Hard Bolt Lift

[inspectormac]

I'm hoping that someone here may have run into this before. I have a Savage Model 12 Varmint Low Profile that I have recently put a new Shilen 22BR barrel on. I followed all the instructions that I could find on the web, and didn't have any trouble at all with mounting the barrel. I used a Go gage from PTG with a piece of .001" shim stock behind it so the chamber wasn't "tight" on the Go, but was near the Go.

The issue that I'm having is that I get easy bolt lift right up until the cocking pin in the bolt starts to engage, then it gets tough to lift the bolt, and I have to pull it up with some force. It only does it with a piece of brass in the chamber, not with the headspace gage, so I'm not sure what's going on. I don't have any pressure signs after firing, and I don't have any problem getting either a full length resized and neck turned round, or a piece of fired brass into the chamber. The beginning of the bolt lift is fine as well. I'm wondering if I somehow screwed up when I put the bolt back together, and that is what is causing my problem.

I'm using Lapua brass and a Forster full length bench rest sizing die. The barrel was a prefit from Shilen cut with a PTG reamer that I have the print for, and everything should clear fine. My case head measures .4705 after firing, and the reamer print calls for the chamber to be .4738 at the bolt face. at .2 inches from the bolt face the reamer should be .4714 and my brass measures just over .469. Do these numbers sound right for clearances in the chamber, or do you think that could be a problem?

Anyway, I'm just fishing to see if I can find some answers, so anything anybody has will be much appreciated. Thanks in advance for your time.


inspectormac

 

[tiny68]

Try one thing. Just for the heck of it take the front action screw all the way out and see if that problem still occurs. Let me know if it solves the problem,action screw is slightly too long and is touching the bolt as it engages the lugs). The easy way to verify is look for a shinny spot on top of the action screw that indicates contact. Without a case the bolt is free to move up a little. I have seen this more than once on Savages including mine. If that doesn't help I make have another idea. tiny

 

[inspectormac]

Right now the barreled action is sitting in the stock without the action screws engaged at all, and it still does the same thing. The action was a 22-250 that I shot until the barrel was done, so I'd think anything like that would have been worked out before, but I could be wrong.

inspectormac

 

[gunsandgunsmithing]

Does the fired brass have rings or marks on it? How's the chamber look? I suppose the bolt could be assembled wron too. Just use a parts diagram and put it together that way and try it if you don't see anything else that may be the culprit. Sounds like really poor timing. Just some thought. Hope it helps ---Mike Ezell

 

[inspectormac]

How is timing in this bolt accomplished? Is it something that is cut at the factory, or something that can be adjusted,and therefore messed up)? The fired brass doesn't seem to have any problems. No real marks at all in fact. I will follow your advice and tear the bolt apart again to look at my bolt and a parts diagram for any discrepancies. Thanks for the suggestion. I just found a good diagram on the SavageShooters forum. In fact, here's the link just in case it might benefit someone else.

Savage Bolt Diagram

 

[inspectormac]

Mike,

After reading your post again I decided to mark the base of one of my resized cases with permanent marker and then put it into the chamber and pull it out again. I did find a small area where the brass seemed to have rubbed, but it didn't rub hard enough to get the brass down to bare metal, in fact it just rubbed the marker a little bit in one spot. Could this be causing the bolt lift issue? I don't think it's really tight enough to do anything since it wasn't even tight enough to take off all of the marker in that one spot. Anyway, just wanted to give an update and let you know that it is rubbing just a hair.

inspectormac

 

[tiny68]

Do you have scope mounts installed? tiny

 

[inspectormac]

No, at this point there are no action screws or scope mount screws to interfere with the bolt, but they didn't cause any problems before the rebarrel, so I doubt they would now anyway. I looked a little closer at some of the brass that was really tight, and it does seem after looking again, like it is rubbing on the body of the brass. That would lead me to think that the brass is too big, even though it's been resized, or the chamber is too small. I happen to be in a unique position to verify which one, as I program and run a coordinate measuring machine for a living. Tomorrow I'll be scanning brass and chamber and comparing it to the reamer print to see what's what. I'll post again when I get some more information off the machine.

inspectormac

 

[inspectormac]

OK, so here's where I stand. This morning I scanned the chamber and a piece of brass that was too tight in the chamber. I found that the chamber is undersized by about .0025 diameter about halfway up the body of the brass. The brass at that point is smaller than the chamber print, but only by about .001. That leaves .0015 crush fit, or interference fit, which is why I'm having such a hard time getting the bolt handle to lift, and extract the brass. These nominals are all from the reamer print that I got from Dave Kiff at PTG. Do you think I should call Shilen and talk to someone in their quality department? It seems to me like the reamer that they used was worn out, and produced an undersized chamber. I don't know what kind of tolerance they put on their chambering, so I don't know if it is specifically out of tolerance, but I do know that the reamer print calls for +.0004" on diameters, so they are definitely outside of that.

Anyway, I guess I'll be calling around to see if I can get some information from Shilen, and hopefully one of you guys has been in this situation before and will have some ideas.

Thanks in advance.

inspectormac

 

[bowers]

take your barrel off then put your brass in the chamber if it drops in easy you have the head space wrong if it wont go send it to me i will re chamber for

 

[inspectormac]

I can't even push the brass into the chamber with my thumb, so I'd definitely say that it's hitting. In fact, after measuring it, I know that it's hitting on the body of the case. I've called Shilen, and they said they'll look into my measurements, which I've sent off to them. I'll see how they want to proceed before doing anything else. I do appreciate the offer to rechamber the barrel, and will keep it in mind if it becomes necessary. Thanks.

inspectormac

 

[SooStan]

Are you using a resized case or a new round?

 

[inspectormac]

The brass is all once fired, which is when I noticed that I had an extremely hard time with the bolt lift. After firing it has been resized with a Forster full length die. The brass measures right at or just bigger than the maximum case size, while the chamber is undersized, hence the interference fit.

inspectormac

 

[inspectormac]

Well,

I guess I've got it figured out now. I called and talked to the guys at Shilen, they measured their reamer, and came up with the same size for the chamber that I did, which is undersized. Unfortunately, now the reamer has to go back to PTG to get reworked, and then they'll fix the chamber. Oh well, I waited 3 months for the barrel, so another month or so won't hurt me any.

On another note, do any of you guys know a good rifle smith in the Phoenix, AZ area? I have a factory barrel for this same gun that doesn't have too many rounds through it, but came with a throat that was about .175" of freebore, which made it hard to get it to shoot well with the smaller bullets. I'd like to look at getting a smith to lop off about a quarter inch of the barrel and rechamber to get me close to the lands. Anyway, if anybody has any reccomendations I'd appreciate them.

Thanks for all the ideas to try and the offers of help, it's much appreciated.

inspectormac

 

[Rustystud]

Take the bolt apart and clean the firing pin, cocking piece. and cocking piece sleeve. Check the rear locking washer to make sure it is not binding on the firing pin. Reset the cocking timing if it is over cocking. Make sure there is no trash under the cocking piece pin causing the head to rub the inside of the action.
Good luck
Rustystud

 

[inspectormac]

I've already taken the bolt apart and cleaned it well, as well as the firing pin assembly, and the coking piece and sleeve. I've got the inside of the bolt cleaner than it's ever been. In fact, I even took the ejector pin and spring out to make sure that wasn't causing a problem with extraction. How would I reset the cocking timing? Would that involve filing the cocking ramp to make sure the bolt isn't over cocking, or something else? Thanks for your time.

inspectormac

 

[Rustystud]

The cocking piece is threaded. The firing pin is screwed into the cocking piece. There is a locking ring washer that is engaged in the cocking piece sleeve. Adjust the amount of travel of the cocking piece pin. Most factory Savages are over cocking and that is part of the hard bolt lift. Be carefull to not completely unscrew the cocking piece because the spring and washer will fly either into your eye or out of sight.
Rustystud

 

[inspectormac]

OK, so I'm with you so far. I see all the parts, and understand how to adjust them, but how do I know when the cocking piece pin has been adjusted correctly. In other words, how do I know that the bolt is over cocking, and not cocking just right. I don't have any problem believing that it is, and I also don't have any problem adjusting it, but how do I know that I've hit the right adjustment?

Thanks,

inspectormac

 

[medicineman]

Re-adjusting the cocking piece will not change the cocking ratio, it will only change the firing pin travel. Changing the cocking ratio requires that the rest of the geometry be corrected as well. This process is something that hobbiests will have a hard time understanding and comprehending, let alone doing it correctly. It takes machine tools and specialty tools along with a formula of parameters to get optimum results.
To get you back to where you need to be, outside of a truing & timing job, adjust your firing pin protrusion to .035-.040". Then adjust the cocking piece for .005" clearance from the bottom of the cocking ramp when the firing pin is fully forward.

 

[SooStan]

I have had dies that would not properly size a 223. Are you using a case gauge to ensure the brass is properly sized. Also check the overall leanth. They grow a lot on just one sizing causing the neck to be jamed into the step in the chamber. Does it open and close on a factory round before firing with out the problem.