Shimming 209's - How much primer "crush"?

[Tigdim]

I have a Knight Original DISC, that I just converted to bare primers with a Lehigh BP, Lehigh Adaptor and a new bolt body.

I was getting ready to order the 0.248" OD shims (0.005" thick) to shim the primer pocket on my knight. The bolt handle falls without contacting the action and crushing the W209 primers I was planning to use. (the one used for testing the fit measures 0.301" ) Using feeler gauges, between the bolt handle and the contact point on the frame, I determined I need a minimum of .012" before I either run the bolt into the action or until I hit the primer. (Can't tell which for sure, it seems like the bolt hits the action at the same time the bolt face hits the back of the primer.) I was planning to just install one shim at a time until I got some primer Crush and ZERO headspace, with the W209 primers.

Just for fun I decided to measure some of the W209's just to see how much variance they have. Turns out, the W209 primers I have vary in length from 0.296" to 0.301" (These were purchased this year. ) And I only measured the first row of 10. ( 3 were 0.300"- to 0.301", 4 were 0.296" and the other 3 were in between )

That got me thinking, how much is too much crush?

If my measurements are correct and three 0.005" thick shims (0.015" total thickness) , gives me 0.003" of crush on a 0.301" tall primer. At the same time I would get 0 crush on the 0.296" primers.

IF my measurements are correct a 4th shim would give me a total thickness of 0.020" and 0.002" crush on the short 0.296" primers. At the same time I would get 0.007" crush on a 0.301" primer.

IS 0.007" crush too much?

 

[sabotloader]

I would believe that 0.007 is to much! I strive for 3 and will accept 5.

The 296 you mention is that a Winchester primer? I am assuming the .301 is a Winchester. Basically when you shim you are shimming for one brand of primers. I choose to use Winchester primers as they are the coolest of the 209 primers. If you are using a hotter shorter primers like a CCI or Federal - it will require more shims.

This older thread may provide you with additional information

https://www.modernmuzzleloader.com/threads/sabot-bullet-total-diameters-primer-dimensions.9798/

 

[Tigdim]

The smallest W209 primer I measured was 0.296" and the largest was 0.301". All from the same box of 100. I have another box of 100 as well.

I will probably measure and sort all of them in the next day or so. Just to see what I have the most of.

 

[MSalyards]

I gave up on the shimming - O-ring thing and just carry a primer removal tool on my lanyard. I also switched from Win 209s to CCI Mag primers and they come out easier. Not advice, just what I do.

Mike

 

[ronlaughlin]

The smallest W209 primer I measured was 0.296" and the largest was 0.301". All from the same box of 100. I have another box of 100 as well...........

Seems you are more or less forced to accept 0.007" crush, or sort primers. If one had two breech plugs, one could shim one for a short average; the other for a long average.

Me, i would be willing to have primers crush 0.007" myself, but of course don't recommend anyone else do so.

 

[birdog]

I measured 3 boxes of Winchesters and kept .299 and longer. The shorter primers I will use for fouling my barrel. Believe it or not I found some quite a bit shorter than .296!

 

[birdog]

Tigdim I sent you a message

 

[Valkyrie]

Fwiw I converted my Knight to bare 209 with a .002 crush using shims. I do sort my federal primers to .297 though. Eventually I may get Bestill to make an improved breech plug, but for now it works fine.

 

[Tigdim]

Birddog, I replied to you message.

Well it turns out I was way off. The .012" I was measuring was the forward bolt movement before I hit the quick release pin. ( I just installed ) After using washers between the bolt face and some spent primers (no adapter installed) I figured out I need 0.031" of shim for ZERO headspace on a 0.301" primer.

 

[jsteurrys]

Yes, those old DISC Originals are threaded deeper than the later Extremes and Elites. My DISC Original is 0.022" deeper than my Elites. I have heard of one that was 0.045 deeper. It was an Master Hunter Cryo.