Hornady factory 300 Whisper brass issues

[Riverguide]

I have a CZ-527 bolt action 300 Whisper that I had made by JD Jones / SSK industries. Its everything I ever wanted including a can but... it does not like Hornady factory brass and I don't think this is the guns fault.

I purchased a few hundred pieces of SSK stamped Hornady brass from SSK. I have several boxes of factory 300 Whisper Hornady ammo (110 and 208) and also tried Hornady factory brass (stamped Hornady 300 Whisper). They all have the same issue in my rifle which are lots of failures to fire.

I sent the gun back to SSK and had them go thru it, thinking something was wrong with the gun. In a Hornady factory box of twenty 208gn Amax loads, I would get at least a 4 or 5 failures to fire. SSK tested with their in-house rounds and said the gun functioned fine. So... Here is what I learned from LOTS of testing.

The bolt closes effortlessly on the Hornady brass, the trigger is pulled and a nice clear dent is left on the primer but no boom. I've tried BR-4, Rem 7.5 and CCI 400 primers. Sometimes a second trigger pull would get a few of the FTF's to fire on the second try. What's happening? I believe something about the Hornady brass allows the firing pin will push the case forward into the battery, enough that an indentation is left, but not hard enough to fire the round, Even with an "improved" firing pin spring from CZ. It takes a lot more to "ignite" a primer than I expected.

SSK sent me a cartridge checker (chamber section) and it appears to have verified what I was seeing. I would insert a round that "FTF'd" and it would settle down into the checker device deeper than it should and even deeper than it did before the round was chambered and had the trigger pulled. Could factory Hornady brass shoulders be a few thousands further down the case? Maybe its the angle of the shoulder which is hard for me to measure.

Now... I have some 300 Whisper brass donated to me that came from Hoser, a pile of 300 AAC brass made from LC mil surplus and every one I have put thru this bolt gun function flawlessly. Even the ones I made myself from the cheapest surplus 223 brass work great. All the non-Hornady brass allows the bolt to close with just a bit of resistance. Chronograph results from the 208 AMAX, 220 SMK's and 220 Outlaw State Bullets so far are consistent, but the weather has not allowed me to do any real accuracy tests (yet). Once it warms up, I can spend more time at the range and tweak the loads if needed.

I have two other Whisper / Blackout platforms to test with and I hope they will not be as picky as my SSK bolt action, but I'm really disappointed so far with the Hornady brass.

CZ-527 300 Whisper SSK build with SSK Can.
16" barrel
7.8gn of N110
CCI BR-4
lake City Surplus 223 case
Hornady 208 Amax
1020FPS (only three shots tested, deviation was about 10FPS)

CZ-527 300 Whisper SSK build with SSK Can.
16" barrel
7.9gn of N110
CCI BR-4
lake City Surplus 223 case
Outlaw State Bullets 220gn
1020FPS (only three shots tested, deviation was about 10FPS)

-Riverguide

[Hoser]

Sounds to me like you might have a chamber that is cut a touch on the large side and the brass is a touch on the short side, headspace wise. Add the two together and your firing pin might not be long enough to light it off.

Glad to hear my brass is working though...

I would not use virgin brass in this bolt gun.

[egraham]

I have a friend who has 4-5 of his bolt action guns and he has the same issue. I loaded some 208's with federal match primers and lake city brass with NATO stamp and the problems went away. The Cz is a better platform than my remington 700 but I don't have to deal with the oal issue with the Cz mag and my gun is lighter. Cz is shorter with the reflex can.