Any advantage to using magnum primers over large pistol?

Why?? Please explain your reasoning if any.

Are we going to go through another of these threads where you suggest something that is generally dangerous without extensive experience, and you continue to insist it's completely fine? It wasn't that much fun last time.

Fact is, pressure signs depend strongly on what cartridge and gun you are loading for. One could easily blow up a nice turn of the century revolver designed around early smokeless pressures before the brass would ever show pressure signs. The reloading companies have the tools to determine what is generally safe; while it may not be the GOSPEL, it is certainly generally advisable to follow this data when working up loads, particularly if you don't have experience and data showing otherwise.

This "why not" crap with regards to safety is getting old. And contributes to giving the impression that gun owners are not a safety-conscious lot, which is generally untrue.

I'm tired of this well it must be bad! No one here has talked about test guns. I'm seriously considering getting a 10mm pressure barrel. But to start I am using my 10mm Blackhawk.

As for dangerous Elmer Keith did a lot of experimentation with weaker guns including blended and duplex powders.

I haven't seen any one advocating the 'tried & true' "just fill the case with powder and shove in a bullet" method,except sarcastically..

If you don't have anything material to contribute then don't clutter up a conversation. The manuals are not the 10 commandments and differ significantly for the same bullet.

When you get your test barrel and generate your data, come back and tell us about it. Or do what "Clark" does on other forums, and provide real data on destructively tested firearms. That's not the same as developing a safe load for shooting, which is what is typically being discussed when referencing reloading. For that purpose, following an aggregate of published reloading data is generally advisable.

All I see is speculation on your part and no hard data. Until you have data that you can prove is safe, you are opening yourself to liability by advocating unsafe practices.

If I followed Lyman's data, all my .44 spcl would shoot is 650 FPS. So I go with Alliant and get 900 FPS. Is that dangerous? I think not!
gramps

gramps said:

If I followed Lyman's data, all my .44 spcl would shoot is 650 FPS. So I go with Alliant and get 900 FPS. Is that dangerous? I think not!
gramps

Click to expand...

Maybe it is, maybe it ain't...depends on the gun and/or how many rounds are fired before any possible accumulative effects set in.

Point is...More than likely, that Lyman-load you are speaking of is a SAAMI-spec load. The "900 FPS" is surely not. Plus, if I was a betting man, I'd bet a dollar to a donut that whatever published data suggest such a load, also advises not to use it in certain guns...sorta like the infamous "Keith load" in that respect.
In other words, just because any certain load doesn't ka-boom right away does not mean it's safe.

DGW

Under that 'logic' no gun is safe! Ban them all!

Nothing is safe; every action is a (hopefully calculated) risk.

There is less risk to using loading data that conforms with SAAMI specifications, since those specifications are used in the design process for firearms. Once you go off book, you are assuming all the risk, because there is not information that will tell you what will happen.

Once again, we come down to the issue of acceptable risk. For most people, there is no reason or desire to accept the additional risk that come from loading above published levels given the small potential gains. You are free to accept as much risk as you feel comfortable with; the issue is that you are (consistently) advocating this with noting the additional risk involved.

You need to learn to read! I'm in no way suggesting over pressure loads! I am saying that in some cases that there are better loads than those in the manuals. The fact is that max velocity loads are rarely the most accurate!

I'm not faulting the manuals. They can only do so many combinations of the hundreds available. Some cartridges get shorted for some uses. In particular 9/10mm get optimized for 4" barrels and therefore perform less well than expected in PCCs with much longer barrels.

I've yet to encounter a manual that tries magnum versus regular primers or small versus large for accuracy.

Your previous posts in this thread make no mention of the pressures your loads might develop BECAUSE YOU HAVE PROVIDED ABSOLUTELY NO DATA. I take that to mean that you haven't collected any, and suggest you go do so before you start advising people to play with loads that are not in books. Or at very least, start suggesting to people how your DOE is going to control for tolerances in chamber size and brass thickness, lot-to-lot variations in powder, the moisture content of the powder when you're weighing it, and the other various factors that might affect the safety of the loads you are developing.

As a followup to your PCC comment, Ballistics by the Inch HAS provided data on the performance of various pistol cartidges in barrels for 2-18". Based on their data, the ideal length for PCC barrels is 12-18", depending on the cartridge. So while you could mess around to get some extra velocity or load heavier bullets, current loads are probably about ideal in terms of efficiency of powder burn.

How you're going to stuff LPPs in cases cut for SPPs to study accuracy I don't know, but there are published studies on accuracy based on primer size and flash hole size for target cartridges. There's also at least one study I know if comparing brisance of regular and magnum primers. Likely, the effects of magnum vs regular primers on accuracy are small and firearm/chamber/component lot dependent in most cases, so unless you're going to go out and collect a representative sample, the data (which you'll hypothetically provide at some unknowable future date) will be anecdotal in nature.

You still need to learn to read! Some cartridges are available for small primers and a different brand cartridge for the same caliber with large. There are obvious factors which need to be adjusted for. e. g. case volume. I would appreciate your giving references for these numerous studies which you reference.

Ballistics by the inch provides excellent data to back me up. They use the same loads of the same powder just different barrel lengths. They essentially get no difference, not the ~100fps per 4" expected. Obviously the powders used are not working as reasonably expected. Likely this can be solved using slower burning powders, but maybe not. I haven't tried yet and don't know of any trials.

Here are a couple published studies I was able to find in the top 10 Google results:
https://rifleshooter.com/2018/05/does-primer-size-matter-6-5-creedmoor-small-v-large-primer-brass-comparisons/
http://bulletin.accurateshooter.com/2013/05/large-vs-small-flash-holes-in-308-win-brass/
http://www.targetshooter.co.uk/?p=2613
http://www.shootingtimes.com/ammo/small-vs-large-pistol-primers-45-acp/

Nowhere did you mention that you were making the choice of a caliber for which multiple primer sizes were available. I know of only 2 such handgun cartridges: .45 ACP and .357 Magnum, and I've only seen one box of LPP .357 Magnum. I know of only a few rifle cartridges that have multiple primer sizes available, though I guess with case forming anything from a .308 is fair game. Still, choice of primer size is more an exception than the rule when it comes to reloading.

There is a hard limit on the amount of gas a given volume of propellant can produce. The 100 fps per 4" is a general expectation for bottleneck rifle cartridges, which have significantly larger propellant volume than the pistol cartridges you are discussing. There is no reason to expect, based on a comparison of the propellant volume and the barrel volume filled with expanding gas, that you are going to be able to cram enough powder into a pistol case to get 100 fps difference per 4" barrel length at a barrel length that does not need to be registered under NFA without severely exceeding the SAAMI pressure limits.

Your failure to address your specific DOE indicates to me that you likely do not have the technical background to be discussing this in a comprehensive way, and that you will likely hurt yourself or damage your equipment through your lack of understanding. That is your prerogative; however, others should not be induced to follow you down your destructive path without being warned about the possible consequences.

Thank you for the large versus small primer references. I shoot some 6.5 creedmor and have wondered. I note that he uses CCI magnum primers for the small primer.

What or where is there a hard limit on the gas volume?

The ~100 fps per 4" is from Elmer Keith's book Sixguns, the figure for necked rifle (308) appears to be around 100fps/ 1".

As for DOE I'm looking for variables that need to be accounted for at this stage. Looks like the magnum primer issue is irrelevant.

Look up the combustion formulae for nitrocellulose and nitroglycerine. They'll tell you how much gas CAN be produced by complete combustion of your load.

Did some searching earlier tonight, and I came up with a null acceleration pressure of ~2.5 ksi for a 9mm bullet. Estimated from the barrel friction of M80 bullets in a study on DTICS. Using the ideal gas law (worst case scenario, all products of the reaction except perhaps water vapor are almost certainly supercritical for the entire length of the barrel, and therefore should produce less volume), 15 grains of pure nitroglycerine will expand to produce that pressure in a 9mm barrel of 0.7 meters in length at 3000K. That's pure NG, smokeless powder is majority nitrocellulose with a max of maybe 30% NG. Using more reasonable numbers like a few hundred K as the gas temp and maybe 80%NC/20%NG, I came up numbers with that agreed decently well with BBTI given the completely incorrect equation of state for the reaction products.

Ever thought of buying QuickLoad or something similar to get a start on your experiment? The problems are not really that hard to solve, the main issue is collecting the data. Would certainly be better than extrapolating from Keith's data which may or may not apply to your situation.

Well not convinced that those estimates are useful. I tried working backward to get combustion temp from PSI but not having the combustion efficiency makes it a WAG.

I'll take another look at QuickLoad, but it doesn't help their demo is down. I looked before and wasn't convinced that it would be worth the ~$160.

Thanks for the suggestions.

Most average people reading this forum could likely tell very little if any difference in magnum vs. non-magnum primers in nearly any cartridge.

I don't know about that. A lot of reloaders are in it for lower cost and others for better accuracy. So anything that improves either is of interest.

The small primers appear to improve accuracy and developing loads with regular and magnum primers for comparison may be worthwhile; particularly with slower powders.

What percentage of readers will be interested in experimenting I don't know.

I'll tell you what scares me, those factory +P loads of Magnum cartridges, like 41mag+P and 44mag+P and those 45Colt+P bear killing loads. I have seen too many problems with factory ammo to trust any of those.

The problem I see there isn't the load but the gun. Recent guns should flag that they-like the Glock-aren't suitable for +P loads. Older guns that are unsuitable may not be flagged with bad results. Particularly problematic with pistols!

It's all fine and well to label guns that are +P rated for cartridges for which +P is defined. I think Jimbo's point is that there are many boutique "+P" loads for cartridges that don't have this standard, some of which are significantly higher pressure than the 1.5ksi standard raise for +P, which may or may not be loaded to well-controlled standards. Some of these (.45 Colt "+P" in particular) are essentially proof loads by SAAMI standards. How do you certify a gun for ammunition that doesn't conform to a standard? The answer is more or less that you cannot.