Gunsmithing What dictates accuacy

[phillip61]

Does the "action" have anything to do with accuracy or is it all barrel? Maybe a dumb question but I don't know. I see these different smiths say their rifles will shoot .25moa or .5moa. I guess what I'm asking is what determines this? I would think 99% of the accuracy claims would come from the barrel......someone please inform me.

 

[jonaddis84]

You are correct, I dont believe its a proven fact (because Gunsmiths still need to make money truing actions etc.), but probably 95+% of the rifles accuracy comes from the barrel. This is assuming the ammo is loaded properly for the setup.

Now, if you have a totally whacked out action, which is very possible to the point that the barrels shoulder is not making even contact with the action face, even the best barrel will not help in that situation. So its more of a joint effort. The barrel is the accuracy, the action and very true chamber are just taking every other variable out of the equation.

 

[ShtrRdy]

The connection of the action to the stock, and the stock itself can influence accuracy too. And how about a scope that won't hold a true zero - could be the base, the rings, or the scope.

 

[James n TN]

Accuracy is a combination of many variables, the action, the barrel, the chamber job, the bedding the type stock used and then there's the ammo that can also be broken down to many variables as well. So there's no one thing to make any rifle more accurate over the other it's the combination of all the components built to achieve the best accuracy possible. Once this is done another variable is the shooter and your ability to shoot your rifle to its full potential.

 

[Blanman]

The 3 B's! Barrels, Bullets and Brass! For the most part anyway.

 

[pappy42]

I think the driver makes the most difference.

 

[STR]

Without getting into a whole long explanation of why the action is trued, the barreled action is bedded, ect, ect, I say the barrel plays the biggest part, and how it's chambered and crowned.

 

[Greg Langelius *]

In a single word, consistency; everything happens the same for each shot.

Where parts relationships allow for inconsistency, they detract from potential accuracy.

I say potential accuracy because of the other factors, absent the rifle itself, which can also detract, like shooter, ammunition, and environment; and this is not a complete list.

Greg

 

[wnroscoe]

Does the "action" have anything to do with accuracy or is it all barrel? Maybe a dumb question but I don't know. I see these different smiths say their rifles will shoot .25moa or .5moa. I guess what I'm asking is what determines this? I would think 99% of the accuracy claims would come from the barrel......someone please inform me.

It's really an accumulation of multiple small details that get rolled into one huge project. I've seen rifles shoot in the .1's with a stock untouched Remington 700 receiver but, that's not the norm. Personally, I wouldn't build a rifle with a Remington 700 without truing it first. The reasons, you never know how concentric the threads are, how perpendicular the receiver face is to the receiver / bolt raceway / thread center line. But to sum it up IMHO it's goes as follows;

#1 Quality Barrel
#2 Quality Receiver and Bolt
#3 Match Grade Chamber
#4 Recoil Lug that is flat
#5 Quality installation of 1, 2 & 3
#6 Stress Free Pillar Bedded Stock
#7 Quality Glass & Mounts
#8 Ammo that has been tuned to the rifle
#9 Someone that can shoot

A full custom is more than capable of a .25 moa guarantee, the problem is there's not too many .25moa shooters out here.

 

[Josh Smith]

Hello,

What happens if the locking lugs don't make the same amount of contact?

Ever hear of those extreme benchrest rifles with bedded barrels and floating actions?

I would say 25% action and 75% barrel. This is excluding ammo and shooter.

Regards,

Josh

 

[mkollman74]

What dictates accuracy?? Hmmmm... I would say: money well spent combined with a talented shooter who practices with purpose.

 

[damoncali]

Mostly barrels and the precision with which they are chambered. It also helps to screw them into the action straight. No rifle will shoot bad ammo well, so that matters too.

But when you see claims of .25MOA guaranteed, take them with a grain of salt. It is exceptionally rare to see someone shoot a rifle outside of a tunnel and get that kind of accuracy consistently.

For reference, check out the results of the 2013 Super Shoot (the grand daddy benchrest match of them all). This is where guys who spend a boatload of money on rifles designed to shoot as accurately as possible go to shoot (super heavy rests, triggers you can set off just by thinking about it, neck clearances of .001", twists on the edge of stability, etc). Only the very best crack the .250 mark. And that is with a field literally filled with wind flags. Now, to be fair, they are subject to arbitrary rules, but still, .250 is very difficult to accomplish. The slightest wind shift will open a group up .1".

2013 Super Shoot Results

 

[Strykervet]

I've got a really killer 6.5Grendel. When I built it at first, it shot about .33MOA group, a 1/3" hole at 100m. This with a 7.62 ACOG and a KAC FF rail and an RRA two stage trigger. It did have a cut rifle, 20" Satern barrel in it though.

I've since upgraded the upper to a VLTOR MUR-1 and built up a Noveske receiver with a Geissle Hi-Speed trigger and the Magpul MIAD grip and aluminum trigger guard I like. Gasbuster charging handle, same KAC FF rail and Harris bipod. It then wore a Leupold Mk4 2.5-8x scope. Still shot .33MOA.

I've since then put a USO 3.2-17x scope on it in a rigged mount that seems to be working fine (although I'm working with ADM at the moment on a new cantilever one piece bolt on (or QD) mount for USO scopes with TPAL). It has a JP Ent. full mass "tactical" carrier in it --super smooth. Still shoots .33MOA. I learned a valuable lesson here, just get the scope for the intended purpose only, nothing more, because as long as it's a good optic, it won't affect accuracy at all (though I don't have full faith in my current mount, USO rings on a Larue QD riser, but until ADM can get this prototype finished, then I'm stuck with it).

Of course it'll shoot wider than .33MOA, it doesn't like SMK's too much so it only prints them about 1MOA. But it LOVES 120-123gr. ballistic tip bullets. Nothing parts-wise changed the rifle into anything more than a more user friendly weapon. That's it. The only changes that could reliably be affected came from ammo --which would lead one to believe if nothing else done to the rifle changed the accuracy, but a few cents worth of lead did, then it seems the barrel played a role here. I also know that a FF tube is critical for accuracy in an AR (or FF in general) because that affects the barrel --groups open up and shift with positions with regular handguards or KAC non-FF rails. This rifle started with a FF tube from the beginning.

Bottom line: accuracy resides almost entirely in the barrel from my experience, 95-99% given to the barrel isn't a stretch, but besides getting a good barrel, you also need to FF the barrel and use the optimized loads for it. This is assuming of course that everything else, receiver, optics, mounts, etc., are all up to par.

 

[MagnumSecurity]

Just about everything can make a difference. Even the torque of the bolts/screws for the action to the stock has caused accuracy issues for me. Changing the barrel would definitely not be the first or second or third etc., thing I would do to resolve accuracy issues.

 

[Graham]

What dictates accuacy

In practical precision rifle shooting the question is always what matters to the shot, and what doesn't.

Accuracy is a product of a system that consists of rifle, ammunition, and shooter.

Whether you hit the target will probably have more to do with your execution of the fundamentals and your ability to judge the range and wind than anything else.

How much of a factor, in all of that, is the type of action you are running on your rifle?

 

[pappy42]

It's really an accumulation of multiple small details that get rolled into one huge project. I've seen rifles shoot in the .1's with a stock untouched Remington 700 receiver but, that's not the norm. Personally, I wouldn't build a rifle with a Remington 700 without truing it first. The reasons, you never know how concentric the threads are, how perpendicular the receiver face is to the receiver / bolt raceway / thread center line. But to sum it up IMHO it's goes as follows;

#1 Quality Barrel
#2 Quality Receiver and Bolt
#3 Match Grade Chamber
#4 Recoil Lug that is flat
#5 Quality installation of 1, 2 & 3
#6 Stress Free Pillar Bedded Stock
#7 Quality Glass & Mounts
#8 Ammo that has been tuned to the rifle
#9 Someone that can shoot

A full custom is more than capable of a .25 moa guarantee, the problem is there's not too many .25moa shooters out here.

From a man who walks the walk on his rifles.

 

[billyburl2]

It's really an accumulation of multiple small details that get rolled into one huge project. I've seen rifles shoot in the .1's with a stock untouched Remington 700 receiver but, that's not the norm. Personally, I wouldn't build a rifle with a Remington 700 without truing it first. The reasons, you never know how concentric the threads are, how perpendicular the receiver face is to the receiver / bolt raceway / thread center line. But to sum it up IMHO it's goes as follows;

#1 Quality Barrel
#2 Quality Receiver and Bolt
#3 Match Grade Chamber
#4 Recoil Lug that is flat
#5 Quality installation of 1, 2 & 3
#6 Stress Free Pillar Bedded Stock
#7 Quality Glass & Mounts
#8 Ammo that has been tuned to the rifle
#9 Someone that can shoot

A full custom is more than capable of a .25 moa guarantee, the problem is there's not too many .25moa shooters out here.

Very well said! I would go a bit further to say, it depends on the person's definition of accuracy. The last 5-10% can get real expensive...

 

[Clark]

If we plug in the average wind speed for the USA, 7.4 mph, with the average SH rifle, a 308 with 155 palma bullet at 2900 fps, we get some errors:
50 yards 0.35 moa
100 yards 0.72 moa
200 yards 1.42 moa
400 yards 3.01 moa
800 yards 7.22 moa
1600 yards 18.77 moa

So who, when, where, and how do you choose the distance to test this guaranteed 0.25 moa rifle?

 

[500grains]

If we plug in the average wind speed for the USA, 7.4 mph, with the average SH rifle, a 308 with 155 palma bullet at 2900 fps, we get some errors:
50 yards 0.35 moa
100 yards 0.72 moa
200 yards 1.42 moa
400 yards 3.01 moa
800 yards 7.22 moa
1600 yards 18.77 moa

So who, when, where, and how do you choose the distance to test this guaranteed 0.25 moa rifle?

You could be like my friend Cal who tests rifles at 25 yards at an indoor range. He will say, "Dan, my new gun shoots great! The holes are almost touching!"

Then he tells me it is at 25 yards. That is worthless data.

I use 200 yards because it is far enough for bullets to stabilize, but not so far that there is a significant wind problem (depending on the day). 100 yds is not a great indicator IMO. And 25 yards is total bullshit.

 

[Goatman007]

Barrels, bullets, brass, I like that. Add Bedding to that. I don't know how many times people buy a new off the shelf rifle, and get disgusted when they put 3 shots down range and get a 1.5" group. Knew more than a couple of guys that traded them right off. First, it takes about a hundred rounds to settle a barrel in, some call it breaking in. Regardless, this is the time to do your load development, powder, bullets etc. Keep all targets!! annotate the groups and clean the barrel between groups. By the time you reach your hundred rounds, you should have a good idea of which powder/bullet combo works best. Now the barrel is the most important to good accuracy with a tight chamber, good bedding is also conducive to good accuracy. About the only receiver work I do is squaring the receiver face, and thats it!!! Ruger's are not renown for their accuracy, I have owned 3 all 3 under 1" one at .75.

 

[Greg Langelius *]

I don't care how accurate a rifle is NIB, things are going to change in the first hundred or so rounds down the bore. I use those rounds to find coarse zeros, fireform brass, and do load pressure testing. I figure I have a better chance of establishing a reliable load after the first hundred are out there than before.

 

[wilecoyote]

..."all" will have to do, and the weakest link of the chain will gladly show himself on the bullseye : talkin' to extremes , try to to put a million-dollar-laser-benchrest-rifle on a worse/cheaper/etc.rest than other competitors, and you will be really disappointed with the final score,anyway_

 

[CAG55]

I believe you have gotten a lot of good info, and no bad. I really don't have any right to be posting on this subject! But I just
couldn't help my self, There is a old saying that I have lived by: ( You have to pay your Dues) I am coming up on 58 and hope to see 59! I have done a lot of shooting in my little world!! I had totally got out of shooting up and till 5 years ago, I tore
up my back so I have a lot of time to read! I had a good friend bring me by some Gun Mags. to look at, and the more I read
the more I got hooked! Like I said earlier, I thought I had shot a lot, but there are Bench Rest shooters that will shoot more ammo in 2 months (if they shoot every weekend in a month) than I have shot in my life !! I forgot to mention that I have been reloading since 1972!
I have done more reading and learning from reading other people post, than I have in my whole life as per 2007 or so! There are
so many things that have to come together at the same time: You also have to take that last statement with your eyes wide open! You can take this as you want, I put 2- 6.5 Grendel AR's together that were pure tac drivers, after getting the scopes sighted in
and with out target ammo???? Those 2 rifles are so much better of rifle's that I can't shoot them to there potential ! Just read all you can, making notes and shoot, shoot, and shoot some more.
Greg

 

[Clark]

I built a 223 Sav 110 rifle this week. I used a Lothar Walther Chrome Moly barrel.
It still needs more paint.
I had some ammo I loaded 8 years ago, 33 gr Vmax 15 gr Blue Dot, mixed brass FL sized with .246" neck .
I took it to the range today and fired 3 shots at 50y to get it sighted in and then 4 groups of 5 shots at 100 yards.

The 4 groups of 5 shots at 100 yards:
1) 0.426"
2) 0.533"
3) 0.533"
4) 0.900"

What was affecting accuracy?
1) wind
2) forgot the rear bag, and the cross hairs were jumping around with my pulse rate, as I used my left hand fist as a rear bag.
3) The Copper fouling was increasing with each group, in this never shot before barrel. It needs to be broken in. The round count is 23 rounds, time to clean.
4) The light was so dim I had to reduce magnification to get the exit pupil up. That got rid of the fuzzies.
5) Heavy gun and light bullet, makes the gun not change direction much before the bullet exits.


What was not affecting accuracy enough to matter?
1) The recoil lug touches nothing but the barrel, the receiver, and air. There is no epoxy behind it, only air.
2) The muzzle has no crown. It is unchanged from when the manufacturer turned the barrel. Rough and with a countersink for a live center.
3) The ammo was not tuned to anything. The blem bullets weigh 33 gr and should be 35 gr. They are moving ~ 3500 fps.
4) The action does not touch the stock or bedding. The action touches two home made 1/2" pillars fitted to the receiver radius.
5) The action is not trued. This is from 1988, days before Savage went bankrupt and never made this 4.522" between screws action again.

 

[Cleftwynd]

We live in a world of tolerances, not absolutes, keeping the tolerances minimal in each stage is what matters. From quality components, to sticking all those components together, to the nut behind the trigger, it all matters. It's when the tolerances become great, and compound upon each other that causes accuracy to degrade exponentially. However one major flaw will ruin the whole combination, such as a messed up crown, or loose rings, etc...

Others have pretty much nailed what matters in order or importance, just remember that consistency is what matters.

Read the wind, and keep em tight!!!

 

[Wannashootit]

All well said above.

IMO, a properly bedded receiver, correctly torqued action screws (on pillars) makes a big diff.

ANY movement of the receiver within the stock- destroys "repeatability".

Repeatability/consistency = accuracy. This game is all about getting the rifle, the ammo, and the shooter to do the same exact thing- every time the trigger is pulled.

 

[Shanerbanner10]

Question: isn't accuracy effected by the axis of the barreled action to the center of bore? (Hopefully that makes sense, and I'm sure I said it incorrectly). Isn't this why actions are Trued/blueprinted, threads recut ect...as well as quality barrel manufacturers produce extremely 'straight' barrels?

So the straighter the action and barrel are (or more square to center axis of the bore- again sorry if I said that wrong) the better the rifle is supposed to shoot?

All if this assuming the shooter is doing their part.

 

[Clark]

It took me from ~ 1992 to 2002 to get a 1" 5 shot group at 100 yards.
A week later I got a 0.45" 5 shot group at 100 yards.

What held me back was all the BS on the internet about how I needed to do benchrest techniques.
I have tried to boil down what is important and what is not to get a 1" group.
This is not based on reading or thinking, this is based on my long frustrating effort while reading internet BS.
With so many out of control variables, some will probably have had different experiences and think THIS post is BS.

Big effect on accuracy
1) shoot when there is no wind
2) get a high power scope
3) practice dry firing and keeping cross hairs on bullseye
4) clean out Copper fouling in bore
5) good bullets
6) No expander ball use
7) jam bullet into lands
8) heavy gun and light bullet
9) float the barrel
10) keep barrel cool
11) expensive bull barrels
12) make sure scope mounts are tight to receiver

Little or no effect on accuracy
1) True the action face
2) true the inner C ring
3) lap the lugs
4) true the bolt face
5) chase the threads
6) speed up the lock time
7) glass bed the action
8) pillar bed the action
9) get a 1 ounce trigger
10) turn the case necks
11) weigh the brass
12) de burr the flash holes
13) weigh each powder charge
14) try different powders
15) use benchrest primers
16) lap the scope rings.
17) Dial in bore when chambering
18) re crown the muzzle

 

[Graham]

It took me from ~ 1992 to 2002 to get a 1" 5 shot group at 100 yards.
A week later I got a 0.45" 5 shot group at 100 yards...With so many out of control variables, some will probably have had different experiences and think THIS post is BS.

As to the first part, if it did take me ten years to shoot a first MOA group I sure as heck would not admit it. But if I did admit it I would not offer advice to others based on that experience.

As to the other part, I agree: It's BS. Not to mention the lack of useful Internet in 1992.

If the variables are as out of control as you suggest then no one would be able to shoot MOA or better. We know that's not true.

Your list is too generic, and too vague, to be useful.

 

[Clark]

As to the first part, if it did take me ten years to shoot a first MOA group I sure as heck would not admit it. But if I did admit it I would not offer advice to others based on that experience.

As to the other part, I agree: It's BS. Not to mention the lack of useful Internet in 1992.

If the variables are as out of control as you suggest then no one would be able to shoot MOA or better. We know that's not true.

Your list is too generic, and too vague, to be useful.

Hell, I was there.

https://groups.google.com/forum/#!topic/rec.guns/tvW26j9uONM
rec.guns ›

Posting in rec.guns
2 posts by 2 authors
Bart Bobbitt 6/30/92

Comments on American Rifleman Article about the
Ruger Mk. II Palma Rifle
In the latest issue of NRA's American Rifleman, there's a short article on
the Ruger Mk. II Palma Rifle. Having been in touch with the US Palma Team
Captain and other team members and learning about their experiences with
the first prototypes and the ones delivered to the team, I thought readers
interested in highpower competitions may be interested in the rest of the
story.
After the 1988 International Palma Matches in Sydney, Australia (I was a team
member), we talked about the possibility of having a complete set of rifles
of the same make and type for the USA team.....

 

[bward]

It took me from ~ 1992 to 2002 to get a 1" 5 shot group at 100 yards.
A week later I got a 0.45" 5 shot group at 100 yards.

What held me back was all the BS on the internet about how I needed to do benchrest techniques.
I have tried to boil down what is important and what is not to get a 1" group.
This is not based on reading or thinking, this is based on my long frustrating effort while reading internet BS.
With so many out of control variables, some will probably have had different experiences and think THIS post is BS.

Big effect on accuracy
1) shoot when there is no wind
2) get a high power scope
3) practice dry firing and keeping cross hairs on bullseye
4) clean out Copper fouling in bore
5) good bullets
6) No expander ball use
7) jam bullet into lands
8) heavy gun and light bullet
9) float the barrel
10) keep barrel cool
11) expensive bull barrels
12) make sure scope mounts are tight to receiver

Little or no effect on accuracy
1) True the action face
2) true the inner C ring
3) lap the lugs
4) true the bolt face
5) chase the threads
6) speed up the lock time
7) glass bed the action
8) pillar bed the action
9) get a 1 ounce trigger
10) turn the case necks
11) weigh the brass
12) de burr the flash holes
13) weigh each powder charge
14) try different powders
15) use benchrest primers
16) lap the scope rings.
17) Dial in bore when chambering
18) re crown the muzzle

I strongly disagree with 1, 4, 6, 7, and 8.

Wind does have an effect on accuracy, but even in tough wind conditions a .25 moa group is doable. Happens all the time in BR matches.
Copper fouling shouldn't even be an issue with a good barrel. I've had rifles with 500 rounds between cleanings still shoot under .5 moa without much trouble.
An expander ball will actually produce more concentric ammo than without. Unless you turn necks.
I jump bullets all the time. I have shot several groups in the .0's with a .030+ jump.
The heaviest bullets in their caliber will not decrease accuracy.

And on to your not important list. Are you joking in regards to 7, 8, and especially 17? You really think dialing in the bore has little effect on accuracy?

 

[Clark]

It was a great surprise to me that dialing the bore had little effect on accuracy.
After I read A. A. ABBATIELLO article in American Rifleman written 50 or 60 years ago, "Gauging Bullet Tilt" that a predicted and verified mathematical relationship between ammo concentricity and accuracy, I falsely assumed that there was a relationship like that for concentric chambers.
Wrong.
What causes the error with ammo is random rotational clocking inserting the bent cartridge.
But the bent chamber always has the same orientation, and flings the bullet on escapement off center to the same small group every time.
I did not figure this out, I accidentally cut a chamber with the reamer wobbling .005" all the way to headspace.
Then it shot a 0.75" 3 shot group at 100 yards. That was an old take off barrel being put on a surplus Mauser in 7mmRM. I did not expect that accuracy if the chamber was dead on.
I had been dialing in barrels with a 0.0001" Intrepid test indicator on a spud like that was important.
Had the ammo been .005", we would expect a ~ 2" increase in group size, per ABBATIELLO's example with a 30-06.