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RimX light primer strikes

King_beardsly

MMPRL & Low Dollar Precision
Full Member
Minuteman
  • Jun 12, 2018
    1,587
    731
    Beast Coast
    Has anyone experienced random light primer strikes with a very low round count through their RimX. I ran through three boxes of an older lot SK Std and had two light primer strikes with a fair amount of round’s between them. Now I put those rounds back through and they went off with out an issue.
     
    Did you hit them in a different spot on the rim the second time? If so then it was probably just missing a tad of primer in that exact spot on the rim.
     
    Did you hit them in a different spot on the rim the second time? If so then it was probably just missing a tad of primer in that exact spot on the rim.
    To be honest I didn’t even check, but there is a good chance it was a different spot and that would make sense since every old timer had the remark of “wow I have seen that box in years”
     
    I have found there to be multiple causes for fail to fire.
    Happens with all types of rimfire cartridges.

    1) Build up of burn residue in receiver, on bolt face, in firing pin channel.
    2) Lack of primer in rim at firing pin impact point.
    Can be caused by issues at the factory, or by rough handling during shipping.
    3) Mechanical problem with firing spring and or pin.
    4) Improperly formed brass, leaves no hollow in the rim for primer to fill.
    Solid brass/no hollow usually identified by a very thin rim
    and pin strike leaves almost no trace of impact.
    Disassemble the cartridge, empty the powder, primer is visible,
    but solid brass is seen all the way to the case head.
    Pin can't crush the brass or ignite primer.
     
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    History of these light strike issues on the RimX dependent on trigger, barrel, and who built it. What barrel are you using and have you verified your headspace using the supplied Zermatt go no go gauge?
     
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    History of these light strike issues on the RimX dependent on trigger, barrel, and who built it. What barrel are you using and have you verified your headspace using the supplied Zermatt go no go gauge?
    The barrel was spun up by keystone accuracy and everything checked out with the gauge, I’ve run other SK std and haven’t had any issues.
     
    Next time it happens, extract the cartridge and pull it apart.
    Dump the powder on a paper towel.
    Check for primer chunks mixed in with the powder.
    Inspect the inside of the now empty cartridge.
    Is there primer in the rim at the strike location?
    If so, weak strike. If not, cartridge caused problem.
     
    The barrel was spun up by keystone accuracy and everything checked out with the gauge, I’ve run other SK std and haven’t had any issues.
    If the barrel headspacing checks out, it likely is a trigger fire control and bolt timing issue. How low do you have your TT Primary set? They are rated for 1.5-4# if you are on the ragged end of minimum try increasing it to 2 pounds just to isolate the issue.
     
    If the barrel headspacing checks out, it likely is a trigger fire control and bolt timing issue. How low do you have your TT Primary set? They are rated for 1.5-4# if you are on the ragged end of minimum try increasing it to 2 pounds just to isolate the issue.
    I think I’m down at the lower limits
     
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    And that my friends is why my RimX is down the road! Almost definitely a firing pin issue. I had a total of 3 control assembly sent, multiple triggers. It took a experienced 22 smith to figure out it's the crappy firing pin geometry/angle, shape.Fixed it, dumped it. Never ever had a failure to fire with either of my Vudoos.
     
    And that my friends is why my RimX is down the road! Almost definitely a firing pin issue. I had a total of 3 control assembly sent, multiple triggers. It took a experienced 22 smith to figure out it's the crappy firing pin geometry/angle, shape.Fixed it, dumped it. Never ever had a failure to fire with either of my Vudoos.
    I don't have an issue with mine as long as I keep it clean. And I have to say that I hear about a lot of issues with all the manufacturers of .22LR products, its not just Zermatt - but I believe its the nature of .22LR vs Centerfire.

    As a personal take - I sort of expect my rimfire to function like centerfire - which is to say with little management or maintenance, but it just is the wrong expectation for a .22LR precision gun.
     
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    That’s the joys of the ultrasonic cleaner, pull apart the bolt assembly and throw it in till it comes out sparkling clean. I try to stay on top of maintenance since I know RF stuff is twitchy when stuff start to get dirty.
     
    And that my friends is why my RimX is down the road! Almost definitely a firing pin issue. I had a total of 3 control assembly sent, multiple triggers. It took a experienced 22 smith to figure out it's the crappy firing pin geometry/angle, shape.Fixed it, dumped it. Never ever had a failure to fire with either of my Vudoos.
    The guy you took it to couldn't have been a very good 22 smith if he actually couldn't figure it out. There are no "firing pin" documented geometry issues according to Zermatt, other than folks that don't head the warning not to excessively dry fire them causing damage. I have 2 RimX actions and early and late model serial number, put together myself, several thousands of rounds through them, never had a single light strike and/or fail to fire. My Primary has a single stage TT Diamond set at 6 ounces, the other a TT Special 2 stage set at 8 and 6 ounces. I chamber clean only between shooting sessions, brush the face of to ensure the extractor groove is clear and wipe the bolt clean, lube. As stated above issues with 22s are inherent in all models and manufacturers. I know several that have had issues with Vudoos that switched to RimXs and vice versa. When you have problems you just have to actually ask the guys that know how to work them out.
     
    I think I’m down at the lower limits
    Most likely the cause, any trigger believed to be set at the "lower limits" can actually be below if an initial measurement was not taken from the factory adjustment. The trigger may adjust lower than the range designed such as your Primary is 1.4-5# but you may actually be 1.2-3 that throws the trigger and sear engagement timing off and the firing control may not fully cock on close as intended.
     
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    And that my friends is why my RimX is down the road! Almost definitely a firing pin issue. I had a total of 3 control assembly sent, multiple triggers. It took an experienced 22 smith to figure out it's the crappy firing pin geometry/angle, shape.Fixed it, dumped it. Never ever had a failure to fire with either of my Vudoos.
    FYI, I believe every single 22 precision platform has had an issue one way or another. I think if you have a good smith put together your RimX then i doubt you will have an issue. I have had two and both of them run perfect. I am diligent about cleaning my RimX. Never an issue with both of mine made by Desert Precision Gunworks or Keystone. The OP issue, I bet is trigger related. I bet if he increases the tigger pull weight, the issue will more than likely solve itself. Good luck on getting the light strikes resolved.
     
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    I am putting $20 on the trigger sear is too high causing excessive drag on the cocking piece, thus absorbing the firing pin spring force. I have seen it with multiple RimX actions and multiple TT triggers. Is your bolt also hard-ish to close?
     
    FYI, I believe every single 22 precision platform has had an issue one way or another. I think if you have a good smith put together your RimX then i doubt you will have an issue. I have had two and both of them run perfect. I am diligent about cleaning my RimX. Never an issue with both of mine made by Desert Precision Gunworks or Keystone. The OP issue, I bet is trigger related. I bet if he increases the tigger pull weight, the issue will more than likely solve itself. Good luck on getting the light strikes resolved.
    Im going to play around with the trigger and if that changes anything. I planned on swapping out the barrel anyways for something a bit heavier, so I’ll just send him a bare action and have him fit up a barrel to rule out anything.
     
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    I am putting $20 on the trigger sear is too high causing excessive drag on the cocking piece, thus absorbing the firing pin spring force. I have seen it with multiple RimX actions and multiple TT triggers. Is your bolt also hard-ish to close?
    It’s a tiny bit tight, so maybe I’ll shoot Ray an email in the morning about this and see what he says. I know my other bighorn/zermatt actions took a tiny bit of finessing especially my origin but swapping out the cocking piece did remedy the issue.
     
    It’s a tiny bit tight, so maybe I’ll shoot Ray an email in the morning about this and see what he says. I know my other bighorn/zermatt actions took a tiny bit of finessing especially my origin but swapping out the cocking piece did remedy the issue.
    I shortened my cocking piece by about 0.025” (in 0.005 increments and test).
     
    Send pictures of fired brass, too. Specifically, the profile view of the cartridge like the attached.
     

    Attachments

    • Profile View - Chamber Radius Story.jpg
      Profile View - Chamber Radius Story.jpg
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    The chamber radius appears to be showing a little in these pictures which would indicate that it's slightly over sized. It may not affect 100% of the rounds, but any inconsistency in the firing pin drop or the primer compound in the brass could create a failure to fire easier than if the chamber radius were not showing in the fired brass.

    Shoot me an email and we'll talk about the options to get this remedied. [email protected]

    Thanks - Ray
     
    The chamber radius appears to be showing a little in these pictures which would indicate that it's slightly over sized. It may not affect 100% of the rounds, but any inconsistency in the firing pin drop or the primer compound in the brass could create a failure to fire easier than if the chamber radius were not showing in the fired brass.

    Shoot me an email and we'll talk about the options to get this remedied. [email protected]

    Thanks - Ray
    Joys of having a prefit barrel, I had one FTF out of 70 yesterday and simply getting an other hit on the rim did the trick.

    I’ll shoot you over an email in a little while and talk options.