'Bolt Bumps' ?

[aixenmemphis]

When you guys talk about "bolt bumps" what are you talking about.

Thanks C.N.K.

 

[tenring]

As far as I know, they are found only on custom bolts. At front and rear of the bolt, the bumps are simply bit larger area than bolt body. You need to look close to see them. Supposed to keep the bolt alighned and slide smoothly in raceway.

 

[tightneck]

"Bumps" can be added to any bolt, but Jim Borden,I believe) is given credit for this concept. What it does is to make a sloppy bolt fit, tight. It can be accomplished by adding a sleeve at the front and/or rear of the bolt and then turning the sleeve's down until they are a snug fit when the bolt is closed. Most of the BR actions out there today have a tight bolt to raceway fit anyway and don't need any sleeving. A Remington or other factory bolt can benifit from sleeving the bolt for a nice fit in the action. With the cost of blueprinting, reaming and sleeving, a custom action is only a few bucks away though. If however, you can do your own work, then sleeving a bolt doesn't cost so much. IMO though, Dave Kiff makes aftermarket bolts for factory actions that just blow the originals away, and he will make it to whatever dimensions you want. When it's all said and done, you might have more money in a reworked factory bolt than you do in a Kiff bolt.

 

[Cheechako]

Sleeves and bumps have been around a long time and back in the days before all the custom actions were available it was about the only way to tighten up a sloppy bolt. Anyone with a lathe can do it but, as Tightneck said, it probably isn't worth the expense if you have to pay to have it done. Not when you can get a custom made bolt from Dave Kiff.

Here's one of my sleeves on an XP 100 bolt.

Ray

 

[rstreich]

"Bumps" are eccentricities either machined with the bolt on Nesika and Borden actions,Jim Borden holds the patent on this--6,209,249) or machined onto sleeves. The eccentricity is aligned with the locking lugs so that the bolt can slide freely, but when in battery, the eccentricities will tighten up any free play in the bolt.

From the abstract of Jim's patent:

A bolt for a firearm has a front and rear portion with increased diameter front and rear bosses, thereby allowing for reduced clearance between the bolt and bolt runway. The front boss has major and minor diameter portions, with the major diameter portions being located directly behind the locking lugs, and the minor diameter portions being equal in diameter to the rest of the bolt body. The rear boss is located directly in front of the handle, and has a uniform diameter equal to the major diameter of the front boss.

robert

 

[Cheechako]

robert

I don't want to get into a pissing match here but bumps were around many years before Jim Borden patented them. His patent was probably accepted because he developed the method for incorporating them into the initial construction of a new bolt whereas those from earlier years all relied on adding them to an existing bolt. As Ole would say, "Same ting, only different."

Ray

 

[aixenmemphis]

So when a you guys talk about boring out the raceways and adding sleeves to a bolt and turning them down to slightly smaller diameter than the raceways you are talking about the same thing as bumps. On the Kiff bolts do you use the internals of the old bolt or are they provided?

Thanks for all of you guys help

 

[Cheechako]

Cullen

Bumps are simply sleeves with a part of the sleeve removed. Only the two sides of a sleeve in line with the locking lugs make contact when the bolt is closed. But leaving a sleeve intact does no harm and they work just as well as when they are turned into bumps. Does that make sense?? It's simpler than it sounds. On some actions, such as a Rem 700, only the rear sleeve or bumps is needed since the bolt nose acts as the forward alignment.

Dave Kiff can make a bolt to any dimensions you want, either to fit a stock action or one that has been bored out. Best to talk directly with him about the particulars.

Ray

 

[aixenmemphis]

Thanks for all of the info

 

[rstreich]

I don't want to get into a pissing match here...

No pissing match here, Ray. It's just that the other posts didn't mention the fact that the sleeves weren't round. So, I thought I'd add a bit more. I mentioned the patent only because Borden and Nesika are the only custom actions that come with them. So, I wasn't disagreeing just adding to what was already there. I'm frequently guilty of being a bit terse in my responses, so I'm sorry if it seemed like I was contradicting you.

Personally, I prefer the bumps over just the tighter bolt, but I don't have a lick of evidence to support that preference. I guess I just like the sales pitch.

robert

 

[Cheechako]

Robert

I guess I worded my post wrong. I didn't mean to imply that I was disagreeing with you. This subject has come up before and there are some who are ready to argue that Jim did indeed invent the bumps. I was simply trying to head that off by saying that I didn't want to revisit the old disagreements.

BTW, I use both the sleeves and the bumps. I haven't found that it really makes any difference but have to agree that the bumps look better on a custom bolt job.

Ray