.010" off the lands?

[.204Rguy]

Hey guys~I'm totally new to this forum, AND to .204 R. I just took delivery of my first one, a Cooper M51 and priority #1 is working-up some loads for it. As I did with my Savage .223 a few years back, I set-out to try and determine the proper OAL for the finished round but found that not only are they all longer than the 2.2598" spec, the results weren't consistent at all. (using a friction-fit bullet seated too far out, chambered, then measured) I did experience this with some high BC rounds in .223, so I guess I shouldn't be surprised. I have Hornday 32 and 40gr. V-Max, and 39gr. SBKs. Anyhow, I did a little searching on here first and found this thread;

http://www.204ruger.com/forum/viewtopic ... gth#p78857

If that advice is correct, I guess I didn't need to go through all that....but was very surprised to see measurements as high as 2.437" on the SBKs. Average (for comparison) on the 32gr. V-Max was 2.38".

Anyhow~if you have anything to add...or...feel like putting my mind at ease, please feel free to chime in! Really looking forward to posting the results of my load testing in a week or 2.

Thanks again!

[.204Rguy]

BTW...no good photos of the rifle yet, but here is a preview! I'm pretty excited!

[futuretrades]

If you want to get serious about your oal in that Cooper, I would suggest an O.A.L tool. I have and use, and can recommend either unit, the Hornady, and the Sinclair tools. Your Cooper may or may not have a SAAMI chamber. You can probably call Cooper, and with the serial # on the rifle, get this information from them. If indeed the rifle has a SAAMI chamber, you will not be able to reach the lands, without the bullet falling out of the case, or having enough bullet in the case to properly grip the bullet. If this is the case, no worries. Most 204's shoot bug holes with a very long, bullet jump. My Howa has over .100 jump with 32gr Vmax. With my hand load, this rifle will print under 1/2 moa at 100 yards. If you do a search on this site, you will find loads of info on just this subject. Best of luck with your Cooper, you are starting out right. Break her in as per Cooper and I will bet it will print way under 1/2 in. moa in no time!

[Lonegunnmenn]

My howa is the exact same way

[Rick in Oregon]

Without a custom reamer, ANY factory 204 Ruger rifle will have had its chamber cut with a SAAMI spec reamer, thereby it WILL have in excess of .100" freebore, and therefore will be about impossible to reach the lands with any normal weight bullet for the caliber.

The good news is that most of these long throated rifles do indeed shoot much better than traditional dogma would suggest.

But as Kevin (futuretrades) mentioned, you DO need to get the Hornady (or Sinclair) comparator tool to properly determine distance from lands. It's also handy for keeping track of throat erosion over time.

Oh, and congrats on the new Cooper repeater! Now the fun really starts!

[futuretrades]

But as Kevin (futuretrades) mentioned, you DO need to get the Hornady (or Sinclair) comparator tool to properly determine distance from lands. It's also handy for keeping track of throat erosion over time.

Hey RIO, I owe you a thank you for calling the comparator, what it is. For the life of me, I could not remember what the correct term is for the tool! This CRS crap is really bothersome. Getting kinda spooky!