7/6.5PRC Pressure and Velocity ammo test

[Sandstorm]

No not at all Sir. Im sure youl be just fine.
Its just I don't like what it does to my brass...Its just a personal thing.
Im not comfortable shooting a match and getting clikkers on extraction. YMMV however
I could only get a few firings before it would not size back down enough to extract as well as when I dont push them so hard is all.
Good luck to you.

 

[CBTobias]

No not at all Sir. Im sure youl be just fine.
Its just I don't like what it does to my brass...Its just a personal thing.
Im not comfortable shooting a match and getting clikkers on extraction. YMMV however
I could only get a few firings before it would not size back down enough to extract as well as when I dont push them so hard is all.
Good luck to you.

I see what you’re saying. Yeah, brass life is important, especially when you’re trying to get enough reloads with the same brass for the barrel life.

I have been trying different brass. Lapua, ADG, and Peterson.

I haven’t gotten any clickers yet that I’ve noticed. I did see the fix to the issue, but not sure I’m willing to lay down the money for the tool just yet.

I will say my ADG hasn’t grown much, but the pockets are loosening up after only 4-5 firings. Only on the second firing of my Peterson and same with the Lapua. I haven’t shot much of the Lapua lately because I was getting good results on target with the ADG and Peterson.

54.8gn was giving me 2880fps with good results on target. If this brass doesn’t get me enough reloads, I may step back down to that on the next batch.

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[noahburleson1]

Barrels are expendable and I have a reamer.
There are guys I know running 57.1gn.

I agree with both sides of this. I’m also running mine in the 2940-2970 range. As long as the primer pockets are tight and you have a roll sizer to keep the bases in check there shouldn’t be any issues. I know people who have never pushed it above 2900fps and still get clickers

 

[FrankG]

Are the pressure readings here for this specific powder charge and this specific FPS?

For example, what if I need a higher charge to get the same velocity due to the powder being store in a more humid location?

Would the higher charge and the same velocity end up with more PSI?

To many variables to answer the question with a definitive answer.

The pressure listed along with the velocity is from the test barrel with a given lot of components.

If you have to go heavier on the powder charge to get X amount for velocity what’s different? Lot of powder different? Bullet lot different? Different barrel specs? Different chamber specs?

So to answer your last question, Yes could be running at a higher psi.

 

[CBTobias]

To many variables to answer the question with a definitive answer.

The pressure listed along with the velocity is from the test barrel with a given lot of components.

If you have to go heavier on the powder charge to get X amount for velocity what’s different? Lot of powder different? Bullet lot different? Different barrel specs? Different chamber specs?

So to answer your last question, Yes could be running at a higher psi.

We’ve got two 5R barrels being chambered with the no turn reamer. It will be interesting to see where these guys land with their loads. Both are going to run 180 Berger’s. One is going to run N555 and the other is going to run 4350. Both are running ADG brass.

I sent the 4350 info to the one, since everyone else up here is running N555.

 

[FrankG]

We’ve got two 5R barrels being chambered with the no turn reamer. It will be interesting to see where these guys land with their loads. Both are going to run 180 Berger’s. One is going to run N555 and the other is going to run 4350. Both are running ADG brass.

I sent the 4350 info to the one, since everyone else up here is running N555.

The test barrels bore and groove measured .2773” x .2843”. So smack dab in the middle of the tolerance.

Unless requested for a given caliber we normally don’t make tight bore barrels. So your two 7mm barrels should be min spec to +.0005” for bore and groove. So that shouldn’t be a variable really.

But lot of powder, bullet lot and actual bullet diameter will be the biggest variables.

As the saying goes…. Barrel, powder and bullet… these three things have to work together more than anything else.

Scott’s barrel from AI shot at the ELR match a couple of weeks ago. He used the PRCW reamer. He was at Hornady during the middle of testing. His loads had H4831sc. His barrel was 30”. Test barrel is 32”. His loads were 35fps faster in the test barrel. His barrel was made 4 years ago. The difference was mainly due to the barrel length from what I seen. Pressures where pretty much on par with the loads I loaded for the testing.

 

[Acyr]

@FrankG have you ever pressure tested a min bore and groove diameter vs a max bore and groove diameter? I am curious what difference .0005 makes in pressure testing, all other things being equal.

 

[Alex Wheeler]

The test barrels bore and groove measured .2773” x .2843”. So smack dab in the middle of the tolerance.

Unless requested for a given caliber we normally don’t make tight bore barrels. So your two 7mm barrels should be min spec to +.0005” for bore and groove. So that shouldn’t be a variable really.

But lot of powder, bullet lot and actual bullet diameter will be the biggest variables.

As the saying goes…. Barrel, powder and bullet… these three things have to work together more than anything else.

Scott’s barrel from AI shot at the ELR match a couple of weeks ago. He used the PRCW reamer. He was at Hornady during the middle of testing. His loads had H4831sc. His barrel was 30”. Test barrel is 32”. His loads were 35fps faster in the test barrel. His barrel was made 4 years ago. The difference was mainly due to the barrel length from what I seen. Pressures where pretty much on par with the loads I loaded for the testing.

How did Scott do?

 

[FrankG]

How did Scott do?

He tied for 1st place. Had to go into a shoot off. Mitch I believe won it. He was shooting a 300 Norma I believe with a 240gr bullet?

Scott said not bad for only shooting one match this year or in the last year.

 

[Alex Wheeler]

Thats awesome!

 

[FrankG]

@FrankG have you ever pressure tested a min bore and groove diameter vs a max bore and groove diameter? I am curious what difference .0005 makes in pressure testing, all other things being equal.

It’s been probably about 10years now and i don’t remember hard numbers. We made a run of ten pressure barrels in 300wm for mk248 mod 1 ammo. Which already runs at like 70-72k psi range. We had several barrels right at .0000” or like a .0001” under min spec. I think that drove the pressure up like another 4kpsi. So they sent them back and we gave each bbl a light finish lap again to take another .0001” to .0002” out and that brought the pressures back down to where they needed to be.

I know on 6.5CM a bore and groove size a full .0005” under min spec drove up pressures 10k psi! Not our barrels but that was the data i got back when they received our test bbls in and reran the test.

 

[FrankG]

Thats awesome!

Yep!

He also sent me pics of groups when he was loading and zeroing the gun up. That thing hammers! Nice work on the gunsmithing!

 

[Alex Wheeler]

It’s been probably about 10years now and i don’t remember hard numbers. We made a run of ten pressure barrels in 300wm for mk248 mod 1 ammo. Which already runs at like 70-72k psi range. We had several barrels right at .0000” or like a .0001” under min spec. I think that drove the pressure up like another 6k to 10k psi. So they sent them back and we gave each bbl a light finish lap again to take another .0001” to .0002” out and that brought the pressures back down to where they needed to be.

I know on 6.5CM a bore and groove size a full .0005” under min spec drove up pressures 10k psi! Not our barrels but that was the data i got back when they received our test bbls in and reran the test.

I had barrels made in different groove sizes for the 6mm. Even past max spec. I didnt do pressure testing, just real world velocity and pressure sign testing. Min vs Max spec was worth over 100 fps in a 6BRA before hitting pressure signs. I took it up in groove size until accuracy fell off. For a long time I specd my barrels a little big. Still trying stuff but for the most part I just order standard spec Bartleins. I think for a 70/30 ratio barrel that middle ground like you did on this one is perfect.

 

[CBTobias]

Looking forward to your RL16 and H1000 data.


-4 groove 33” barrel- All loads had BR2 primers. 180 Hybrids at .020” of jump.

55.2gn of RL16 gave me an average of 2950fps

Only did one shot of each to see speeds.

56gn of H1000 gave me 2785fps

56gn of N570 gave me 2755fps




55.8gn of N555 is giving my buddy 2890fps in his 32” 5R barrel.

 

[FrankG]

Looking forward to your RL16 and H1000 data.


-4 groove 33” barrel- All loads had BR2 primers. 180 Hybrids at .020” of jump.

55.2gn of RL16 gave me an average of 2950fps

Only did one shot of each to see speeds.

56gn of H1000 gave me 2785fps

56gn of N570 gave me 2755fps




55.8gn of N555 is giving my buddy 2890fps in his 32” 5R barrel.

As soon as I get the RL data and I'm waiting for one more on the H4831sc with the 190 Atips I'll update the thread.

I know he told me they were going to run that last load with the ATIP's last. As the other load was already past 65k and was just over 68k on a few rounds. So my guess is this other load will be running low 70ks range.

The pressure transducers are good for 75k. When you start hitting 75k or more you can wreck the pressure sensor and if I recall correctly are around a couple thousand dollars each. No need to be wrecking stuff.

 

[CBTobias]

Well, I think you could run compressed loads with H1000 and never hit pressure. I ran some 9.5m’s this morning in the slow powders. Best I could muster up with 56.8gn of H1000 was 2792fps. Groups were all sub 1/2 MOA.

Back for more tomorrow morning with the RL16 charge that showed potential at my current tuner settings. I’ll probably run a string of it and my current N555 load at the match on Sunday, if it does half way decent during tomorrows testing.

844 rounds on this barrel, so it’s got a little life left in her.

 

[Alex Wheeler]

I couldnt hit pressure with h1000 in a saum with 180s. I dont see you doing it with this case for sure.

 

[EdHarley]

Anyone try Retumbo? I may have missed it on the other thread.

 

[CBTobias]

Anyone try Retumbo? I may have missed it on the other thread.

I tried it today. 56.9gn only got me 2757fps. N570 didn’t even crack 2750fps, but it did give me single digit SD’s and ES. Not saying much with only three shots.

 

[CBTobias]

I couldnt hit pressure with h1000 in a saum with 180s. I dont see you doing it with this case for sure.

I was considering running some hotter primers and working right at jam to see what it could do. Might be a project for next week to shoot at the 600yd match.