.45 ACP - VV320 Load Problems

[2kcrewcab]

Hello all....

I'm running into a problem I'm hoping you all can help me with. I'll try to post as much info as I can about the problem and what I have done to try to correct it (hopefully it's not too much that this becomes annoying to you).

I started loading .45 ACP about a year ago on a Dillon 550 using Rainier 230 gr plated bullets, Federal Primers, and approximately 5.4 gr of VV320N, OAL of approximately 1.274", for use in IDPA in a 4" 625 Revolver. Everything seemed to be fine for me until the place where I get my bullets decided to switch to Berry's.

Well, the Berry's .45 ACP bullets are shaped a little different than the Rainier's, so I figured I'd better do some new test loads and chrono them. I left everything setup pretty much the same on my 550 and loaded up a few, took them to the range and one day after an IDPA match, I just set the chrono up to quickly test a moonclip full. Much to my surprise and dismay, there was a HUGE difference in FPS from one shot to the next.

My first thought was that I did something wrong on my loads, so I put everything up, and decided to check my machine out and then load some more.

Well, the other day, I went back to the range with a 5" XD Tactical, my 4" 625, some factory CCI Blazer Brass, some of my "original" Rainier loads, and some of the new Berry's loads. I wanted to do 2 things: #1) Find out how different the velocity was between a 5" Auto and a 4" Revolver, and #2) Find out how much deviation I would see between the different loads in the different guns. The factory stuff was obviously to use as a baseline between the Auto and Revolver.

I shot 6 rounds of each kind of ammo out of each gun for the following results (highs and lows for each string in bold):

4" Revolver:

Blazer Brass - 801.8, 807.4, 793.2, 788.2, 794.9, 813.2

Rainier Bullets - 743.2, 751.0, 739.5, 747.8, 732.6, 747.3

Berry's Bullets - 714.7, 732.5, 748.7, 699.3, 647.9, 748.5

5" Auto:

Blazer Brass - 823.0, 853.9, 855.1, 832.3, 844.0, 838.7

Rainier Bullets - 766.7, 753.1, 776.8, 781.3, 769.5, 715.8

Berry's Bullets - 737.2, 781.3, 798.4, 755.4, 729.8, 772.4

So the answer to Question #1 was not difficult to figure out: The 5" Auto did add a little velocity over the 4" Revolver, but not enough that I would bother changing the load between the two if I chose to shoot CDP vs ESR - I could use the loads for either and still be ok as long as I made power in the Revolver.

The answer to Question #2 was a little more puzzling. Why is there such a big difference in the velocities for the Berry's bullets vs. the others? I'm not sure what kind of spread I should be seeing here, but I'd be willing to bet that 100 fps isn't right. Oh, and let me note that I was tilting the barrel of the gun upward and shaking all of the powder to the rear of the case before each and every shot in both the Auto and the Revolver.

I thought maybe something was wrong with how this VV 320 powder was metering for me, so I tested some .38's and 9mm's and they were so consistent it's not even funny, so there has to be some dynamic here that I'm missing.

So, I got to thinking about it, and the main variable that I could see that would be different in the various calibers is the volume in the case. I decided that I should seat the Berry's bullets a little deeper than I had been to try to remove a little of that air space. I adjusted my seat die down a little bit to an OAL of approx 1.254", and took a few of those out to the range to see if that helped. Well, the velocity increased ever so slightly, but I still had a spread of around 100 fps over 6 rounds that I shot.

Can anyone point out anything that I need to try next?

Sorry for the long post, but I wanted you to have all of the information I do about the situation.

Thanks in advance....

Mike W.

[ben b.]

Weigh the rounds for actual weight? Mike them for actual diameter? There is not such a big variance in the auto. A sampe of 6 in each load X gun is a small sample.

......................Mean (Std Dev)

Blazer Brass - 799.8 (9.4)

Rainier Bullets - 743.6 (6.7)

Berry's Bullets - 715.3 (38.2)

5" Auto:

Blazer Brass - 841.2 (12.5)

Rainier Bullets - 760.5 (24.0)

Berry's Bullets - 762.4 (26.5)

[2kcrewcab]

Thanks for the info.

Anyone else have any suggestions, comments?

Could it have to do with crimp? Should I try seating a little deeper? Also, how many rounds should I consider to be a valid "sample" for statistical purposes?

Any help is appreciated!

Thanks,

Mike W.

[Duane Thomas]

The owner's manuals that I've read that come with chronos have consistently recommended 20 rounds to give real, meaningful data.

[Canuck-IL]

A lot of the apparent variation is due to a single really low reading (647) in the Berry's revolver speeds ... an example of why a larger sample is needed to 'damp out' the effects of the occ oddball reading.

20 is a good number and, just to get a feel for the impact of outliers, keep track in sets of 10.

I wouldn't think crimp or OAL are relevant factors as long as those are consistent across the rounds.

/Bryan

[2kcrewcab]

Thanks for the replies guys. I'll load up a few more and take them to the range this weekend.

Appreciate the feedback!

Mike W.

[schroed]

see if this helps:

Point the gun vertical between each shot.

This will place the powder against the back of the case giving a constant burn pattern inside the case.

[RePete]

Mike:

My load of 5.5gr/N320 under a 230 Frontier CMJ w/OAL = 1.238" and a crimp = 0.469" gave me a velocity of 743fps for a PF of 170. That's too close to the line, I'm looking for about 175PF.

You could try seating the bullet a little deeper.

I have loaded some using N310 but it's too cold to road test at this time.

Edited February 7, 2009 by RePete

[dirty whiteboy]

Bullet diameter? Maybe the Berrys is letting some gases blow by. Check for variation.

[D.carden]

Plated bullets have been known to "creep" in revolvers. Under recoil, the unfired bullets move forward thus creating increased case-space/powder ratio resulting in lower pressues. Fire a couple of rounds and then remove the remaining cartridges and see if they've moved forward. You may need to add more crimp if you crimp at all. Plated bullets with revos are finiky in that area....

Dan

[2kcrewcab]

Thanks guys for all of the suggestions.

Friday evening, I decided to play around with it a little more. I added another 1/10th of a grain of powder, putting me at 5.5 gr, and I rechecked my Hornady Reloading Manual for OAL. For a 230 gr. RN bullet, it listed the OAL as 1.230", so I adjusted the seat die down to about 1.235". This put the bullet right down against the powder...not compressing it, but touching it from what I could tell. I also rechecked the VV loading reference charts, and they listed the MAX charge at 5.2 gr. This concerned me a little, but I figured based on my previous tests that it shouldn't be a real problem.

I still had some of the 5.4 gr loads sitting there on the bench too, so I decided to run some of them back through the press and seat them down to 1.235" as well.

So, after the IDPA match on Saturday morning, I tested these loads out. I ran the "re-seated" bullets with 5.4 gr first, and they did MUCH better than before. They were around the 760 fps mark, and much more consistent than before. Out of curiosity, I went ahead and ran some of the 5.5 gr loads through as well, and they were up closer to the 800 fps mark but still way more consistent than previous loads.

So, now I'll just back the powder measure back down to 5.4 gr and leave the OAL at 1.235" and rock on.

Thanks again guys for all of the help!