rimfire rifle accuracy

Discussion in 'Firearms' started by Tango3, Dec 1, 2009.


  1. Tango3

    Tango3 Aimless wanderer

    Everybody loves the looks of a bull barrel; I assumed the purpose was the extra weight,but I stumbled upon this thread:

    Here is what I've learned:

    Regarding 100 yard shooting with a little 22.

    Yes, it is certainly possible to do so. In fact, 100 yards is just the beginning. There is also a subculture of gun nuts out there that play with these at 200 yards. It's called "Mini Palma" and it is a hoot to shoot.

    Palma is 800, 900, and 1000 yard competitive shooting. Rifles are only allowed to be chambered in 308 Winchester and they must use a 155 grain bullet. Iron sights only and you shoot from prone.
    No bags, rests, or bi pods are allowed.

    Mini Palma is (this part varies a little depending on where you shoot) 100, 150, and 200 yards with a 22 rimfire. Same general rules though. Iron sights and you shoot from prone. Some matches change the 100 and 150 yard distances to fit their ranges better.

    A 22LR at 200 yards is very close ballistically to a 308 at a 1000, in terms of making a windage call anyways. This is why its a great training aid for LR shooters.

    Ok, got side tracked, sorry.

    Gun specifics. Yes, you can certainly build a 10/22 to hammer at 100 yards. It starts with a premium barrel.

    100 dollar drop in "bull" barrels aren't really the answer here if you truly want a high performance 22.

    300 dollar barrels are where you should be looking.
    If you are like most, you are working within a budget. Given the choice between fancy triggers, stocks, and scopes.

    Buying a premium barrel will give you the most significant performance/accuracy increase.

    Premium ammunition is the second thing to focus your money on.

    Dan Lilja, owner of Lilja Rifle Barrels up in Montana makes a drop in barrel for 10/22's that has the right chamber already cut. Anyone who tinkers with NBRSA knows Dan's reputation as a barrel maker. Great guy and great products!

    The chamber:

    A competitive bolt gun in 22LR uses a very tight chamber. I learned about all this working for Neal Johnson and Anschutz as a gunsmith on Olympic Target Rifles for resident athletes at the Olympic Training Center in Colorado Springs.

    The throats on the chambers are short and they are tight. Match grade barrels typically run the minor bore dimension a couple thousanths tighter than what the SAAMI tolerance is.

    This "chokes" the bullet and helps insure that it is running concentric to the bore's centerline.

    Well, that's great on a bolt gun where you have a powerful camming action when going into battery.

    Blow back operated semi autos won't put up with this, so it's modified to what is commonly called the "Benz" chamber. It's a compromise between the two.

    The throat region is kept "almost" as tight while the back half of the chamber, the part that supports the case, is loosened up a bit to facilitate operation. (Feeding, chambering, and extraction)

    The bullet gets the support it wants and the chamber will let the gun "run" right.

    Barrel vibration:

    This topic gets so abused and terminology ends up being misused.

    I won't go into a long dissertation about grammar.

    Simple fix. If you want to devote the time to it, buy a barrel tuner from Neal Johnson's Gunsmithing in Colorado Springs. ( "Neal Johnson's Gunsmithing, Inc. Online Target Shooting Equipment Manual" )

    Here is a simple way to explain how all this works.

    Take a 12" ruler and screw it to your dining room table with 10" of the ruler hanging out in space.

    This is your barrel.

    Flip the end of the ruler so that it "boings" back and forth.

    This represents your barre l as the shock wave from the firing pin spring/hammer drives the striker/hammer into the primer and the cae rim crushes against the barrel resulting in ignition. Chamber pressures rise, and the bullet begins traveling down the barrel. (All this makes the barrel wiggle)

    Observing the ruler as it wiggles back and forth will show you there are two locations where the barrel is seemingly motionless for a brief instant.

    Time your bullet to leave the crown and enter its flight path at one of these two locations and you gain accuracy.

    This is what a barrel tuner does. Tape a penny to the ruler. It alters the ruler's "wiggle".

    Change the location of the penny on the ruler, and it will alter this yet again.

    A barrel tuner uses a threaded, rotating cylinder that has graduations marked on it. Much like the barrel on a micrometer. By fiddling with the clock position/location of this cylinder, you can "time" the barrel to the ammunition.

    This has much the same affect as when you suddenly gain substantial accuracy from bumping a charge a few tenths of a grain on a centerfire rifle cartridge. People call this the barrel's "sweet spot."

    Tuners work, but they can also drive you nuts because if you change ANYTHING you must be prepared to start your testing all over again.

    Here's a list of things NOT to change if you don't want to spend another full day fussing on the bench:

    1. Lot numbers on ammo
    2. Guard screw torque.
    3. Changing a scope (torque load on ring screws)
    4. Changing/replacing any internal fire control parts. (10/22 titanium hot rod parts for instance)

    All this should be considered with barrel tuners.

    You also need to glue (epoxy) the sleeve to the barrel when using one of these. Clamping it won't work. It'll move and goof you up.

    Ok, next subject:

    Semi autos and how they kill accuracy.

    22LRs are rimfire cartridges. Stack them up in a magazine and what happens? The rim of the case being chambered is pushed over the bearing/sealing ring of the bullet beneath it as the bolt strips it out of the magazine and chambers it.

    Because the bullet is soft lead and the case is brass, an inclusion is formed from the brass rim scraping over the bullet. This causes a very subtle change in the center of rotation for the cartridge.

    Typical match grade 22LR ammo has a muzzle velocity of around 1050 to 1200 fps. There's a reason for this big deviation that I'll get to.

    Barrel twists for target/bench guns are usually 1-16. Doing the math, that breaks down to the bullet spinning between 47,250 and 54,000 rpm.

    Now, just imagine a football being thrown with a tire weight taped to the outside. It's going to wobble. The bullet does the same thing.

    This wobble will induce a subtle change in flight path and it will cause a group to spread more than if this didn't happen.

    I'm not claiming that its a huge difference, but it is there.

    Match ammo velocity. One would think that supersonic ammo is for longer distances and subsonic is for close up.

    Actually, it's the opposite. The supersonic won't stay supersonic out to 100 yards. It'll shed enough velocity to where it passes back through the sound barrier. This causes a reduction in accuracy.

    Subsonic will stay subsonic through its entire flight path so its better for longer ranges. (100 yards and beyond)

    All ISSF (International Sports Shooting Foundation) competition for rimfire is held outdoors at 50 meters. (Olympic type shooting) The supersonic ammo will stay above the sound barrier at 50 meters. This is helpful because it reduces time in flight just a little and makes it just a bit more resistant to conditions.

    Back to gun stuff:

    The other obvious reason for larger groups in semi auto 22's is the use of energy to operate the fire control of the rifle/pistol.

    Bolt guns don't do this, all energy generated by the powder charge is used to propel the bullet.

    Ok, class dismissed.

    No quiz today. . .

    Here's a sample of a highly accurate 22LR rifle.

    [​IMG]

    I built this for Cathy Winstead. Cathy is the only person in the history of smallbore silhouette to win both world championship events in small bore rifle silhouette. She won in the heavy gun unlimited class and the hunter lightweight class. Lucky for me, I built both of her rifles. (woo hoo!)

    This was done in South Africa in early 2004.

    The rifle pictured is an Anschutz 54 action with a custom barrel. The stock is a Boyd's design intended for a 10/22 Ruger. I ordered it as a blank and did the inlet and bedding work.

    The scope on it is just a test scope that I use for performance testing on the bench. The gun would never make weight with that big monstrosity on it.

    Cathy has always shot a pink gun. She's been shooting since she was very young. We decided it was time for a "ladies pink" instead of the "Gawddy Miami Vice pastel Pepto "dismal" pink" that she had been using.

    So, "Rose Quarts Metallic" from PPG it was.

    I like it personally. Looks sexy to me.

    At 100 yards using Eley TENNEX EPS the gun shoots a five shot group that averages right at about 3/4's of an inch.

    Now, five shot groups aren't all that impressive to me. What I was taught with 22's is to shoot TEN five shot groups and then average the spread.

    So, you end up shooting a 50 shot group to achieve a "real world" average and expectation for performance.

    So, thats the story about the Pink gun.

    Hope this helped someone.

    Thanks for listening to my rant.

    Last spring I did a lot of experimenting with making a 10/22 shoot better and here is what I found.
    The standard factory barrel haqs a chamber that requires the bullet to have a jump of almost 1/4 of an inch befor it hits the lands. This makes sence to prevent ejacting a loaded round and having the bullet remain in the barrel because its stuck in the lands. However that jump ruins accuracy no matter what ammo you are shooting. I took the barrel off and turned the reciever end shorter so that the bullet was just short of touching the lands and then cut a new extracter slot and also turned the part of the barrel that fits in the reciever the same same amount. Well here is the result of the test. 5 shot groupe of less that .14 of an inch from center to center of the widwst shots with 8 differant brands of ammo. Then I but on a bull barrel and the groups were much much larger. Its not the sive of the barrel that maked the most differant in the accuracy of a 10/22, its the chamber. The benz chamber happens to have a larger jump that the one I make.

    There are a few other things you can do to them that is imporant. I have learned how to modify the sear to give a reliable 2 1/2 pound trigger and that is a must no matter what stock or barrel is being used. Also qa slight modification to the V block that holds the barrel in the reciever helps so the barrel is not pulled down like it is from the factory when you tighted it up.Should any one be interested in how to modify the factory stock or any thing else about making that little rifle out shoot the $800 jobe feel free to contact me and I would be glad to pass on more details .


    http://www.gunandgame.com/forums/22-rimfire/30144-best-22lr-rifle-100-yard-shooting-2.html


    where a rimfire competition 'smith goes over a few things on building an accurate rimfire.He says a heavy barrel is to combat poa change dueto barrel heating.and that the rimfire doesn't heat thebarrel excessively under normal conditions.( not from the above quote , read too many today got em mixedup... )
    So is a "sporter" barrel giving up accurracy for less carrying weight? Or not?
     
  2. gunbunny

    gunbunny Never Trust A Bunny

    Wow, reading that was like reliving the last five years. When I bought a .22 lr suppressor (yeah, $200 stamp tax, fingerprints, the whole nine yards) a while back, I figured I would get the most of it by putting it on the end of almost everything I could.

    Luckily .22's were cheap and plentiful back then. Besides the gun that started the whole thing, a Walther P-22, I got conversion kits for an AR-15, Glock, and a 1911. I couldn't imagine trying to get all of those kits with today's market. That's not even factoring in how long it would take to get the pistol kits threaded today. I sent my kits to TROS, in Montana, and they were worth the three months and every cent of Dinero.

    I threaded rifles, too. A Winchester Model 69 (1" MOA at 100 yards), Walther G-22, and a Savage in .22 WMR. The savage didn't work out so well; even though I reloaded the .22 WMR's to a lesser powder charge for subsonic performance, they exibited poor accuracy and subsonic consistancy, and started to have hangfires. Anyone trying to develop subsonic loads should understand that hangfires are dangerous! I also decided it wasn't worth the risk of damaging my suppressor, either. The nice people at Tactical Innovations almost had a cow when I told them what I was doing with their suppressor.

    Hey, you have to try stuff if you want to know if it will work.

    Luckily my wife likes the suppressor because it makes shooting easier. No earmuffs or plugs. You can hear the wind rustle the leaves and the chirping birds and squirrls while you are shooting. It's really nice. I'd recommend a suppressor to anyone, even if you have to do the paperwork to get one. Eveyone that shoots my suppressor for the first time in their life gets a grin from ear to ear.

    I also did goofy things; I bought a Sterling .22 and had the barrel extended and threaded. The suppressor is bigger then the gun, and looks neat, but the bullets keyhole so I never shot it with the suppressor attached. I even paroused the halls of Gunbroker in search of a TEC-22, thinking that it would be a fun little gun to take to the range and act like an adolescent again, but reality took over. It seems that the TEC-22 has quite a cult following and these little pistols go for some big $$. Well, bigger than I wanted to pay for a POS little fun-toy.

    Anyway, some things I learned: a shorter barrel doesn't mean less accuracy, most times it's quite the opposite. It just gives you a slightly slower bullet and a barrel that has a little less harmonics.

    Shoot subsonic ammo at matches for the consistancy. Remington subsonics are very consistant from shot to shot. That's one of the reasons they cost more. I was keeping up with the olympic competitors at my first summer biathlon because the Rem Subs shot well out of my gun, and I practiced a lot with that combination.

    If you drop a round on the ground, don't shoot it out of your match gun. My Win mod 69's both were basket cases, but the bores were mint. They were shot a lot, but a .22lr bullet with it soft lead has very little abraision to it- unless you drop it and it get covered with dirt. Then the little bullet becomes a sandpaper slug.

    Suppressors are not only fun, but they help with the functionallity of semiautos. Sometimes. The suppressor acts like a longer barrel, and creates more backpressure for simple blowback actions. If the weapon functions great without the suppressor, then you may have to "tune" it with some heavier springs and such. I ran into that with my Ceiner kit for the AR-15.

    Suppressors will enhance the accuracy of the weapon, if it didn't already have a target crown. It will change the POI when you shoot the rifle with the suppressor and sight it in, then take it off and shoot some more. It's easy; just take the suppressor with you when you go shooting, and don't forget it and feel like a fool because a friend from Florida stopped by and wanted to try out the thing you were telling him about for the past five months... "Oh $hit, I didn't bring the suppressor!" DUH.
     
  3. Seawolf1090

    Seawolf1090 Adventure Riding Monkey Founding Member

    I used to really like the low price of typical twentytwo rifles and 'acquired' my share. But the day of the "Fifty dollar .22 rifle" is gone. At last rollcall, I have more than 30 rimfires of all persuasions - single shot 'boys rifles', basic RugRemChesters, Marlins, Savages, Mossbergs - and then a few nice old target rifles. Each has it's draw.
    If I can put all five shots into an inch at 100 yards, I am quite happy. I have a few rifles that will do that, and ONE that will do it with an aperture sight, using good ammo - my BSA Mk.II Martini target rifle.
    But, I get as much fun shooting my Henry lever rifle at the charging soda cans on the 50 yard line.......

    I sometimes consider trying to really get the most from one .22 rifle or another - but I am NOT a competitive shooter, and sometimes the money expended just would not be justified.
     
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