Which Rabbit Hole should I go Down.(Velocity Variation) {UPDATE}

[JPB4BAMA]

As a brief history: I bought a straight 284 from a member and shot it very well till the Barrel finally went south.
I re barreled it with the same 30" Bartlien 5R, 8.75 twist on a 1.25 to 1.1 taper. Chambered with a standard PTG 284 reamer. "Broke in" the Barrel for 150 shots. On the new barrel brass availability has me using Peterson which measures 65.7 gr H2O versus the old Lapua at 67.8. I am loading H4350 at 49.2gr (+/_ 0.02 gr), and using Berger 180 Hybrids and Remington 9-1/2 primer and New Peterson straight 284 Brass. The first 50 rounds of break in had VERY heavy bolt lift and hard clickers and even hard to extract even at this rather mild load. After research is came to be apparent that this was a Brass issue, as I tried some spare Lapua with the same components up to 51 grains and no issue. I got a Redding Small base die and sized the Peterson and all is ok.

So now I begin the load development using history and some of the break in groups as a starting point, starting -0.015 and going out by 0.005. Mixed results on paper, BUT the big issue is velocity variation. 30 rounds fired over a Labradar,

Mean 2740
Stdev 22.1
ES 86 (Low 2688, Hi 2774)

Average Velocity is pretty much where I was shooting before, but the variation was really high by 2X+ where I was before, with SD's right about 10 on 60+ round strings. So now I'm thinking whats up to show this big and wild variability.

So to the topic - I started thinking about primers and thought about going down the rabbit hole of weighing them to see if there was any benefit, but on reading many posts I think that will be little more than an academic exercise. But it does beg one question as to the futility of it. Pretty much everyone agrees that primers matter, brand/lot etc... and since they all pretty much use the same materials and compounds if Brand A vs Brand B, or for that matter Brand X vs Brand X "match" really matters, why not weight? At this stage I'm not really sure where to go next as I truly expected to have very similar performance to the previous barrel. What am I missing, could it be the Brass?, but again weighing brass sort of falls into the same hole as weighing primers as far as it seems from what I read, but that is at least one change that is certain, everything else is the same- Same Jug powder, lot of bullets, Lot of primers, Just the brass and having to size the base to make it cycle.

And as a final note, With very limited results on paper, it seems to want to group abut 045 off the lands, but the "fliers" from what I hope might be a group are definitely associated with the odd ball velocities, even at 100 yards, so its not an issue of what does the target say, because to me it says goofy velocities mean goofy groups.

Any words of wisdom are appreciated.

 

[boltfluter]

If the only thing that changed is the brass, you have your answer, or a very good starting place. At least to my way of thinking.
Paul

 

[FeMan]

Interesting. I would definitely try a different primer just to shoot over the chrono and make sure a primer change isn't the solution (bad lot of primers?). Probably not with ES that large but its cheap and easy.

When the rifle was rebarreled, was the bolt/fp disassembled? I would start with a new firing pin spring and check the pin fall to make sure you don't have an obstruction in the bolt preventing proper ignition. A weak fp spring, insufficient fall, and/or drag/obstruction can cause the issues you describe. I have seen really worn out fp springs cause higher ES than you are seeing. Again, a really cheap and easy thing to try. Your velocity data suggests something in the fire control system as the mean and high velocity are very close and the low is off the charts.

Do you have excessive head space on the new brass? If it excessive, that can rob you of ignition energy.

Those are my thoughts. I hope you get it figured out!

 

[JPB4BAMA]

Interesting. I would definitely try a different primer just to shoot over the chrono and make sure a primer change isn't the solution (bad lot of primers?). Probably not with ES that large but its cheap and easy.

When the rifle was rebarreled, was the bolt/fp disassembled? I would start with a new firing pin spring and check the pin fall to make sure you don't have an obstruction in the bolt preventing proper ignition. A weak fp spring, insufficient fall, and/or drag/obstruction can cause the issues you describe. I have seen really worn out fp springs cause higher ES than you are seeing. Again, a really cheap and easy thing to try. Your velocity data suggests something in the fire control system as the mean and high velocity are very close and the low is off the charts.

Do you have excessive head space on the new brass? If it excessive, that can rob you of ignition energy.

Those are my thoughts. I hope you get it figured out!

Thanks. you bring up an interesting point.
Nothing was done to the bolt, and the fact that the change in consistency was so abrupt from before/after I really had/have no reason to suspect this as it is a relative new Defiance action and well tuned.
But that aside, as I stated in the original post the chance to Peterson resulted in a very tight post firing chamber fit which basically stuck the cases in the chamber, which was a similar condition that others on this forum posted back to me about. Thus I did the Small base die resizing. In that process I did the original sizing to -0.001 headspace as measured on a Whidden chamber headspace comparator. Test fitting the empty cartridges in the chamber with a stripped bolt still showed a tight fit and a fair amount of pressure to close the bolt, and noticeable resistance on extraction. I then snuck down on the base sizing until I got to an almost free fall on the bolt handle and no extraction resistance, but the overall headspace remained at -0.001 to -0.002 using the same method. I now wonder if that additional sizing process may be a contributor even if the base to datum headspace is the same?
And yes it is the Low MV anomalies that killed my groups all hitting high, maybe again hinting at ignition and or my rifle handling or a combination of both.

 

[J_idaho]

Sounds like you either have inconsistent neck tension or case capacity issues.

 

[Big Mc]

As a brief history: I bought a straight 284 from a member and shot it very well till the Barrel finally went south.
I re barreled it with the same 30" Bartlien 5R, 8.75 twist on a 1.25 to 1.1 taper. Chambered with a standard PTG 284 reamer. "Broke in" the Barrel for 150 shots. On the new barrel brass availability has me using Peterson which measures 65.7 gr H2O versus the old Lapua at 67.8. I am loading H4350 at 49.2gr (+/_ 0.02 gr), and using Berger 180 Hybrids and Remington 9-1/2 primer and New Peterson straight 284 Brass. The first 50 rounds of break in had VERY heavy bolt lift and hard clickers and even hard to extract even at this rather mild load. After research is came to be apparent that this was a Brass issue, as I tried some spare Lapua with the same components up to 51 grains and no issue. I got a Redding Small base die and sized the Peterson and all is ok.

So now I begin the load development using history and some of the break in groups as a starting point, starting -0.015 and going out by 0.005. Mixed results on paper, BUT the big issue is velocity variation. 30 rounds fired over a Labradar,

Mean 2740
Stdev 22.1
ES 86 (Low 2688, Hi 2774)

Average Velocity is pretty much where I was shooting before, but the variation was really high by 2X+ where I was before, with SD's right about 10 on 60+ round strings. So now I'm thinking whats up to show this big and wild variability.

So to the topic - I started thinking about primers and thought about going down the rabbit hole of weighing them to see if there was any benefit, but on reading many posts I think that will be little more than an academic exercise. But it does beg one question as to the futility of it. Pretty much everyone agrees that primers matter, brand/lot etc... and since they all pretty much use the same materials and compounds if Brand A vs Brand B, or for that matter Brand X vs Brand X "match" really matters, why not weight? At this stage I'm not really sure where to go next as I truly expected to have very similar performance to the previous barrel. What am I missing, could it be the Brass?, but again weighing brass sort of falls into the same hole as weighing primers as far as it seems from what I read, but that is at least one change that is certain, everything else is the same- Same Jug powder, lot of bullets, Lot of primers, Just the brass and having to size the base to make it cycle.

And as a final note, With very limited results on paper, it seems to want to group abut 045 off the lands, but the "fliers" from what I hope might be a group are definitely associated with the odd ball velocities, even at 100 yards, so its not an issue of what does the target say, because to me it says goofy velocities mean goofy groups.

Any words of wisdom are appreciated.

Either way the hole just keeps getting deeper.. Tommy Mc

 

[JPB4BAMA]

Sounds like you either have inconsistent neck tension or case capacity issues.

I'm pretty sure of neck tension, although maybe a bit low. I'm measuring 0.001 to 0.0015 and the seating force is really consistent on this 1X brass at 20-25 # as measured on the K&M arbor press (Not Hydraulic),
As for case volume I did a random sample prior to loading and it was really consistent, however unfortunately my ammo box tipped over on the way home from the range so the ones I had noted as outliers are all mixed up now, so that will have to wait till the next trip.

 

[J_idaho]

I'm pretty sure of neck tension, although maybe a bit low. I'm measuring 0.001 to 0.0015 and the seating force is really consistent on this 1X brass at 20-25 # as measured on the K&M arbor press (Not Hydraulic),
As for case volume I did a random sample prior to loading and it was really consistent, however unfortunately my ammo box tipped over on the way home from the range so the ones I had noted as outliers are all mixed up now, so that will have to wait till the next trip.

Get some Cci br primers and see if that helps. That still sounds like allot of spread.

 

[JPB4BAMA]

Get some Cci br primers and see if that helps. That still sounds like allot of spread.

Unfortunately that is not an option at this time, as the unicorn teeth are unavailable. But that aside, I did try them in the previous barrel and quite frankly on a limited test of about 25 shots they were actually worse than the Remington. That said I certainly am not against trying others, but would like to really understand what is going on first.
Thanks

 

[Webster]

As a brief history: I bought a straight 284 from a member and shot it very well till the Barrel finally went south.
I re barreled it with the same 30" Bartlien 5R, 8.75 twist on a 1.25 to 1.1 taper. Chambered with a standard PTG 284 reamer. "Broke in" the Barrel for 150 shots. On the new barrel brass availability has me using Peterson which measures 65.7 gr H2O versus the old Lapua at 67.8. I am loading H4350 at 49.2gr (+/_ 0.02 gr), and using Berger 180 Hybrids and Remington 9-1/2 primer and New Peterson straight 284 Brass. The first 50 rounds of break in had VERY heavy bolt lift and hard clickers and even hard to extract even at this rather mild load. After research is came to be apparent that this was a Brass issue, as I tried some spare Lapua with the same components up to 51 grains and no issue. I got a Redding Small base die and sized the Peterson and all is ok.

So now I begin the load development using history and some of the break in groups as a starting point, starting -0.015 and going out by 0.005. Mixed results on paper, BUT the big issue is velocity variation. 30 rounds fired over a Labradar,

Mean 2740
Stdev 22.1
ES 86 (Low 2688, Hi 2774)

Average Velocity is pretty much where I was shooting before, but the variation was really high by 2X+ where I was before, with SD's right about 10 on 60+ round strings. So now I'm thinking whats up to show this big and wild variability.

So to the topic - I started thinking about primers and thought about going down the rabbit hole of weighing them to see if there was any benefit, but on reading many posts I think that will be little more than an academic exercise. But it does beg one question as to the futility of it. Pretty much everyone agrees that primers matter, brand/lot etc... and since they all pretty much use the same materials and compounds if Brand A vs Brand B, or for that matter Brand X vs Brand X "match" really matters, why not weight? At this stage I'm not really sure where to go next as I truly expected to have very similar performance to the previous barrel. What am I missing, could it be the Brass?, but again weighing brass sort of falls into the same hole as weighing primers as far as it seems from what I read, but that is at least one change that is certain, everything else is the same- Same Jug powder, lot of bullets, Lot of primers, Just the brass and having to size the base to make it cycle.

And as a final note, With very limited results on paper, it seems to want to group abut 045 off the lands, but the "fliers" from what I hope might be a group are definitely associated with the odd ball velocities, even at 100 yards, so its not an issue of what does the target say, because to me it says goofy velocities mean goofy groups.

Any words of wisdom are appreciated.

Check Eric Cortina video's. What powder does he use? He test like crazy.
Just looked at one of Erik's video's. Reloading for a 284 Wheeler it looks like he is using N555 powder. That's whats written on the powder measure tube.

 

[Old Navy]

Same free bore in both barrels? Try .003 bump and a little more neck tension.

 

[JPB4BAMA]

Same free bore in both barrels? Try .003 bump and a little more neck tension.

Im all in for upping the neck tension and brass already in process to a another thousandth. Maybe I'm not with it here, but I don't understand the logic of bumping back more. Not that I disagree, just don't get the logic.
Thanks

 

[Phillip Crowe]

I'd think maybe the barrel doesn't like that load. In my Kreiger 8.5 twist 284 barrel (straight 284) with Peterson brass, 51 gr of H4350 gives me a mv of around 2850. With very good accuracy. S@B primers.

 

[JPB4BAMA]

I'd think maybe the barrel doesn't like that load. In my Kreiger 8.5 twist 284 barrel (straight 284) with Peterson brass, 51 gr of H4350 gives me a mv of around 2850. With very good accuracy. S@B primers.

Lucky you. I had some S&B LRP back several years ago, and they were fantastic. Picked up 1K on a sale ar Cabela's in Wheeling WV for a whopping $10, wish like hell I had bought them all, but that was just a what if buy thinking they were an off brand and at least would be good for junk plinker loads.

That reminiscing aside, I may go up, but the previous barrel that I tried to copy shot best at the in the 2750 range, and thus that is my starting point.

Since you are also using Peterson, did you/have you had any issues with tight fit and difficult extraction? That has been an issue as I noted in my initial post, and I originally took it back to the smith thinking maybe something with the chamber, but that sort of died when I tired some Lapua and ran it all the way up to the 51+ grain level without an issue, but the Peterson still hangs up pretty hard even at the 49.2, which calculates out to only 55kPsi in quickload which is 3k below the 51gr in Lapua. My Peterson is New 2024 production.

 

[J_idaho]

I’ve only seen huge variations in es when case capacity was a mess. Or when I stop annealing usually around the 4th reload. Or when I don’t care about having perfect powder charges. How much variation was there in the break-in before switching to small base die? Also I can’t confirm but I’ve heard Keith glasscock mention in a video one time that if you are just tickling the lands he says he sees huge swings in es. He says he stays .006 off or in to stay safe. You say your .005” so maybe double check your lands measurement. My personal opinion is that your rifle doesn’t like that powder or you’re over sizing the body and the case isn’t sitting the same in the chamber every time.

 

[JPB4BAMA]

I’ve only seen huge variations in es when case capacity was a mess. Or when I stop annealing usually around the 4th reload. Or when I don’t care about having perfect powder charges. How much variation was there in the break-in before switching to small base die? Also I can’t confirm but I’ve heard Keith glasscock mention in a video one time that if you are just tickling the lands he says he sees huge swings in es. He says he stays .006 off or in to stay safe. You say your .005” so maybe double check your lands measurement. My personal opinion is that your rifle doesn’t like that powder or you’re over sizing the body and the case isn’t sitting the same in the chamber every time.

No, I started and 15 off and then moved out by 005. The weird variability ran the whole span from 015 off to 055 off. Your last statement is what concerns me a bit, but If I just use the Whidden FL die I can easily feel the friction of the the case near the web both on closing and extraction with a freshly sized case and a stripped bolt. I did actually try to increase the bump to make sure I was getting clearance and not closing on the shoulder but even at 005 bump it is still there, particularly on extraction. But take the Small Base die and a bump of 1 to 1.5 closes freely and also extracts fine on both a newly sized case and also on the same case after firing.

 

[Walt Krafft]

How is your neck clearance? Not just on a sample of one or two cases. Check a bunch.

 

[JPB4BAMA]

How is your neck clearance? Not just on a sample of one or two cases. Check a bunch.

I'm going to assume that I measure fired case necks and compare them to loaded cartridge necks?
If so I will do that once I get the next batch loaded and fired. On that note, I already know that the Peterson necks are thicker by a touch over .001 to 0.0015, however on the virgin brass as well as the small die sized I don't feel any on chambering that indicates any resistance, but It's probably well worth the test.

 

[Phillip Crowe]

New Peterson brass gave me problems with extraction. That went away after full length sizing with a Hornady die. I have a Redding small base die but don't use it as I get the same results with the Hornady die. Forgot to mention in the previous post the bullets are Berger 180 hybrid.
Good luck.

 

[JPB4BAMA]

New Peterson brass gave me problems with extraction. That went away after full length sizing with a Hornady die. I have a Redding small base die but don't use it as I get the same results with the Hornady die. Forgot to mention in the previous post the bullets are Berger 180 hybrid.
Good luck.

Thanks, I'm starting to see a trend from multiple folks both here and at my home range with that issue.
Now I have to get in touch with Whidden, as if I move the die in anymore I'll start over bumping. Right now if I size right on the SAAMI spec according the Whidden gauge I still have 0.030 clearance between the shell holder and the base of the die, might have to send it back and get ir bored a few thou deeper to get to the base in one pass.