Bolt lift comparison

[generalzip]

I've heard this action is lighter than that one blah blah blah too many times. Is there a way we can settle this once and for all scientifically? I have access to a tikka, impact, Defiance Deviant, TL3, and soon a Curtis Vector. Is there a scientific way to measure bolt lift (after firing pin is down) at a set distance from the bolt to compare apples to apples which action actually has the lightest bolt lift? Would be interesting to see how some of the newer 60 degree throws compare to the 90's as that is always the classic drawback argument. Does anyone have any other actions they could throw into the mix and have an idea on what scale to use to test and a procedure for testing?

 

[arm017]

Nice topic.

IMO the biggest differentiator of any of the custom actions is feel, and bolt lift is definitely a huge component of that. These actions all serve the same function- to deliver a round to the chamber and strike a primer. Once this task happens reliably, then we make threads to discuss all of the nuances that go into micro differences in actions. Having owned nearly all of the big names, I would tell anybody researching - its all good stuff.

Bolt lift is important because it dictates the resistance met when first opening the bolt that directly impacts one's ability to maintain site picture and keep the rifle level as well as speed and fluidity of the bolt stroke.

As far as quantification of said variable - I am all ears.

 

[kthomas]

We also need to keep in mind the bolt close effort. Shortly after closing your bolt, you should be preparing to send a round down range. A light bolt lift is great and all, but having a solid sight picture on the target is more crucial when you close the bolt (right before you send a round) than opening. I personally would rather have a slightly heavy bolt lift then bolt close.

 

[generalzip]

Good point. I guess in my experience I’ve never felt a bolt close that was so heavy that I felt it threw me off target anywhere near as much as the lift. Obviously the weight of the rifle plays a huge factor in all this in terms of feel and how subjective this factor becomes. Bolt close might also be a bit harder to measure from a testing standpoint. Especially for some of the CFR actions.

 

[clyancey]

I'm very interested in this as well. Bolt lift is obviously not the number one concern for an action but it it's a luxery/feature worth quantifying I believe.

 

[steve123]

A metric which to be included should be using the same firing pin spring weight, otherwise the results would be skewed. Maybe even the trigger timing checked, as well.

 

[Greg Langelius *]

Bolt lift is (within reason...) a subjective matter. I keep hearing that Savage rifles have stiff bolt lift, and I believe that.

But bolt lift has never been an issue for me. I push the handle up, the bolt lifts. End of story. Move on...

I had an Enfield once, and yes, the bolt worked exceptionally smooth. But the rifle wouldn't shoot for doodoo. For me, there is no connection.

Greg

 

[arm017]

There are numerous factors that contribute to increased bolt lift.

Also likely depends on ones shooting discipline - for the prs folks, light bolt lift is a thing.
Prone precision marksmanship where you have time- yeah probably not as much of an issue as you could correct a bit of cant.

firing pin spring weight and I'm sure plenty more on the spring metallurgy, etc.
angle of cocking ramps
coatings on bolt and action
Type of bolt knob/ angle / etc will go in to leveraging and thereby decreasing the engagement force

 

[g.ross]

Spring wieght and pin fall . A light weight spring and short pin travel will make it feel light . It would be hard to do a true test with all the variables . I have also ran multiple different actions by the same manufacturer that had a different feel to each one. Good luck on the venture it will be interesting to see the results !!

 

[redneckbmxer24]

Just the tolerance in springs can make a difference in bolt lift in the same exact action, it's not likely to be enough to be felt but it'll be there.

To me, when comparing 90 degree action they are all pretty similar. I've never met a 90 degree that I would call "heavy". The smoothness of the lift is much more noticeable action to action for me. Handle and knob length also play a huge part in the effort required to lift the handle. I also find actions with straight handles to feel more effortless than those with swept handles.

Without comparing them with the same exact handle lengths, knobs, and handle angle then no comparison would be a fair one.

Personally I don't get wrapped up in bolt lift unless it's a problem, and if it's a problem on a 90 degree then there's probably something wrong with the action itself. Shorter bolt lifts like 60's can get tricky though, they're a different ball game all together. The only 60 degree I've ever liked is the AI, but I haven't played with a Curtis and I hear they're very nice. There's some tweeners like Tikka and Nucleus neither of which feel heavy to me.

I'm far more concerned with how the action feels and feeds, and that it doesn't bind when being run hard. There's a fine line between having a tight enough bolt to action clearance to not bind, but enough clearance that the littlest bit of dust won't lock it up. Some manufacturers have that figured out and some don't. I've yet to go to a match that wasn't either very dusty or very muddy, so that's a major concern. You can only do so much to keep that shit out of your action.

 

[generalzip]

As far as a procedure I'm thinking to measure a set distance (maybe 2.5") from the center axis of the bolt. Mark the spot and tape a piece of spring so that the radius is constant for all tests. Lift on an uncocked action, perpendicular to the handle, 5 times and record results. As far as spring weight, piring pin travel, timing etc I'm going to test the action as they came from the factory. I will use a triggertech special (the same exact trigger) for all testing. I'll be using the same spring scale for all testing as well to try and remove as many variables as possible.

Does anyone see any major issues with this test procedure? Granted I will only be measuring peak force and not impulse (F/t), but I think peak force is the most important factor that would jar a rifle to the side and knock you away from your target.

 

[generalzip]

Handle length does not matter if you measure to the same spot every time. Handle angle does not matter either as the test will keep the string perpendicular. As far as swept handle angle, I agree they feel heavier. Plus, you are adding torque in a direction that will add friction to the bolt lift. However if the action maker made the design that way it is fair to test it how it was designed in my eyes.

I agree with you reliability and feeding are far more important however I'm talking about comparing 1400 dollar custom actions here. There really shouldn't be any feeding issues or reliability issues that should be attributed to these actions.

Just the tolerance in springs can make a difference in bolt lift in the same exact action, it's not likely to be enough to be felt but it'll be there.

To me, when comparing 90 degree action they are all pretty similar. I've never met a 90 degree that I would call "heavy". The smoothness of the lift is much more noticeable action to action for me. Handle and knob length also play a huge part in the effort required to lift the handle. I also find actions with straight handles to feel more effortless than those with swept handles.

Without comparing them with the same exact handle lengths, knobs, and handle angle then no comparison would be a fair one.

Personally I don't get wrapped up in bolt lift unless it's a problem, and if it's a problem on a 90 degree then there's probably something wrong with the action itself. Shorter bolt lifts like 60's can get tricky though, they're a different ball game all together. The only 60 degree I've ever liked is the AI, but I haven't played with a Curtis and I hear they're very nice. There's some tweeners like Tikka and Nucleus neither of which feel heavy to me.

I'm far more concerned with how the action feels and feeds, and that it doesn't bind when being run hard. There's a fine line between having a tight enough bolt to action clearance to not bind, but enough clearance that the littlest bit of dust won't lock it up. Some manufacturers have that figured out and some don't. I've yet to go to a match that wasn't either very dusty or very muddy, so that's a major concern. You can only do so much to keep that shit out of your action.

 

[Sheldon N]

I have also ran multiple different actions by the same manufacturer that had a different feel to each one.

Same here. I've got a pair of actions right now, one is smoother than the other with lighter bolt lift/bolt close. Not to mention that degree of cleanliness and how the action is lubed makes a difference. Another factor is break in. A new action is going to have more effort than one with 20k cycles on it.

Cool idea to want to test, but too many variables and too small a sample size for the results to be definitive.

 

[W54/XM-388]

I had an Enfield once, and yes, the bolt worked exceptionally smooth. But the rifle wouldn't shoot for doodoo. For me, there is no connection.
Greg

The Enfield rifles usually have a spring assisted bolt opening system for quick reload times, makes for very smooth fast reliable reloads.

 

[kthomas]

Trigger timing can have a pretty drastic effect on percieved bolt lift as well.

Me and a buddy both have Mausingfields, from the same batch. They feel very different. The bolt lift is light on mine, and exceptionally light on bolt close. His has stiffer bolt opening, and his bolt closing is much stiffer.

I have a Bix 'n Andy Tacsport trigger, his is a Huber. I just dropped in my trigger, and it felt amazing out of the box. His was assembled by a gunsmith, but I believe that he could benefit from trigger timing.

 

[MountainHunter]

I don’t think it needs to be such an apples to apples comparison as far as measuring from the same leverage point and whether or not they’re the same degrees of bolt throw.

It’s such a subjective topic, I’d like to see a subjective test ha ha ha

I’m interested in what my hand feels when I manipulate the bolt. With that in mind I’d just measure max poundage it takes to open the bolt from a fired firing pin and measure it from the bolt knob.

Obviously different length shafts/knobs will effect the results but that’s what my hand feels and that’d be interesting to see the difference from one action to another.

 

[NateVA]

Me and a buddy both have Mausingfields, from the same batch. They feel very different. The bolt lift is light on mine, and exceptionally light on bolt close. His has stiffer bolt opening, and his bolt closing is much stiffer.

I have a Bix 'n Andy Tacsport trigger, his is a Huber. I just dropped in my trigger, and it felt amazing out of the box. His was assembled by a gunsmith, but I believe that he could benefit from trigger timing.

That's quite interesting. I have a Mausingfield build with a Huber trigger and I also believe that it could benefit from trigger timing, as the bolt lift is a bit stiffer than I expected. Is this something most precision rifle gunsmiths could accomplish? I don't know how complicated the procedure is.

 

[Gil P.]

Since every action has a different bolt handle length and design, why not measure from the center of the bolt knob regardless of distance from the bolt? No one works the bolt from the bolt handle shafts, and it's apart of what gives each action its unique feel.

 

[kthomas]

That's quite interesting. I have a Mausingfield build with a Huber trigger and I also believe that it could benefit from trigger timing, as the bolt lift is a bit stiffer than I expected. Is this something most precision rifle gunsmiths could accomplish? I don't know how complicated the procedure is.

I would talk to a gunsmith that works with a lot of Mausingfields and really understand the action. Perhaps @LongRifles Inc. or @bohem .

I'm not a gunsmith so I'm not an expert on it. My gunsmith won't do trigger timing on Mausingfields, but he has only handled 5 or so - so he doesn't know them inside and out. Others may.

This is just my best guess as to why my action feels different than his. I'll let the experts take over from here.

 

[Ledzep]

Ted was toying with the idea of an adjustable sear for the M5 bolt. It may be a thing in the future but I would imagine after the nucleus ordeal settles down.

I have talked to trigger tech and they don't make different Sears and won't, even when I asked nicely... So the best hope is the adjustable sear from ARC.

 

[generalzip]

Since every action has a different bolt handle length and design, why not measure from the center of the bolt knob regardless of distance from the bolt? No one works the bolt from the bolt handle shafts, and it's apart of what gives each action its unique feel.

True, but I’m interested in what action has the better design in regards to bolt lift. I can slap a 5” handle on a bolt and it will be super light but will have further travel and thus slower to manipulate. I’m interested in which action inherently has the lightest bolt lifts. Not which guy can build the longest lever if that makes sense.

 

[ThePretzel]

That's quite interesting. I have a Mausingfield build with a Huber trigger and I also believe that it could benefit from trigger timing, as the bolt lift is a bit stiffer than I expected. Is this something most precision rifle gunsmiths could accomplish? I don't know how complicated the procedure is.

That could also just be the Mausingfield. I've heard from multiple people that have them that the new ones are stiffer than the original was in an effort to fix a light primer strike problem. One described it as feeling as though there's a small hitch in the bolt lift.