Model 700 stiff bolt action

M

model14

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My Model 700 .223 has a very stiff bolt action caused by the cocking of the firing pin. This becomes quite irritating after 25 rounds from the bench, due to aggrevating a slightly arthritic thumb joint, and having to reposition my rifle on the bags after each bolt cycle. I have heard that custom built bench rest actions have so little cocking force that the rifle does not rotate in the bags when the bolt is cycled. My bolt assembly is super clean and well oiled/greased. Any suggestions on how I can reduce the force required to cycle the bolt? I can't think of any and I don't understand how the custom actions can get by with so little cocking force.
 
Exactly where you lubricate your bolt is important. Lube the locking lugs and the cocking cam (on the rear of your bolt). Also be sure your chamber is clean and DRY. When your ammo sticks well to the chamber wall, it puts less force on the bolt face. That can make it easier to open your bolt. Wipe the sizing lube off your handloads with a solvent, and be sure your handloads aren't "dragon" loads.

- Innovative
 
There is more to it than just the cocking of the firing pin although this is a significant part of the problem. The loose fit of the bolt in the rec is part of the problem. The roughness of a factory rec bore. The locking lug abutments in the rec are usually pretty rough and this causes a lot of friction when there is a fired case in the chamber. The locking lugs on the bolt may be out of true. The shortness of the std remington bolt handle is another problem.

I have spent a lot of time massaging my 40x bolt and the bolt lift on an empty chamber is pretty good but the bolt lift on a fired case is pretty bad. Since the last match I made a tool and lapped the abutments in the rec and then lightly lapped the bolt locking lugs. I haven't fired the rifle yet so I don't know if there will be a significant improvement.

If there isn't a big improvement I will never fire this gun in a match again !!!
 
To reduce the cocking force on the 700 I can think of some things to do... and not.

To do:
- not only polish but recut the cocking ramp for better footprint. You do this by carefully watching the greasemarks and removing metal such that you effect an even tracking surface up the cam. A wide track will hold lube better and be slicker. (I word this poorly, hope it makes sense)
- lengthen the bolt handle, increase the throw, decrease the felt force. This does NOTHING though to help with bag upset.
- recontour the bolt knob, get rid of the annoying checkering and spoon the knob at 20-30degrees off horizontal. Match the angle of the knob to your finger/knuckle whatever you slap it with.
- take the bolt apart and polish the firing pin length, inside the spring. Also polish the ends of the spring and add a thin brass washer if possible.
-GENTLY lap and lube the bolt shroud thread-to-bolt fit. Here's where a
Delrin shroud is awesome.
-GENTLY polish the bolt itself and inside the rear raceway (rec ring) try to remove as little metal as possible. You're gaining frictive advantage at the loss of binding advantage. This approach is iffy if you've already got a loose bolt.
- bush the bolt ALA Borden Bumps.
-And lastly, this is an Alinwa Redneck Special...... take it with a grain of salt! I've replaced the rear base screw with a meticulously hand-fitted screw which extends down to bear on the bolt body. End of screw to be flattened, hardened and highly polished. Set to take up play in the ring. So far I've found no deleterious effect, no dimpling or weird wear from bolt slap. Try this only if you're a weirdly experimental sort as I'm........ It can help. I've toyed with the idea'r of tapping other balancing/tuning screws in but just haven't found time, especially since this only approaches ONE of a dozen problems with the 700 action. It's just always cheaper to buy a custom. ALWAYS....

NOT to do:
- lighten the spring tension. Done properly using a new pin and bushed boltface this CAN be done BUT.... don't just lighten the spring.

re custom actions:

Custom rifles approach this in a number of ways. First, they can offer a better balance of weight VS spring tension VS throw by utilizing tricks like .062 firing pin diameter, less tolerance stacking loss, less hysterisis loss etc. Just tighter and better engineered. Tons-a-detail here....

Next, custom cocking ramps. Lower, longer etc.... Some like the three-lug offer a larger bolt body just to lengthen the ramp.

Roller cocking cam. This is de rigeur on the three lug BAT f'rinstance. I've got a 2-lug BAT with a roller...... the roller nearly eliminates drag on the ramp.

Without getting into too many gory detail suffice it to say that a custom action can be FLICKED open with a fingertip or knuckle. Amazing.

hth


al
 
Alinwa,
Thanks for the very informative post. I am still having fun trying to get more from my 700 without spending more money. Unfortunately, my biggest problem now is I can't locate any primers or good bullets in my area. The situation seems to be getting worse.
 
What has already been said is true. Surface finish/lubrication is the most obvious thing to look at. There are a couple of things I do here in the shop when I have a stiff one. The basic mechanics are the firing pin has to be moved a specified distance in approximatley 90 degrees of bolt rotation. That is done using the bolt camming surface. Custom action lay this angle out as shallow as possible. Remingtons on the other hand have a steep angle and the firing pin travel distance is reached in less than 90 degrees rotation. Steeper angle means more effort is required to cock the bolt. I don't recommend the novice do this but I've done so many it works here. I take the bolt over to the grinder and alter the sweep/angle on the cocking surface. I lay that surface down/back as much as I can. Clip the top off the usually deep notch on the end of the bolt and polish all surfaces to a mirror finish with a cratex wheel. Lube and assemble. That takes care of I'd say 50% of the problem.


Dave
 
I do basically the same as Dave but I do have a concept that I use. I call it 'falling rate'. I remove the 'detent' portion of the cocking ramp. I use the side of a dremel cut off disc as a grinder to carefully level off the full cock notch BUT without reducing the actual full cock distance. Just knock down the detent bump.

I then carefully [ there's that word again ] blend the full cock notch to the existing ramp. I probably only blend the last 1/4 to 1/3 of the ramp. Most of the cocking is still down on the first part of the ramp. As the bolt handle is being lifted up towards the end of it's travel the FP spring is requiring more and more effort to compress BUT the cocking piece is now on the new more gradual ramp which is reducing the effort required.

Every cocking piece I have inspected has vertical machining marks on the nose that bears on the bolt's cocking ramp. I stone the marks away.

Ditto on what has been said about getting the maximum amount of bearing surface on the cocking piece nose and the cocking ramp. My newest aftermarket action was only bearing on about .020" of the ramp and on the inner sharp edge. By careful stoning of the ramp I moved the bearing surface out towards the middle and greatly increased the actual rubbing surface area. This and doing my normal cocking ramp rework greatly improved the bolt lift.

The pic below shows before and after on a PTG bolt body. You may have to study the pic a while to figure out what you are seeing.

40xcockingrampone.jpg
 
If the 700 in question is one of the later ones with the J-Lock firing pin. assy, replacing it with a 'normal' 700 firing pin assy. would be the first thing I'd do. Pierce Engineering makes excellent replacements as do Gre-Tan and others. -Al
 
Al Nyhus said:
If the 700 in question is one of the later ones with the J-Lock firing pin. assy, replacing it with a 'normal' 700 firing pin assy. would be the first thing I'd do. Pierce Engineering makes excellent replacements as do Gre-Tan and others. -Al
Click to expand...

>>>Yes<<<......... Big improvement with the J-Lock assy!
 
crb

That's what I do only I'm blending it in about 1/3 of way down the camming surface. Shallower angle and a good polish job makes all the difference.

The issue with the cam angle has been mention to Kiff. I just got a bolt in and he hasn't changed it yet.
I need to talk to him anyway I'll give him a call Monday and suggest a variable camming angle. Reduce the angle the last .080-.100" of travel. That's what CNC equipment's for.

Dave
 
700

Check to see if the number etched on the bolt body matches the rifles serial number.
 
Dave, crb,

I did the cocking ramp leveling you suggested and it definitely helped. Thanks.
 
Last edited by a moderator:
Al Nyhus said:
If the 700 in question is one of the later ones with the J-Lock firing pin. assy, replacing it with a 'normal' 700 firing pin assy. would be the first thing I'd do. Pierce Engineering makes excellent replacements as do Gre-Tan and others. -Al
Click to expand...

Al,
Will this help in reducing cocking force? My rifle is post lock (2002 700 VLS).
Also, with the Pierce, I wonder if getting rid of the convoluted spring will also help?
Thanks.
 
Polishing ramp

Dave Tooley said:
snip Clip the top off the usually deep notch on the end of the bolt and polish all surfaces to a mirror finish with a cratex wheel.Dave
Click to expand...

What, exactly, is a "Cratex Wheel". Is this a Dremel attachment?
 
Roy .........

Craytex is a mild polishing abrasive that is formed into different size wheels and bullet shaped bits. They're made for Dremel tools, and they do a great job of polishing. For cutting the basic shape, you'll need to use a small cut-off disk. Be sure not to remove the detent at the end of the ramp, because that's what holds the firing pin in the cocked position. The picture provided by CRB is a very good example of the job done right.

- Innovative
 
Just so you'll know where I'm coming from

I have a 6ppc on a Rem 700 SA built by Don Geraci. Bob Brackney blueprinted the action and it has a Krieger Lt. Varmint barrel. The firing pin is by Pierce Precision.

I don't know if it is the new firing pin/spring, etc. or if there is something you guys know that I can do to the Pierce before I go altering the bolt cam.

I'll also try with my old pin and see if I can find any difference.

Maybe I should just reduce my N133 powder charge. I run from 28.5 to 29 grs. with a hard bolt lift most times.

What do you think?
 
You should pull the bbl so you can closely inspect the locking lug abutments in the receiver. If they are a bit rough I think you can forget having a smooth bolt lift on a fired case.

It is relatively easy to get a decent bolt lift on an empty chamber and of course this is the first step. It's the bolt lift on the fired case that really matters. Due to tweaking my lower back I didn't get to shoot in the match last Saturday so I don't yet know if my new lapping tool made a difference in the bolt lift on my 40x.
 
I filed the notch off the cocking ramp of my bolt this weekend and gave the entre ramp a polish. Helped alot with the stiffness of the bolt. I think the worst part now that you can feel is overcoming the strength of the spring. I have a gretan firing pin spring in it now. Might put the stock spring back in it and see how it is.
 
Never thought about that

crb said:
You should pull the bbl so you can closely inspect the locking lug abutments in the receiver. If they are a bit rough I think you can forget having a smooth bolt lift on a fired case.

It is relatively easy to get a decent bolt lift on an empty chamber and of course this is the first step. It's the bolt lift on the fired case that really matters. Due to tweaking my lower back I didn't get to shoot in the match last Saturday so I don't yet know if my new lapping tool made a difference in the bolt lift on my 40x.
Click to expand...

That's a distinct possibility. I'm going to pull the barrel today and inspect the receiver face. Thanks for the heads up.

Roy
 
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