Basic Bolt action terms and definitions?

[rocketsci]

Hey there,

I'm a relative newcomer to the bolt-action scene, and I'm trying to understand a few terms specific to them. Could anyone help me?

1) "Bolt throw": does this refer to the radial distance (inches/cm/etc) the bolt moves through when actuating it, or just the angular movement?

2) A "smooth" action: is this referring to the lack of a "gritty" or rough feeling in the bolt handle as the bolt moves horizontally in the receiver, or does it include difficulty in bolt movement as you turn the bolt handle as well? Or am I completely missing the point?

3) "Bottom metal": is this referring to the lower part of the receiver housing the trigger group and the magazine well? Does "top metal" refer to anything?

I used to own a Remington 700 SPS which I ended up giving to my FIL, so I'm not totally ignorant of the basic construction of bolt action rifles, but I never really got into the minutae. I've decided to add a new one to the collection, but this time I'd like to be better armed with information.

Thank you in advance!

[NorCalFocus]

1. Yes

2. Go to the store, operate a Rem 783 bolt, then a Tikka. You will understand gritty vs smooth. A tough to open action usally happens after a round is fired and you have some issue.

3. Yes the bottom metal is just that. The piece of metal that goes on the bottom of the stock.

[rocketsci]

1. Yes

2. Go to the store, operate a Rem 783 bolt, then a Tikka. You will understand gritty vs smooth. A tough to open action usally happens after a round is fired and you have some issue.

3. Yes the bottom metal is just that. The piece of metal that goes on the bottom of the stock.

Thank you!

So:
1) making the bolt handle shorter reduces the throw (but reduces leverage to actuate the bolt).

2) What does it mean if it is difficult to close the bolt on both an empty and on a loaded chamber? Is this normal?

Thanks again! This is really helpful as I start looking for a new one.

[Xtracrispy]

I am not an expert, but I always thought bolt throw was in degrees. Like old Mosins and Mausers had a 90* bolt throw, newer guns are usually 60*(I think) for use with scopes.

Usually if the action is smooth with an empty chamber, but hard with a round in, it either means the ammo and/or the chamber is out of spec.

[Fjold]

Thank you!

So:
1) making the bolt handle shorter reduces the throw (but reduces leverage to actuate the bolt).

2) What does it mean if it is difficult to close the bolt on both an empty and on a loaded chamber? Is this normal?

Thanks again! This is really helpful as I start looking for a new one.

1) It reduces the distance of the bolt handle rotation but not the angle. It gives you less leverage, that's why match shooters who shoot under time constraints like longer levers. It increases the travel but reduces the force so you disturb the sight picture less.

2) if it's tough to operate both empty and loaded then it usually means that the lugs are a tight (or rough) fit to the lug recesses in the action. This will usually work out as the action wears in.

[toby]

After you handle all the others pick up a Weatherby Mark V, this has a 54* bolt lift and either 6 or 9 locking lugs depending on caliber, then a Sako If you can't decide find a nice old Winchester. M 70...

[vliberatore]

After you handle all the others pick up a Weatherby Mark V, this has a 54* bolt lift and either 6 or 9 locking lugs depending on caliber, then a Sako If you can't decide find a nice old Winchester. M 70...

Jesus would get a Remington 700

[toby]

Jesus would get a Remington 700

I highly doubt that! Jesus would want old world craftsmanship.

[ar15barrels]

Hey there,

I'm a relative newcomer to the bolt-action scene, and I'm trying to understand a few terms specific to them. Could anyone help me?

1) "Bolt throw": does this refer to the radial distance (inches/cm/etc) the bolt moves through when actuating it, or just the angular movement?

2) A "smooth" action: is this referring to the lack of a "gritty" or rough feeling in the bolt handle as the bolt moves horizontally in the receiver, or does it include difficulty in bolt movement as you turn the bolt handle as well? Or am I completely missing the point?

3) "Bottom metal": is this referring to the lower part of the receiver housing the trigger group and the magazine well? Does "top metal" refer to anything?

1. Both.
There are short action and long actions.
Long actions have about 3/4" more bolt travel.
There are 90 degree lift, 75 degree lift and 60 degree lift depending on the number of lugs and how much of the lugs are engaged.

2. There are many different areas of an action that you will feel when cycling.
Starting with a fired case in the chamber:
Bolt lift is the unlocking of the bolt lugs, the primary extraction of the cartridge from the chamber and the cocking of the striker.
Then you have secondary extraction as the bolt is drawn rearwards.
At the end of rearward travel, you will have ejection.
Then as you push the bolt back forward, you have feeding of the cartridge into the chamber, breeching and final locking.
During breeching, the cocking piece is handed off from the bolt body to the trigger.

There can be bumps and hiccups that you feel in ANY of these steps.
Some actions are simply better designed than others so they get a reputation of being "smoother" in that there are not as many things you feel while cycling.

3. Bottom metal comes in many different variations, from a simple triggerguard in a single shot or a fixed magaine setup, to a "drop magazine" as is typical in most factory rifles, to a detatchable magazine setup which allows separate magazines to be inserted and removed.

[ar15barrels]

2) What does it mean if it is difficult to close the bolt on both an empty and on a loaded chamber? Is this normal?

That is not normal.
It would be from several different reasons from damaged lugs on the receiver and bolt to the improper screws being used to holt the gun into the stock to improper screws being used to hold a scope mount to the receiver as well as other issues.

[rocketsci]

That is not normal.
It would be from several different reasons from damaged lugs on the receiver and bolt to the improper screws being used to holt the gun into the stock to improper screws being used to hold a scope mount to the receiver as well as other issues.

By difficult, I mean that when lowering the bolt handle to close the breech, I could feel some definite resistance, probably when the lugs were being engaged. Not insurmountable, but it took a deliberate grip with thumb and forefinger to close the bolt, and to lift it again after the round was fired. It definitely wasn't one which could be opened/closed with a flick of the forefinger (are there even bolts that operate that way?)

Randall, thank you very much for the detailed description above!

[thegiff]

Few bolt actions are so smooth and light they can be operated with a finger. The reason is the cocking piece (firing pin assembly) needs to be reset and the spring is under a lot of tension. Most rifles do this on opening (cock on opening). Some are cock on closed. At some point if it were a cock on opening like a remington the sear needs to pick up the force of the cocking piece and hold it while the bolt is cycled completely into battery. A remington has a detent to keep the cocking piece from free-spinning also, and cycling the bolt throw (angular) moves the cocking piece out of engagement with the detent while engaging the cocking piece onto the sear.

[LynnJr]

If you have a round in the rifle and it is difficult to close the action you most likely need to bump the shoulder back a small amount.

If a round closes but is tough to open the area right in front of the casehead has swelled and needs more sizing.Some shooters call it "bolt click" because as you lift the bolt handle it comes straight up until it hits the primary extraction cam.Once there the bolt will start moving rearward and you can hear it make an audible click as the casehead pulls free from the chamber.

If bolt click becomes an issue and small base dies don't fix it some shooters will have there gunsmith polish the chamber to gain more clearance.

[ar15barrels]

Basic Bolt action terms and definitions?

By difficult, I mean that when lowering the bolt handle to close the breech, I could feel some definite resistance, probably when the lugs were being engaged. Not insurmountable, but it took a deliberate grip with thumb and forefinger to close the bolt, and to lift it again after the round was fired. It definitely wasn't one which could be opened/closed with a flick of the forefinger (are there even bolts that operate that way?)

On some guns, this can be tuned-out by re-fitting the relationship between the caulking piece and the sear.
I call this bolt tuning and offer it as a service on all 700 type actions.
Once properly tuned, the bolt movement is MUCH easier and 1 finger bolt closing is certainly possible.
Opening will be more difficult as that is when the striker spring is being compressed.
A properly timed caulk-on-open fire control system won't be compressing the spring during closing.

Yes I know its C-O-C-K-I-N-G, but the word filter blocks that...