#1
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Bolt Issue, Cooper Model 21
Not sure what I have going on but I will do my best to explain it. I do have a call-back request in place with Cooper. I figure the holiday has created a bit of a backlog on their end.
Cooper Model 21 chambered in 20VT. No ammo changes whatsoever. Bolt lift is normal until the final 1/16-1/8". At this point, I have to place my palm against the bolt knob, wrap my fingers around the scope tube and squeeze HARD. When it lets go, it does it all at once and the bolt slides back like butter. It is doing this after every firing. However, it will also do it after chambering a fired round and pulling the trigger. It will also do it on occasion when removing a live round. I have even experienced it after placing a round in the chamber and lowering the bolt handle just a fraction of its' throw. It absolutely WILL NOT do it cycling the bolt on an empty chamber. I have separated the shroud/firing pin assembly from the bolt body, flushed/cleaned/greased with no change. Did not disassemble shroud/ firing pin assembly as I don't see how it could be the cause. Ejector is in place but, spring has been removed. Also, bolt lug recesses are squeaky clean. I suspect I have some kind of issue in the extractor itself? This rifle has always required just a smidge of extra 'ooomph' on the last bit of bolt lift but nowhere near what it is doing now. I do not have knowledge of how this extractor is removed/installed, maybe Cooper will share this with me. It does seem to move freely. The movement and profile appear to be the same as our Model 21 204R under a loupe. I can't swap bolts between our two rifles for a cycle check as one is LH and the other is RH. Any words of wisdom, fellas? I will share what, if anything I learn when I hear from the factory. Thanks in advance. |
#2
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Sounds like the brass may be getting too big in the base, are you full length sizing or only neck sizing?
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#3
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Full length, Redding Type-S dies. The largest measurement I can find is 0.3730".
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#4
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I agree, it really sounds like the brass is too big at the base. Is this new brass or has it been fired? Lots of reamers are ground too small at the base compared to the sizing dies.
Aaron |
#5
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This is LC brass on it's 2nd and 3rd firing. Bases are measuring the same as freshly formed cases measuring as far down the body as possible.
That being said, there is a difference measuring the minor diameter of the extraction groove. New brass is running 0.3275" and the current rounds are at 0.3300-0.3310". Never run into this before. This may be forcing the extractor out too far for the action to accommodate? |
#6
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I agree with brass issue but having said that, Model 21's are known for stiff on the lift and especially the last little bit. I've had to send my model 21 22PPC in to get it reworked and also my 222 Rem Mag. Please post the information you get from Cooper customer service I'll be curious what they say.
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#7
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Yep, I will share what I find out once I hear from them.
On Edit: I just took a minute to call and check in with Cooper. I had called Tuesday and was told that the tech's only take calls from 2:00PM 'til closing and they would give them my info so one of them could call me back. I figured I would not hear back until the 5th. I was just told that both of their technicians decided to take the rest of the week off. I'm not pizzed yet, but teetering on the edge. I just think it is poor form to close an entire department down for three days running unless there is an emergency. Last edited by ramos; 07-05-2018 at 09:45 PM. Reason: add |
#8
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I recently replaced my firing pin and spring (light primer strikes)on my model 21. My bolt lift was extremely hard to lift with new pin/spring, so I clipped off 1.5 coils off the new spring in order for it to feel decent when opening bolt(probably shouldn't have done that, but it strikes well now). Coopers are definitely shooters but I have heard several complaints regarding their bolt/firing pin assemblies. The technicians should have more to say on the subject. I'm curious....
Jaybird |
#9
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I really doubt anything is wrong with your extractor. The purpose of the extractor in the bolt is to hold the case while it's being pulled from the chamber. It seems like its doing that. The extraction cams do most of the actual pulling until the case is far enough out for you to pull the bolt to the rear.
Do you have any Remington 221 brass you could try? From the ones I've measured they are quite a bit smaller at the base than LC 223 or Lapua 221. You could also try running the case through a small base 223 die with the guts removed. I have a 20JI that the reamer is to small at the base and I get the same symptoms unless I use a small base die. Aaron |
#10
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The thing is, there is nothing new here. The rifle, the brass, the forming, the sizing, the load has remained unchanged for a number of years.
One thing that MAY be worth noting: The bolt always closes easy as can be. The opening issue is present even without firing. |
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