Author Topic: 124 RNFP, anyone else have issues with OAL in a 75b?  (Read 8211 times)

0 Members and 1 Guest are viewing this topic.

Offline outdoor_guy

  • Newbie
  • *
  • Posts: 23
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #30 on: July 26, 2012, 01:55:29 PM »
I don't quite see it the same way.  If I were starting from scratch with the loads/gun, I would definitely see the logic though.

I know it's not 100% scientific, but over the course of several hundred rounds initially in the gun, using the other loads (RN or HP, regular powder charges), I had VERY consistent accuracy.
With the (accidentally) FP bullets loaded over the same powder, but being compressed to the shorter OAL (by the guns' action) I also had excellent accuracy.
Loading to the shorter OAL (1.030), and lower charge (3.9gr), the gun seems to shoot very inconsistently.
Agreed, there are several variables in play, but the 1.030 is somewhat fixed, based on the chamber, and the powder charge is limited unless I hear othwise, or very carefully test some loads with .1 gr difference.

That's what I'm mostly trying to determine, if using the previous combination again it will shoot consistently. 
If so, I'll probably stop messing with the XTreme FP bullets I've got and either sell them, load them for my carbine, or if I hear back from Hodgdon's with additional load-data, load them up a bit and see if they produce consistent results.

I like to fiddle, to an extent (used to be a mechanic, way back), but in general my time at the range is limited and I'd like to enjoy shooting mostly, and not wonder if my latest batch of loads is going to be consistent.
9mm bullets are cheap, and life is short, to summarize  ;D

-pete

Offline Wobbly

  • Moderator
  • Hero Member
  • *****
  • Posts: 9170
  • Loves the smell of VihtaVuori in the morning !
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #31 on: July 26, 2012, 08:06:15 PM »
I don't quite see it the same way.  If I were starting from scratch with the loads/gun, I would definitely see the logic though.

Pete -
Don't look now, but you ARE starting from scratch.  ;D The only things you have nailed down are your OAL for that bullet and your primer.

Best of luck my friend and enjoy safe shooting.

 ;)
In God we trust; On 'Starting Load' we rely.

Immature reloaders ask: What's wrong with this gun?
Mature reloaders ask: What did I do wrong

Offline 1SOW

  • Hero Member
  • *****
  • Posts: 15026
  • GO GREEN - Recycle 9MM
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #32 on: July 26, 2012, 09:31:32 PM »
Pete, I don't see the benefit in loading up more of previous loads with different bullets for any meaningful comparison.

Choices:  You have the bullets.  You have some experience with that powder.  You can follow thru with your load development in .1 gr steps.  You may find you don't like the bullet-powder combination, or you may find the 9mm Holy Grail.  You won't know until you test the load SAFELY step-by-.1 gr step.

Tightgroup is not a very adaptable/forgiving powder.  You can try Win 231/HP-38,  which is much more adaptable with its much wider load range for your short oal .   

If you aren't comfortable with that bullet's short OAL limitations, I also understand that.  I'm not real happy with very short oals either.  I personally draw the line at 1.09+" oals.   You can switch to a different bullet that will allow longer oals.  Your bullets can probably be sold locally .

Reloading gives choices.  Benefit #1.   



 

   

 



« Last Edit: July 26, 2012, 09:33:45 PM by 1SOW »

Offline outdoor_guy

  • Newbie
  • *
  • Posts: 23
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #33 on: July 27, 2012, 01:08:26 AM »
Can you explain more on the load range of 231/HP38 in 9mm?  I see more or less the same range (about 0.3-0.4 gr between min/max) for both powders, and the pressure min/max is pretty close, although I admit 231 tops out at ~28K with 231 and ~30K with Titegroup, so there's a little more pressure safety on both ends of the loads.
Is that what you mean by "adaptable".

I do play around quite a bit with different powders, but more when loading 357, 44Mag/Spl, and rifle, since there's a HUGE variability there.  The pressure differences loading 44 are enourmous, for the same given velocity, depending on powder selection, as I'm sure you know.

Loading 9mm and 40 I tend to default back to Titegroup for probably 95% of the loads, although I have done some with Longshot, and a few with HP38.

Thanks again, both you in particular.  I know I may seem a little random, but I've actually thought the process through pretty carefully, in terms of my options.  My background is math/physics/engineering, so do ok with that kind of stuff, usually;-]
The problem I have sometimes is not "seeing the forest through woods", which can happen when reloading, I'm learning more and more.  Like anything, experience is worth more than a ton of reading/research.

I did load some of my FP loads at 4.0 tonight (still at 1.030), and some regular RN (also 124gr) at 1.125, mainly so I can see how the accuracy plays out next time I get to the range.

-pete

Offline outdoor_guy

  • Newbie
  • *
  • Posts: 23
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #34 on: July 27, 2012, 05:54:16 PM »
Tested some again, this time my FP loads at 4.0, 50 of those, still loaded at 1.030 for proper feeding.
Same deal, not shooting accurately at all.  Had someone else at the range try it, plus I shot from the bench, same deal, all inaccurate.  No signs of overpressure though, at least not in terms of the primers.

My new 124gr RN loads with 4.2gr (same powder, same weight, 1.125 OAL) shot fine though, dead-on as is typical for my CZ. 
I think what I'm finding, more than anything else, is that my CZ doesn't like loads on the really slow side, it seems to prefer mid-hot.

I could push my FP's 0.1 grain more I guess, but I was hoping to hear back from Hodgdon on their load data at 1.030, I sent them a request two days ago.

I think I'm going to make at least a local attempt to sell my 1800 or so of the FP bullets, they're just not worth the "hassle factor", to me anyway, plus even loading the 1.030 as it stands is outside of my comfort range.

-pete

Offline 1SOW

  • Hero Member
  • *****
  • Posts: 15026
  • GO GREEN - Recycle 9MM
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #35 on: July 28, 2012, 12:08:18 AM »
Load data shows 4.1-4.4 for titegroup with a 1.09" oal with a 124gr jacketed bullet.--a .3gr spread min to ma

On one powder burn rate chart, Titegroup is 12th fastest and Win 231/Hogden HP-38 is 22nd.
When you are near the top of the load data, pressures could spike quite high by going above the listed max.  231 burns a little slower and isn't as "spikey" as TG.  The pressures listed in the data are for loads 'within' the data range.  Loads that are compressed or above the load range will increase beyond the the data pressures listed.  It MAY NOT be a linear increase.  Pressures could skyrocket with a very small increase, depending on the powder.  Slower burning powders typically don't skyrocket when the data is stretched just a little.  This all leads to the comment "Win 231 is a little more forgiving".  I don't use TG.  I know several others who love TG with 124gr.

Using oal to powder load proportions, at 1.03" oals , 4.1 grs of TG is almost the max in the LEE data for your oal.  This also assumes there is some empty space left in the case with that oal.  Your decision to make.

re accuracy:  Most powder loads do tend to be most accurate somewhere above mid-range.  Some powders show big improvements, some not as much.
Most of my shooting is inside 20 yards.  My go-to powder for 124gr loads out to 25yds doesn't 'tighten up' that much with more powder..  The patterns do get some smaller above mid-range loads.  My load is soft and within minute-of-6" steel plate at 25yds. ;D

I wish I could have found 'good news' for you with that powder-bullet combination, but I can't find any.   



 



 

Offline outdoor_guy

  • Newbie
  • *
  • Posts: 23
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #36 on: July 28, 2012, 04:33:29 PM »
Thank for jogging me on the spike issue and the shorter powders.   I'm pretty clued into this for rifle, but for whatever reason I didn't think of that relative to my 9mm loads, I think mostly because I'm pretty conservative with most of my pistol loads, always making sure I've got plenty of space (longer OALs) and pressures aren't near max.
I think for now I'll just shelve the FP bullets, maybe do some seperate loads for my carbine or something, and shoot RN in my CZ; they're fine seated at reasonable lengths, and accurate at the same, so fooling around with the FPs just doesn't make a whole lot of sense, IMHO.

Thanks again, for all the replies, I've learned quite a bit, plus it's made me think about certain reloading concerns that had only been on the periphery for me previously...

-pete

Offline loaded

  • Jr. Member
  • **
  • Posts: 61
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #37 on: July 29, 2012, 12:20:21 AM »
Am I missing something here, I loaded up some dummies with Berry’s hbrn 124gn. And
124gn fp.   The aol of the  hbrn is .620 and the aol of the FP is .532

The difference is .88 so if you load a 124 hbrn  @ 1,137 you have .212 of the bullet in the case, and load a 124 fp 1.051 you have only  .202 of the bullet in the case so how can a shorter oal with a shorter bullet be a problem with the same powder charge say 4gn hp38.

You do have a shorter aol but you still have as much space in the case does this make sense or do I have this all wrong.

Offline 1SOW

  • Hero Member
  • *****
  • Posts: 15026
  • GO GREEN - Recycle 9MM
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #38 on: July 29, 2012, 01:20:36 AM »
He's using Titegroup powder and a different bullet.
« Last Edit: July 29, 2012, 01:22:35 AM by 1SOW »

Offline Wobbly

  • Moderator
  • Hero Member
  • *****
  • Posts: 9170
  • Loves the smell of VihtaVuori in the morning !
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #39 on: July 29, 2012, 08:38:27 AM »
Am I missing something here, I loaded up some dummies with Berry’s hbrn 124gn. And
124gn fp.   The [bullet length]  of the  hbrn is .620 and the aol of the FP is .532

The difference is .88 so if you load a 124 hbrn  @ 1,137 you have .212 of the bullet in the case, and load a 124 fp 1.051 you have only  .202 of the bullet in the case. So how can a shorter oal with a shorter bullet be a problem with the same powder charge say 4gn hp38.

You do have a shorter aol but you still have as much space in the case does this make sense or do I have this all wrong?

Mr Loaded -

Welcome aboard.


Not "wrong" at all, you simply overlooked a very basic fact. Unlike the FP, the RNHB has a "hollow base". Therefore it does not have the flat base of the FP so you can''t compare the 2 bullets side-by-side mathematically without using an "effective bullet length". That is to say, what the RNHB bullet length would be if the hollow portion disappeared. Obviously the "effective" bullet would be much shorter than the physical.

You're thinking the right way, but we have to compare apples-to-apples. You'd get an answer closer to what you expected by comparing the standard Berry 124gr RN to the 124gr Berry FP.

Hope this helps    ;)
« Last Edit: July 29, 2012, 08:42:43 AM by Wobbly »
In God we trust; On 'Starting Load' we rely.

Immature reloaders ask: What's wrong with this gun?
Mature reloaders ask: What did I do wrong

Offline loaded

  • Jr. Member
  • **
  • Posts: 61
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #40 on: July 29, 2012, 10:51:16 AM »
Wobbly. thanks that make sense so I have some 124gn fbhp so I should be able to compare the two
right.  The HP oal is 563,  FP oal is 532 both have flat bottoms.

Offline outdoor_guy

  • Newbie
  • *
  • Posts: 23
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #41 on: July 29, 2012, 01:58:41 PM »
My 124 FPs (the ones in question) are .510, and my RN 124 are .588. 
I feel pretty comfortable seating my RN at 1.125 or so, which translates down to about 1.047 on the FP, or thereabouts.  That's close to my 1.030, I must admit.

As mentioned, they seat and function at 1.030, with 4.0 grains of TG. I might try some HP38, just to see if I can bump into the mid-range and get my accuracy back, or I might sell 'em, I'm still debating.

The whole RN/FP actual depth relative to the powder/case bottom is very interesting though.  I've often pondered this, given that the OAL isn't really even remotely consistent in terms of providing a normalized seating depth. 
I wish more bullet manufacturers would publish clear and comprehensive data here, since they are the one's who know *exactly* when they're bumping into pressure tolerances, in terms of case volume. 
We're sort of "guessing", based on known good published data and bullet lenghts relative to volume.  Unless I'm missing something?

I'm really glad I started loading .40 first, a couple of years ago, it's still a small case, but not nearly as close tolerances as 9mm, in terms of volume.

-pete
« Last Edit: July 29, 2012, 09:38:57 PM by outdoor_guy »

Offline Wobbly

  • Moderator
  • Hero Member
  • *****
  • Posts: 9170
  • Loves the smell of VihtaVuori in the morning !
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #42 on: July 29, 2012, 02:29:39 PM »
Wobbly. thanks that make sense so I have some 124gn fbhp so I should be able to compare the two
right.  The HP oal is 563,  FP oal is 532 both have flat bottoms.


I understand that the newer Berry 124gr FP and HBFP now share a very similar ogive shapes, resulting in identical "max OAL" readings from a "push test". The older versions were completely different. So my answer depends on which bullet version you have!!

If both your bullets are the newer versions, then in theory, the lead displaced by the "hollow" is added onto the sides. When comparing 2 cartridges constructed with each of these bullets at same OAL, this makes the case volume under the bullet also equal. Therefore, one could also surmise that given the same powder load, the chamber pressure is the also same for both cartridges. Any difference in bullet performance would then be due to the drag created by having the longer sides of the HB bullet contact more of the barrel.

Details. Details.  ;)
In God we trust; On 'Starting Load' we rely.

Immature reloaders ask: What's wrong with this gun?
Mature reloaders ask: What did I do wrong

Offline outdoor_guy

  • Newbie
  • *
  • Posts: 23
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #43 on: July 29, 2012, 09:33:49 PM »
Along the lines of my previous comment.
What would really be interesting is a table that shows:
volume displacement(cu/in?)/.01 in. OAL of a seated bullet (this assumes a specific caliber, such as 9mm).

This way, if you had known combinations that were good (say Berry FP for example) at a given charge, you'd know the remaining case volume for that bullet at a given OAL.
From there, it's a simple ratio calculation to determine if your powder/OAL combination is in the safe volume margin, given the displacment/length table for your particular bullet(s).

One could probably build these  up, by seating to known given good lengths, with no primer, and back-filling the cases with water.  The water wouldn't be the same, volume-wise, but as long as you were comparing a known good combination with water and your case with water, you could extrapolate the data pretty easily (spreadsheets are handy for this type of thing  ;D).

Just a thought, I'm surprised something like this doesn't exist, or maybe it does and I'm just not "in the know"?
It sure takes all the OAL "guesswork" out of the equation, you know for certain if you're in/out of safe maximums.

-pete

Offline 1SOW

  • Hero Member
  • *****
  • Posts: 15026
  • GO GREEN - Recycle 9MM
Re: 124 RNFP, anyone else have issues with OAL in a 75b?
« Reply #44 on: July 29, 2012, 11:42:08 PM »
The 9mm case is straight-wall but tapered top to bottom.  The volume would change constantly per .01" as you went deeper into the case.
Every headstamp will also have slightly different internal volumes and lengths. At a given oal, the internal distance from the primer hole to the base of the bullet would be moderately consistent.
It might still provide a "guide" though.

Maybe you could use a syringe to measure and find the total case volume using water and figure in a rough allowance/distance for the taper.
Easy for me to "guess".  ;)