New rifle, new load development, new brass, what’s wrong??

[ta6ppc]

Just to be clear on this rifle, it’s pretty near perfect I had a Ceracast of the chamber it measured to spec, the barrel looks excellent under a borescope, it’s cleaning up with minimal patch work no brush needed. I would like to know what the velocity is, but I got to say everything I’ve shot is under 1”, with most groups of 5 being 1/2”, I did have 2 groups that were 1/4” of 5 but it was still leaving the ejector mark. I have exactly 126 rounds fired as of today.

I have tried 3 separate lots of 4350
2 lots of 4831
And a Varget load

which are all minimal loads with ejector swipe.

 

[David Christian]

I’ve just read this entire thread top to bottom for the second time. @ta6ppc, can you post case measurements between your Hornady brass that shows no pressure signs and the Peterson brass that is showing pressure signs. Could you have a carbon ring? Could the Peterson brass be longer in the chamber?

Also, instead of your colored sharpie way of measuring your lands, can you try the Wheeler/striped bolt method shown here? Look at “Finding Lands” video

Videos | wheeleraccuracy

www.wheeleraccuracy.com

Something very obvious, yet elusive is at play here with your Peterson brass, not just case volume differences.

 

[ta6ppc]

I think I figured it out, looks like I was over sizing the case and my shoulder bump was in the .004-.005 range. I also went past my gun smith and we checked everything out. I got some loaded up and will sneak up on max on of these days if the weather cooperates.

my oal with the Berger 150 hybrid to the touch was 2.948 using the wheeler method. So my hand load setting at 2.910 is in the ballpark of .030 off.
My gun smith said virgin Peterson brass in a Curtis action always leaves a impression and that’s why he used Lapua over the Peterson. I loaded some lapua and still have a slight mark but it’s shaped different than the Peterson brass.
I just loaded and shot the Peterson brass I didn’t size it, an unfired case measured almost .007 shorter than a fired case. My smith says that he almost always would have some mark on first firing and after the initial firing the mark would not appear. I have set my die up to bump the shoulder only enough to barely feel slight resistance when closing a stripped bolt. I’m thinking this will fix everything.

thanks for the discussion and everyone’s suggestions it got me thinking and help me to correct my rushing sloppyness.

 

[Tokay444]

Yes, the Russians were sloppy tonight.

 

[MattPeetz]

Good thing you had a chronograph to figure it out.

 

[Capt. Oblivious]

hahahaha but if he had he would have known it wasnt pressure

 

[WEL]

That is quite obvious and profound but he specifically made a statement that is absurd and dumb and is always used without knowledge.
Velocity does not dictate pressure.

That statement says no matter the barrel length, if you reached the Max velocity then you have reached max pressure. That is absurdly false.
I never said it wasn’t a tool but with some common sense you can figure out pressure issues without a chrony.

This is not what I meant you just inferred it. Of course you have to take barrel length into consideration. Only a fool would not. From my experience 1” equates to approximately 25 fps or close to it. So it’s pretty easy to see where you are in relation to the published data. Without a chrono you have no clue. If the max velocity listed is with a 24” barrel and I’m bumping that with a 22” then I should probably slow down. Obviously with a 26” you would able to meet or exceed max velocity by 50 ish fps. Again without a chrono you have no clue.

 

[MattPeetz]

This is not what I meant you just inferred it. Of course you have to take barrel length into consideration. Only a fool would not. From my experience 1” equates to approximately 25 fps or close to it. So it’s pretty easy to see where you are in relation to the published data. Without a chrono you have no clue. If the max velocity listed is with a 24” barrel and I’m bumping that with a 22” then I should probably slow down. Obviously with a 26” you would able to meet or exceed max velocity by 50 ish fps. Again without a chrono you have no clue.

I did infer anything. That is exactly what you said. You are just clarifying now because you didn’t earlier.
you obviously haven’t had fast and slow barrels.

 

[WEL]

And how would you have any clue wether your barrel is slow or fast without a chrono. That’s kind of the point.

 

[Tokay444]

And how would you have any clue wether your barrel is slow or fast without a chrono. That’s kind of the point.

Figure out your drop at distance and do the math?

 

[WEL]

Figure out your drop at distance and do the math?

Yes you can do that but its after the fact. WTH do you people have against a Chrono. In fact my chrono has saved me a hell of a lot of money on components by shooting a one shot ladder to find max pressure and accuracy nodes. It’s real time data. Of course we didnt always have them. But there is no reason not to as cheap as they are.

 

[Tokay444]

A chrono is also after the fact. It can’t measure shots that haven’t been taken.
I have a chrono. Never shoot without it. I have nothing against it.

 

[Texas10]

Sounds like you’ve figured out that your chamber is on the smaller, perhaps even minimum side of SAAMI specs and using Hornaday brass will get you to a higher velocity. My 24 inch X-Caliber barrel is liking 40.2 grs of H4350 with a 140 SMK and Hornaday brass delivering 2665 fps with excellent accuracy. I've shot this with very good results to 800 yds and as some say regarding absolute velocity, there's nothing less impressive than a fast miss!

 

[MattPeetz]

And how would you have any clue wether your barrel is slow or fast without a chrono. That’s kind of the point.

no. I never said not to use a chrony. I’ve said you don’t need one to figure pressure.