Another 38 Special Question

[ancient-one]

Sierra, as stated in another thread, shows 850 fps with their 158 gr JHC.
I have some 158 gr Remington SJHP I would like to load using Bullseye but can find no data on that combo.
What problems would I run into using the Sierra data? Their bullet is similiar in the fact it has exposed lead nose but looks like a slightly a longer jacket. Thanks for any comments.

 

[Skip Sackett]

Physically compare the bullets.

Here is a basic rule for using data from one bullet to another, compare physical characteristics.

What I mean by that is this; what are the bullet, not cartridge, OALs? Are the bullets the same length? Where is the crimp groove in relationship to the BASE of the bullet? Is it closer to one end on your bullet? Is more of one going to be in the case than the other?

The thing that matters most is how much of the bullet is in the case.

Case in point: Say one 158gr JHP has a really round nose and the other has a more "TC" type. More weight can be placed in the nose of a RN bullet than in a TC causing the RN to be shorter in OAL but the cannelure is .100" closer to the nose of the bullet. That means, if loaded to the cannelure, it is going to sit much deeper in the case. That would raise pressure considerably. If there is a significant difference in that measurement you may have to reduce the powder charge even below the suggested starting weight for your bullet.

What do I do? If it is over .030" different in the measurement mentioned above, I reduce the minimum charge by .5gr and start there when using fast powders like Bullseye. I work up the load until I get the desired velocity paying close attention to the only pressure signs I have to watch, primer condition and extraction.


FWIW

 

[Rule3]

Skip,
I am actually starting to be able to understand what you are talking about
I do mean that in a good way. Excellent explanation.

 

[LoboGunLeather]

I recall reading of a number of incidents back in the 1970's involving Bullseye powder and jacketed bullets. In some (larger) cartridge cases, low-density loads of Bullseye do not ignite properly and the force of the primer can push the bullet into the barrel where it becomes lodged.

I remember experiencing this once, then doing some research on the subject.

I don't remember the specific source(s) of this information, but I personally stopped using Bullseye for jacketed bullet loads in .38 Special and larger cases for this reason. Since then I have made a point of using slower burning propellants that have a higher loading density (less air space in the loaded cartridge).

 

[cmort666]

I recall reading of a number of incidents back in the 1970's involving Bullseye powder and jacketed bullets. In some (larger) cartridge cases, low-density loads of Bullseye do not ignite properly and the force of the primer can push the bullet into the barrel where it becomes lodged.

I remember experiencing this once, then doing some research on the subject.

I don't remember the specific source(s) of this information, but I personally stopped using Bullseye for jacketed bullet loads in .38 Special and larger cases for this reason. Since then I have made a point of using slower burning propellants that have a higher loading density (less air space in the loaded cartridge).

That'd have to be a REALLY minute charge.

Years ago, "Guns & Ammo" recommended the use of kapok as wadding to keep the powder charge close to the primer in low density loads. Back in college around '80, I used little squares of toilet paper for very light loads in the .45acp, but I gave that up, since I never load anything under 3.7-3.8gr. of Bullsye in the .45, and 2.7-2.8gr. in the .38 Special and I always get proper combustion with those.

 

[Steve C]

What problems would I run into using the Sierra data?

You won't run into any problems using the Sierra data. Its quite common to use data from bullet specific manuals for other type bullets of the same weight.

In magnum and other high pressure cartridges its very important to use a start level load and work up if you want to optimize velocity and accuracy while looking out for excessive pressure. With low pressure cartridges like the .38 spl there's no point in looking for pressure signs as they would not appear until you are way beyond maximum for the cartridge, a condition that will not happen staying within published data.

If you are shooting in a K frame or any magnum chambered pistol there is no danger in using heavier loads but if you have an older J frame or aluminum frame revolver then you can assume that the maximum load is likely at at +P level unless the manual is of later issue where +P loads are specifically listed.

 

[Skip Sackett]

Hope this helps more!

Here is a picture to help illustrate my point above. There is a certain part that is by way of analogy.

These bullets are the same length from the cannelure to the nose of the bullet. If seated to the same case OAL, which one is going to be in the case further? Right, the one that is longer from the base to the cannelure.

For the sake of argument, let's say they are the same weight. Which one is going to develop more pressure? The one with more of the bullet inside the case. Can't the OAL be the same? YES!

Think about this, it's important.

 

[butchd]

When I stated reloading back in the 60's I stuck a jacketed bullet in the crown of a 4" mod 19 bbl. A tiny footnote in the Speer #8 said that the bullet I was using had to exceed 750 fps (by memory) to avoid the problem.

 

[ancient-one]

Thanks to all for the info..Smith Crazy, I definitely understand what you are saying. I am going to try to obtain the base to the cannelure measurement on the Sierra 158HP bullet.

 

[oldRoger]

Just to amplify what smith crazy has pointed out, the amount of space between the powder and base of the bullet has an important bearing on pressure. All things being equal (obviously all things are never equal) the closer to a full case you have the more the pressure will be influenced.
If the load was 6.0 grs of Bullseye in a .357 case we might expect less influence on pressure than if the load was 13.9 grs of 2400, given the two bullets he uses as examples.
I have a set of cases which I have opened enough so that I can slip a trial bullet in and out. This lets me observe what's happening inside the case with powder loaded and bullet seated at the proposed depth.
Using my "slip-fit" 10MM case, I have found 800X—10MM loads people on other sites recommended to be very highly compressed. Highly compressed scares the stuffing out of me when were talking about smokeless powder.

 

[Treeman]

The initial space in the combustion chamber can have a dramatic effect on peak pressures but compression should not be terrifying in and of itself-many loads are developed based up a 100% loading density or compressed powder charges. All shotgun loads require compressed powder charges. I will grant that usually the wad column itself is compressible (not in .410) allowing some initial easy expansion of the combustion space as the burn commences but the powder IS compressed and shotgun pressures remain low. The dangers come ito play when we change the combustion space from what the initial data was based on or compress powders which are not well suited to such treatment.

 

[oldRoger]

I should have expanded that comment a bit, Rifle loads are also frequently compressed. In my experience handgun loads are infrequently compressed. Lyman indicates compressed loads in their data, for example; the only compressed loads I see for the .357 are; max H4227 and N110 loads.
Using smith-crazys examples you could easily go from a load with free space above the powder to a compressed load and so going from free space less than no space.
Many of us are forced to use a generic load for jacketed bullets, only good luck gives us a variety of published loads for the exact bullet and powder we want to work with. Especially when working with self-loaders we are restricted to overall length. So I think it wise to keep track of what's is going on in the case.

Black Powder loads are also compressed, the rule seems to be compressed as much are possible.

 

[ancient-one]

A little update. I tried to buy a box of the Sierra 158 gr JHC(so that I could measure base to cannelure distance) and as expected no one had them, not dealers, the distributor or Sierra who said not to look for any until next year.
I talked to one of the reloading technicians at Sierra to find if they had the measurements which they didn't. When he found out what I was wanting to do he computed the distance and said that it could be slightly off because he didn't know where on the cannelure that they crimped the case. His measurement was .385 and when I checked the Remington it was .385 to the center of the cannelure.
It sounds safe enough to use the Sierra data. Again thanks to all of you and the very nice employee at Sierra.

 

[Treeman]

Checking is always appropriate but FWIW nearly every 38cast bullet in the 150-173grain range has the crimp groove positioned to give the same powder space encroachment. I don't buy jacketed bullets for 38 special or .357 mag but I am not surprised to hear that multiple brands have the cannelure positioned at about the same height.