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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
60* or 90*, preference? One better than the other?
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<blockquote data-quote="Fiftydriver" data-source="post: 2590121" data-attributes="member: 10"><p>Generally, if you have a 90* and a 60* bolt and both have a 25 lb firing spring for example, and if both bolts striker assemblies need to be pulled back the same distance to the fully cocked position. The 60* bolt has to move the striker assembly the same distance back but in a shorter rotational distance. That means that the angle on the cocking piece will be a sharper angle. To cover the same rearward distance with shorter rotational distance requires a steeper cam angle.</p><p></p><p>steeper cam angle with same weight firing pin spring results in a heavier load on the cam and as a result on the bolt handle. Now you may have rifles with relatively mild firing pin springs and this may not even be noticeable but in reality, the 90* bolt can use a less aggressive cam angle for the cocking piece.</p><p></p><p>another way to look at it, imagine your rolling a 100 lb drum up two ramps, each 10 feet high. One ramp is a 20 degree angle grade, the other is a 45 degree angle grade. 100 lb drum is much harder to roll up a 45* angle then a 20* angle. Same idea here, just much smaller scale.</p></blockquote><p></p>
[QUOTE="Fiftydriver, post: 2590121, member: 10"] Generally, if you have a 90* and a 60* bolt and both have a 25 lb firing spring for example, and if both bolts striker assemblies need to be pulled back the same distance to the fully cocked position. The 60* bolt has to move the striker assembly the same distance back but in a shorter rotational distance. That means that the angle on the cocking piece will be a sharper angle. To cover the same rearward distance with shorter rotational distance requires a steeper cam angle. steeper cam angle with same weight firing pin spring results in a heavier load on the cam and as a result on the bolt handle. Now you may have rifles with relatively mild firing pin springs and this may not even be noticeable but in reality, the 90* bolt can use a less aggressive cam angle for the cocking piece. another way to look at it, imagine your rolling a 100 lb drum up two ramps, each 10 feet high. One ramp is a 20 degree angle grade, the other is a 45 degree angle grade. 100 lb drum is much harder to roll up a 45* angle then a 20* angle. Same idea here, just much smaller scale. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
60* or 90*, preference? One better than the other?
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