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Discussion Starter · #1 · (Edited)
Need someone to explain the acronyms here in the Hodgdon tables. They list these 2 bullets:

1.) 125 GR. SFIRE IMR 4895 at 2.700", starting 43.0gr, 2772 fps @42,100 PSI... max 48.0gr, 3068 fps @ 55,000 PSI

2.) 125 GR. SIE SP IMR 4895 at 2.700", starting 48.0gr, 2969 fps @45,600 PSI...max 51.8C, 3185 fps @ 55,200 PSI

question...what are the 2 abbreviations... SFIRE ? Who makes it? ..and is the second one Sierra SpirePoint, SoftPoint, Spitzer ?

I have Speer 125gr TNT JHP, is this the same as #1 or #2 ?

How can there be so much difference in the powder charge for the same weight of bullet and the same powder? The max of #1 is the starting point for #2 ? Don't get it....

I'm using 41gr of 4895. I can't imagine jumping up to 48gr !! Isn't that a little hot for both of those loads ?

Sorry for all the questions...and thanks.
 

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SFIRE - Sinterfire frangible bullets
http://www.sinterfire.com/
Bullet length 1.110" shank length 0.287"

SIE SP - Sierra Spitzer-Pointed
Bullet length 0.882" shank length 0.059"

Speer 125 gr TNT
Bullet length 0.920" shank length 0.097"

(shank length is the portion from the base to the ogive)
(all lengths are approx. based on data from QuickLOAD ballistics software)


The Sinterfire bullets are longer than the Sierra bullets. That means that, with the same overall length, the frangible bullet is seated deeper in to the case. This creates higher pressures and therefore you need less powder to achieve the same pressures and speeds as you get with the shorter Sierra bullet.

48 grains of IMR 4895 with the Sinterfire bullet will produce about 57000 - 58000 PSI and with the Sierra bullet you should get somewhere around 49000 PSI (based on my QuickLOAD software and an overall length of 2.7"). I know that the Hodgdon book says different but it all depends on how much volume is in the case and they may be using different brass than I accounted for.

I don't know what to tell you about your load other than it is a very light load according to every reference I have. 41 grains of IMR 4895 is a normal load for a 168 grain bullet, a lighter bullet would be capable of using far more powder than that. Your load is probably only developing about 31000 PSI, barely enough to even operate the system. You could easily go up to 48 grains of powder with your bullet and maybe as high as 49 grains using the right brass, primer, and seating depth. 48 grains would probably put the chamber pressure at about 50000 PSI.




Need someone to explain the acronyms here in the Hodgdon tables. They list these 2 bullets:

1.) 125 GR. SFIRE IMR 4895 at 2.700", starting 43.0gr, 2772 fps @42,100 PSI... max 48.0gr, 3068 fps @ 55,000 PSI

2.) 125 GR. SIE SP IMR 4895 at 2.700", starting 48.0gr, 2969 fps @45,600 PSI...max 51.8C, 3185 fps @ 55,200 PSI

question...what are the 2 abbreviations... SFIRE ? Who makes it? ..and is the second one Sierra SpirePoint, SoftPoint, Spitzer ?

I have Speer 125gr TNT JHP, is this the same as #1 or #2 ?

How can there be so much difference in the powder charge for the same weight of bullet and the same powder? The max of #1 is the starting point for #2 ? Don't get it....

Cole distributing has a 308 125gr Soft Point, #Bullet-01A... http://www.coledistributing.com/ is this the same thing as what Midway has here ? .. http://www.midwayusa.com/viewProduct/default.aspx?productNumber=337808

Would either one of these bullets be similiar to the Speer TNT 125gr bullet I have ?...as the Speer shoots great out of my M1A, but thats using 41gr of 4895. I can't imagine jumping up to 48gr !! Isn't that a little hot for both of those loads ?

Sorry for all the questions...and thanks.
 

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I your thinking of pushing the Speer 125TnT past 3000fps don't! they tend if spin apart.
 

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Sorry Phil, I should have pointed that out, I was just trying to show that he could safely move the TNT faster if he wanted to. Thanks for catching that.


I your thinking of pushing the Speer 125TnT past 3000fps don't! they tend if spin apart.
 

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Discussion Starter · #5 ·
Thanks for the great explanation of that Rammac ! Never would of thought of checking the shank length...that explains it all. And thanks for the heads up Phil, no i wasn't thinking of really pushing the envelope on the TNT bullet.

Even assuming those loads are for commercial brass and me using the NATO brass reducing the starting load to 46.5 gr still seems like a LOT ! I just got done reloading some TNT 125 loads @ 2.70" with CCI#34 primers, increasing my last load by only .5 gr to 41.5 gr to see if that improves the accuracy of an already accurate round. But even at that low level, according to you guys, that seemed like the case was pretty darn near full already ! Maybe it was just an illusion, but now my curiosity is up....may have to go back to garage and see how full 46.5gr really is !
 

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Well definitely use your best judgement and never take anybody's word for powder charge weights. I posted that info based on software calculations (QuickLOAD ballistics software) and my personal experience (at least the part about the 168gr loads). You might be using a case with a volume that is far less than I'm using, in which case the pressures will go up. Seating depth is another factor, my updated numbers were based on an OAL of 2.7", initially I used 2.83" (my normal OAL for the 155gr and up) and the pressures were a couple thousand PSI less with the longer OAL.
 

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Discussion Starter · #7 ·
Well definitely use your best judgement and never take anybody's word for powder charge weights.
Right, sure...I'm using the Winchester White Box brass btw, which when I use I always go about 1.5gr less than stated in the manuals just to be safe.

And I also use the 2.70" OAL for this load...

my personal experience (at least the part about the 168gr loads)
And that's exactly why I started this thread as my 168gr loads, I also use 41gr of IMR4895 in the same brass @ 2.80". I was thinking like you...why am I using so little powder for such a smaller weight bullet ? Honestly, I can't remember where I got that figure for the TNT bullet, might of been here, and thought I'd try it...seemed light though, like u said.
 

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One of my SM M1As shoots extremely well with this load...

125 TNT - 41.5 IMR 4895 - Nato brass - 210M - 2.770" AOL

42.0 is good, but if I go up to 43.0 & 43.5 the groups open up big time.
 

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Discussion Starter · #9 ·
Thanks for that levisdad...looks like I'm on the right track then. I just adjusted the weight to 41.5gr of 4895 @ 2.70" OAL....Pretty close to yours then....that was gonna be my next step in playing with the length.
 
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