In order to participate in the GunBroker Member forums, you must be logged in with your GunBroker.com account. Click the sign-in button at the top right of the forums page to get connected.
Options
6mm and 243
bperdue21
Member Posts: 1,457 ✭✭
How do you like IMR 4831 in these cartridges? pushing a 75 grain sierra hp. i like how it fills the casing well, but was kind of concerned when i read that the 243 has pressure problems with slow burning powders and can cause the action to lock or splinter the stock. thanks.
I'm not an expert, but i did stay in a Holiday Inn Express last night.
I'm not an expert, but i did stay in a Holiday Inn Express last night.
Comments
I use a lot faster powder for 243. Varget or one of the 4350's are much better suited to the 243.
.
I'm not an expert, but i did stay in a Holiday Inn Express last night.
First things first. IMR/H-4831 are not suitable for use in the .243 Win. with light bullets. IMR-4831 can be suitable in conjunction with 95-100 gr. grain bullets but H-4831 is still too slow.
Powders that are suitable and efficient in the .243 Win. with these light bullets are:
AA XMR-4350
H/IMR-4350
V V N-150
The discussion of slow burning powders and high pressure excursions is ongoing. Use this link to read a breakdown that explains the sequence of events.
http://www.aeroballisticsonline.com/articles/mystery_solved.html
Best.
The wider shoulder of the .243 case allows for a more efficient burn of slower powders. I don't have a scientific basis regarding this, just what I know works in this case. The .243 is efficient enough to use 4831 down to 80 gr. bullets. It goes along with the shorter fatter powder stack theory.
I have used 44 grs. of 4831 behind an 85 gr. bullet for years as my best load. Most of the deer I took with a .243 were with that load. I also had great success with 42 gr. of 4350 using the same weight bullet. My older Hornady manual shows clear up to 49.5 grs. of 4831 for a 75 gr. bullet. But that is like a lot of things in reloading, the closer you get to max the less you jump when upping the powder charge. I will say though if you want to shoot 75 gr. bullets you can move up the powder speed. 4895, 4320, 4064, VVN140-150.
The longer and somewhat thinner case of the 6mm Rem., I think, would lend itself better to faster burning powders like VV N130-133, XMR2015 H335, BL-C2, AA2460, go with 4895 and VV N140 with medium weight to heavier bullets in this caliber.
We have the second amendment so that all the rest are secure....UNK>
I'm not an expert, but i did stay in a Holiday Inn Express last night.
Light bullets in the .243 Win. case is an inefficient situation at best. There isn't a great combination that a completely full case and all of the burning in the barrel completely except for the XMR-4350.
"it was listed for 75 gr bullets in both calibers in the hornady manual, volume 8 i believe."
They also list 75% loads of H-322 as well but that's not a load that I want to play with. They cover the spectrum of slow to faster powders in order to provide a decent selection for the reloader. That certainly doesn't make every load perfect or even appropriate at all.
Just because it is printed doesn't mean that it is gospel. And I don't write this lightly. Reloading manuals are just as prone to having mistakes printed as are any other written source, unfortunately. I know of 2 manuals that had to have retractions printed due to mistakes and one complete manual that had to be reprinted. Read the article at the link supplied above to get a better understanding of what this problem is all about.
Filling the case with the APPROPRIATE powder is always a good thing with regard to consistancy. But choosing the wrong (slow) powder just because it fills the case, can lead to additional problems with blockage in the neck of the case and false or secondary ignition. There is a gunsmith that I know who has tested this with a graphic piezo sensor set up because he had a problem in a similar situation. Potential danger to the shooter is not worth it in my opinion. And yes there are those that will say "I've been loading my _____ this way for 40 years and never had a problem!" Well good for those that are the exception. There's always an exception. Someone is watching over them. Read the article.
Balancing the load with a full or nearly full case is a plus, like I wrote above, but if the powder is too slow to burn completely in the barrel and produce the plasma to push the bullet out of the barrel, that powder is just plain wasted. This is the situation with the H/IMR-4831 powders. At least 10% of the powder load is wasted due to incomplete burning in the barrel. Do the math for yourself, that's throwing away 10% of your cash that you paid for the powder every time you pull the trigger. So the full case of slow powder doesn't really do you any good except to waste your money and be a potential safety problem.
This is like tilting at windmills...
Best.
I hate to interject this way but I can't say I fully agree with either the author of the article or the article critic. I will agree with nononsense in that if you are blowing 10% of your powder out the end of your barrel it is just a waste. So overloading with a slow powder is wasteful. It is also a waste if the extra powder you put in is getting burned but is past the curve when it supplies meaningful pressure to the bullet. This would be more common I would think in a long barrel/light bullet combo.
What I get from the article is that the powder tested was "non-cannister". Am I to assume that this was a ball type powder? I could understand ball powder, no matter what the burn rate, causing this problem because there is so much more surface area to ignite than extruded. During a pressure spike and the burn rate acclerates there would be that much more powder surface that would burn faster than if it were extruded powder. Not that this won't happen with extruded powder, it just seem more plausible with ball. I have read of the rifles blowing up during competitions. Most of the incidents involved ball powder. So I have read, but not statistically had this broken down to the facts. If there is data behind the various failures it would be good to know what type powder was used. The article nononsense posted could well be more accurate in my mind if this is the case.
I guess I always go back to what I learned, fortunately not the hard way, that under-powdering a load is what causes S.E.E. or as we called it reverse ignition. This has always made sense to me as it is the principle we used in demolition when I was in the Army. Sending a shock wave directionally to where it meets itself in whatever form of shape charge is what is used to cut trees, pillars, concrete blocks, etc. in pieces or shatter it. The very effectiveness and efficiency of each cartridge has a lot to do with the shape of it. If the rear and front of a powder charge are ignited and the front burn comes back and meets the rear burn the shockwave will want to go directly outward instead of continuing forward like it should. This is just a couple more cents in the kitty, very interesting topic though.
We have the second amendment so that all the rest are secure....UNK>
I'm not an expert, but i did stay in a Holiday Inn Express last night.
Eric
allamericanarmsco@frontiernet.net
All American Arms Company
www.galleryofguns.com
VIP Code: AAAC
Veteran Owned and Operated
I'm only wearing Black untill they make something darker
Let's go back to the beginning with your comments regarding slow powders and pressure problems. Bear in mind that this problem is not limited to just the .243 Win.
I went back to the Hornady manuals where your statements about failures originated. Their example was slow powders that don't fill the case which is an example of S.E.E. or Secondary Explosive Effect. Their example is when the powder falls below the 60% level and the jet effect of the primer passes across the top of the powder for the entire length of the case and ignites the powder from the completely exposed horizontal surface of the powder charge and burns downwards, yielding an extremely high pressure release instead of the normal pressure release when the powder is ignited from just the bottom of the powder column only. It's a matter of how much surface area is exposed to the primer jet. The bottom of the column is small in surface area and the powder burns in the manner in which it was designed. If the powder is laid along the bottom of a horizontal case (in shooting position) and at mid-level or below, the powder is ignited across a huge surface area by the primer causing significant over pressure excursions. Plainly and simply it is the release of extreme pressure, faster, because of the larger exposed surface area of powder.
This is the reasoning for their caution.
However, IMR/H-4831 in conjunction with light bullets in a .243 Win. case is not the optimal solution simply because it is inefficient and too slow for the case and the bullet selection. Filling the case with inefficient powder is wasteful and results in ugly fouling in the bore which requires extra effort when cleaning. This is avoided by using a powder appropriately suited to the bullet/case combination. This is fact not just some supposition off the top of my head. Selecting the appropriate powder burning rates is crucial when attempting to create the best, most efficient ammunition possible. The reloading manuals that list a preference for powder selection mostly choose a version of 4350 powder. The various 4350 powders will fill the case when loaded with the 75 gr. Sierra HP and perform efficiently. But again, start low and work up slowly to a safe and accurate load.
The IMR-4831 can be acceptable when used with the heaviest bullets available for the .243 Win.
sandwarrior,
Since the 6mm Rem. and the .243 Win. are only one grain of powder apart in case capacity, they function very nearly the same as one another when using the same powder. In essence, the powder column of the 6mm Rem. has slightly more taper and is longer but the capacities of the two cartridges are virtually the same. The powders used in one will be the same for the other.
Using the powders that you list for the 6mm Rem. will result in cases being filled to only the 80% level or less when charges are at the very highest or peak operating pressure level. The pressure curve is short and burning will be complete in less than the first 10" of the barrel. This can lead to aberrations in the consistancy of these loads.
Best.
These exact same loads with the same references have been listed in both manuals since 1976 or for at least 29 years. Any guesses as to how many lot groups have gone by the wayside in 29 years of production? And no new testing in 29 years? No updating whatsoever? Besides, Sierra's manuals list test rifles as "Universal Receiver" which have no bearing on accuracy results in the real world. That's why it's pretty worthless to list pet loads or accuracy loads from our individual rifles for someone else to use in their personal rifles. No application. Again, there are always exceptions... and material published in reloading manuals are for reference only, really.
"There is load data in almost every major reloading manual for this powder and these calibers, and believe me it wouldn't be there if it wasn't safe."
Let's see...
Sierra has announced that the Sierra Rifle & Handgun Reloading Data, Edition V manual and Sierra Infinity Suite computer software program have incorrect data regarding the Remington 300 UltraMag. Some of the loads exceed SAAMI maximum pressure suggestions and could result in damage to firearms and/or * injury. Contact Sierra at 888-223-3006 or by e-mail at sierra sierrabullets.com for a replacement section of data for the manual. Those who purchased the Sierra Infinity Suite computer software program may download a program patch by visiting Sierra or can contact the company to have a program patch sent on CD-ROM. [Source: American Rifleman, April 2004]
Hodgdon has issued a warning for the .45 Colt data in its 2004 Hodgon Annual Manual. On page 132, two lines of data using Longshot powder in the standard .45 Colt section were intended for the .45 Colt section (Ruger, Freedom Arms and T/C only). This data appears in the 250-grain Hornady XTP and 300-grain Sierra JFP sections. DO NOT USE THESE LOADS IN A STANDARD COLT OR ANY REPRODUCTION MODEL. EXCESSIVE PRESSURE MAY RESULT AND CAUSE FIREARM DAMAGE OR PERSONAL INJURY. For more information, contact Hodgon at 913-362-9455 or e-mail to helphodgdon.com
Best.
I will have to reiterate that the shape of the case makes a difference. If you had a primer that just for instance could throw a flame column through normal density powder 1.5" centered on the flash hole and burning outward, would it not nearly cover the length of the .243 where it would still be 1/4" short in the mauser case?
I'll give an example. It isn't a dead on comparison because at the time I didn't directly compare bullet to bullet in the same caliber between the two cases. I quit using 4350 in my short barreled .257 Rbts. (same case as the 6mm, just necked up .014" for those of you following along, I know most of you already know) using 4350 behind a 100 gr. bullet I got a flame about a foot long out the end of the (20") barrel. Now, using 4350 behind an 85 gr. bullet in a 24" barrel in the .243 I don't get a great big flame out the end. The .243 case has more powder exposed to the initial flame of the primer.
In order to get my .257 to quit spitting flame I had to speed up the powder to burn within my 20" barrel. The best powder I found there was Vihtavuori N140.
That is why I say the .243 case burns slower powder more efficiently. I do believe you can still overload a .243 case with 4831. But, I'm not convinced it happens the way the article states in your earlier post. Also, the lower powder issue to me seems to be much more of a problem than does overloading slow powders causing s.e.e.
I appreciate your time and input though with this post nononsense. As usual it is a well researched post and good food for thought. Things may not always be as we have thought them for years. I think it's well worth looking into. thanks.
We have the second amendment so that all the rest are secure....UNK>
Rob
why chase the game when the bullet can get em from here?....
Got Balistics?