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Custom Rifle Series Part 2: Factory Rifles and Factory-modified Rifles

By Frazer Winskill

Modification comes down to purpose nine times out of ten in New Zealand as we are a well-documented bunch of pragmatists. By far the most common modification is to remove some barrel length and add a suppressor. Other modifications include trigger lightening, bedding the action into the stock with epoxy, or adjusting the stock’s length of pull. Overall, these help with accuracy, ergonomics and practicality.



Factory Rifle Pros: Most factory rifles are imported in numbers and therefore when you’re purchasing the wait time is non-existent. They come in a variety of models that generally do what 75% of all hunters need them to do. They are also the cheapest option out of the categories described, and maintain their value. They’re easy to sell if you decide to change calibre or brand.


Factory Rifle Cons: Being massed produced by lower skilled workers (compared to NZ gunsmiths) means lower tolerances and possibly poorer accuracy compared to custom rifles. I have had more than one factory rifle that was not 100% reliable. We’ve all had a friend who needed to hold his rifle a certain way and work the bolt holding his tongue in his cheek to get the action to cycle, eh...!


Factory chamber tolerances are not always within SAAMI specification. Often the throat length in the chamber is so far off spec that you cannot get a projectile seated out far enough to enable it to shoot accurately and still fit in the magazine (a common Tikka issue). I have had a few rifles that will not chamber certain types of brass despite trimming, base sizing and annealing.


“...modifying the OEM parts will always give you better ergonomics and maybe another 3-5mm in accuracy overall.”


Just because the rifle comes with an accuracy guarantee doesn’t mean it will meet it. Often the devil is in the detail, read the fine print and see what type of ammunition has to be fired through the rifle to achieve the guarantee (and how much it costs!).


Some factory stocks are less than desirable when it comes to flex and they apply pressure on the barrel when you’re firing with a bipod.


Careful testing produces meaningful data – the numbers don’t lie!


You cannot choose the twist rate the factory barrel is chambered in, which can be an issue if you want to reload with a certain projectile. At times also, the internal finish on factory barrels is rough and leads to copper fouling, affecting accuracy.


Often factory triggers have the pull weight set high to prevent law suits (a trend with US manufacturers) and poor action to stock bedding has a negative impact on accuracy.


Factory Modified Pros: The addition of a muzzle brake or suppressor will reduce recoil. Bedding the action into the stock with epoxy often increases accuracy and prevents leaves and water getting in between the stock and metalwork.

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Adjusting the trigger pull weight, creep and overtravel makes for a more accurate rifle that is easier to shoot.
If you are shorter or the rifle is going to be used by a smaller framed shooter (youth & women) then having the length of pull adjusted will help with recoil management.


You can feel content with a rifle that is personalised to your use, has better ergonomics, and generally is more accurate than an out of the box example.


Factory Modified Cons: Resale value takes a dive once you have modified a rifle and on resale you will probably not recover what you’ve spent. It also costs more than a factory rifle.


Often you will void the factory warranty, and modifications are not always guaranteed to fix the accuracy issues in the first place.


You are still stuck with the original chamber and barrel. If the barrel fouls and/or the chamber throat length is too far out as previously mentioned, you cannot fix this without replacing the barrel.



My wife recently purchased a Kimber Hunter in 6.5 Creedmoor. The Kimber is specifically designed as a lightweight rifle and weighs a mere 5.5 lbs out of the box. With a scope it tips the scales at 6lbs even. Kimber has kept weight down by combining the lightweight polymer stock with a #2 contour 22” barrel and their minimalistic Mauser action.


The Hunter comes with a three-shot minute of angle accuracy guarantee, so I shot the rifle with two types of factory Norma and Hornady ammunition before having the barrel chopped down to 16” and a suppressor fitted. I also developed handloads for the rifle and tested these at both barrel lengths.


Table 1   
Ammunition Avg. Group 22” Vel. 16” Vel.
Norma 130gr Match 46mm 2788 fps 2577 fps
Norma 130gr Pro Hunter 46.5mm 2762 fps 2551 fps
Hornady Precision Hunter 36mm 2597 fps 2424 fps
Hornady American Gunner 50mm 2674 fps 2470 fps
Avg. Factory Ammo  44.6mm    
120gr GMX / IMR 4350 39mm 2904 fps 2650 fps
120gr GMX / AR2208 36mm 2974 fps 2630 fps
140gr SST / IMR4350 33mm 2606 fps 2553 fps
143gr ELD-X / IMR4350 28mm 2703 fps 2502 fps
Avg. Handload 34mm    
120gr GMX / IMR 4350 28mm    
120gr GMX / AR2208 31mm    
140gr SST / IMR4350 34mm    
143gr ELD-X / IMR4350 19mm    
Norma 130gr Match 30mm    
Hornady Precision Hunter 26mm    
Avg. Factory Modified 28mm    


As you can see in Table 1 above, we found that with factory ammunition the average group size in the standard configuration varied from 36mm to 64mm, and averaged 44mm overall. I put this poor accuracy down to the fact that the rifle’s thin barrel does not like to get too hot and the five shot groups were beyond the three shot MOA accuracy guarantee.


Three shot groups were then fired once the rifle cooled, but this did not change our data. At this point I referred to the data I have accumulated in six years of gun writing and produced Table 2. The average group size across a dozen rifles with factory ammunition comes in at 32mm or 1.25 inches.


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Table 2 
Rifle/Calibre Avg. Group
Norinco .223 43mm
Bushmaster 300BLK  23mm
Barrett .50BMG 31mm
BCM 5.56mm 32mm
Remington 5R .223 34mm
Weihrauch .22 Hornet  34mm
Kimber Hunter .308 Win  24mm
Kimber Hunter 6.5 CM 42mm
Remington 783 .270 Win 25mm
Ruger American .243 28mm
Ruger American 223  43mm
Howa 6.5x55 SE 25mm
Avg. Accuracy 32mm


The Kimber Hunter managed to shave 5mm (or 0.2 inches approx) off the mean group size with handloaded ammunition and preferred a slower burning powder such as AR2209 or IMR4350 with an average group size of 34mm. Once I had the barrel shortened and a suppressor added the recoil disappeared and the groups shrunk a further 5mm to an average of 28mm.


“The average group size across a dozen rifles with factory ammunition comes in at 32mm or 1.25 inches.”


This improvement in accuracy is consistent with what I have seen in most of my rifles that I have had modified by adding a suppressor or a trigger job and bedding (more often than not I get all three done). My Howa Mini-Action in 6.5 Grendel had an average group size of 30mm with factory ammunition, but after a suppressor, trigger polish and epoxy bedding the average group shrunk to 25mm.



Based on the data I have collected over the last six years, factory rifles are on average just over one-inch shooters at 100 metres. This rings true with what most rifles are capable of with quality factory ammunition. Handloading will gain maybe another 5mm of accuracy in a factory rifle and modifying the OEM parts will always give you better ergonomics and maybe another 3-5mm in accuracy overall.


Frazer’s family hunts too... he’s found that modified (shortened) stocks are beneficial for shooters of smaller stature.


Before conducting the analysis of all of the rifles I’ve tested so far, I would have told you that, based on anecdotal evidence, I believed factory rifles shoot just under an inch at 100 metres and that modifying them would gain another 5-8mm of accuracy at that distance.


I just wasn’t expecting them to collectively shoot that poorly. Next in the series we will look at the semi-custom; a rifle with one of the four major components changed for an aftermarket option and a “blueprinted” factory action.


Warm barrels and stay safe out there!




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