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Old September 29, 2013, 01:21 PM   #1
Pond, James Pond
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Should I go up? Seat deeper? Crimp more? All of the above?

N320, 5.1gr, small pistol primer, assorted brass, 125gr copper-plated bullet. All went bang, but one only just! It was a weak pop, but it did leave the barrel.

Bear in mind that this load was the stronest of 4 charges I loaded and tried. It is Lyman's listed as the max load for a 125gr JHP.

These cartridges were not particularly accurate, even at about 7 yds, and chrono'ed at only about 640fps (2" barrel, 125gr bullet on Ballistics By The Inch gives a value of about 750fps).

Between that and the single weak shop, I'm guessing it is a borderline weak load, despite being near max for the hollow-point Lymans lists.

So, how to proceed, considering that my .38Spl is a relatively fragile type and wouldn't take high pressures very well?
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Old September 30, 2013, 12:56 AM   #2
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I do not have data in front of me,this is opinion/observation.

When the Cowboy action shooters pursue low velocity for low recoil,they do start sticking bullets in the barrel with too light of loads.I do not think you will find many loads listed below 700 fps.I'd stay above 700.(opinion,not rule)

A significant factor,you mention you are using copper plated lead bullets with jacketed bullet data.That may be your problem.I'd use cast bullet data with plated bullets.Jackets produce higher pressure with a given charge and bullet weight.(Generally speaking about handgun loads).

The opposite is also typical,a cast bullet will produce lower pressure/velocity with a given charge.Most smokeless powders require a certain minimum pressure to burn properly.

maybe that will help.
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Old September 30, 2013, 01:22 AM   #3
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A significant factor,you mention you are using copper plated lead bullets with jacketed bullet data.
True, particularly as a HP bullet will have great volume to fill the case mouth than a cast one.

There is data for Rainier bullets at 125gr, but even there the max value listed for N320 is 5.2gr. That would put me at between 0.15 and 0.05gr below max for a cast bullet. So I should still be getting decent velocity.

I was thinking pressure was lowish and so a deeper seat and/or a tighter crimp would help.
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Old September 30, 2013, 08:14 AM   #4
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It may or may not. The force it takes to engrave a jacketed bullet into the lands is greater than for the soft plated bullet. This offers added resistance for the powder to build pressure against. The roles reverse if the pressure is high enough to bump the lead up in the forcing cone.

The other problem is you are working with a 2" barrel. Any degree of irregular ignition has the effects exaggerated by a short barrel. I've found in the past that a quick, easy-to-light powder like N310 produces better velocity consistency in them.

Another thing to check is that none of the bullets are backing out of the cases during recoil, increasing the volume the powder starts burning in. The lighter the revolver, the more likely this is to happen. A good roll crimp is generally used to prevent this. I don't recall the bullets you are using having a crimp cannelure, and that could be a real disadvantage with the lightweight gun. You can buy a tool to roll them in, but I don't know how the plating handles that. You could try the military method of painting liquid asphaltum (pitch) around the inside of the case mouth to glue them in. You will want to degrease both cases and bullets them before doing that.

In your shoes, especially in light of your catsneeze ignition in one round, my first step would be to try magnum primers, working the load back up again. The purpose of magnum primers is to make more gas in th case to raise the start pressure the powder burns in. That may be just what you need here. After that, consider faster powder and more extreme crimping measures.
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Old September 30, 2013, 01:47 PM   #5
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Thanks UncleNick. I'm glad you've explained that mine is a difficult platform to reload for: I was starting to think I'd never find a suitable load!!

Magnum primers may be an option. I'm sure I bought some once. But a standard load would also be good to have for when the magnum primers run out (and believe me there will be a time when they can't be found for love nor money!!)

I may also try a bit more crimp.

I won't touch the charge before I've tried those, in fact I may drop the charge a bit when the mag primers go in!!
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Old September 30, 2013, 05:02 PM   #6
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I understand you do not have good component availability.

Another issue you may be up against is bullet dia vs cylinder throat and bore dia.

Particularly if these copper plated bullets are actually 9mm bullets measuring .355-.356.

Most important is the cylinder throat.Measure those as best you can,or use a bullet as a gage.If it is a loose fit,you may require a larger dia bullet to get good results.

I suppose it might not hurt to check the gap between the cylinder and barrel.Unclenick would be the man,but its worth checking.

At your velocities,I would not back off the charge much,at least beware of plugging the bore with a squib.Don't pull the trigger again.
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Old October 1, 2013, 12:26 AM   #7
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Particularly if these copper plated bullets are actually 9mm bullets measuring .355-.356.
This is something I have not checked yet and will have to do as well as the throat. The bullets are H&N and should be decent quality so I expect their .357" to mean that, but we'll see!!

Quote:
At your velocities,I would not back off the charge much,at least beware of plugging the bore with a squib.Don't pull the trigger again.
Been there, done that...

I really hope I can get the N320 to work: it is only one step below N310, IIR. I just don't want to shell out on yet more powder!!
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Old October 1, 2013, 06:40 PM   #8
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James,

Are these the gold-colored H&N's with the transparent polymer cladding? If so, their lubricity (relative to actual copper) is quite high, which lowers start pressure even more than normal. Good, consistent quality, but you may find you need a little extra powder with them to get enough start pressure. N310 and Norma R-1 should be good powders to use with them to overcome the lack of start resistance, and they are brands you can tap on your side of the drink. They just won't get to same velocity as the N320 before reaching peak pressure limits.
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Old October 2, 2013, 02:20 AM   #9
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Are these the gold-colored H&N's with the transparent polymer cladding?
Yes, they are.

As I said earlier, it seems that I have been unlucky to attempt cutting my reloading teeth with a relatively fragile 2" snub!!

At this stage I don't really want to buy another powder, but if my exiting plans fail, then that will be my next move. At least I can use the N320 in my .44Spls if I do end up ditching it as my .38 powder.

So my plan of action is two fold:

1) try to get magnum primers and make some loads for those, starting perhaps at 4.9/4.8gr of N320

2) keep my exiting primed cases as they are, but up the powder by 0.1gr increments and see how it goes.

I will never see flattened, loose primers in my cases. To my mind, in a revolver as trim and lightly built as the 680, sticky extraction would be something I'd heartily like to avoid.

So, this leaves one question:
What, in a low pressure, slow round like .38Spl, is the best way of gauging pressure that is creeping too far?

My guess is velocity: both realistic fps and a steady incremental rise should mean safe pressures.
Leaps in velocity or speeds that are unlikely for a 2" would be a sign to back off. Agreed?
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Old October 2, 2013, 11:04 AM   #10
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I dont have any valuable info regarding this.topic, however, i was reading and noticed someone mentioned jacketed and plated bullets. I recently purchased some plated bullets, usually buy jacketed bullets. I didnt realize there was a difference. I just assumed that was a different manufacturer calling it plated rather then jacketed, figured it was the same thing. Would anyone care to give me a brief explantion regaurding the differences and if using plated bullets with jacketed data will make my rounds unsafe to use.
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Old October 2, 2013, 03:17 PM   #11
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As I understand it, it is partly to do with volume.

A 125gr bullet that is mostly lead with a very thin layer of copper plate will take up less "space" than a bullet with a thick layer of copper given that lead is denser than copper.

So, using the same charge and same AOL, there will be less empty case space in the cartridge with the plated bullet than the jacketed.

Another aspect is that, certainly in the case of my H&N plated bullets it seems that the slick polymer film over the bullet reduces in less friction in the forcing cone than the plated bullet meaning that there is less pressure build-up behind the bullet than in the jacketed bullet's case.

Disclaimer: I may be completely wrong... I am a reloading novice. Secondly, there are probably loads of other factors influencing this, assuming my first points are correct.
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Old October 2, 2013, 04:16 PM   #12
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Jeff2131,

They are different manufacturing processes and materials. A jacketed bullet is usually made by what is called the cup and core process in which a jacket cup is drawn from gilding metal, which is a form of low brass, having only about 5% zinc (not enough to make it yellow) but which is still rather harder than pure copper. Once the cup is drawn, the bottom is formed either into the base (match bullets and modern expanding bullets) or into the nose (full metal jacket bullets). A piece of precision cut lead or mild lead alloy wire is then swaged into the cup by a hydraulic ram. Dies then form the open end of the cup around that lead to take final shape as the nose or the base (FMJ's) of the bullet.

Plated bullets are generally made of a swaged lead bullet core or a cast lead core that are electroplated with pure copper. The idea is to make a covering that limits how much lead is put into the air at firing or on impact with a backstop. But it's not nearly as hard. These bullets are coming to replace pure lead and cast lead bullets in places where environmental lead exposure needs to be limited. This is mainly at indoor ranges.

In general, plated bullets are not as precise for target accuracy as jacketed bullets, but they also cost less.

The one exception to the above is Hornady's AMP jacket process. This process electroplates actual gilding metal alloy onto pre-formed lead bullets in a way that maintains high enough precision (thickness symmetry) for match bullets.


James,

Velocity doesn't measure pressure very well. I had a link I can't find to a site showing three different .223 rifles shooting the same loads and getting similar pressures but significantly different velocities, despite having the same barrel lengths, but I can't locate it at the moment. It works out that kinetic energy of a bullet is proportional to the average pressure behind it (less bore friction), but the average can consist of significantly different ratios of peak pressure to muzzle pressure, dependent on how well and how fast the powder starts burning. In general, for a given velocity in a given gun using a given bullet, a fast powder will make higher peak pressure and lower muzzle pressure, and vice versa in achieving the same average pressure and velocity.
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Last edited by Unclenick; October 4, 2013 at 02:38 PM.
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Old October 4, 2013, 12:26 PM   #13
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Wow, thanx, great explanation! Almost like watching "How its made"! Hahaha you rock!
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Old October 11, 2013, 02:56 AM   #14
Pond, James Pond
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1) try to get magnum primers and make some loads for those, starting perhaps at 4.9/4.8gr of N320
Last pack of CCI 550 Mag small pistol primers bought. It means that I may never see another pack on sale here (I'm sure they just play lucky dip when ordering reloading parts...).

However, it also means that I can see if the mag primers make usable .38Spl cartridges for my snub using N320.
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Old January 25, 2014, 10:05 AM   #15
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I am now reloading some new cartridges for the snub. I will use the results to compare with the original velocities that prompted this thread in the first place.

Here are the loads:
4.9, 5.1 and 5.2gr of N320 seated to 35.5mm (1mm down from 36.5mm OAL), half turn crimp.

4.9, 5.1 and 5.2gr of N320 seated to 36mm (0.5mm down from 36.5mm OAL), half turn crimp.

4.9, 5.1, 5.2 and 5.3gr of N320 seated to 36.5mm, but with three quarter turn crimp (extra 1/4 turn crimp).

And finally,
4.5, 4.7, 4.9 and 5.1 of N320 seated to 36.5mm, half turn crimp but magnum primers.

3 shots of each over the chrono.

I don't know if 0.5mm increments in seating depth are too small. I hope not because metering those charges out took ages! I just didn't want to over-strain my little snub. It is not a hefty gun.
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Last edited by Pond, James Pond; January 26, 2014 at 07:40 AM. Reason: change to actual figures
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Old January 25, 2014, 04:06 PM   #16
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Didja look here? http://www.lapua.com/en/products/rel.../relodata/6/34
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Old January 25, 2014, 06:58 PM   #17
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like the others said, use the plunk test, and load it so it cycles, I'm getting +/- 1000 FPS from mine..
124 lead..
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Old January 26, 2014, 03:30 AM   #18
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like the others said, use the plunk test, and load it so it cycles, I'm getting +/- 1000 FPS from mine..
124 lead..
Did you two mean to post those on the 9mm thread?

What is the plunk test?! Sounds unhygienic.

As for Lapua load pages. Yes I actually use those quite a bit, but usually as a guide as they rarely have my chosen bullet. Just bullet weights. If I'm lucky they will have several of the same weight as in the case of .308!!
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