Rifle accuracy - the action


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Wedge
December 5, 2008, 10:11 AM
For those that want accuracy defined. 1/2 or better MOA.

I know that the action is your building block to the accurate rifle, but what makes a custom $1000 action more accurate than a say a surplus Mosin Nagant or Mauser Action? I'm looking for the technical reasons they are better, not just the "you get what you pay for" responses.

How does the super accurate action interact with the other parts of the rifle then? What makes it work as an accuarate system.

Bogie, I know you should have some input on this subject.

Thanks!

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Horsemany
December 5, 2008, 10:50 AM
Custom actions will have a longer threaded portion so the barreled action will be more ridgid. They can also be of a larger diameter to give more mating surface with large diameter barrels. Some will have a completely flat bottom for more bedding surface. They will accept the finest triggers on the planet and have very quick lock times. No matter what you do to a milsurp action you will never get a lock time anywhere close to a custom action or Remmy 700. They really are better in any way you can measure an action for target use (other than price).

Olympus
December 5, 2008, 10:58 AM
They will accept the finest triggers on the planet and have very quick lock times. No matter what you do to a milsurp action you will never get a lock time anywhere close to a custom action or Remmy 700.

Yeah but Savage has the Accu-trigger which is the greatest thing since sliced bred! Sorry...I couldn't resist...

:neener:

Wedge
December 5, 2008, 11:27 AM
Don't really care about triggers other than how it relates to the action.

Used Mil-surps as an example of a cheap action out there.

What about things like bolt fit, headspacing, etc.? Is that a function of the action or more a function of barrle and bolt - which are both part of the action.

Does the action rigidity itself play a large role in the accuracy potential as well.

Horsemany
December 5, 2008, 11:33 AM
You should care about triggers if you are asking about 1/2moa actions. Most of the accuracy comes from the barrel. The trigger is probably as important as the action itself to provide consistent accuracy. I do not think the action's ridgidity makes much difference really. Once the lugs are locked in it's hard to imagine whatever happens behind them will have a dramatic effect. Although I'm sure it makes some difference, I don't think it's high on the list of influential properties.

Olympus
December 5, 2008, 12:10 PM
I agree, get yourself a good solid action trued and have the lugs lapped then I wouldn't worry about it much other than having the action bedded. If you're really concerned with accuracy, you can't ignore the importance of the trigger. Take a custom target rifle and put a cheap trigger on it and you'll be able to see a big difference. Check out a lot of the guys that shoot target rifles. You'll see they've go some really fancy and tweaked triggers. Go to some target shooter forums and read up on all the threads that deal with triggers and trigger pull technique. I've seen competition rifles that have had their trigger guard completely removed and some wickedly things put in the place. There's a lot of shooters who subscribe to the "pinching" technique for shooting where instead of squeezing the trigger, they use their thumb and forefinger and "pinch" the trigger between their finger and a stud built behind the trigger or the rear of the trigger guard. You can't ignore triggers when talking about accuracy.

fineredmist
December 5, 2008, 12:35 PM
Wedge, I will try to make this as simple as possible. A bolt action rifle consists of three main components, the stock, the receiver (action) and the barrel. The stock is the platform which holds evrything together and it must be solid, the receiver must be solid and competely mated to the stock, the barrel must be rigid and properly fitted to the receiver. When the rifle is fired the bullet is forced down the barrel and sets up vibrations which must be controled or accuracy is poor. A receiver which is properly fitted to the stock and is solid in design will limit the vibration of the barrel and produce consistent results. If the receiver is not then both the receiver and the barrel will vibrate and the rounds will fly where they will.
Squareing the bolt face and the locking rings will eliminate any side pressure put on the barrel when the round is loaded reducing any stress that will effect accuracy. The receiver, bolt and barrel must be in perfect alingment and square to make it work properly. A good trigger is necessary to avoid changes in the sight picture when the actual firing takes place.
There is a different setup which is popular in benchrest shooting where the mounting of the components is changed. Instead of mounting the receiver to the stock, the barrel just in front of the receiver is set in a block (4 - 6" long) which is mounted to the stock. This reduces the length of the barrel which can vibrate and changes the function of the receiver from a mount to a loading and fireing system. The barrel in front of the block and the receiver are free floating. This follows the design of breech loading artillery where the barrel is fully supported and the breech is for loading and fireing.

SHvar
December 5, 2008, 12:52 PM
My ruger model 77 target rifle makes it so easy to make groups from the entire 4 rd magazine that look like 1-2 rds on top of each other at 100 yards. One of my semiauto rifles also makes very very tight little groups with a much shorter barrel.
An important factor is the shooter, after gun shows I always see plenty of mosin, enfields, and other legendary accurate old military rifles appear at the range. Many of these new owners seem to have trouble hitting paper sometimes at 25-50 yds even, after a few weeks these rifles and their owners seem to disappear again.
Many things effect the rifles accuracy, and many features can assist some shooters in being more accurate with that rifle.
Recently I was reminded about this while seeing many people checking their deer rifles before the season started at a few ranges. People that spent all day trying to make an acceptable grouping, some that never did, but I blame this on the gun owners that haul out a rifle once or twice a year to check its grouping then walks into the woods to go deer hunting with no practice or time behind the trigger in between seasons.

Wedge
December 5, 2008, 12:59 PM
I said I didn't care about triggers, because I was looking for a technical difference in actions between a 1/2 MOA action and a grabbed off the rack cheap action.

I should have been more specific, all I am interested in is what makes really good receivers/actions of such high quality when compared to a lesser receiver.

Jim Watson
December 5, 2008, 01:04 PM
Does the action rigidity itself play a large role in the accuracy potential as well.

Yes.
In the 1950s, when surplus Mausers and Springfields were REALLY cheap and the custom actions seen now were not even being made, there were all sorts of things done to stiffen the action. Heavy one piece scope mounts might have helped a little, a welded-on "strongback" did more. But the development work was being done with Remingtons and if you notice, a lot of the custom actions now look a lot like a Remington, only bigger, stiffer, and straighter.

SlamFire1
December 5, 2008, 01:07 PM
Consistency of dynamic response. Generally, the most rigid structure is preferred.

fgr39
December 5, 2008, 01:11 PM
I think what you are really after is that an action for a custom gun or benchrest gun that is really accurate is that all tolerance is at a minimum. Every thing is trued and straight and in perfect alignment and when mated with a good barrel and stock gives repeatable results. Factory off the shelf actions are good but you still have manufacturing tolerances that can be corrected by a gunsmith to make them better. This usually is making sure everything is square and true.

Ol` Joe
December 5, 2008, 01:15 PM
In the 1950s, when surplus Mausers and Springfields were REALLY cheap and the custom actions seen now were not even being made, there were all sorts of things done to stiffen the action. Heavy one piece scope mounts might have helped a little, a welded-on "strongback" did more. But the development work was being done with Remingtons and if you notice, a lot of the custom actions now look a lot like a Remington, only bigger, stiffer, and straighter

There is a cottage industry built around sleeving and stiffening Remington M700 actions for target shooters. They still are not the "prefered action" for top shooters.
The actions need to be dead concentric to the bore, very stiff, with even,tight bedding to the stock.

USSR
December 5, 2008, 01:15 PM
Wedge,

You're barking up the wrong tree. Assuming a trued action (which should be done prior to installing a barrel), it's the quality of the barrel and smithing work that make for a .5 MOA rifle. Off the rack actions such as are found on commercial factory rifles, once trued, become .5 MOA capable actions when mated with a high quality barrel installed by a good gunsmith. However, a high quality custom action mated with a crappy barrel will disappoint you every time.

Don

Howard Roark
December 5, 2008, 01:40 PM
I think the answer to your queston is tolerances.

Have you ever taken one of those surplus actions you mentioned and closed the bolt and then moved it around in the action? How about watched the bolt drop in the rear when the trigger bar tension is released when the trigger is pulled.

Production actions are not straight as they come off the line. They are threaded with a thread mill. The bolt race is created with a broach. These processes are not exactly precision. The plus or minus on the prints are most likely in the thousands.

Custom actions tolerances are held to under half that of factory actions. The bolt raceway is often made by EDM. The threads are single point cut on a lathe on center. The bolt is one turned piece. These practices allow tolerances under half a thou to be held.

A trued factory action can be very accurate and competitive. The long range nationals at Perry was won last year by Kent Reeve shooting a Mauser action. It was won in 2006 and this year by John Whidden using a Winchester action.

Wedge
December 5, 2008, 02:15 PM
Thanks Jim, that is what I was thinking.

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