Posted: 6/27/2009 12:06:08 AM EDT
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A thought occurred to me during a competition recently - its stages consisted of 10 rounds very rapidly at 200 yards on very small targets - although not a puny fellow, I did notice that the physical effort required to operate the bolt seemed to widen the groups particularly for the last couple of each detail. I never noticed this with my old Remington 700 and I assume its because of the extra effort involved with overcoming the mainspring as opposed to the non sprung bolt of the Remington ? IIts not sticky extraction as the rounds are not overly stoked up being factory match rounds. Or maybe I am just getting older............
Questions - 1, Are there differing strengths of mainspring available ? 2, Does it do anything to assist keeping bolt locked or is that purely down to the rotating lugs ? 3, Would it feed ok without mainspring ( or very light one ) - ie, just pushing the bolt handle forward rapidly / firmly ? |
| The spring is used to provide the driving force for the firing pin, nothing else. Stronger springs are available, usually with lighter firing pins designed to reduce lock time. If you have a standard spring already fitted a lighter one will probably result in light strikes and lots of frustration. |
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Quoted:
The spring is used to provide the driving force for the firing pin, nothing else. Stronger springs are available, usually with lighter firing pins designed to reduce lock time. If you have a standard spring already fitted a lighter one will probably result in light strikes and lots of frustration. I meant the main spring - the one housed in the butt stock. |
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Quoted: A thought occurred to me during a competition recently - its stages consisted of 10 rounds very rapidly at 200 yards on very small targets - although not a puny fellow, I did notice that the physical effort required to operate the bolt seemed to widen the groups particularly for the last couple of each detail. I never noticed this with my old Remington 700 and I assume its because of the extra effort involved with overcoming the mainspring as opposed to the non sprung bolt of the Remington ? IIts not sticky extraction as the rounds are not overly stoked up being factory match rounds. Or maybe I am just getting older............ Questions - 1, Are there differing strengths of mainspring available ? 2, Does it do anything to assist keeping bolt locked or is that purely down to the rotating lugs ? 3, Would it feed ok without mainspring ( or very light one ) - ie, just pushing the bolt handle forward rapidly / firmly ? You could try a carbine length spring if you have a standard length one fitted, but I think the idea of pushing the bolt handle forward is asking for jams... (Some sort of spring is required to keep pressure on the back of the bolt carrier to stop the bolt unlocking...) |
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Quoted:
A thought occurred to me during a competition recently - its stages consisted of 10 rounds very rapidly at 200 yards on very small targets - although not a puny fellow, I did notice that the physical effort required to operate the bolt seemed to widen the groups particularly for the last couple of each detail. I never noticed this with my old Remington 700 and I assume its because of the extra effort involved with overcoming the mainspring as opposed to the non sprung bolt of the Remington ? IIts not sticky extraction as the rounds are not overly stoked up being factory match rounds. Or maybe I am just getting older............ Questions - 1, Are there differing strengths of mainspring available ? no, but there are different buffersprings for carbines, rifles and AR10s 2, Does it do anything to assist keeping bolt locked or is that purely down to the rotating lugs ? just the locking lugs 3, Would it feed ok without mainspring ( or very light one ) - ie, just pushing the bolt handle forward rapidly / firmly? you will need the force of the bufferspring to ensure that the bolt locks I dare say that heat plays a part here as you mention rapid fire, and remember that a bolt gun will have primary extraction which an AR doesn't. I would suggest that you review the following:
As he now has a licence for a drill and a hammer and a hacksaw - pay streetfighter a visit |
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A thought occurred to me during a competition recently - its stages consisted of 10 rounds very rapidly at 200 yards on very small targets - although not a puny fellow, I did notice that the physical effort required to operate the bolt seemed to widen the groups particularly for the last couple of each detail. I never noticed this with my old Remington 700 and I assume its because of the extra effort involved with overcoming the mainspring as opposed to the non sprung bolt of the Remington ? IIts not sticky extraction as the rounds are not overly stoked up being factory match rounds. Or maybe I am just getting older............ Questions - 1, Are there differing strengths of mainspring available ? 2, Does it do anything to assist keeping bolt locked or is that purely down to the rotating lugs ? 3, Would it feed ok without mainspring ( or very light one ) - ie, just pushing the bolt handle forward rapidly / firmly ? Must have misunderstood, are you talking AR or 700? If its AR then mainspring is the incorrect terminology, it should be action or recoil spring. If you only notice the problem on the last few rounds of a rapid string it could be down to the fact that the chamber is heating up faster than it can cooldown as is therefore getting a little tighter. Probably need to eat more Weetabix. 
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Shooting position prone.
Large right hand cocking lever. Factory match ammo ( getting .5 moa when zeroing ) Chamber - the barrel is a Douglas XX - what can I do to improve chamber ? Can it be polished etc ? Might be an element of rushing involved I guess. Another though occurred to me - when the bolt on a straight pull is pulled back, then allowed to travel forward chambering the round - does the bolt slamming home cause any vibrations / harmonics in the barrel ?? Enough to affect accuracy ? |
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Quoted: Shooting position prone. Large right hand cocking lever. Factory match ammo ( getting .5 moa when zeroing ) Chamber - the barrel is a Douglas XX - what can I do to improve chamber ? Can it be polished etc ? Might be an element of rushing involved I guess. <-This Another though occurred to me - when the bolt on a straight pull is pulled back, then allowed to travel forward chambering the round - does the bolt slamming home cause any vibrations / harmonics in the barrel ?? Enough to affect accuracy ? I think you're grasping at non-existant mechanical straws here. I think the most likely explanation is that you're just moving position as you pull the bolt back, opening your group up. As the chamber heats during rapid fire, you just need to get used to pulling harder, but without moving position. |
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Shooting position prone. Large right hand cocking lever. Factory match ammo ( getting .5 moa when zeroing ) Chamber - the barrel is a Douglas XX - what can I do to improve chamber ? Can it be polished etc ? Might be an element of rushing involved I guess. <-This Another though occurred to me - when the bolt on a straight pull is pulled back, then allowed to travel forward chambering the round - does the bolt slamming home cause any vibrations / harmonics in the barrel ?? Enough to affect accuracy ? I think you're grasping at non-existant mechanical straws here. I think the most likely explanation is that you're just moving position as you pull the bolt back, opening your group up. As the chamber heats during rapid fire, you just need to get used to pulling harder, but without moving position. Yes, I am sure a little grasping is going on 
Not the best rifle shot there is and still working on my technique. Was just wondering if there was anything I could do to assist with the mechanics................. |
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More rapid fire practice. Are you shooting the NRA CSR Championships? Loads of practice, lots of positions, a little running and a lot of upper body weight lifting. Come out with us tomorrow. We're going open country searching in full kit and plates in a forecast 30 degrees. I really hope it chucks it down.................. 
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