barrel question
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Ned Ludd
Silver $$ Contributor
5R barrels are an excellent choice for for heavy .224" bullets. When pushed hard, the 88s and 90s have a tendency for jacket failures, especially in barrels with twist rates faster than 7.0. The trapezoidal shape of the lands in 5R barrels, as well as the fact that the lands do not directly oppose one another in a 5-groove configuration, seem to be a bit easier on bullet jackets.
There are several factors that contribute to jacket failure when using the 88-90 gr .224" bullets, specifically, those bullets offered by Hornady and Berger. Among them, muzzle velocity, barrel length, bore diameter, and land/groove configuration seem to be the most critical. Long barrels (i.e. ~30"+) can be a problem, as can be using tighter bore, i.e. 0.218" bore. Any and all of these factors (high velocity, long barrel, twist rates faster than 7.0, tight bore) can contribute to the problem of jacket failure with long heavy .224" bullets (i.e. 88s-90s), so choosing the barrel carefully can be of benefit. The loads that many F-TR shooters have been running that resulted in jacket failures tend to be in the range of 2800-2850 fps or so out of a 30" barrel. Reducing velocity can help with this issue, as can using a shorter barrel, or using no faster than a 7.0-twist barrel, which is sufficient to stabilize the 88s-90s. You may choose to use a barrel much shorter than 30" length on your build, which would be in your favor, but you are also using a .22-250 Ackley, which can push bullets a lot faster than the much smaller .223 Rem cartridge, which would be a negative as far as pushing the envelope of jacket failure. When so many different factors/contributions are in play, even minor increases in any one factor may be the straw that broke the camel's back as far as jacket failures.
The two things that seem to have the most beneficial effect in preventing jacket failures with the 88s/90s are 1) use a 0.219" bore barrel, and 2) stick with the 80 gr bullet offerings. F-TR shooters have reliably been using 88s/90s with barrel twist rates faster than 7.0 with a 0.219" bore, rather than 0.218", even when using barrels of 30+" in length. It also seems that the ~80 gr bullets are far less prone to jacket failure than the 88s/90s, probably due to the shorter bearing surface. Of course, the caveat is that the ~80 gr bullets don't have the BC of their heavier/longer cousins. Another item of note is that the Sierra 90 gr .224" bullet seems to have a much thicker/stronger jacket than the 88/90 Hornady/Berger bullets. I have not observed any jacket failures with the Sierra 90s out of a rifle/barrel combination that has blown up a number of 88s/90s from Hornady and Berger.
The bottom line is that you want all your bullets to reach the target, and you don't want to hamstring the performance of your new rifle by having to use reduced loads to prevent jacket failure. So careful selection of the barrel specs and/or bullets to be used is warranted.
There are several factors that contribute to jacket failure when using the 88-90 gr .224" bullets, specifically, those bullets offered by Hornady and Berger. Among them, muzzle velocity, barrel length, bore diameter, and land/groove configuration seem to be the most critical. Long barrels (i.e. ~30"+) can be a problem, as can be using tighter bore, i.e. 0.218" bore. Any and all of these factors (high velocity, long barrel, twist rates faster than 7.0, tight bore) can contribute to the problem of jacket failure with long heavy .224" bullets (i.e. 88s-90s), so choosing the barrel carefully can be of benefit. The loads that many F-TR shooters have been running that resulted in jacket failures tend to be in the range of 2800-2850 fps or so out of a 30" barrel. Reducing velocity can help with this issue, as can using a shorter barrel, or using no faster than a 7.0-twist barrel, which is sufficient to stabilize the 88s-90s. You may choose to use a barrel much shorter than 30" length on your build, which would be in your favor, but you are also using a .22-250 Ackley, which can push bullets a lot faster than the much smaller .223 Rem cartridge, which would be a negative as far as pushing the envelope of jacket failure. When so many different factors/contributions are in play, even minor increases in any one factor may be the straw that broke the camel's back as far as jacket failures.
The two things that seem to have the most beneficial effect in preventing jacket failures with the 88s/90s are 1) use a 0.219" bore barrel, and 2) stick with the 80 gr bullet offerings. F-TR shooters have reliably been using 88s/90s with barrel twist rates faster than 7.0 with a 0.219" bore, rather than 0.218", even when using barrels of 30+" in length. It also seems that the ~80 gr bullets are far less prone to jacket failure than the 88s/90s, probably due to the shorter bearing surface. Of course, the caveat is that the ~80 gr bullets don't have the BC of their heavier/longer cousins. Another item of note is that the Sierra 90 gr .224" bullet seems to have a much thicker/stronger jacket than the 88/90 Hornady/Berger bullets. I have not observed any jacket failures with the Sierra 90s out of a rifle/barrel combination that has blown up a number of 88s/90s from Hornady and Berger.
The bottom line is that you want all your bullets to reach the target, and you don't want to hamstring the performance of your new rifle by having to use reduced loads to prevent jacket failure. So careful selection of the barrel specs and/or bullets to be used is warranted.
A number of years ago, I built a 22-250ai to shoot prone. It had an eight twist barrel. Shot great for 10-12 shots, then the barrel was hot enough that no bullet that I tried would stay in one piece and make it to the 600 yard target.
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