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bonanza
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Primer question
      #124361 - 18/01/09 03:24 AM

What are the effects of using a magnum primer when a large rifle is called for?

--------------------


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Tatume
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Reged: 09/06/07
Posts: 1091
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Re: Primer question [Re: bonanza]
      #124364 - 18/01/09 04:08 AM

That's a very simple, straightforward question. Too bad there isn't a simple, straightforward answer.

With higher flame temperature, and more violent injection of the flame into the powder, ignition will probably be more immediate, resulting in higher pressure. In fact, pressure attributable to the primer alone is significantly higher. Even without a powder charge primers produce significant pressure.

A more violent primer usually causes reduced accuracy, but in a hunting cartridge you probably won't notice it.

The short answer is, if your loading practice is conservative, the added pressure will probably not put you over the top. If you load right to the edge, and accidentally substitute magnum primers, you're probably in excess of maximum now.

If, but, maybe, shoulda coulda woulda. There is no easy answer to the question. Sorry.

Take care, Tom

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9.3x57
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Reged: 22/04/07
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Re: Primer question [Re: Tatume]
      #124365 - 18/01/09 04:36 AM

Some have surmised that a mag primer is worth a grain or two of extra powder. I can't confirm that at all, but it is a fairly safe bet the mag primer increases pressure under most circumstances.

Oddly at first blush, I've read that mag primers can DECREASE consistency in burning of certain types of powders due to the added blast effect forcing powder away from the initial force of explosion before the powder ignites. I also cannot confirm that but it would seem to make a bit of intuitive sense.

Regardless, it bad loading practice to simply replace a Standard primer with a Magnum primer in a max load that was worked up with a Standard primer without backing off 5% and working up afresh and using the mag primers from start to finish.

--------------------
What are the Rosary, the Cross or the Crucifix other than tools to help maintain the fortress of our faith in Jesus Christ, the Son of God?

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bonanza
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Reged: 17/05/04
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Re: Primer question [Re: 9.3x57]
      #124384 - 18/01/09 08:19 AM

Thank you gentleman,

I have no intention of substituting a magnum for a large rifle. Just wondering what-if...

--------------------


"Speak Precisely" G. Gordon Liddy.

"Life is absurd, chaotic and we must define its purpose with our actions" Abert Camus

"I''m the dude playing a dude disguised as another dude."

"Yo! Mr. White"

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Tatume
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Reged: 09/06/07
Posts: 1091
Loc: Gloucester, Va USA
Re: Primer question [Re: bonanza]
      #124435 - 19/01/09 12:56 AM

Hi Bonanza,

I've never done any extensive primer testing, though I've read of some. It is widely held that "weak" primers produce superior accuracy. Thus, magnum primers should be used only when standard primers are insufficient to properly ignite the powder charge. This would occur when very slow powders are used, and when very large amounts of powder are used. Frequently (but not always) one implies the other.

It is my experience that # 4350 is at the cut-off point. In the 30-06 standard primers work best. Many reloading manuals recommend magnum primers in the belted magnums when loaded with # 4350. I use them myself in the 300 Win Mag and the 375 H&H, but I am not convinced that they are needed, and may even be inferior. Perhaps this summer I'll load two batches of otherwise identical ammo the test the hypothesis.

Very cold weather is another indicator for magnum primers. Powder becomes harder to ignite, and pressures are reduced when air temperature is greatly reduced. Loads for very cold weather should be developed in cold weather. Likewise, loads for very hot weather should be developed in hot weather, as the opposite is also true. Pressure is increased when it is hot outside. Primer choice could easily depend on temperature.

Large cases alone do not signify a need for magnum primers. Ammo for my 458 Ruger #1 is loaded with # 4198 or # 4895. Neither benefits from magnum primers.

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Ripp
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Reged: 19/02/07
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Re: Primer question [Re: bonanza]
      #124453 - 19/01/09 03:09 AM

Quote:

What are the effects of using a magnum primer when a large rifle is called for?




Just read an article recently--will look at my home regarding this--but actual tests were done with different primers using the same loads in I believe the 308W...

Agree with others and per the article--pressures will increase..

Ripp

--------------------
ALL MEN DIE, BUT FEW MEN TRULY LIVE..

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93mouse
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Re: Primer question [Re: Ripp]
      #124458 - 19/01/09 03:51 AM

Hm - when I was developing my 9,3x74R load with GSFN mono solids I did it with close support from Gerard from GS - he insisted on using magnum primers with drive band bullets - in his words:

"One of the big differences between drive band bullets and smooth bullets is the lightness with which a drive band bullet slips through the throat of the rifle and into the rifling. The resistance to engraving is about a quarter of that of a smooth bullet. If you use a magnum primer the pressure from the primer igniting will move the powder charge and the bullet forwards so that, when the powder ignites, the bullet is already engaged in the rifling and you have artificially created a bigger case. As we know, the same charge in a bigger case lowers pressure.This whole principle works best when the selection of powder is such that the bullet sits tight on top of the charge. The principle is almost unnoticable if a very fast powder is used with low charge levels and there is a lot of air space in the case. Air is compressed and the bullet does not move under primer ignition alone."

I don't know about pressure, but recoil was noticeable "softer" when using mag primers in my case.

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Tatume
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Reged: 09/06/07
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Re: Primer question [Re: 93mouse]
      #124469 - 19/01/09 07:02 AM

Quote:

If you use a magnum primer the pressure from the primer igniting will move the powder charge and the bullet forwards so that, when the powder ignites, the bullet is already engaged in the rifling and you have artificially created a bigger case.



So much of what we read in the gun world is speculation that "just sounds right." I'm not saying this is wrong, but without evidence to support it I can't accept it either. It just sounds right.

--------------------
Take care, Tom
NRA Life Member

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450_366
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Reged: 17/01/07
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Re: Primer question [Re: Tatume]
      #124471 - 19/01/09 07:08 AM

Quote:

Quote:

If you use a magnum primer the pressure from the primer igniting will move the powder charge and the bullet forwards so that, when the powder ignites, the bullet is already engaged in the rifling and you have artificially created a bigger case.



So much of what we read in the gun world is speculation that "just sounds right." I'm not saying this is wrong, but without evidence to support it I can't accept it either. It just sounds right.



But if the buller sits 1mm behind the rifling? Would this realy make a difference?

--------------------
Andreas

"Yeas it kicks like a mule he said, but always remember that its much worse standing on the other end"

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Bramble
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Re: Primer question [Re: 450_366]
      #124489 - 19/01/09 09:21 AM

Also would depend on crimp. Some BR guys have very loose necks but seat into the lands to control pressure deviations.

Not enough testing has ever been done on these variables because it does not benift those who have access to the equiptment and those that want to know dont have the gear. Hence so much trial error and differing opinion.

Regards

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450
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Re: Primer question [Re: Bramble]
      #124517 - 19/01/09 07:35 PM


I use Rem 9 1/2 mag primers in all of my rifles from .243 to 450-400. It is the most accurate primer in my 243 win and provides the least load to load velocity variation. IMHO I find that by using one primer all the time allows me better to read pressure (danger)signs as brand to brand primer cup hardness varies and some flatten easier than others. I find federal 210s will flatter more than Rem 9 1/2s with the same load. In the December Handloader there is an article by Gary Sciuchetti on the effects of various components in working up a 308 load. In this article a table gives the effect on accuracy only of various primers with all other components being the same. A pity that loads were not chronographed. There is also a table on Brass endurance with some cases giving up after 11 shots and others lasting until 24 shots after being full lengthed every shot. It gives food for thought.

--------------------
The worst days shooting and hunting is better than the best day at work

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Tatume
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Re: Primer question [Re: 450]
      #124530 - 20/01/09 12:03 AM

450,

Quote:

In the December Handloader there is an article by Gary Sciuchetti on the effects of various components in working up a 308 load. In this article a table gives the effect on accuracy only of various primers with all other components being the same.



How many groups were fired with each component combination to determine accuracy?

--------------------
Take care, Tom
NRA Life Member

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Ripp
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Reged: 19/02/07
Posts: 16072
Loc: Montana, USA
Re: Primer question [Re: Tatume]
      #124532 - 20/01/09 12:49 AM

Quote:

450,

Quote:

In the December Handloader there is an article by Gary Sciuchetti on the effects of various components in working up a 308 load. In this article a table gives the effect on accuracy only of various primers with all other components being the same.



How many groups were fired with each component combination to determine accuracy?



Tom
That is the article I mentioned in my earlier response in this thread...I believe they shot 3 or 4 different groups with each load..will look tonight and try to find it..

450 is correct, could not believe some brass gave it up that easily..was a very good article...

Ripp

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Huvius
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Re: Primer question [Re: bonanza]
      #124542 - 20/01/09 02:11 AM

Quote:

Thank you gentleman,

I have no intention of substituting a magnum for a large rifle. Just wondering what-if...



I wonder, just what was the need for developing a magnum primer in the first place? Maybe there wasn't one and magnum primers are just filling a hole that hasn't been dug yet. Sort of like short magnums...

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He who lives in the past is doomed to enjoy it.

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Ripp
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Reged: 19/02/07
Posts: 16072
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Re: Primer question [Re: Tatume]
      #124604 - 20/01/09 03:07 PM

Quote:

450,

[quote How many groups were fired with each component combination to determine accuracy?



Got the article and reread it again..really interesting..basically the author, Gary D Sciuchetti, did an amazing job..in an attempt to develop the most accurate load for a .308W..tried various brands of brass, primers and bullets..but kept the powder the same..using Varget..

Gary states in his findings that using a magnum primer does increase pressures and suggests if you switch from a regular to a magnum you back off your loads by 2 grains and work back up from there..He also states that magnum primers are good if you need them but if you don't need them he suggest not to. States a magnum is primarily designed for a large volumne of slow-burning powder or extreme cold weather..of which the 308 for this test did not qualify.

His tests show the effect of primers on accuracy, how long various brands of brass last during full length resizing and the accuracy of bullets tested..

In the end he suggests he come away with certain findings in his test..they are as follows:

Changing the quanity of powder can change groups by up to .75 inch
Changing the brand and type of primers can change groups by up to .313 inch
Changing brass brand changed groups by up to .25 inch
Changing brands of bullets changed groups by up to 2 inches
Seating depth fo solid copper bullets was crucial

One final item I thought was intersting was that he also test factory ammo and it was amazing how accurate some loads were---yet the reloads all in all were more accurate overall..

It is an very interesting article for anyone reloading..

Ripp

--------------------
ALL MEN DIE, BUT FEW MEN TRULY LIVE..

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