Pressure signs in low pressure rounds

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MattE93

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I just finished shooting first ever reloads. .38 S&W using 200 gr SWC sized to .359” with overall length of 1.175” over a charge of 2.3 gr of true blue powder. These performed much better than factory ammo, hitting closer to point of aim, as the British revolvers were sighted in for 200 gr loads.

There was however unburnt powder in the barrel and in some cases. I understand this is from a light load, but please correct me if I am wrong. I want to work up my load to improve accuracy and make them a little more stout. The manual I am using calls for up to 2.6 gr of powder for a max load. My question is how to go about working this load up.

My two main concerns are the min and max loads differ by .4grs of powder, so I don’t have much wiggle room to work up the load. Second, I have read that high pressure signs are harder to diagnose in low pressure rounds, and that when you see things like flattened primers you have gone too far
 
There is no easy way, especially when you are playing with a low capacity round, with a heavy bullet, as you are with the .38 S&W and 200 grain bullets. It might be very difficult to reach a point where you have sufficient pressure to cleanly burn the powder, and not blow up the gun. I have had the same problem with Bullseye, which is usually all consumed in other cartridges as it is easy to ignite and functions well at low pressures.
Your two options are really to use a chronograph to see how your loads are comparing to factory loads in your gun, or better yet, stick with your current load as it is close to point of aim. There is little point in trying to make a .38 S&W 'more stought'. Get a .357 Magnum.
If you insist on trying, get a chronograph. Primers will tell you little or nothing (flattening can be a result of many reasons, not just high pressure).
 
Maybe I’ll stay put. No need to blow my guns or me apart to get a little more velocity. The rounds I made work well. They are just a little low of point of aim but I can deal with that as they are much better than factory
 
check trailboss loads all work, sorry in a hurry to message... they have a site... its a hoot to send a 300 win mag 200 yards and wait for it too hit ...
 
The first high pressure sign that you may get in an old low pressure gun could be when it blows up.

If you are shooting low you may need to DECREASE your charge to bring it to zero. That sounds wrong but it's not.
 
MattE93 said:
Maybe I’ll stay put. No need to blow my guns or me apart to get a little more velocity. The rounds I made work well. They are just a little low of point of aim but I can deal with that as they are much better than factory
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jethunter said:
The first high pressure sign that you may get in an old low pressure gun could be when it blows up.

If you are shooting low you may need to DECREASE your charge to bring it to zero. That sounds wrong but it's not.
Click to expand...

Increasing the velocity may well result in it shooting lower.
 
True Blue will leave lots of unburnt powder at low pressure just like Blue Dot. Work up the load as you would any, sticky cases are your most likely sign to encounter since the pressure will be much too low to produce any signs at the primer. I'd also suggest a chronograph. It's the single most useful tool you can buy for load development.
 
Trying to diagnose overpressure with flattened primers and sticky cases is kind of like rying to measure the speed of a car by looking at it on the highway. It's not a very good measurement. A chronograph is much better because it's an actual measurement, and there is a relationship between pressure and velocity, but still far from perfect. I have seen plenty of flattened primers on rounds that were not overpressured by any amount.

It's gonna be hard for you to get where you want with true blue. Suppose you have 10% of your powder that's unburnt, it means 0.23grn out of 2.3grn (you have in effect 2.07grn of powder that burns). Then you decide to add another little 0.3grn, and take it to max charge of 2.6grn, that's 13% more powder. At the same time as pressure increase, the amount of powder that burns goes up from 90% to 100%. At that point, 2.6grn of powder burns and creates pressure in the case. The relationship between the pressure is linear (if I oversimplify), so your pressure would increase by about 26%. That's a lot of pressure for a small increase of powder.
 
Maybe I’ll stay around where I am. The rounds work and out of these old DAO revolvers you aren’t going to win any medals. The rounds only need to hit near POA and shoot without killing me or the gun. With the load I have these criteria are met
 
MattE93 said:
Maybe I’ll stay around where I am. The rounds work and out of these old DAO revolvers you aren’t going to win any medals. The rounds only need to hit near POA and shoot without killing me or the gun. With the load I have these criteria are met
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Pretty well every reloader I have met starts off chasing speed, then learns accuracy and function are much better attributes to seek. Your gun is old as you said, I would be shooting the lightest loads that produced good accuracy myself.
 
MattE93 said:
Maybe I’ll stay put. No need to blow my guns or me apart to get a little more velocity. The rounds I made work well. They are just a little low of point of aim but I can deal with that as they are much better than factory
Click to expand...

Good idea especially if it's just for plinking and don't have to worry about power factor, etc.
 
Blue is a slow pistol powder. Not a particularity good choice for a 38S&W.

I would use Unique or 231. And a Chrony would be a big help.

Don't worry about blowing up your gun if if you stay within published loads.

Guys have shot 9mm in their Enfileds. Those are 35,000 psi in a 15,000 psi gun.
 
Ganderite said:
Blue is a slow pistol powder. Not a particularity good choice for a 38S&W.

I would use Unique or 231. And a Chrony would be a big help.

Don't worry about blowing up your gun if if you stay within published loads.

Guys have shot 9mm in their Enfileds. Those are 35,000 psi in a 15,000 psi gun.
Click to expand...

Interesting. The Lyman manual listed it as the most accurate .38 powder they tested
 
MattE93 said:
Interesting. The Lyman manual listed it as the most accurate .38 powder they tested
Click to expand...

It might depend what kind of powder thrower you have. Some throwers will not throw a flake powder at all.

Blue is a powder usually used for making full power ammo. For 38 S&W a fast powder like Bullseye, TightGroup, or 231 would be my choice, although my current horde of 38S&W ammo is loaded with a non-canister ball powder about Unique in speed..
 
Al-Sway said:
There is no easy way, especially when you are playing with a low capacity round, with a heavy bullet, as you are with the .38 S&W and 200 grain bullets. It might be very difficult to reach a point where you have sufficient pressure to cleanly burn the powder, and not blow up the gun. I have had the same problem with Bullseye, which is usually all consumed in other cartridges as it is easy to ignite and functions well at low pressures.
Your two options are really to use a chronograph to see how your loads are comparing to factory loads in your gun, or better yet, stick with your current load as it is close to point of aim. There is little point in trying to make a .38 S&W 'more stought'. Get a .357 Magnum.
If you insist on trying, get a chronograph. Primers will tell you little or nothing (flattening can be a result of many reasons, not just high pressure).
Click to expand...

Actually, with the small difference between the .38 special and .375, the extra capacity was needed when the cartridge was developed; with todays modern powders, there is lots of room to get .357 performance using .38 special cases... Just don't use them in a light framed .38 revolver.
 
MattE93 said:
I just finished shooting first ever reloads. .38 S&W using 200 gr SWC sized to .359” with overall length of 1.175” over a charge of 2.3 gr of true blue powder. These performed much better than factory ammo, hitting closer to point of aim, as the British revolvers were sighted in for 200 gr loads.

There was however unburnt powder in the barrel and in some cases. I understand this is from a light load, but please correct me if I am wrong. I want to work up my load to improve accuracy and make them a little more stout. The manual I am using calls for up to 2.6 gr of powder for a max load. My question is how to go about working this load up.

My two main concerns are the min and max loads differ by .4grs of powder, so I don’t have much wiggle room to work up the load. Second, I have read that high pressure signs are harder to diagnose in low pressure rounds, and that when you see things like flattened primers you have gone too far
Click to expand...

Use a fast burning, low volume powder. I use HP38 (same as Winchester 231) in everything from 9mm to .38 special. It is not expensive, it is clean and reliable; even with very light loads in high volume casings (you can hardly see 3.1 gr. in the bottom of a .38 special. It works exceptionally well behind 200g SWC .45s. Heavy bullet, small casing. :) Work your loads up gradually until you see some flattening on the primer then back off.2-.5 gr. British revolvers are strong. A S & W of that era; not so much.
 
MattE93 said:
Maybe I’ll stay put. No need to blow my guns or me apart to get a little more velocity. The rounds I made work well. They are just a little low of point of aim but I can deal with that as they are much better than factory
Click to expand...

Factory loads are made to be safe in old weak revolvers; the Webly Enfields are not weak.
 
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