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Be careful, myths about pressure signs.

 
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  #15  
Old 01-08-2008, 08:11 PM
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When you extract your fired case and the primer falls out is that a good sign?
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  #16  
Old 01-08-2008, 08:26 PM
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Quote:
Originally Posted by Buffalobob View Post
When you extract your fired case and the primer falls out is that a good sign?
Only if it falls on the ground and not into your action :eek:

AJ
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  #17  
Old 05-05-2008, 03:23 AM
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Join Date: Apr 2008
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Sticky bolt 264 Win Mag

My grandfather handed me his 264 Win Mag Sako Finnbear which he had for 20 years. Good factory ammo is quite expensive so I decided to start hand loading. I loaded 160 grain sierra tips with 57 gr S385 and 129 grain hornady tips with 62 gr S385. We only get 140 grain ammo in S.A which works well.

I went to shoot in the rifle with the new ammo and found that the 129 grain bullets made my bolt stick that I could only get it open after 5 seconds. The 160 and 140 grain bullets did not give any problems. The primers of all three casings look the same after firing. Can this be a sigh of over loading or too much pressure?

The gunsmith I use said I should seat the tips 1 millimeter deeper, this will bring the pressure down. Is this true or not? The fact that the bolt is sticky, is this harmful to the gun or not?
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  #18  
Old 05-05-2008, 11:33 AM
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Just how accurate is Quickload? Lately it is being thrown out here as the all knowing infallible answer. Unless manually manipulated, it does all of its calculation with standard factory barrel, factory chamber for which gun and reamer we do not know, assumed H2O capacity etc and "assumed" mag OAL only for seating depth.

changing the seating depth by .100 out on quickload drops 4k pressure for the WSM.

Changing primers based on actual pressure tests can raise or lower pressure over 3k.

so when someone jumps up and says quickload says this or that, just exactly how did they get there. It is only based on the parameters that qucikload used to get their initial data and nothing else. Same as a reloading manual, at least they list exactly what load, primer and oal they used to get their data.

That is exactly why they also caution you anytime you change any one of the above, drop 10% and start over.

BH
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  #19  
Old 05-05-2008, 12:55 PM
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Quote:
Originally Posted by AJ Peacock View Post
Actually, Quickload lists 63gr as just over 64k psi for the OAL I'm using. So I am now up at max with no signs, where before I was showing signs below max.

AJ
This is where people get in to trouble with Quickload. The powder charge is irrelevant. It's the velocity you should look at and corrolate with the pressure.

Example: I loaded my Remington M700 24" bbl .280 with 58grs of N160 behind a 140 Ballistic Tip. At the range a 3 shot string gave the following chronograph readings. 3165, 3159, 3162. Very fast...too fast in fact, though it showed no "classic pressure signs". I had a buddy run N160 with 140 BT (with default settings). I seat my bullets out to the lands, so the default seating depth would be less case capacity. Anyway, it puts me in the ball park. It said 58grs should give 57Kpsi, but it also said it would be at 2900fps. Looking down to the velocity I was getting, It said something like 62grs and 74Kpsi. Well, 62 grains would be waaaaaay too much. I read the pressure at the velocity, not the powder charge. Having talked to a couple of gun writers about it, they'll tell you the same thing. Sometimes the powder charges are way off. The velocity, with the given powder, determines your pressure.
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  #20  
Old 05-05-2008, 01:27 PM
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Bounty Hunter,

I am by no means an expert on QL, heck I cant even figure out half the settings. I can tell you this, it has been very accurate for me thus far. I cannot tell you that such and such load has this pressure, but can show you where QLs predictions were within .5 grain or so of being the predicted velocity in my rifles.

Like any other loading reference you must start lower and use good judgment in devoloping your load. Where I have found QL to be extremely helpful is in its ability to find the right powder. The powder that goes with your bullet and COAL like peas and carrots. As you know some burn rates match certian bullet weights better than others in different length barrels.

I am guessing here because I am in no way a ballistician or expert on internal ballistics, but feel that the limiting factor we all face is the intitial pressure spike. If a powder is the appropriate burn rate it seems that the initial spike will be less and that pressures past this spike will continue to be higher through out the bullets path down the barrel. Based on this IMO there are instances where one powder can give you greater velocities than other powders with less pressure. I keep hearing velocity is pressure from some people and have to agree to some extent, but timing of the pressure curve seems to give a different outcome.

I have only used QL to work out loads for myself in about 15 different custom rifles. In every instance I had my best results with the powder that QL predicted to be the best. In a few instances I learned that a lot of folks pet loads were not even close to being the powder. I may not use the absolute best powder listed by QL because of other factors such as temp sensitivity or availability but always try and use one of the powders that is predicted to be a top performer. It has worked out very well thus far and some of the powder choices are sort of surprising to me. So surprising and seemingly counter intuitive that I have even resorted to using a string to pull the trigger on a 6x284 that I couldnt get to shoot as well as I would have liked. I finally found an acceptable load using QL and the rifle shot pretty well, too bad I had toasted the throat using data from every other source before I bought quickload. Everytime thus far QL has been spot on.

It has also worked very well in working up loads for wildcats. For example my 22-6.5x47 Lapua. When working that load up I used another case with a similar water capacity (I think it was the 220 swift) made adjustments to the case capacity and pressure paramaters and ran the program. I backed off the QL prediction and started working up toward the predicted max. By watching the chronograph and pressure signs (even if it is like reading tea leaves) I worked up to about .5 grains over QLs max. My velocity and presumbably pressure mirrored QLs results.

Until strain gauges become readily available for the handloader I would say a chronograph and quickload results with a bit of good common sense and independant verification where available is about as good as you can get when working up a load.

But then again I do not know that much, but I am learning from all of the posts that more experianced guys here share.
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  #21  
Old 05-05-2008, 01:37 PM
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There is a way to alter the start pressure if you like to load into the lands that will get QLs predictions to mirror your results and thus make the powder charges closer. I usually run mine with the default start pressure and start lower working my way up to the predicted max velocity. I have never had the predictions off by more than about 2gr.s using this method. Once I adjusted the start pressure, because I was jamming the bullets, it was spot on. As you said velocity is the best indicator.
It is too bad that primers are completely ignored by QL.
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