แล้วกับปืนไรเฟิล .223 ของ CZ 527 ล่ะครับ.....................
รังเพลิงเป็นแบบเดียวกันกับ เรฯ700 หรือเปล่า
เท่าที่จับใจความได้ ของซีแซดถึงแม้ว่าช่วงเทเปอร์จะเป็นไปตามสเปคของพานิชย์ ซึ่งทำให้แรงดันในรังเพลิงสูงแต่เนื่องจากการออกแบบของไรเฟิลจะมีเซฟตี้แฟคเตอร์อยู่ประมาณ 2 เท่า ดังนั้นปืนซีแซดซึ่งขอรั้งใหญ่และแข็งแรงมาก จึงไม่ต้องกังวลว่าจะหัก สรุปว่าของซีแซดยิงกระสุนทหารได้ครับแต่น้ำหนักหัวกระสุนที่ใช้ต้องสัมพันธ์กับระยะครบรอบของเกลียวด้วยครับ ข้อดีคือแม่นกว่าลำกล้องทหารครับ(ลูกศิษย์นอกทำเนียบตอบไปก่อน รอครูสุพินท์มาแก้ทีหลัง อิอิ)
มีรายละเอียดมาแปะอีกแล้วครับhttp://home.sprynet.com/~frfrog2/miscelld.htmQ. Are the 7.62 x 51 mm NATO rounds and the .308 Winchester really the same round?A. Well, er, ah, umm--kinda. The cartridge cases themselves are substantially identical with the exception that the NATO specification rounds (those marked with the NATO "cross in circle" mark) have substantially thicker cases than the commercial variety and slightly different tolerances on some dimensions . They are thus able to withstand stretching better when fired in loose chambered military weapons (done for reliability purposes).
The NATO specs for the cartridge case dimensions reference different datum points for some measurements but these can be interpolated. Base diameter specifications .2" from the base of the rim are approximately .4706" - .006" for NATO specifications and .4703" -.008" for SAAMI. The specifications for the diameter at the shoulder of the case is difficult to compute as it is at the intersection of two datum lines but would probably be slightly larger (.4543" -.006 by my interpolation) than the SAAMI specification of .4540" +/- 0 at 1.450" from the base of the case. SAAMI gives the case to shoulder length from the base to the .400" datum on the shoulder as 1.627" - 1.634" while the NATO spec is 1.628" - 1.634". However, I have gauged many military rounds as being well under the minimum specification, especially non-US military surplus. (After all it was surplused for a reason.)
The GI .7.62 mm chamber has a larger diameter neck (.3445" +.020 vs. .3442" +.020 SAAMI), a different shaped and dimensioned bullet seat and throat, and more generous diameter tolerances, (.4730 + .002 (interpolated at the .200 reference line) compared to .4714 + .002 for SAAMI. I am working on obtaining drawings for both the cartridges and the chambers and will post them when available which will show the differences more clearly.
The headspacing requirements for the NATO chamber is much more generous than that of the SAAMI commercial (.308 Winchester) specifications as can be seen in the table below. (All dimensions are from the breach face to the .400" datum point at the shoulder and are taken from SAAMI or US government specification sheets.)
Problems can arise when commercial .308 ammunition is fired in military specification chambers since the minimum military chamber is .0015" longer than the SAAMI maximum chamber. Since commercial ammunition is generally dimensioned to fit in a minimum sized SAAMI chamber, the thinner commercial brass can be stretched to the failure point when fired in maximum sized military chambers, while minimum spec military brass is thick enough to stand the stretching.. In addition, military chambers may also be cut on the "generous" size diameter-wise to allow for functioning with dirty chambers. In the other direction, some military ammo may fail to chamber properly in very tight commercial chambers, although it appears that military ammunition is generally on the minimum side of specifications.
While reports of catastrophic failures seem to be almost unheard of, it is prudent to keep in mind that there IS a difference and to use commercial .308 ammunition only in firearms marked as .308 Winchester. The headspacing "problem" with military chambers can be taken care of for a particular rifle and reloads by careful adjustment of your sizing die . Most "commercial" rechamberings are done with SAAMI spec chambers. If in doubt or really paranoid do a chamber cast.
Q. Are the 5.56 mm NATO rounds (and M193 types) and the .223 Remington really the same round?A. This is another of those "Well, er, ah, umm--kinda" items. The cartridge cases themselves are effectively identical with the exception that military and/or NATO specification rounds (those marked with the NATO "cross in circle" mark) may have thicker cases and are thus able to withstand stretching better when fired in loose chambered military weapons (done for reliability purposes). Once again, the chamber dimensions are where the brown stuff impacts the rotating air dispersion device. From the data I have seen the headspace specifications are identical for SAAMI and military ammunition although measured to different datums and the dimensions of the cartridge cases and chambers are for all intents and purposed identical--just minor tolerance differences.
However, commercial SAAMI specification .223 chambers have a much shorter throat, a smaller diameter bullet seat, and less freebore than the military chamber. When military specification ammunition is fired in a SAAMI specification chamber chamber pressure can increase dramatically--sometimes up to 10,000 psi. While this should not cause any problems in modern well made rifles it should give one pause. Conversely, SAAMI specification commercial ammunition when fired in a military chamber gives significantly lower pressures and velocities. See the drawing below for the details.
It must also be noted that all 5.56 x 45 mm NATO ammunition (such as US M855) requires a 1:9" twist or faster rifling to stabilize the long 62 gr ball bullet and a 1:7" twist to stabilize the extremely long tracer variation. The standard twist used for .223 Remington commercial chamberings is 1:12" or 1:14" neither of which will stabilize the NATO type ammunition. The NATO ball ammunition is easily identified by its green bullet tip.
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