# Starting/Maximum Powder Charge and DNR



## Viscomm (Oct 16, 2009)

Good Day!

I have (with a lot of help from members of the Forum) successfully loaded 250, 45 ACP rounds. They were reloaded in cleaned, sized cases with a maximum length of .898". The primers were CCI300 and the bullets were Speer 230 gr TMJ RN, set to an AOL of 1.260". The powder was Alliant Unique. The Alliant Reloaders Manual specifies a maximum charge of 6.5 grains. But many other reloading manuals also give a starting charge OR recommend charging initially at 90% (light by 10%) of the maximum charge. So I charged them with 5.8 grains of powder. I shot them in a new Sig 220 and an AR-15 chambered for that caliber. All shot accurately without any malfunctions in both guns. But here is where it gets sticky. 

I recently had an e-mail discussion with a senior technical coordinator at Speer. I was asking for some information about reloading 38 Spl ammo. He gave me the specs and then told me the powder charge values were DNR (Do Not Reduce) which just happened to be the "maximum" values from the Alliant manual. I asked him:

1) Am I in trouble with the way I am loading the 45s? 
2) What are the "whys" behind the DNR limitation/warning?
3) What problems would I create if I loaded the .38 Spls 10% light? Is there an issue with not sufficiently filling the cases? I am shooting a Ruger SP101 with a 3-1/16" barrel and a Ruger LCR snub-nosed. 

He came back with a number of points that I would appreciate your collective opinions. He asked how would I know I left a bullet in the barrel? The need to manually rack the slide on the Sig would be a definite clue that a bullet remained its barrel. But I wouldn't be that lucky in the AR because it would most probably cycle the next round. Then I would have what has come to be known as a KABOOM. The next stop would be looking for replacement guns/gun parts/body parts. He said that too light a load can/will cause near as many problems as too heavy.

He said that Speer calls for 5.5 grs of Unique as a MIN 45 ACP load and this was determined using a Sig P220 - so I would be fine with that charge for the pistol. However, if I add the effect of the longer barrel on the AR, the rules will change. He went on to say that for any reloading for the AR, I should stay near the very top of the load values which is 6.5. 

He wrote that DNR's are set so that shooters do not leave a bullet in the bore. The pressure is low enough in the 38 Spl (17,000 psi). When you throw-in "barrel-cylinder-gap", a little pressure could escape with a gap of less than a 0.012". He said that 5.7 grs of Unique should work well in the Ruger - which is, again, the maximum charge from the Alliant manual.

Should I load every round exactly the same according to the reloading recipe ... or should I continue starting at 90% ... or split the difference? Or, should I load different rounds for the Sig and the AR?

What do manufacturers do? I understand they never load to maximum charge but not as light as a target load.

So how do I proceed? 

Best regards,

Robert


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## dosborn (Apr 17, 2009)

The first thing I would do is get one or two more manuals and see what they recommend for min/max charges. 

Another option is to look at other powders. I like Bullseye. I have loaded some as low as 3.8 with it and it cycled fine through my full size 1911 and Sig.

In my experiences, .45 is pretty forgiving.


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## zhurdan (Mar 21, 2008)

Personally, I load at about 2-3 grains less than the max, which is usually the "recommended" loading in most manuals. I use Speer manuals, but I'm guessing Alliant manuals have a similar denotation. I load 10, test and look for any signs of over pressure on the case using the weapon I'm loading for. If it's accurate enough for my purposes, I stick with it, if not, I'll take it up a grain and retest, again checking for signs of overpressure. I've rarely used the maximum loading for my reloads, but that's because I don't use reloads for defensive carry. (Yes, I realize there are many schools of thought regarding the legal side of reloads involving an actual shooting incident, but I prefer to take the "factory loads were used" approach.) For my practice rounds, I generally load them so they match the POA/POI of my defense rounds, and in general, they don't have to be near the maximum loads. 

As far as the DNR classification, it's a damn good idea to ensure that your load weights are consistent and unless you're loading down for a "gaming advantage", say SASS or other shooting sport, you probably won't find any benefits to loading near the lower range of the listed powder charges. With any new load I work up, the testing always involves checking the bore prior to testing, and then after each shot until I'm comfortable that the load is consistently leaving the barrel. Usually, for me, this is overkill as I don't load near the lower end of the chart, but it's still not a bad practice, especially when dealing with things that go boom as part of their function considering that a mistake or incorrect loading may make it go boom in a way that it's not supposed to.

Someone mayl need to correct me on this as I don't have my manuals with me at work, but I recall something about if there's more than 50% case volume empty, it can cause problems, but in .38spl and .380, you'd probably have to be waaaaay down the chart in regards to light loads to get to that point using Unique (which I use almost exclusively). 

Best advice, stick with the charts unless you know what to look for on the casings for high pressure and check your bore for bullets from a low charges. There's a fairly noticeable audible difference in a squib or severely undercharged round, but you have to be paying attention. Reload testing is a one at a time affair for me. Shoot, check, check again... shoot the next one until satisfied with safety.

Good luck, hope that helps.


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## mikld (Jun 20, 2009)

As for the DNR (Do not resusitate?), some powders should not be loaded down; H110 and W296 come to mind. "Detonation" and extremely high chamber prssures can occur with reduced loads. In such a situation I just go with the recommended load...

I doubt if your AR would cycle a new round into the chamber with a squib round. If there isn't enough power to get the bullet out of the barrel, there would not be enough to cycle the action. With your revolver, you must be aware. If sompin' ain't rite, stop and check 'er out! If your last shot sounded wrong/light, STOP! *Every shot should make a lot of noise and recoil!*


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## TOF (Sep 7, 2006)

My first rounds of a new formula are shot over a chronograph. and into either paper or dirt.

If the chrono doesn't give me a reading or the paper doesn't have a new hole or the dirt bank doesn't show an impact or I hear a pop instead of boom a full examination of the firearm occurs.

If I were you I would load no more than 10 samples near the bottom and ten near mid range of the manual your formula comes from. Five of those would be chronoed and if velocity and primers looked OK the next five would be tested for accuracy.

If the results were acceptable more can be processed.

Don't approach the top of the chart till you have loaded for a while and have become a bit more comfortable with the process.

Have fun but stay safe.


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