Gunsmithing  Help with pressure problem

nuclabuyer

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I have been having pressure and hangfire problems on my Sako 30-378 and I was informed to use Federal primers. I got some and that seems to have gotten rid of the hang fire problems. Now as you can see I am still have pressure signs. I have 3 pictures so you can see what they look like. I dont have a chrono to tell you the velocity but I am shoot a 210gr berger vld on top of 101.5gr of Retumbo, Federal 215 Primers and brand new Nosler Custom Brass and also all these are off the lands.

From Hodgdons website.
200 GR. Retumbo start 98.0 2992 44,900 CUP 105.0C 3209 52,600
220 GR. Retumbo start 101.0 2954 44,700 CUP 107.5 3155 55,000

After looking at the reloading data, I am thinking that possibly I am getting detonation due to a reloading data problem. Do you thin that Hodgdon has some incorrect data on the 200gr bullet? Here is a 190

190 GR Retumbo 105.0 3154 43,600 CUP 111.5C 3374 54,500

DSC_0720.jpg


DSC_0719.jpg


DSC_0718.jpg
 

yotedog65284

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Re: Help with pressure problem

I had a simular problem in a 204 Ruger. Try seating your bullets deeper or more grip on the bullet (crimp). you need to get the powder burning good before the bullet releases, to get your case expanded so you dont get blow by.
Good luck Chris
 

CaptLink

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Re: Help with pressure problem

Reloading manuals are dedicated to bullet manufactures if the exact bullet model is not listed you are just guessing at loads its not by bullet weight but model#.
I recommend you get data from the bullet source and if you are using magnum powders do not go below a minimum charge and use magnum primers only.Your pictures indicate a dangerous over load.Double check everything,powder lots make a difference as do primer and bullets.
 

nuclabuyer

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Re: Help with pressure problem

The reloading book that I have isn't dedicated to any particular bullet, the brand of book is Lyman. Lyman books are known for going a little hotter on all the loads then a dedicated Sierra or Hornady book. Also if you look at the original post I suggest that the reloading website, Hodgdon, has some info that is incorrect. I understand they, Hodgdon powders, are tied to a specific bullet maker and model but I would say for the most part a 200gr bullet, whether it is made by Nosler, Speer or Berger, is going to show you the same characteristics. If you want to tell me that a Nosler 200gr Partition is completely different then a Nosler 200gr accu-bond by enough to make a dangerous difference then I will say that is incorrect. A 200gr bullet, no matter the maker, should yield roughly the same pressure.
I have been talking to a gunsmith online and have came to the conclusion that do to some wrong reloading data, those are way under pressure.

Thanks to all for the help
 

300sniper

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Re: Help with pressure problem

those shoulders sure look to have quite a radius to them. i've seen pictures of something similar when 7-300wsm brass was used in a 7wsm chamber or visa versa (can't remember which way it was). the carbon on the outside of the case says the chamber isn't sealing properly also.

is your brass shorter than it should be?

edit: after reading your post above, i could see too low of pressure causing the issues. with low pressure, the shoulder doesn't blow forward mirroring the chamber and also doesn't seal it properly.
 

nuclabuyer

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Re: Help with pressure problem

That is what the gunsmith was saying also, so he told me to try 106gr of Retumbo instead of the 101gr as seen in the pictures. The ones with 106 are still are not sealing up. I am not sure if I should go higher because I am fairly sure that I am stretching the primer pockets out like crazy from the way the case head is flowing into the ejecter hole of the bolt.
 

kraigWY

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Re: Help with pressure problem

When Ruger first came out with the Ruger #1 in 204 my wife bought me one.

To start mey reloading for this I started with the "accuracy" load listed in Sierra's manual.

Didn't work. I got high pressure sign's, poor velocity, and accuracy. I was using Fed SR Match primers.

I did nothing but change to CCI Standard primers, less pressure, more velocity, and better accuracy.

I know it dosn't make sinse, but it worked, changing nothing but the primers.
 

nuclabuyer

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Re: Help with pressure problem

I have shot different powder and I dont get the accuracy out of them. I get nothing bigger then a 1" group at 100 with Retumbo powder. With RL-25 I get terrible accuracy but I get a seal which says that I am in the correct pressure range. I am trying 50 BMG with 185's because I shot all the 210's that I had.
 

longshooter

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Re: Help with pressure problem

Suggestion - Don't fireform the new cases with Retumbo. Use a different powder to fireform. Then, try the Retumbo.
 

nuclabuyer

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Re: Help with pressure problem

I dont have to fire form anything, this is 30-378 brass. Also some of these have had 3 firings through them so they are as fit to my chamber as they are going to get. On some of those new pcs of brass that I took a picture of, the primer pocket is stretched so much that the case is unusable. Damn that pisses me off.
I will say that 50 bmg powder is working fine. I am going to see if I can get a group. Next thing I have a problem with is on the hodgdon website it says that the range for a 185gr bullet is 116-120gr. On the 8lbs jug it gives the max of 120, then is says to reduce all loads by 10% for the starting load. Well that is 12 grains. So that means that the starting load should be 108 with a max of 120, I hate conflicting info. I shot a 112gr load and all seems well, no pressure, no leak. So I moved up to 115 and a 116 to see what happens.
 

excaliber

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Re: Help with pressure problem

To 300sniper, the 30-378 weatherby is supposed to have radiused shoulders. It is called venturified. The 224,240,257,7mm,300,30-378,340,338-378,378,416,and 460 all have radiused shoulders.
 

CaptLink

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Re: Help with pressure problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nuclabuyer</div><div class="ubbcode-body">The reloading book that I have isn't dedicated to any particular bullet, the brand of book is Lyman. Lyman books are known for going a little hotter on all the loads then a dedicated Sierra or Hornady book. Also if you look at the original post I suggest that the reloading website, Hodgdon, has some info that is incorrect. I understand they, Hodgdon powders, are tied to a specific bullet maker and model but I would say for the most part a 200gr bullet, whether it is made by Nosler, Speer or Berger, is going to show you the same characteristics. If you want to tell me that a Nosler 200gr Partition is completely different then a Nosler 200gr accu-bond by enough to make a dangerous difference then I will say that is incorrect. A 200gr bullet, no matter the maker, should yield roughly the same pressure.
I have been talking to a gunsmith online and have came to the conclusion that do to some wrong reloading data, those are way under pressure.

Thanks to all for the help </div></div>
200 gr bullets from different manufactures or going from solid to sp or hp will give different pressure curves as the ogive of the bullet will vary by model number of the bullet even by the same manufacturer.If this rifle was custom chambered it may not have the <span style="font-weight: bold">customary Weatherby long free bore </span>that will also in-cress your pressures.I am a professional gunsmith and a re-loader for over 3 decades and a flat primer is <span style="text-decoration: underline">not</span> a under-load.
 

300sniper

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Re: Help with pressure problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: excaliber</div><div class="ubbcode-body">To 300sniper, the 30-378 weatherby is supposed to have radiused shoulders. It is called venturified. The 224,240,257,7mm,300,30-378,340,338-378,378,416,and 460 all have radiused shoulders. </div></div>

i guess it's pretty obvious i haven't worked with any of those chamberings. thanks for the information.
 

wnroscoe

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Re: Help with pressure problem

From Sierra's Reloading manual;

200 grain SBT & SMK
Accuracy Load 94.5g of N170 @ 3,100 fps
Hunting Load 110g of H870 @ 3,200 fps

H1000
Start 90 grains 2,950 fps
Max 94 grains 3,050 fps

RL22
Start 78 grains 2,800 fps
Max 86.5 grains 3,050 fps


220 grain SMK & RN
Accuracy Load 103g of H870 @ 3,000 fps
Hunting Load 106g of H870 @ 3,050 fps.

RL22
Start 76 grains 2,700 fps
Max 83 grains 2,900 fps

H1000
Start 86 grains 2,800 fps
Max 88 grains 2,900 fps
 

nuclabuyer

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Re: Help with pressure problem

I see a little bit of a flat primer but I also see symptoms of detonation as opposed to a true over pressure load. I get those same symptoms all the way from a 101.5 load to a 106, primers are pretty happy with no seal around the neck during the shot. And to honest the 101.5 loads are the ones that ruin the cases, this is due to detonation instead of a proper burn. With both 50 bmg and reloader 25 I get good pressure and everything is happy, but this gun shoots really good with retumbo except I cant get the pressure under control.
 

CaptLink

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Re: Help with pressure problem

Is this a factory chambered gun?. Can you mike the case web and neck? All of those primers are flat and I can see the ejector button on one case head.Detonation is normally caused by weak primers and slow magnum powders that are under charged.All are major over pressure signs.
 

nuclabuyer

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Re: Help with pressure problem

This is a 32" Pac-Nor barrel and pacnor did all the fitting and truing of my action. When I first got the barrel I was having some signs of pressure. So I sent it in and they ran through it and said everything is correct according to the specs they had. I changed to Federal 215 primers and that got rid of the hang fires. Every other powder is fine except the Retumbo. I have 3 - 1 lbs bottles of it, and the gun shoots awesome, about .5 moa but the pressure is really high, I think do to detonation. With reloader 25 it shoots all over the place and with 50 bmg there seems to be no problem, just need to get to the range and see about a group.
 

Brain

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Re: Help with pressure problem

Pressure isn't high when cases are being deformed from the outside and covered in soot...it is initially too low.

As was stated earlier, you need to seat the bullets deeper...or switch powder.

Retumbo is a very slow powder and takes a bit (relatively) longer to obturate the case than faster powders such as H1000 or similar.

If you are chasing the lands with the VLD's, and by chasing I literally mean it with a 30-378, there may not be enough bearing surface held in the neck of the case for it to fully obturate prior to the bearing surface of the bullet clearing the case mouth. The pictures indicate that this is what is happening.

How much bearing surface of the bullet is in the neck of the case? A few thousandths more could very well cure your problem.

Been there before with Retumbo and VLD's.
 

Clark

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Re: Help with pressure problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nuclabuyer</div><div class="ubbcode-body">.. If you want to tell me that a Nosler 200gr Partition is completely different then a Nosler 200gr accu-bond by enough to make a dangerous difference then I will say that is incorrect. A 200gr bullet, no matter the maker, should yield roughly the same pressure. ..</div></div>
After years of being a consulting engineer, I can say that 90% of the time a problem is solved quickly, one of the client's own engineers figures out the solution himself.
I still sent an invoice, and always got paid, because the problem was solved
grin.gif
 

nuclabuyer

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Re: Help with pressure problem

To answer a couple questions, this barrel has a long throat, I can not reach the rifling with a 210 vld. I never could, I would say this has about 150 rounds through it, so I would say it is not a eroded throat. Maybe a 230 will be able to reach so I can jam it or just off the lands to boost the pressure alittle. About the bearing surface, there is roughly .225" of 308 diameter bullet touching the neck.
I know that retumbo is slow but I get a good seal and correct pressure with 50 bmg powder which is a slower powder, I also can go to a quiker powder, RL-25 and be fine also. I just dont know what it is about retumbo. I emailed berger to see if they can tell me a range for Retumbo and the 185, 210 and 230 VLD's. I would really like to shoot the 230's. I should get a box on Wednesday.
Also I don't want to sound like I know everything, because I certainly don't. But I almost always figure something out and this one is kicking my ass.
 

hero's machine

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Re: Help with pressure problem

My advice is to stop shooting until you can shoot it through the lights. You are just guessing right now. You are using nosler brass.....have you checked water capacity? Most data was written for wby brass and if nosler is different it will cause issues....been there. Shoot it through to chronograph. What's a hundred bux anyhow.....you will ruin that much brass trying to get the answer.