h4895 high pressure issues...?

[ackertjosh]

Hey all again. So I'm here at my range at s beautiful 7:00am trying some 40gr v max loads with H4895..

Hornady brass, CCI BR4 primer and 40gr v max.

Took load data from Hodgdon webpage as a max load of 27.7gr. So I loaded up starting at 27gr working up in .2gr increments. First thing I noticed was strange high velocity... (3 shot average of 4020fps)... No usual signs of cratering in the primer or sticky bolt life... So I carried on. Got to 27.4gr and had cratering but no sticky bolt lift and an average velocity of 4050fps. Thinking it was my chrony I threw in some RL10x loads and at 25.2gr i got my average of 2830ish.

Can anyone explain this... These are by far the most accurate 40gr loads i have but at this velocity I'm sure there is either over pressure for sure or something else is going on.
And the rifle is a CZ527 Varmint. Thanks

[ackertjosh]

Here are some photos of my groups and the brass/primers.. hope this helps

Thanks again

[Rick in Oregon]

Josh, I'll let others help you sort out your issues, but if you want to display photos here, use the "IMG" code on the pic instead of the "http" code, then your pics will show up on the forum instead of having to click on each code to display the pic.

HTH

[Darkker]

Your bottles of powder say "Drop loads by 10% when switching lots". What that tells you is that have nominal burning rate swings of up to 10%.
Does the load info you looked at give the lot number of the powder tested? No, it doesn't, so never assume you have the same thing.

Also watching primers and case stretching for " signs of pressure " won't tell you anything useful. If you don't know the alloy used and specs then you can't read anything. Over 40,000psi, very carefully calibrated copper crushers will show swings of up to 20,000 psi, from the very same load. If they can't tell you pressure, magically your primers aren't more accurate at it.

So what to do for your answer?
Start at the starting loads, working up by a half a grain; all while testing groups on the chronograph. Your production rifle has looser tolerances than the pressure testing equipment they used, meaning you will not have the same velocity. So watching your loads when you suddenly star catching up to published speeds (relative to what you were) then you have found yourself going over pressure.

[ackertjosh]

Thanks Darkker.. This is the 1st Firearm I have ever reloaded for that i have run into this issue.. i was suspecting powder but thought i would ask for some other insite. Currently i have 60 loads made up with RL10x for dad to use this winter on Coyotes while im away for work but cannot find it any more so was hoping to find a back-up load with 4895/Varget. Ill Continue with 4895 and start down at 26gr and start working up in .2gr incorments again...

Thanks again
Josh

[Travelor]

Your primers are showing that your firing pin/bolt face have too much clearance between them and the primers are flowing back into that clearance. This is pretty common for factory guns as opposed to custom actions and is not a sign of excessive pressure.

To fix this you have two options: live with it and reduce your loads; or get your bolt face bushed (which is my recommendation).

http://www.gretanrifles.com/services/viewEntry.jsf

[TrapperDan]

I agree with Travelor. My 700 remmy does the same thing even with reduced loads.

[Jim White]

I agree with Travelor. My 700 remmy does the same thing even with reduced loads.

So does mine...

[ackertjosh]

Thanks all!!! I have a gunsmith who as built me a couple customs that Im sure he would be able to do exactly what is needed.. unforanitly i got the call for work so bushing the bolt will have to wait until i return. Until then or if im not back before we get snow and start running the dogs chasing down those yellow eyed basterds i have made up 60 of the 40gr RL 10x loads that are moving around 3830ish.. (kinds temp sensitive) but the groups dont change much and hover around the 1/2"-3/4 mark which is more then enough to wack a couple coyotes on the run........ What im not understanding is why my varget/RL10x and H322 didnt do this at all.. Only 4895.... either or im sure you all ahve more experiance with the .204 then me as im new to the round.. i still shoot my CZ550Lux in 22-250 but dad much prefers the CZ527 in .204.. His exact words are... "you cannot beat the 204".. and i honestly believe him.... MY lastest coyote rifle is an older Rem788 that was in .222 that had a buggered barrel so i ordered a 6mm 1-8 twist from Ted Gaillard in Sask and i will have myself a 6mm-222(60gr bullet at around 3050-3100fps).. but im still hakering the need to buy another .204... or have one built... hummmm..

Thanks all again
Josh

[Darkker]

Uncalibrated primers don't tell you anything, don't read too much into them. If you want a definitive answer, skip over to RSI and buy a Pressure Trace system. Do a quick chamber cast, and you will KNOW what is happening.
You get to see things like this: