What makes a PCP consistent and accurate?

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fe7565

fe7565

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Oct 13, 2015
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Just focusing on the gun only and not the shooter, scope, etc....I figured I'd ask: What makes a PCP consistent and accurate?

Will an accurate barrel on a consistent action lead to accuracy? Is a consistent action that can deliver consistent and precise (repeatedly the same) power behind the pellet? What is an accurate barrel? Assuming that the barrel is straight, free of inside burrs, etc, inside diameter is consistent, and a properly sized pellet is used in it...what makes one barrel more accurate vs. another?

Why is that an average Discovery or Marauder is not as accurate as a high-end FX or Daystate, Vulcan, Edgun, Cricket, etc? Is it a difference in workmanship or design? I heard of people who made their Discovery and Marauders as accurate as any factory high-end gun. 

So in essence, my question: is accuracy designed or built into a gun?
 
Time and money in R&D. The more you spend on that the better the gun is, and more expensive to the end user.
Typically to get a marauder, discovery, hatsan or other entry level pcp to the level of say a daystate, fx, steyr will cost close to if not more than buying one of the higher end guns if you can not tune it yourself. Most folks don't tune their own guns and realize after the fact they should have just spent the money up front for a gun they don't have to touch out of the box.
 
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"John_in_Ma"Time and money in R&D. The more you spend on that the better the gun is, and more expensive to the end user.
Typically to get a marauder, discovery, hatsan or other entry level pcp to the level of say a daystate, fx, steyr will cost close to if not more than buying one of the higher end guns if you can not tune it yourself. Most folks don't tune their own guns and realize after the fact they should have just spent the money up front for a gun they don't have to touch out of the box.

While I agree precision costs money, you don't have to spend $2K to make a Hatsan or Marauder shoot with a FX or Daystate. BWalton has proven that with Hatsan. A lot of what you are paying for with FX and Daystate is the built in cost of buying from a socialist nation.
Click to expand...
 
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@ Alan How would someone decide on what is "decent quality"?

I hear "pouring money into a rifle makes it accurate". I guess some original design limitations can be overcome by new or modified parts. And some quality issues affecting accuracy which were not intended to be fully addressed in the first place during build by the manufacturers for cost reasons can be remedied with some expert labor. If you can improve a $500 Marauder to shoot as a $2,000 Daystate (just an example), how much further can you improve on the Daystate?

(High-end implies "accuracy". Calling airguns "low-end" should be no means be taken as negative)
 
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First and foremost, the barrel and projectile fit is where precision starts. All barrels vary in dimensions---some more than others. When you get a barrel that the pellets fit properly, and has a uniform rifling and size all the way down, it is capable of shooting precisely. However there are two other factors that play into this: the crown and the breach/chamber. The crown needs to be uniform and square to the muzzle end of the bore. The chamber needs to be just the right size and concentric and parallel to the breach end of the barrel. 

The barrel does not really have to be straight, but it does need to be uniform in size. A small bit of constriction from the breach to the muzzle is o.k., but not the other way around. Chokes are a "get-around" for many of the size discrepancies. However, a choked barrel (IMO) will never meet the capabilities of a very good unchoked barrel with a properly fitting projectile.

Now the second most important part is that barrel vibrations must be uniform and the muzzle movement minimized upon projectile exit. Here, all kinds of things come into play, and which many cannot be predicted easily. Among the variables are: the thickness of the barrel; where and by how much it is supported; how the supports themselves move and vibrate over time; how the impulse of air pressure starts the vibrations of the receiver, barrel, supports, etc.; how the hammer, valve, and remaining reservoir pressure affect the vibrations; and how the stock, sights, and shooter influence the vibrations as well.

The initial vibrations can be made more uniform with good tuning and regulators. This is the reason you see these being applied to the better guns. But, the more things inside the gun, and work to tune it cost more, especially if they are tested and reliable.

Now as far as barrels go, much has improved over the years in technology to mass produce barrels that have a uniform size. Bullets have long since been held to much better tolerances than barrels. Until recently, precision barrels had to be hand lapped from slightly undersized bores to meet the bullet sizes. Now, rifle bores can be held to nearly the same tolerances. Pellets, on the other-hand, still vary as there has not been a uniform standard made, and have been made to fit a wide variety of barrel sizes. Too, air gun barrels still vary from manufacturer to manufacturer, and are usually made to a price point rather than to a tolerance level. 

Until a governing body for airguns, similar to SAAM (Sporting Arms and Ammunition Manufacturers' Institute), is recognized, the pellet and barrel size differential problem will not be resolved any time soon.
 
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@I_Like_Irons Thank you for the clear and concise addressing of the key issues making an airgun accurate, great info on barrels, chambers, harmonics. Wish I could give you another "accuracy" point but maxed out already.

So, in essence most airguns can be improved upon with either some hard work by those who know what they are doing or are willing to pay for it. Some obvious and 
"low hanging fruits" that some manufacturers decided to forgo during their design and manufacturing process may be worth to remedy, especially on lower end guns where a there are a lot of them... While on higher end guns those modifications/polishes require a lot more expertise and/or money to make them worthwhile because of the already higher built-standards (as reflected in the original sales price).
 
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Accuracy starts with the barrel. Get the barrel right and then you can focus on the air delivery system. BSA, LW and Kricket (no experience with them) build great barrels. I've had 7 or 8 BSA's and there hasn't been a bad barrel in the bunch. Pellet on pellet accuracy as long as I do my part. They are moderately priced compared to Daystates and many other guns but they are as accurate as any of them. And they are, for the most part, not pellet fussy. Mine have been more accurate than my Daystate, Air Force (both LW) or Brocock guns. Beyond the barrel, BSA mechanics are not high end. Well made but moderate. The fit and finish don't compare with higher end guns. Even unregulated, the curve is predictable. My understanding is that Krickets are the same way, hard to find a bad barrel in the bunch.

Then comes the air delivery system. Being able to consistently shoot at X power addes to accuracy. A regulator is a deeper step to the mix. You get even more consistency, which helps with accuracy.

Beyond that, it's mostly the shooter.
 
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Sure there's a quality component but in the example of Discovery/Marauder vs. FX/Daystate to me the standout is the regulator. Look at the effort powder burner shooters go through in projectile weight and charge consistency. Most PCP shooters are trying to achieve a good curve where the powder burner is looking for a flat line and regulators really help flatten the curve for PCP's. 
 
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I am going to add my 2 cents here. Quality materials, close tolerances and an appreciation to adapt the laws of physics.
I shot long range high power weapons for many years and had some of the best schooling and training on the planet. I was also fortunate to have a splendid group of armory personnel prepping the weapons I shot and used in competition. It all comes at a cost, such as giving up your life for many years and having your buddy's back in all situations because they also had your back.
So how does all this training relate to the air guns that we are shooting with today. Nearly everything transfers. I applaud the manufacturers for putting forth introductory products especially the PCP's that many can enjoy today compared to those products of just a few years ago. Anyone today can purchase hole on hole accuracy out to a reasonable range or distance. Then it is up to the individual to hone his skills by practice and participation with others in the sport. There is a direct correlation between each of the disciplines as in the powder burners to the Air Guns, read all you can and listen to what is being said by those around you. Take the good and throw out the bad.
I find too many trying reach beyond the capabilities of the rifle they are shooting and becoming frustrated. My dad used to say a carpenter should not blame his tools for a job poorly done. With that in mind I always tempered my expectations knowing a tool in practiced and capable hands can and does sometimes create a masterpiece.
Ok getting off track slightly. So a lot of work goes into building a true and accurate rifle barrel. Harmonics of a well made barrel come at a higher costs with the closer tolerances as does bedding the barrel or free floating the barrel. We are fortunate that the temperature equations from a shot fired in a powder burner generally do not apply with our air gun barrel but rather rapidly moving air through the air gun may still affect the valve and regulator with repetitive shooting. O rings and nylon mating surfaces will eventually fail but hey rebuilding them is relatively inexpensive. 
Trigger management, breathing, rifle support, pellet quality and fit. Relax and enjoy the experience. Unfortunately for us the pellet manufacturers are no where near the consistency you find in bullet choice for a powder burner. You just have to live with selection and what the barrel shoots to some form of consistency. Unlike PB rifles we do not have a very wide range of propellants. Trust me good clean air in the PCP has saved all of us a lot of work. Even CO2 is manageable but temperature sensitive. 
So I place my expectation level with the piece of equipment I am shooting at the time. I enjoy shooting my 22 caliber Discovery. I do not try to shoot beyond the capabilities of this rifle nor expect it to perform like my FX or DayState rifles. Shooting the 2300 Crosman at 10 meters can be a challenge but doable. I just do not expect it to compete against the high end purpose built target pistols. Still fun, relatively inexpensive platform and great to build your skills. You know punching paper, plinking soda cans or smacking that varmint in the garden, what a great gift we have to share.
 
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@fr8rbum747 Thank you for your insight, it does provide some great guidance to managing expectations. 


"I find too many trying reach beyond the capabilities of the rifle they are shooting and becoming frustrated"

For the longest time using springers (R1, RWS 54) I was mostly operating at the 25-30 yards and once went out to the 75 yard with the RWS 54. I used commonly available pellets (no JSBs back then) without much thought of their importance. Then was introduced to PCPs with FILARMS rifles and later with an AA S410C...and my expectations expanded as well as my quest for accuracy and distance. I think it's a never ending quest to find out how accurate the rifle really is, and even if you achieve that you will always doubt if the shooter (you) did indeed brong the best out of the rifle or not? I guess that's why PCPs are so addictive because the envelopes are still being pushed daily.

Your post also made some other (more technical) great points, especially about pellets. I never sized pellets, only weight sorted them before, so far from being an expert. I think that pellets are the weakest point in a proper high-end setup because they introduce the most variables that are most overlooked, difficult to see and therefore to control. The wind, rifle hold, etc all can be mitigated but often the variables with pellets are invisible to casual shooters without further examination. Even JSBs seem to have enough variance in head sizes and to some lesser degree weight. Based on the little I know about ballistics/drag and pellet shapes/form...a badly designed or manufactured pellet has a huge role in an otherwise perfectly accurate rifle's performance. Most shooters seems to end up with JSB pellets...not necessarily because they are so much better designed then the others, but because they are so much more consistently manufactured and without widespread physical damage to skirts and heads in comparison with other brands.

@thurmond At times I wonder if someone should make a business of custom sizing and quality-controlling existing off-the shelf JSB (or other quality) pellets and sell them for those occasions when someone wants to test their new rifles for ultimate accuracy. For everyday shooting it may be too expensive, but I would certainly pay around $10 for 100 perfectly sized, weighed, inspected pellets for those occasions.

I think that with larger caliber airguns coming on the market in numbers the traditional diabolo pellet shape for these .30 and above calibers will be replaced with more firearm bullet shaped projectiles. Accurizing these bullets may slowly cross into what the firearm reloading folks are doing on a regular basis. But going back to the pellets...I think the pellet quality is the biggest limiting factor to ultimate accuracy and consistency if you have a perfectly functioning high-end rifle and a good shooter..
 
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