone says.

The key to that chart is at the bottom where it says velocities for all but the Grendel from loading manuals but the Grendel is from actual velocities. The 6.8 will push the 115 to 2800fps from an 18" barrel. act. 308 -2540 from a 18" act. Charts are only fair if you hot rod every one of the entries or shoot everyone to the same pressure. Then if you compare the best bullets available with every case which the 175SMK is not. Drop a 155 Scenar in there if you want to compare the best to the best. grendel velocities from grendel.com How many people shoot ARs at 1000yds? 300-500 is a much more usable range for 90% of us. I can't think of 1 1000yd competitor that uses a AR. Highpower sure.

I don't sell much to 3 gunners because there are too many others selling .223s, I mainly deal in wildcats for varminters and AR10s for big bore guys. Besides I don't want anymore business I can't keep up now. I'll throw a plug for PRI mags and LWRCs "Advanced Combat bolt" whenever I get a chance, they've made everything I do alot easier. Nope I don't sell them so you'll have to go direct. presentation of the "ACB" to the DOD Development and Testing of a Replacement Bolt for the M4/M16 Service Rifle Abstract Field failures of the M4 and M16 bolt have been widely reported and are considered a substantial problem that impacts weapon reliability and warfighter safety. While there has been significant work by others in the field, no heretofore proposed solution has proven entirely successful. This paper outlines the origination, design, development and testing of a possible direct replacement for the existing bolt providing a potential ten-fold extension of component life. Introduction The M16 rifle was fielded into the U.S. Army in 1968 during the Vietnam War. The rifle has since been the primary assault rifle used by U.S. forces. The M16 has been through several modifications in its more than 30 years of service in the military and the most recent modification has been given the designation M4. In July of 2003, an increasing trend in the frequency of M16A2 bolt failures was observed by the U.S. Army amongst a sample of rifles that had been used for nine years during summer military training. The results prompted numerous other studies that collectively provide a valuable source of data from which to build a comprehensive understanding of the dynamic interactions of the rifle and design of the standard bolt. The most recent data suggests that the M4 appears to suffer from a higher degree of failures than the M16A2. From the results of the published studies, XXXXXXXXXXXXXXXX concluded it was possible to design a bolt that overcame the flaws of the original design. Extensive live-fire testing was carried out in field conditions to demonstrate that the final design met the reliability objectives and provided a minimum bolt life of 35,000 rounds, an improvement of at least 1,000% over the standard M16A2 and M4 bolts. Failure experienced with the Original Bolt Finite analysis of the original bolt design had shown high von-Mises stress distribution around the fillet, or root, of the locking lugs and even higher stress concentrations were present in the two locking lugs immediately adjacent to the cartridge extractor. All of the failed bolts had fractured at these specific locking lugs. The design of the original bolt is such that the extractor cut-out in the bolt body creates an asymmetry, or imbalance, in the bolt. When the rifle is fired the pressure of the cartridge forces the bolt rearward and the lugs transfer this energy to the matching locking lugs of the barrel extension. The bolt flexes at the rear inside corner of the lug during this process. Because of the extractor cutout and resultant lack of symmetry, the stresses are unevenly distributed and the deformation is greatest in the area of the two lugs immediately adjacent to the cutout. A series of engineering analyses suggested that the two lugs on either side of the extractor, of seven total lugs, each receive a disproportionate amount of the total recoil load: approximately 20% of the total load each while the remaining 5 lugs each carry approximately 12% of the total load. The integrity of the bolt is further compromised by the fact that these overloaded lugs are undercut in order to accommodate the extractor claw, lowering their yield strength relative to the under-loaded lugs by 48%. Most bolts will start to exhibit small cracks before they reach 3,000 rounds fired with terminal failures occurring between 6,000 and 8,000 rounds. See Figure 1, below. Figure 1. Fractured bolt specimen. The original bolt design also experiences fracture failures at the cam-pin hole located midway along the bolt body causing the bolt body to fracture at this point. Another major reliability problem is poor extractor spring life, which leads to failures to extract fired cartridge cases from the chamber. Approach To resolve all of the problems and achieve acceptable bolt life required a fundamental redesign of the bolt. The only parameters constricting creative development were that the proposed design should be a “drop-in” replacement and work with as many component parts in the existing rifle as possible, i.e., bolt carrier, firing pin, barrel extension etc. Other than these, the design elements were open. Computer modeling was carried out using Solid Edge from UGS and finalized designs were prototyped and sent for proof testing. Material Choice Because the standard bolt material, Carpenter Steel 158, has proved to be susceptible to corrosion, a new bolt material was selected. Chemical analysis of the composition of the failed bolts revealed no significant differences between the failed bolts and Carpenter Steel 158 specifications; failures were not ascribed to flawed material batches, but a suboptimal material choice. After extensive evaluation and prototyping of potential material choices including the xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx The final design embodied a number of improvements over the original bolt design. Working within the constraints outlined above, the first approach was to reduce the amount of stress transferred to the fillet or root of each locking lug during the firing phase of operation. This was accomplished in by adding a radius to every 90° angle of the locking lug. The effect of this is to dramatically reducing the amount of stress transmitted down the lug to the root fillet. The improved design also incorporates a fully supported bolt face. The original bolt has a substantial area of the bolt face removed to accommodate the extractor claw and therefore a combination of the bolt itself and the extractor claw support the cartridge head. This arrangement leads to further flexing of the bolt assembly during firing and increases stress on the bolt lugs adjacent to the extractor claw. By fully supporting the bolt face, a significant reduction in bolt flex was achieved in this area. Additionally, the undercuts in the lugs adjacent to the extractor accommodating recess were removed, and instead a radius transitions from the side of the lug adjacent to the extractor accommodating recess into the fully supported bolt face. The omission of the 48% undercut beneath each of these locking lugs has increased the strength of these lugs from around 24% of the strength of the uncompromised lugs to approximately 85% of their strength. Finally, the locking lugs were held to the maximum tolerance indicated in the Technical Data Package for the original bolt design so as to provide as great a surface area as possible without altering the barrel extension. Due to the modifications incorporated into the bolt head to strengthen the locking lugs, it became necessary to redesign some elements of the extractor claw to allow it to fit into the new design. Although the extractor claw appears radically different than the original design, there was no requirement to change the material choice. The extractor spring itself is an area of weakness in the original bolt, in particular the placement of the pivot point. Noting that others had already looked at a twin extractor spring arrangement and met with varying degrees of success, the placement of the pivot point was changed. The final design allowed for the use of the original spring design and added an O ring developed by the Naval Surface Warfare Center at Crane, Indiana which extends the bounce resistance to 230,000 cycles per minute and extends life expectancy to 10 million cycles. Finally, as with the standard bolt the spring is integrally dampened with a synthetic insert that is designed to increase spring life and reduce the chances of extractor claw bounce during fully automatic fire. Even with the above modifications to the body of the bolt, the original firing pin is compatible. The new bolt is manufactured in the same fashion as the original, including the heat treat method and shot peening of the bolt body although an additional shot peening is carried out after final grind to further enhance the outer molecular structure of the bolt. Suppliers of the original bolt have all the expertise and equipment necessary to manufacture the new design, although the new bolt is more complex and takes more time to machine as a result of the attention to detail needed to ensure a reliable product. Testing and Qualification Once the first prototypes had been produced, they were subjected to proof testing with a 30% over-pressure load (approximately 70,000 psi) followed by a crack inspection. One bolt has been subjected to 18 proof loads to date with no deformation or cracking. The bolts were subjected to live-fire testing over a period of several months to ensure that the bolt and its component parts were not susceptible to fatigue or accelerated wear from heavy use. Round counts on individual bolts varied from 9,000 to over 40,000 in full auto, semi-auto, and mixed fire modes with no failures, cracks, or signs of wear or fatigue. The original claw of the extractor was redesigned to create 25% greater surface area to grip the case rim. The use of this second-generation extractor claw eliminated extraction failures, even from barrels with roughly finished or otherwise sub-standard chambers. Generation II extractor claws are identified by the ????? engraving on their surface. The extractor claws are shown in Figure 2, below together with the original bolt design. Figure 2. From left to right, the original bolt, the new bolt with Generation I extractor and with Generation II extractor. The fully supported bolt face is clearly seen in this photograph. Once internal testing was completed and had demonstrated that there were no safety or reliability issues inherent in the design or the material choice, the bolt is now being offered for initial commercial sale. Conclusion The test results and commercial use of the “Enhanced Performance Bolt” (EPB) demonstrated a drop-in replacement for the original bolt that eliminates premature wear and failure and alleviates continual inspection and frequent replacement of the original bolts. The use of a bolt design that allows lifetime use of the host weapon without the need for extraction enhancing devices means that in a hostile situation the warfighter can be confident in the abilities and reliability of his primary defensive weapon platform. The EPB’s material choice with its resistance to corrosion, combined with its ability to handle repeated high pressure loadings, the stress relieving design, and the strengthening if the weak areas of the original bolt have resulted in a component that exceeds all current government requirements in terms of component life. Although primarily designed for military use, these benefits are passed on to commercial and competitive users resulting in consistent headspacing upon lock-up and improved extraction and ejection together with the lifetime durability detailed above. Acknowledgements Figure 1 photograph:

What do you mean by "badly"? Can you give examples? ballistic comparison

There are several cartridges that will badly beat the Grendels ballistics now. 6mmAR, 6mm Turbo, 6mmBanshee, 6.5Banshee, 6mmHagar, 5.56x42DMR. the .243 95gr Sierra MK with a BC of .480-.510 makes it easy to smoke the Grendel. 2965fps from a 22" Banshee. and a .224 75gr Amax at 3150fps from the 5.56x42. Doesn't look like any of those go major? The 6.5 Banshee has about 200fps on the Grendel so if the grendel does it then the banshee will easier. Big debate here, no one wants to shoot major anyway but if you do the 6.8 will do it with 130s and the 30HRT will with 125s or the cheap 147 FMJ. On top of all that the PRI mags are much better than the CPs. you can load to 2.31"

There are several cartridges that will badly beat the Grendels ballistics now. 6mmAR, 6mm Turbo, 6mmBanshee, 6.5Banshee, 6mmHagar, 5.56x42DMR. the .243 95gr Sierra MK with a BC of .480-.510 makes it easy to smoke the Grendel. 2965fps from a 22" Banshee. and a .224 75gr Amax at 3150fps from the 5.56x42.