Rifle Performance

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RosinBag

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Things like bedding the action, free floating the barrel, trueing and squaring the bolt and action, I would hope are done with everyone's rifle. If you don't, accuracy will never be as good as it could be. If these are done correctly, ammunition choice should be the only variable.

Standard Deviation in our ammunition comes from the ammunition not being exactly the same from cartridge to cartridge. These include powder charge, seating depth and temperature. If you shoot your cartridges through a chronograph, the chronograph should have a Standard Deviation readout. A good rule with ammunition is a SD of 1% of your velocity. So if your velocity is 3000 feet per second, you want your SD reading to be 30 or under. When that is achieved with your ammunition, your groups should be consistent if all else is equal. There are very few factory loads that meet this requirement.

Once that is completed, manipulating your bullets seating depth can then decrease your overall group size. Rifles are very indivual and they generally will shoot only a couple different loads at their very best.

Lastly, it is not a given a 1" group at 100 will equate to a 4" group at 400. Some rifles will do this, but aside from good custom ammunition, your barrel and squared action have to be very good quality. Average barrels won't maintain their groups as distance increases.

Bottom line, like most things, but the best you can afford, have a gunsmith give your rifle a tune up, then work up a custom load your rifle shoots well.
 
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bearguide

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great additional information/ what rifle do you like
 

robby denning

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RosinBag,
thanks for your input and suggestions on accuracy- spot on- and not expensive or hard to do, either.

I have one question on something you said: "Lastly, it is not a given a 1" group at 100 will equate to a 4" group at 400. Some rifles will do this, but aside from good custom ammunition, your barrel and squared action have to be very good quality. Average barrels won't maintain their groups as distance increases."

I don't understand. How can the mathematical linear relationship of group size vs. distance be changed once the bullet leaves the barrel? Everything I've researched and experienced is contrary to what you said.
 

RosinBag

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From my experience, 100 yards is not far enough away from the muzzle to determine if your mathematical equation would be accurate. Barrels will directly affect bullet stabilization. If you start at say 300 with a 3" group you are more likely to know your bullet is stabilized and capable of your original equation. Ballistic Coefficient can also affect the equation, higher BC bullets are more capable than lower BC bullets, all else being equal, because they are less affected by environmental factors, such as wind.

Most of the science is accurate, but even something like BC is variable. Same bullet in your gun will have a slightly different BC in my gun.

I also think that 75% of shooters can shoot a 1" group at 100, but can't shoot a 5" group at 500. Any shooting form issues are exaggerated the longer away you get from the muzzle. I see this countless times at work and the shooters are quick to blame everything but themselves. Sometimes it is the gun, but the majority of time it is them.
 

JPhelps

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Or the effect from environmental conditions that the shooter can't control but do their best to account for. Environment is the main reason groups fall apart at distance.
 

RosinBag

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Robby, another issue I didnt specifically mention, but related to barrels, is bullet weight to the barrels twist rate. They both need to fall into a range to match each other. That is another reason 100 yards is to close at times to determine this. Some companies will put this info on their websites or printed on their boxes.
 

robby denning

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OK Rosin, I understand what you mean now. Thanks for clarifying and would agree that unstable bullets behave exponentially, not linear. I was talking math, you were talking real world. I get it.

You mentioned "at work". Do you work with guns?
 

RosinBag

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I get the math, scientically MOA would do exactly as you say with no other factors involved.

And I work around guns everyday, one of the benefits, but only long range stuff about once a week, short range rifles and hand guns the rest of the time.
 

BuckSnort

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Here's a load I worked up for my dads 270.. The group size is nothing to special but the low SD shows it's a winner...

 

philw

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Robby, I know your article didn't focus on this but a couple of other simple, inexpensive things that should probably be done to increase accuracy and repeatability before you'd delve into truing the action/lapping the bolt lugs would be to have the trigger adjusted and re-touch the crown.
 

robby denning

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Yes Phil, I agree. I wrote the article with the last step in mind: ammo tuning. You and others are right about the steps before that. If they aren't done, you'll never get the best accuracy out of your ammo- thanks
 

robby denning

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bucksnort, great group and is highly related to that low (0!) SD in velocity. Have you done a 3-shot, 3-group average? By my understanding, other variables influence SD besides velocity.
 

BuckSnort

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bucksnort, great group and is highly related to that low (0!) SD in velocity. Have you done a 3-shot, 3-group average? By my understanding, other variables influence SD besides velocity.

I have done something similar but a little more complex... The Ladder Method.. http://www.6mmbr.com/laddertest.html

It really makes sense if you understand BBL harmonics and internal ballistics... But to be honest I get the same results with my load development without the extra cost of more bullets,primers, propellant, and BBL life...
 

Bryan Martin

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Robby and Rosinbag, you have both made some good points. Thanks for sharing this with the readers. Ballistics, custom rifles, shooting, etc. is a huge topic and important for shooters to know some good facts. There are many variables for one to consider. Owning and Custom rifle and reloading for it, will definitely give one the best consistency and performance. The most important aspect, given a reasonably good product, is the man behind the gun. Trigger time, experience and confidence in ones own ability is key to becoming a great hunting shot. Good shooting.
 

robby denning

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Thanks Bryan! Good advice and great to have you on the thread. Thoroughly enjoyed your gear reviews with HF over the years. Learned alot.
 
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