First Shot in Magazine has Lower Velocity

First topic message reminder :

Not shooting pistol competively (yet) but I like accuracy and think I have a decent pistol.  A Springfield Range Officer with a Weigand Scope mount, Herter's Grips, and a Match Dot.  I also enjoy reloading ammo for accuracy.

Haven't shot it for quite some time, but recently re-joined my local indoor pistol club and looking for some Winter fun.  For my 45 Auto I would have preferred some 200gr SWC like I have used before, but with the new polymer coat.  Unfortunately those 200gr SWCs are like hen's teeth these days and I have less than 100 in-house of my old ones (uncoated 12 brinnel from MBC).  I was able to find 1000 Berrys plated 230gr RN bullets, so I bought them.  I already had a couple pounds of Bullseye and a pound of VV N330.  So I set out to develop a new load for the Berry's 230g RN bullets using Bullseye in new Starline brass.

Initial goal was 700-750 fps on 5 shots with max spread of 25 fps over a 5-point range of 4.20gr to 5.00 gr Bullseye.  New Starline brass (resized with my dies) was used with WLP primers.  Powder trickled in to nearest 0.02 gr in each individual case.  Light crimp.  1.250 OAL 

I had already started to load a few 200gr SWCs, some with my old Bullseye load, some with N330 to VV minimum, some in old Starline brass, and some in old Blazer ammo brass.  Figured I would shoot it up first to condition the gun a bit.

I shot strings of different weights and measured the velocity using a Beta Chrony.  See attachment.

Procedure for each string was to:
Prepare target
Load 5 shots in magazine
Immediately insert magazine into pistol
Aim and fire first shot within 15 seconds of loading clip
Around 10-15 seconds between each shot.
About 5 minutes between each string.
Temp was around 60 degrees and guns were transported in a warmed vehicle.
I didn't see a huge difference in groups on the targets.

Max spread did not meet expectations at 30.9 fps - 58.76 fps.  I did notice that the low velocity was the first shot on 4 of 5 strings.

Eliminating the first shot of each string gave a max spread of only 5.8 fps - 15.4 fps for 4 of the five strings.  5.8 fps - 30.9fps for all 5 strings.  The 200gr SWC ammo did not show this, but it was shot first.

So I've been thinking about why this was true, in hopes of figuring something out before I load a bunch more the same way.  Any ideas?

I've thought of:
Something about the 230gr bullet itself
Something about the OAL
Something about the way the powder sits differently in case after first shot
Something from shooting the 200 gr SWC beforehand
Temperature effects on powder
???????

Thanks in advance

p.s. I have refinished my deck since the photo!

O'Gill wrote:How cold was everything when you started ?

Today took all equipment directly from my house to pre-heated truck and then directly into indoor range.  It was about 65 inside.

Shot 25 of same weight - 4.22gr BE, Carefully and individually weighed to 0.02 gr.  Crimped .003 more than before.  Tilted gun skywards between each shot (and after chambering first round).  Used both mags.  No difference than before.  First shot out of clip always significantly lower velocity, 5 out of 5 times.

Did not have this experience with 200gr SWCs (uncoated 12 BHN) in two diferent mags with two different powders.  First round no different.

I'm going to have to say that it seems like something is going on with the plated Berry RN bullets.  I will say that the 5th one in seems a bit more difficult (stiff) to put into the magazine, but it's not specific to one mag.  These are mags that came with my Range Officer.

At the distance I'm shooting I'm sure it doesn't really matter, but it sure makes me wonder why.

You will not get good accuracy from plated bullets.

If you read the web sites, you load a cartridge.  Pull the bullet and see if the coating is compromised.  It can crack the plating and expose lead which kills accuracy and fouls your bore.  If the plating is split, use less crimp. 

What kind of accuracy are you getting?

David

50 ft NRA Slow Fire Targets shot at 50 ft are shown in Sheet 1 of the Excel file a couple of posts back.  These were shot from a simple plastic rest through the chronograph.  Sheet 1 is original data and Sheet 2 was yesterday.

Originally I had light crimp and increased the crimp this time as a diagnostic.  I observed no difference in velocity (or accuracy).