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Pressure signs?

This is a discussion on Pressure signs? within the Reloading forums, part of the Firearm Forum category; Reloading for my first No1, a stainless 6.5x55. Custom 26" barrel, 130gn Accubonds. I am experiencing Very flattened primers, with a deep firing pin indent, ...


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Old April 28th, 2013, 06:30 PM   #1
 
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Pressure signs?

Reloading for my first No1, a stainless 6.5x55. Custom 26" barrel, 130gn Accubonds. I am experiencing Very flattened primers, with a deep firing pin indent, but no piercing, ruptures or visible damage. Extraction is a little tight or perhaps sticky? Velocity is 2870fps. Am use to bolt actions, so experience is zero with these actions. A guy at the range says its ok, as the action is so strong and that it could just be soft primers (winchester large rifle). However ,I feel that these are pressure warning signs that should be heeded. It is a very consistant tight little group, and so would like to leave it if possible. Any thoughts from experienced hand loaders would be great. Cannot believe it took me this long to buy a no1, loving it!
Cheers and thankyou for your time.



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Old April 28th, 2013, 07:10 PM   #2
 
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no 1 swedish,

Could be a soft primer, but when you say your having some sticky extraction, that does sound like excessive pressure.

My new Nosler book lists velocity in the 2800+ range only with two powders and those ONLY at 2800 and 2801fps. This is however with a 23" barrel so there could be some increase in velocity with your 3" of extra barrel length.

Not knowing the powder you are using, I'd still say it appears to be excessive pressure from this end because your seeing both the greatly flattened primers and stick extraction.

Clearly you are getting high velocity and with my experience with the chronograph, I think I see 3 basic groups of rifles as per the velocity produced.

First and much the largest group are those who fall well below published velocities for a given powder an bullet compination. The second and smaller group is those that about match published data, and the last and smallest group are the rifles that exceed published data while still loading within published data guide lines.

It is a good possiblity that your rifle/barrel is one of those shower barrels found in the latgest group, and if this were the case, you might just be well above safe pressure levels with the upper 2800fps velocities your showing.

Keep us posted as to your findings.

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Old April 28th, 2013, 07:22 PM   #3
 
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Primers And Pressure

copy and paste the above link ....use the above strictly as a thought provoker ...until someone comes along with the lab to backup the thoughts (such as a manufacturer ) in the industry

with that said I will say I disagree with little said here and there is no doubt that the metallurgy of various makers varies making experimenting with various primers crucial to loads near the top end of the pressure curve ....I do not load your caliber, have loaded for #1's , do not know your powder/weight etc but something is wrong ....win LR primers are not real soft as a rule so I would tend to pay attention to cratering and flat primers

reduce powder, change powder for a different burn curve ...do something as brass extraction might have some friction in extraction but not sticking

Good luck
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Old April 28th, 2013, 07:24 PM   #4
 
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Hi Crusty,
Thankyou for your prompt reply. I am using an Australian ADI 2209 powder, 45 grains off.
Cheers. Again.
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Old April 28th, 2013, 08:44 PM   #5
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no1 Swedish, I ran your load through QuickLOAD software. For your 130gr bullet and 45gr of ADI 2209, it indicates 2851 fps from a 26" barrel at a peak chamber pressure of 53,126psi. Your gun is rated at 55k psi so you are safely under max and your chronograph data is very close to QL's prediction.

Primers are a very poor indication of chamber pressure. Many factory loads behave much like yours and have flat primers with a dent. If you experience ruptured primers or can't see a notable dent, then yes, you might be pushing the limits. Sticky extraction is another common issue that happens with different brands of brass. I wouldn't get too concerned at this point.
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Old April 29th, 2013, 09:56 AM   #6
 
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Some good info here!

However, I come back to the fact that each and every firearm is a rule unto itself, as shown by the wide range of velocities produced by different firearms, but with the same loads.

Until equipment to take pressure readings becomes as cheap/available as chronographs have become, we can only go by the indicators, poor though they may be, to guesstimate pressures.

Therefore a program such as QuickLoad only provides us with an educated guess, after which we as handloaders must use the indicaters we have available, again poor though they may be, to assure we remain safe.

As said above, little chance you'll blow up your #1 with this load, but you may be at the upper reasonable pressure limits.

If this were not true, then every firearm out there would give exactly the same velocity as the published date we have, providing we used the same barrel length, same powder, same primer, same --------------etc.

There would simply be no firearm to firearm differences.

This just doesn't happen in the real world. I have seen a drop of 100 or more feet per second in velocity with just the change from one lot number of powder to powder of a different lot number.

A few publications back of the Speer loading manual, there was a load listed that would every high velocity freaks, dream. Yet in real life, even with a 26" barrel that load produced a velocity 100s of fps slower then the published data.

Wow to have a big supply of that powder in that lot number.

Flat primers may be a poor indicator of high pressures, I think most of us agree with that, but it is an indicater. But coupled with sticky extraction which the origional post listed as a possible sign present with this load/rifle, just may mean what it seems.

The sticky case is clearly something which needs to be verified one way or the other.

Also one very important fastor which has not been brought out here is temp. at the time of the firing of the test loads.

IF (????) the signs seen do in fact indicate high or excessive pressures, and it was a cool day, well a warm/hot day is likely going to produce blown or smoked primers at the very least and possibly blown or stuck cases.

Great pass time/hobby we have! Just be safe!!

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Old April 29th, 2013, 12:44 PM   #7
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Something I experienced with loading for my 7mm08 Rem was false pressure signs due to slight traces of oil on the chamber walls. The primers were somewhat flattened and the case heads showed signs of the bolt face. I found out that just wiping out the chamber with a clean patch wasn't enough. Now I use an evaporating degreaser on my chamber prior to shooting. The 'pressure signs' then went away.
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Old April 29th, 2013, 01:47 PM   #8
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Crusty Deary Old Coot, you make some very good points and I don't disagree with any of them except your comments about velocity versus chamber pressure.

Here's the deal with chamber pressure .... if the same exact ammo is fired in two different rifles, chamber pressure will be virtually identical ... even if headspace or the throat is different. All rifle powders will reach peak pressure within 2~2.5" of bullet travel. After the bullet starts moving down the bore ... all bets are off because a slight difference in bore diameter, rifling, striation marks, or barrel length can change muzzle velocity. Yes, you can certainly expect different guns to chronograph the same load at different velocities but it's not because of chamber pressure ... it's because of the bore and/or barrel length. Further, a faster burning powder will create higher chamber pressure than a slower powder in the same rifle with the same bullet. In this case, faster burning powder will result in lower muzzle velocity because it does not continue to burn and push the bullet faster. So .... chamber pressure does not track with muzzle velocity ... never has and never will.

All factory ammo is loaded to pressures very near SAAMI max pressure specs. This is where the overall performance .... velocity and accuracy .... are typically the best. When a cartridge is designed, the designer submits data to SAAMI and that becomes the standard. The rifle itself must hold up to proof loads, which are pressure rated much higher than published specs. The 6.5x55mm Swede is a bit unique because it was developed back in the late 1800s for the Swede Mauser Rifle... long before pressure testing was invented. It has two sets of pressure specs ... one for the old Swedish Mausers (51k psi, military and SAAMI spec) and one for modern rifles (55~58k psi) ... kind of like 45 Colts with "Ruger Only" loads. With exception of Lapua and a few other European ammo manufacturers, store bought 6.5x55 ammo is loaded to the lower 51k psi spec. A modern rifle like a Ruger #1 is made to take 58k psi Lapua loads with ease. If you have a Speer #14 manual, check out page 311 where Speer loads go up to 58k psi.

I use QuickLOAD for a sanity test but not for actual reloading data. In this case, ADI's reloading manual lists loads for a compatible bullet with the minimum charge at 41.5gr and the max at 46 gr. no1 swedish's load is a full grain under max so even if QuickLOAD is not accurate, ADI's load data is. Turns out ... both are very close to the same velocity and chamber pressure so I tend to believe them.

Granted, not all rifles chambered for the same cartridge are created equal. Some have much stronger actions, some have better metallurgy, some are thicker, thinner, etc. but chamber pressure will be near identical with the same ammo despite the mechanical differences. Ruger #1s have a very strong action ... much stronger than a comparable bolt action rifle in the same chambering. Ruger uses the same action in huge elephant guns such as a 458 Lott so it has to be very strong.

Yes, temperature can increase chamber pressure considerably. Perfect example ... I worked up a 223 Rem load with Win 748 powder that was very accurate and showed no signs of over pressure at the range. During a prairie dog hunt, I fired several rounds in rapid succession from my Mod 700 BDL. The barrel got pretty hot and after just 4 rounds, I experienced hard extraction. The fifth round totally locked up the action until the gun cooled down. Soon after, I changed to Varget powder that is temperature compensated (called "extreme rated"). On the next prairie dog hunt, my problem went away and I still had a very accurate load at the same velocity as Win 748. BTW, ADI makes many of the powders for Hodgdons to include Varget so it wouldn't surprise me if ADI 2209 is also temperature compensated.

I do respect your cautions ... it's the best attitude you can have when dealing with reloading. Keep up the good work!
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Old April 29th, 2013, 04:49 PM   #9
 
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A little more info on " powder sensitivity".
ADI/Hodgy powders that are "insensitive" are only so under a certain set of parameters, and not a universal property. Most of the claims of being sensitive are specifically misunderstood. The transfer of heat from barrel through brass, is the issue; not the powder by itself. With the 308, and 150gr bullets, Varget works "as advertised". In the 223, Varget is a rather streaming pile, for insensitivity. Even in Hodgdon's own testing, many of the "proof of insensitivity" claims aren't statistically valid anyway; so read scientific testing before you believe everything you hear.

Dr. Denton Bramwell has done a fair amount of testing of Varget, et al, with regards to the claims.

As said, "reading brass" is a very poor specific method, even though we all do it to one extent or another. Cartridge brass "spec" has a tensile strength of +- 70,000psi. Now ASSuming that the manufacturer actually followed that spec... You will see "large noticeable" stretching at that point; not good. It also doesn't account for specific chamber/rifle variances and configurations. Remember that a good chrono is your friend, and 90+% of barrels are slower than books show. So follow charge weights and record speeds. Richard Lee has some VERY good info on 1/2 gr incremental changes. Read-up on the topic, and you will get a good feel for the small velocity changes affecting large pressure changes.
Also for the price of a new rifle, you can buy yourself a pressure trace, and see what your specific rifle is doing.
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Old April 30th, 2013, 12:47 AM   #10
 
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Hi Guys,
Firstly, would like to thank you all for your knowledge and time.
Some great info, tips, links and ideas. The initial reloading was undertaken in the warmer months, at a guess, it was probably around 24 degrees Celsius.
I really only hunt in the cooler months so that might alleviate any spikes (?), in pressure. However, I think I might reload some batches, in half grain increments down from 45gr.
Hopefully, by dropping just a grain or so I will find that the sticky lever will disappear and the somewhat unreliable indicator of a flattened primer will also be removed. Whilst still retaining good velocity and groupings.
This will should give me the confidence that I am not stressing the action or burning out the barrel!
I have been targeting wild dogs beyond the 350yd range, and so far it has been successful. Love the rifle and cartridge combo.
Once again thankyou, you have helped immenseley as I had no experience with a falling block. I will continue to monitor the thread for any further replies and will also let you guys know how I go, hopefully in within the next month.
Cheers, Aussie swede.
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