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Adjusting the speed of .22 RF Ammo

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  • Adjusting the speed of .22 RF Ammo

    Ok, first and foremost I like to tinker and being retired I like having projects so my mind has a tendency of wandering. I have a number of target .22 and everyone likes the slower target ammo that runs about 900 to 980 FPS. I have a bunch of regular ammo that runs at 1,050 to 1,500 Feet Per Second. Right now target ammo is running $9.50- $15.00 a box while regular .22 ammo is less than half that amount.

    So my thought is would the cheaper ammo shoot as well or close to the target ammo if I slowed it down? I know that things like more care in powder measuring or priming material are also going to impact accuracy but some of my rimfires shoot higher speed ammo quite well and target ammo very well so my thought is slowing down the high speed stuff would get me tighter groups.

    My thought is to port the side of the barrel about 12-14 inches from the muzzle (think AR15 gas port) then make a block(again think AR-15) that would slip over the barrel with an adjustable port in it that would allow you to limit the amount of gas you ported off allowing you to tune for the round you are shooting. This would be held in place by a set screw or two. This would also allow the use of supersonic ammo dialed back to subsonic if a supressor was added to the mix at a later date.

    This would be used with bolt action or single shot rifles only.


    Last edited by wbldon; 06-16-2022, 04:07 PM.

  • #2
    I would suggest measuring velocity out of a single shot or auto pistol to see what velocity you get out of short barrel. this will let you decide where to put a hole in a long barrel or even if it is worth the bother. I would be very leery of putting a hole in a target rifle, might unbalance the bullet as it passes.if so there is no fix.



    • #3
      Accurate powder measuring isn’t necessarily going to increase accuracy. What it will do is increase consistency. Consistency is what you want when you are chasing “accuracy”.

      I think the “match” bullets will have a lot more consistency on the projectile over the cheaper “bulk” rounds. This should play a lot bigger role over FPS.

      In general for a given caliber, a slower FPS usually means a heavier projectile. Not always, but usually. Weather conditions will have less of an impact on a heavier object. When talking a relatively light projectile like 22lr, weather (wind) is something that needs to be watched while chasing “accuracy”

      I would suggest taking the “cheap” rounds you have and weighing them with an accurate scale and get them separated into similar weight groups. I’m talking rounds from the same box. Then go do some practical shooting and see where you get. Not all rifles like all rounds and some will preform better than others. You are basically trying to find what your rifle likes.

      I don’t know your skill level but some more practice may have the biggest impact on your quest for “accuracy”, at least for a little while.


      • #4
        Are you somehow actually reloading rim from re .22lr? Never seen this.


        • #5
          Bob, That is a good idea using a single shot or auto pistol to check speed reductioin of the shorter barrel. Thank you!

          Oxford, been shooting for almost 50 years now. With my target ammo (Wolf Match Target) getting 5 shot groups at 50 yards from my vintage Winchester 52 & CZ 457 MTR about 3/4 inch, 1/2" when I get lucky. I agree more practice is good.

          no704, I wish I could as I have loaded for most of my centerfire guns and it is nice to tailor loads to squeek out the best accuracy. Unfortunately I don't reload .22rf ammo and do not know anyone that does.

          Thanks for the input folks... Lot's to consider...



          • #6
            A port might slow down the bullet, but it seems rimfire ammo is fairly dirty. Between the remaining residue and the lead bullet, the port would require cleaning regularly. Most who shoot cast bullets in an AR or have a suppressor, shoot powder coated bullets because of fouling.


            • #7
              Muzzle speed isn't the magic quality of target vs budget ammo. As other have mentioned - bullet quality and consistency, powder and charge consistency, primer quality and consistency, brass quality and consistency - these are the things that make true target 22 LR ammo.

              Yes, slowing the ammo down so that it starts below the speed of sound will prevent the bullets from fighting the transition from super to sub-sonic. That's a theoretically good thing, and may well make a measurable difference in accuracy. But simply slowing down the bullets isn't likely to be the complete solution. If you don't start with quality, consistent bullets, powder, powder charges and brass, you are probably wasting your time trying to turn budget ammo into target ammo.
              SE MI, USA


              • #8
                Something else to consider would be to machine a shrink fit sleeve or collar for the muzzle to add some small amount of constriction.

                It could double as a bloop tube or blast forwarding device (BFD ;-) if overhung

                The idea is similar to a shot gun choke or the "Smootth Twist" rifled barrels as fitted to FX brand Air rifles (known for acceptable accuracy)

                Heck, you could produce a micro adjustable "harmonic barrel tuner" while you are at it. (Which actually might be why the hotter loads spray a bit. Even if only a .22rf, when it goes off, EVERYTHING MOVES! It's just a matter of degree.)

                Playing around with the hows and how much, along with front sight design would while away untold hours in the machine shop ;-)

                ps I enjoy shooting the Small bore 50 foot target at 50 yards. off a simple bag, using aperture sights. I've gotten some half decent scores.

                ten bulls on one target sheet, five rounds to each bull. That's a box! It can take me a couple hours to finish the set. Very relaxing.
                Last edited by CalM; 06-17-2022, 01:05 PM.


                • #9
                  I spent a long time (20+ years) shooting the Bullseye pistol gallery course in local and regional competition... 10 rounds slow fire (10 shots in 10 minutes), 10 rounds timed fire (2 strings of 5 shots in 20 seconds) 10 rounds rapid fire (2 strings of 5 shots in 10 seconds), twice around.

                  60 shots of either 22 rimfire or centerfire (mostly 45 ACP)... I would drive home from matches both very relaxed and mentally whipped.
                  Last edited by DrMike; 06-17-2022, 01:41 PM.
                  SE MI, USA


                  • #10
                    Try the Federal Auto Match ammo from Walmart, 333 rounds for $20


                    • #11
                      Its already been mentioned, but the slightly slower speeds arent what makes match-grade ammo match-grade, its consistency thats key, and you wont get consistency just by porting the barrel. Find a brand of ammo your specific rifle likes, stock up on it, maybe get a barrel tuner if you want to shrink the groups a tiny bit more. CCI standard or green tag, mini-mags, eley club, lapua center-x, plenty of good ammo options


                      • #12
                        perhaps adding a barrel tuner to find the best node with the faster ammo would be a consideration. Jim


                        • #13
                          Originally posted by epicfail48 View Post
                          Its already been mentioned, but the slightly slower speeds arent what makes match-grade ammo match-grade, its consistency thats key, and you wont get consistency just by porting the barrel. Find a brand of ammo your specific rifle likes, stock up on it, maybe get a barrel tuner if you want to shrink the groups a tiny bit more. CCI standard or green tag, mini-mags, eley club, lapua center-x, plenty of good ammo options
                          Slower speeds are just the necessity of staying out of the trans sonic velocity range. There is absolutely NO good reason to stay in that area. Above or below, but not in there.

                          Air guns are testimony .

                          I feel the op's goals are a good adventure. Bleeding gas pressure might achieve the goal of using less costly rounds to achieve rewards. But in my mind, the disruption due to attached "issues" might confuse the results. A blow off hole would be one of my last approaches due to the possible deformation of the bullet. A few shots into a wool filled tube with followup inspection under magnification might tell the tale.

                          One thing, a "Too-o ... long" barrel will slow the Muzzle velocity. Hard to get though,

                          A "too-o.. short barrel will slow the bullet also, but the muzzle blast WILL disrupt the projectile as it departs. The propelling gasses ALWAYS get to the muzzle before the lead slug.

                          Let friction do the work! ;-)
                          Last edited by CalM; 06-18-2022, 11:53 PM.


                          • #14
                            Drilling a clean "port" hole into a barrel is not an easy task. Any slight burr on the interior and you are shaving lead for a long time and you can forget about accuracy. As mentioned, I think your best bet to get better accuracy from mid-level ammo is to install a tuner and learn to set it. The other option is to use the cheap ammo as-is and practice on targets sized to compensate for the larger groups. If the Rem Golden Bullets shoot 50% bigger groups than Wolf Target, use a proportionally bigger target. You still get valuable feedback if you stack all the Golden Bullets in the larger X-ring. This is especially true if you are shooting from position and not bench rested.


                            • #15
                              Here is something to consider.... (in my mind...;-)

                              A properly ported barrel (whatever that may be? Lands or grooves? 2, three, or an array) will certainly relieve gas pressure somewhere along the barrel length. (Where is maximum velocity obtained? (powder burn rates and all that.)

                              Will it also lessen the disrupting blast that "barrel crown" is so significant in taming?