Where do you run Pressures for a match load?

[CShooter92]

I recently had a new 6.5 Creedmoor barrel put on my Surgeon action for match season this year. Same length, same twist as the previous barrel. I took it to the range to zero the other day and fired about 30 factory Hornady 147 Match loads I had left over to condition the barrel. Cleaned with wet patch of G96, let sit, scrubbed with nylon brush and then dry patched until clean.

On Wednesday, I went and shot some reloads I had for my old barrel to see how they'd shoot in the new barrel. Virgin Lapua Brass, 130 gr Berger hybrids and 43.0gr H4350. This load is not compressed and I never saw pressure signs in my old barrel. I fired about 20 rounds at 100 yards and they exhibited no pressure signs and shot very accurately.

Cleaned again after this range day.

Now on Sunday, I took another box of reloads I had for the old barrel, these ones were the same with the exception the brass was once fired and then FL sized w/ .002 neck tension. Different range but similar weather conditions (55 degrees, 50% humidity, 2600ft DA). I shot about 35 rounds and never noticed a heavier bolt lift but when I got home, I noticed the brass had a very slight ejector mark on it, no sweep, just a very faint circle on about 25% of the cases.

I'm curious if I should back it off a bit for match season this summer? I never really thought this load was that hot but this has me questioning things. Any insight would be helpful!

 

[Deleted member 113831]

On Wednesday, I went and shot some reloads I had for my old barrel to see how they'd shoot in the new barrel. Virgin Lapua Brass, 130 gr Berger hybrids and 43.0gr H4350. This load is not compressed and I never saw pressure signs in my old barrel. I fired about 20 rounds at 100 yards and they exhibited no pressure signs and shot very accurately.

Velocity is the first and the most measurable and most accurate indicator of pressure. They don't make magic barrels.

According to Berger, the max charge for this bullet is 41.6 grains of H4350. By all indications, that load was developed by them in Hornady brass, not Lapua. Lapua is thicker and less roomy than Hornady, so that max load would be slightly less still.

According to Berger, you are almost 2 grains over max.

 

[MakeSawdust]

He's right. Not sure if it is the barrel or the lot of powder or a combo of both, but I had to drop the load 2 full grains from my old Criterion .243 AI shooting H1000 and 105-115 bullets to be at the same velocity/pressure.

 

[CShooter92]

Velocity is the first and the most measurable and most accurate indicator of pressure. They don't make magic barrels.

According to Berger, the max charge for this bullet is 41.6 grains of H4350. By all indications, that load was developed by them in Hornady brass, not Lapua. Lapua is thicker and less roomy than Hornady, so that max load would be slightly less still.

According to Berger, you are almost 2 grains over max.

Any chance you could send me where you found that data? Everywhere I look (Nosler, Sierra) says that 43 grains is the max load for a 130gr bullet.

Thanks!

 

[spife7980]

http://www.hodgdonreloading.com/data/rifle

Its a different bullet and they are usually semi conservative but I have also had them be pretty damn spot on more times than not.


Notice the cartridge overall length on the loads from all the various sources. The closer you are to the lands the higher the pressures can spike. The further back you are the more "blow by" you can get which gives you a bit more wiggle room.



Also, are you sure that you completely dried out the chamber after the last cleaning? A wet chamber will not only increase the pressure via decreasing the volume via liquids dont compress but they also prevent the case walls and neck from sealing off which allows the case to push back harder and increases bolt thrust. Might be something to check on.

 

[Deleted member 113831]

Any chance you could send me where you found that data? Everywhere I look (Nosler, Sierra) says that 43 grains is the max load for a 130gr bullet.

Thanks!

 

[ShtrRdy]

I have found the Berger loading data to be conservative. They generated much of it with Quickload. That being said, velocity is a good indicator of the pressure being created.

 

[Deleted member 113831]

That Berger manual is near worthless.

But worth more than your opinion? Do you really believe the Berger book could be off by almost 2 grains with H4350?

I don't understand how a snapshot of velocity is an indication of pressure....

So you don't believe pressure and velocity are related?

....unless you're talking about doing a full ladder.

An Audette ladder? How is that gonna indicate pressure accurately?

I've had 80fps velocity differences in different lots of powder,...

With the same charge weight I presume. So what did you do, adjust charge weight to match previous velocities? Hmmm....I thought you said they weren't related?

...and the pressure isn't an equal ratio to velocity.

Of course it isn't, nobody said that.

Velocity is the most measurable result tied to pressure. All else being equal, more pressure equals more velocity. That is just fact.

Don't get stupid and start picking nits when you know this is fundamentally true. No one gets a free 100 fps.

 

[Deleted member 113831]

Oh boy. Mr. multi-quotes....

Yes that book is worthless compared to actual load development. If anyone loads a 6 Dasher to the Berger recommended max of a 105 HYB at 2800fps they're missing the boat. That's called a 6BR.

I'll just use a single quote if that helps.

Question...., are we supposed to believe now that benchresters are known for running SAAMI chamber pressures?

 

[Deleted member 113831]

Oh boy. Mr. multi-quotes....

Yes that book is worthless compared to actual load development. If anyone loads a 6 Dasher to the Berger recommended max of a 105 HYB at 2800fps they're missing the boat. That's called a 6BR.

Never said pressure and MV aren't related. I said, I don't know how you determine chamber pressure from just MV alone. Here's an example. I'm shooting a 6 Dasher/ 105 Hybrid at 2900fps. What's my chamber pressure? Bore Size - mystery, freebore - mystery, barrel length - mystery, powder and charge - mystery, COAL - mystery. What is the chamber pressure?

Or do you mean MV relative to the Berger book? Okay, I'll play that game too. Same example but I'll fill in some of the blanks for you: Dasher/ 105 HYB/ 2900fps/ H4350/ 35grs/ COAL: 2.4",..... Bore size: mystery, Freebore: Mystery, land & groove configuration: mystery

PlS tell me what that chamber pressure is. We see all the time where someone can shoot a load that is to high in someone else's rifle. If you're just going to point to a reloading manual, why do load development? I have and use QL and it is often quite inaccurate. I have dried powder out and gotten more velocity with less pressure. QL didn't match up before I dried it, after I dried it it matched. I've had to tweak RL26 in QL to match MV. QL gives you many options to tweak burn factors and powder characteristics. Why would they do that if it was a universal linear curve? Which is what you're suggesting.

Sure, more pressure creates more velocity. But that is a sophmoric approach to the OPs question of when is too much pressure. How are you determining when is too much when someone says.....2870: go

Here is another single quote if it helps you out.

So, you are telling me that two guns, with the same length barrel...same brass... same bullet... same powder....same or similar chambers....getting similar velocity.....can in no way, be deduced to have similar pressures....because the exact pressure can't be known?

And if one of those barrels was outfitted with say, I don't know.... some pressure gauging equipment of some sort, then that comparison would still be irrelevant, because the exact pressure of the second gun can't be known?

And if one of those guns was getting a significant amount more or less velocity, then it can in no way be inferred that the pressures must in some way be dissimilar?

 

[Deleted member 113831]

No. I'm not saying any of that, seriously. Not just being dismissive; that is not what I was trying to convey.

And this is my last response to you. Have a nice weekend.

Good shooting to you sir.