My thoughts on 22lr barrel length...

Jim Boatright

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I've heard everything from 9" to 16" of barrel length for max bullet speed with different types of 22LR ammo. I would estimate about 12" of bullet travel for match ammo.
 

jbell

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    I've heard everything from 9" to 16" of barrel length for max bullet speed with different types of 22LR ammo. I would estimate about 12" of bullet travel for match ammo.
    Yeah 16” - 18” are the most common numbers thrown out there.
     

    Jim Boatright

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    Some notes on crosswind sensitivity for 22LR rimfire:
    As was formulated by DeDion in 1859, air drag causes wind drift "downwind" across the target which is proportional to the actual time-of-flight with air drag minus the hypothetical time-of-flight to the target at the undiminished launch speed. Rimfire match 22LR bullets have very low ballistic coefficients (i.e., high coefficients of drag) relative to Very Low Drag (VLD) rifle bullets. The coefficient of air drag is greatest in the transonic speed range for all bullets, especially for 22LR match bullets. The transonic speed range is from Mach 0.8 to Mach 1.2 for any non-VLD bullets. The "speed of sound," Mach 1.0, is 1116.45 fps for sea-level ICAO-standard air at 59 degrees Fahrenheit and varies primarily with the square root of the absolute temperature (T + 459.67 degrees F) of the ambient air. Thus, Mach 0.8 is 893 fps at 59 degrees F in that standard atmosphere, and 911 fps at 80 degrees, etc.

    Actually, the highest airspeed at which no "sonic crack" will be heard from firing a 22LR match bullet is at about Mach 0.75. That "crack" indicates that some portion of the airflow around the rather blunt 22LR bullet exceeds Mach 1.0. That Mach 0.75 airspeed would be 837 fps at 59 degrees. As airspeed falls below this critical transonic value, the subsonic coefficient of drag drops dramatically from about 0.4 (+) down to about 0.1 at Mach 0.70. [The lowest possible subsonic drag coefficient is about 0.03 for an elongated "teardrop" shape.] The 22LR match bullet is an excellent subsonic bullet design and flies serenely to great distance with very little loss in forward speed (and very little crosswind sensitivity). The whole trick is firing them below Mach 0.75 in that day's ambient air temperature. Available 22LR match ammo needs at least a 30-inch barrel to approach this low muzzle speed, and still needs a hot summer day when the speed of sound is relatively high. Perhaps a shorter barrel could be made to accomplish this feat reliably by venting some of the propellant gasses away within the first 10 inches of bullet travel.
     
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    JBoomhauer

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    @Jim Boatright

    Would you say this is similar to a boat coming off plane where the bow can become unsettled on the horizon. Not necessarily unstable, but a bit of instability during the transition.

    Stability likely isnt the right word.
     
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    Jim Boatright

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    @Jim Boatright

    Would you say this is similar to a boat coming off plane where the bow can become unsettled on the horizon. Not necessarily unstable, but a bit of instability during the transition.

    Stability likely isnt the right word.
    Yes, that is a pretty good analogy. Transonic flight through air is often described as "turbulent" for planes as well as bullets. Long-nosed supersonic rifle bullets tend to become unstable when they fall into the transonic speed range even though their gyroscopic stability is very high (Sg > 5.0) at that point in their flight. Air drag shifts from being proportional to the 1.5 power of airspeed in supersonic flight to being proportional to the square of subsonic airspeed. This is similar to planing over the water surface versus plowing at hull displacement speeds through the water. The stern wave swamping your transom causes the instability. I suppose that hypersonic flight above about Mach 5 could be analogous to hydrofoiling with the hull above the water surface. Those transitions with speed changes are much more gradual and stable, however.
     
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    JoshPutman

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    I have a Winchester model 75 which has a 28" barrel, and an adjustable barrel band near the end of the stock. Supposedly you can adjust the tension to tune for the ammo you are shooting. I haven't messed with it much yet, though.

    Were there very many rifles made this way? How effective is it really?
     
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    nockhunter

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    Yeah 16” - 18” are the most common numbers thrown out there.
    Yes popular, but that doesn't equate to optimum speed generated for the barrel length. My sons rimx with a 22" green mtn barrel exceeds manufactures stated velocity by a bit, and a friend of his that has the same setup is fast also, both 1:16", Barrel length is not the only thing that affects velocity. You really don't know until you do some shooting.

    Mike
     
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    jbell

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    Yes popular, but that doesn't equate to optimum speed generated for the barrel length. My sons rimx with a 22" green mtn barrel exceeds manufactures stated velocity by a bit, and a friend of his that has the same setup is fast also, both 1:16", Barrel length is not the only thing that affects velocity. You really don't know until you do some shooting.

    Mike
    Agreed
     

    obx22

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    Some notes on crosswind sensitivity for 22LR rimfire:
    As was formulated by DeDion in 1859, air drag causes wind drift "downwind" across the target which is proportional to the actual time-of-flight with air drag minus the hypothetical time-of-flight to the target at the undiminished launch speed. Rimfire match 22LR bullets have very low ballistic coefficients (i.e., high coefficients of drag) relative to Very Low Drag (VLD) rifle bullets. The coefficient of air drag is greatest in the transonic speed range for all bullets, especially for 22LR match bullets. The transonic speed range is from Mach 0.8 to Mach 1.2 for any non-VLD bullets. The "speed of sound," Mach 1.0, is 1116.45 fps for sea-level ICAO-standard air at 59 degrees Fahrenheit and varies primarily with the square root of the absolute temperature (T + 459.67 degrees F) of the ambient air. Thus, Mach 0.8 is 893 fps at 59 degrees F in that standard atmosphere, and 911 fps at 80 degrees, etc.

    Actually, the highest airspeed at which no "sonic crack" will be heard from firing a 22LR match bullet is at about Mach 0.75. That "crack" indicates that some portion of the airflow around the rather blunt 22LR bullet exceeds Mach 1.0. That Mach 0.75 airspeed would be 837 fps at 59 degrees. As airspeed falls below this critical transonic value, the subsonic coefficient of drag drops dramatically from about 0.4 (+) down to about 0.1 at Mach 0.70. [The lowest possible subsonic drag coefficient is about 0.03 for an elongated "teardrop" shape.] The 22LR match bullet is an excellent subsonic bullet design and flies serenely to great distance with very little loss in forward speed (and very little crosswind sensitivity). The whole trick is firing them below Mach 0.75 in that day's ambient air temperature. Available 22LR match ammo needs at least a 30-inch barrel to approach this low muzzle speed, and still needs a hot summer day when the speed of sound is relatively high. Perhaps a shorter barrel could be made to accomplish this feat reliably by venting some of the propellant gasses away within the first 10 inches of bullet travel.
    Got me wondering is there is a correlation between good or bad accuracy and whether the slug has passed Mach 1 and slowed back below Mach 1 before exiting the muzzle? (Thinking my old prone rifles w/28” barrels).
     

    justin amateur

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    With the 22lr, my only worry about muzzle velocity, is how much it differs shot by shot.
    It can be 1052 fps, or 1300 fps, as long as it's consistent. It's mv spread that burns my biscuits.
    The greater the difference in mv, the worse the the vertical difference in point of impact.
    I don't care if it's with an 18 inch barrel or 28 inch barrel, mv spread ruins results.
    Spend a few years shooting every box of rimfire across a chronograph, recording the data,
    it gets real easy to correlate point of impact to the displayed muzzle velocity.
     
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    littlesister

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    With the 22lr, my only worry about muzzle velocity, is how much it differs shot by shot.
    It can be 1052 fps, or 1300 fps, as long as it's consistent. It's mv spread that burns my biscuits.
    The greater the difference in mv, the worse the the vertical difference in point of impact.
    I don't care if it's with an 18 inch barrel or 28 inch barrel, mv spread ruins results.
    Spend a few years shooting every box of rimfire across a chronograph, recording the data,
    it gets real easy to correlate point of impact to the displayed muzzle velocity.
    I totally agree. What's the big deal with maximum mv. So what if you loose a few feet per second. Maximum mv doesn't translate into maximum accuracy. It is consistency you need for accuracy no matter what speed. If I had to choose between a 16.5 in barrel and a 30 in " actually I don't like either lengths" I would choose the 30. 16.5 is barely long enough for a complete powder burn and with a 16t you barely have one revolution of the bullet before it exits the crown. There is something to be said for stabilizing a bullet before it exits the barrel.
     

    drglock

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    Yes popular, but that doesn't equate to optimum speed generated for the barrel length. My sons rimx with a 22" green mtn barrel exceeds manufactures stated velocity by a bit, and a friend of his that has the same setup is fast also, both 1:16", Barrel length is not the only thing that affects velocity. You really don't know until you do some shooting.

    Mike
    From my experience(2 Green Mountain’s on my RimX and a friends on a CZ457) Green Mountain barrels are on the fast side. Mines a 22” now and really contemplating going to a 24” GM for better balance and see if I can squeeze a tad bit more accuracy out of it. My 22” shoots most Center X 1090fps-1105fps depending on lot and time of year.
     

    JG26_Irish

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    I want to chime in on the bbl length discussion. I shoot with a group of marksmen who put on a "Outlaw" bench rest match each week that is limited to repeating 22lr rifles shot from sandbags. A good bit of freedom is allowed for mods but the rifles range from box stock to highly modified. No custom match rigs however as would be seen in unlimited ARA competition. The skill level of this group of about 16 is stellar and there are 3-4 past ARA national champions on the line every week and at least 4-6 other shooters who are capable of winning on a given day. For example we shot an IRL 50y card the other day and one of the guys scored a 249 with 12x and was in 6th place. Winchester 52's are a common winner in this match. These are 28" bbl. Anchutz 64 and 54 rifles usually make up 3-4 of the competition and are also capable of winning. I think their bbl is of similar length. My 1413 Super Match is a 27.5" bbl but as a single shot is normally excluded from this match (lucky for them), lol.

    A mixed bag of shorter Tikka T1X, CZ457, VuDoo, Sako Quad, and other rifles grace the line from time to time. Their bbl lengths range from 16" to about 24". Some like the CZ are available is 16.5, 20.5 and 24 inch lengths, I think. Or something close to that. I shoot rifles in this match that range from 20", 22", 24" and 28". They all shoot well. The 20" Bergara carbon is the least accurate and is really not a contender, in this match. The 22" Sako with Lilja bbl is a hard competitor that is capable of winning but is usually about a 3rd to 4th place gun. It is equipped for long range PRS and is not scoped for bench rest and this does handicap it ever so slightly. The 24" CZ 457 VPT is my factory gun and is not good enough for this match but is only a fraction behind the Sako. I have three Winchester 52's. One had the bbl cut to 22 and 3/4" length. It used to be a regular winner in this match 4-5 years ago. But about 3yrs ago about half the competitors all bought Winchester 52's. When I really want to win, I bring one of the 28" bbl 52's. I do not always win, but I can with those rifles and rarely can with the others. I shot this past week with my Sako and was 2nd on two cards and about 10th on the other three. 1st thru 3rd on the last three were all Win 52's with 28 bbl. I saw at least three perfect scores on ARA and IR50 cards and one on the IR50/50 which is much harder to clean. I think the longer bbls are slower and also allow for the hot gases to cool and expand a little more and as a result might produce slightly more consistent muzzle velocity within the limit of the ammo. We are all using Lapua and Eley ammo with occasional RWS shooters. Nobody else has a product that can win.

    As for the transonic discussion. I also shoot long range rimfire PRS out to about 400y. This is with the Sako. It has a nice 6-24x FFP MIL optic and is a good rifle for that game. The muzzle velocity for my ammo in the 22" bbl is running from 1048 to about 1060 fps depending on lot and temp. I am using CenterX with this one. On a bench at 50y it can shoot 1/4" c-c groups. The muzzle velocity is in the transonic range and even out to 400y, it is still on the tail end of that. If you position with the sun at your back, and conditions are right, you can often see the bullet as it arcs to the tgt like a pitchers curve ball. They all wobble badly, regardless of rifle used. If you search for slow mo film of 22lr bullets in flight, you can see this better. Makes me marvel that we ever hit what we aim at. We shoot year round and it is common to see accuracy diminished at colder temps. Part of this could be due to the muzzle velocity is deeper into that transonic zone. I often wonder if the 16" bbl rifles are going supersonic just a little?
     

    68hoyt

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    Long barrels… I too feel as if they work best, my best shooters are long barreled rifles. I own/have owned several Winchester model 52’s. Pre A’s, B’s, C’s and a D. All that I currently own wil shoot sub 1” at 100 on a 6x5. The Bull Barrel and the cut down C (24”) will shoot .7-.75 on low wind days. My Mark Penrod H&R model 12 is a .6-.75” rifle. I’m pretty sure it’s 28” (I’m away from the rifle for the moment sorry) and it has a tuner. My Vudoo (22”) is a bit finicky on ammo but is a .75-.85 rifle when I find the right ammo. Once found, it is consistent, but doesn’t come close to the Model 12.

    All of this to say, if you’re trying for the best accuracy, long barrels are the place to start.
    I would like some details/info on your m12
     

    simpletoms

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    I would like some details/info on your m12
    2F2C97A3-CAE9-40F9-AF44-1C8BCD1A8014.jpeg

    Here it is, I purchased it second hand from a guy in Indiana. It was built by Mark Penrod. It’s my first/only rifle with a tuner and I do think it helps. When tuned, I think it improves groups .1 - .2” If I could improve one thing on the rifle it’d be the trigger. I’m pretty sure it’s a Shilen barrel. I shoot it regularly out to 250 yards.

    Let me know if you have any questions.
     
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    68hoyt

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    Nice , people have done or have had done the pin relocation like the win52 c/d kenyon mod , where the pivot pin on the trigger is moved up giving better mechanical advantage and lowering trigger pull
     

    gr8guns

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    You folks are way to scientific for me. I simply like a 20 inch heavy barrel for the inertia and balance. That barrel weight/ length feels best to me when I shoot off hand and on the bench......the amount of effort to keep the muzzle steady is what I am used to and prefer
     
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    gr8guns

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    Nice , people have done or have had done the pin relocation like the win52 c/d kenyon mod , where the pivot pin on the trigger is moved up giving better mechanical advantage and lowering trigger pull
    I have three Kenyon worked triggers. My two 52 C rifles and my 52E all have Kenyon worked triggers. He would tell you a trigger he worked the pin re-location on was just as smooth as the complete triggers he turned out. I had the privilege of talking to him a couple of times.