questions on bolt/sear interaction and tweaking

[scythefwd]

OK, looking at how the bolt interactions with the sear... lets see if I have this right.

the inner tab on the sear sticks up through the groove in the action and interferes with the cocking nob on the bolt from going forward.

You lift the bolt handle, and because that cocking nob is captive, its forced back by the angled part of the cut in the bolt body. Its held in that place by a slight indent. This also compresses the firing pin spring.

You pull the bolt, cycle your round, or just lower the handle.. and the nob pushes up against the sear lever through the action, forcing the sear against the ledge on the trigger. The nob is held back by the sear against the trigger now, and is off the notch in the bolt body.

You pull the trigger, sear slips off the ledge on the trigger, and the spring in the bolt body thats been pushing on the firing pin the whole time (and applying pressure on the sear) overpowers the sear spring and jams the firing pin through the bolt face and into the primer sitting there...


pulling the bolt handle up disengages the locking lugs on the bolt head from the front of the action, so I'd not expect any extra friction on that interaction (though some may occur from the primary extraction at the back of the bolt handle).

SO, here is the point of my rambling.

Polishing up the ramp on the back of the bolt handle should remove any friction occuring during the primary extraction, which should be minimal.
Polishing up the cocking nob handle and the cut on the bolt body that cams it back up into the cocked position should also remove some friction. Making it feel a little smoother, BUT not effect the bolt lift too much, unless those slots are really out of wack.

It appears that you could actually remove a bit of the bolt lift force by going with a weaker firing pin spring in conjunction with a sear spring.

Those two springs are in direct opposition, and while leverage on the sear is going to make this not a 1:1 ratio, I'd expect that dropping them both by similar incriments, you could really take a bit of weight off that bolt lift by almost the number of lbs that you remove from the firing pin spring (again, not 1:1). I think you could really do some good doing this if you could find a replacement sear spring... You can trim the firing pin spring to remove some of the preloading (keeping some as well), but I dont know what to do about lowering the sear spring...


Thoughs, comments, suggestions, "I've already done this and it doesn't work like you think because ... "

[BillPa]

Those two springs are in direct opposition"

Firing yes, cocking (bolt lift) no.

The sear torsion spring has zero effect on the bolt lift. It's sole purpose is to reset the sear so it can be picked up by the trigger to cock the bolt. When you press on the bolt release (an extension of the sear) the tension you feel is what the firing pin has to overcome when firing.

Bill

[scythefwd]

A greed Bill, BUT that relation is important to note I think. If I lower the sear spring so that it still moves the sear back into position, I can go lower on the firing pin spring (which has to overcome the sear spring to move the FP forward) weight. That firing pin spring weight will effect how difficult it is to cock the rifle and is directly related to the bolt lift.

The sear spring doesnt directly effect bolt lift, but going to a reduced power one lets me go even further down on weight on the FP spring I believe before I risk inconsistent primer ignition.. I could lower the FP spring weight alone, but I think I would have weak strikes sooner only screwing with one of the springs.

But good point on the pressure to remove the bolt.. I couldnt go much lighter I fear without going too far.. Its definitely something I think I'm going to play with. I'll keep this thread updated with results and details. First spring wire I'll be looking at is .06 diameter or .05 diameter for making a new sear spring... I'm gonna have to find a place for a custom firing pin spring.. I dont want to cut coils if I can avoid it (or not until I have a spare stock spring to revert to).

Thanks for the point of view.. tells me I'm not crazy, just not very well explained :D

[stangfish]

Preload of the firing pin spring loads the cocking sleave against the BAS. The narrow contact surface has tremendous (PSI) force where two relatively large diameter and flat surfaces need to slide. Reducing that preload and or reducing the contact area as well as the load surface is a good way to reduce the bolt lift force.

That preload does have an impact on sear presure but a finely polished surface at correct angles will be safe, break light, smooth and clean, even if there is some creep. turn on some light and grab a high power magnifying glass and take a looksee.

[scythefwd]

The sear spring is .041 spring wire. I just made one, no difference in feel... May need to go thinner.

I do have the trigger down to 2 lbs. chasing bolt lift now... Looking at spring preload and the ball bearing mod. Will look into polishing surfaces up.

[stangfish]

What ever distance you add to the BAS and the cocking sleave stack you need to relieve it with a spacer or by removing the distance off the BAS or the cocking sleave for the full effect.


BTW....Your hooked!!!

[BillPa]

The sear spring is .041 spring wire. I just made one, no difference in feel... May need to go thinner.



I use McMaster-Carr P/N 9287K78.

http://www.mcmaster.com/#torsion-springs/=m3i1dn

Bill

[scythefwd]

Ive tossed more in upgrades than the rifle costed me. I sought out savages cause they are a tinkerers rifle.

I figured it could be a nice project rifle.. so I made it one. Just "finished" the build so to speak. I'll do usability tweaks on it here and there..

Thanks for the link Bill.. I'll have to take a look at it in depth later. Would you happen to have a source for a factory savage firing pin spring???

[BillPa]

Ive tossed more in upgrades than the rifle costed me.


Other than changing the barrels, triggers, stocks, lugs, truing and straightening mine are all bone stock :p

[scythefwd]

new barrel, recoil lug, nut, stock, custom aluminum pillars, tuned trigger to 2 lbs. Only thing left is the bolt assembly and the action..

Hopeing for a different bolt body some day, bolt handle. Will be doing some tweaks inside the bolt too.. so it'll be about 90% worked over. A true and time from SSS may happen some day.

[stangfish]

bolt handle.

Aw naw, now you up and dunnit.

[scythefwd]

???

[iusmc2002]

I bought 3 Wolfe Extra-Power springs for 3 of my Savages, plus I had to purchase a whole new firing pin for one of my caliber conversions.... Shoot me an address and I'll pass along one of those extra FP springs to ya'. You can chop the hell out of it and see what it gets you

[scythefwd]

Where on the website did you find the springs man? I went looking through and didnt see any.

You have PM in bound with my address.

[scythefwd]

any of yall need some rough cut pillars?

They be knurled. Overly long (I requested that the be over long so I could cut them to exact length). They are .5" OD, .3" ID. Front pillar is countersunk (too short for the LONG factory factory screw, too short for a 1" long socket cap screw). The front needs to have the counter sink deepened a little to use the socket cap screw.. which is what I did with my installed set. A 3/8 bit is perfect for that..

[iusmc2002]

The Wolfe springs? I bought them from Midway this last winter when I had too much snow on the ground to do anything, so I fiddled with my guns. Glad I got them when I did because they're hard to find now. I will say, though, the 3 rifles that have the Wolfe springs in them are noticeably more difficult to cycle the bolt once fired than my other rifle is, that doesn't have the Wolfe spring. I don't know if that's a "Duh" or a "Hmm, interesting" observation.

I bought several bolt retaining pins, ejectors, ejector springs, ejector pins, extractor or two, and some of the extractor springs. Think I even got an extra bolt head. Anyone need any 7mm Rem Mag take-off barrels? :cool:

[scythefwd]

Dang man..

Yeah, the lifting of the bolt cams the pin up that ramp cut into the bollt body. The FP spring is the force you have to overcome.. so I'd see that increasing bolt lift ;).. I'll get her hacked down quite a bit and see if I can lessen the bolt lift a bit.

[iusmc2002]

Midway has them in stock now, if you were wanting any. $7.99 per

[scythefwd]

I'll let you know about how well the home made sear spring holds up. I had a bunch of .041" spring wire left over from my spring upgrade on my trigger.. so I made one, only to realize that spring was the same diameter as the one I made..

The spring is UGLY.. but hey, why not give it a try right?

[scythefwd]

Playing around a little more with it.. the only resistance comes from that spring. Removing the cocking lug (which leaves everything else in place, but removes the spring compression) and its lighter than a 1 finger lift. Looks like I have some polishing and spring trimming to do. I still think the 38 spc bolt lift mod will do wonders in removing some resistance..