Tell me about Borden Bumps on bolts.
- Thread starter LorenC
- Start date
Boyd Allen
Active member
What do you want to know? It sounds like you already understand what they are. I guess the only comment that I would make is that there seems to be a lot of very good benchrest shooting done with actions that do not have bumps. From that I conclude that if bolt clearance is small enough (and everything else about the action is correct), perhaps there is little to be gained from bumps. On the other hand, I find no fault with their theory of operation.
r44astro
New member
It is possible with a number of different CNC machines; to machine a bolt body slightly elliptical so that the diameter measures larger in line with the lugs than opposite them. In fact it has been done on manual lathes by using the 4 jaw chuck and a "cat head fixture" to set the bolt slightly off center and machine each side slightly in 2 operations.The elliptical feature may be confined to the front and rear part of the bolt body that are actually surrounded by steel when the bolt is closed, or the entire bolt body may be uniformly elliptical. I have one, but it is packed up at the moment, so I am not sure how Jim actually does them. I have a custom action by another maker (No longer in business) that has the entire bolt body machined about .002 out of round. The only purpose is to allow a little more clearance so that the bolt slides open and closed easily.
Scott Roeder
Tell me about borden bumps
Borden actions are some of the finest made. The bumps lock up tight , there is enough clearance to work the bolt properly.
If you shoot fast though that may be a little harder. shooting {picking] is where they shine.
I have 2 and I love both of them I'm a picker not what they call a runner They are smooth.
Borden actions are some of the finest made. The bumps lock up tight , there is enough clearance to work the bolt properly.
If you shoot fast though that may be a little harder. shooting {picking] is where they shine.
I have 2 and I love both of them I'm a picker not what they call a runner They are smooth.
Either or...
I had Borden rework a Remington 40XB single shot action for me. The original bolt was used. He added "bumps" to the bolt. So the answer is that that bumps can be added to a bolt lacking them or can be integral to a newly made bolt.
I had Borden rework a Remington 40XB single shot action for me. The original bolt was used. He added "bumps" to the bolt. So the answer is that that bumps can be added to a bolt lacking them or can be integral to a newly made bolt.
Jim does or has done both. They can be visible or subtle. I have a Borden TPE made through the Nesika contract which has very pronounced bumps integral to the bolt body.
I am a strong proponent of the Bumps and have personal ideas re whether or not they should both be the same size, (Borden Bump(S) plural occur on both ends.... others copy the idea and some only put them on one end....) and whether or not they should be concentric or eccentric.
Traditionally the add-on collars are epoxied, soldered or silver brazed in place.
hth
al
Great, answers found.
My reasons for this coming to mind is thinking of poor triggers, and that for a trigger to work well it'd have to have a sear with reliable positioning. Bumps would sure be a good solution to that issue. I have a Mauser with a Mcgowan 7br on it and some model of sako trigger. At 6 ounces pull it gets pretty erratic and I'm guessing bumps may have an excellant chance of making it better, along with squaring up the bolt. It shot good enough when i stopped shooting years ago its worth a bit more effort put into it.
My reasons for this coming to mind is thinking of poor triggers, and that for a trigger to work well it'd have to have a sear with reliable positioning. Bumps would sure be a good solution to that issue. I have a Mauser with a Mcgowan 7br on it and some model of sako trigger. At 6 ounces pull it gets pretty erratic and I'm guessing bumps may have an excellant chance of making it better, along with squaring up the bolt. It shot good enough when i stopped shooting years ago its worth a bit more effort put into it.
Dick Grosbier
Club Coordinator
Put a few "little to be gained" items together and you have a serious improvement. I think winning at BR is about getting all the little things working together at the same time.
Dick
Borden Bumps are a special feature applied on airgun or rifle bolts, primarily designed and developed by the manufacturer Borden Rifles. This feature is intended to improve the accuracy and enhance the stability of the bolt during opening and closing.
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