Zero 185 JHP Diameter too large?

Shooters,

Last week I received my back ordered 2K Zero 185gr JHP bullets labeled part #187 and started loading some this evening.

I noticed right away that the bullets don't hand seat nearly as far into the case (barely at all) as the Hornady XTP and HAP bullets I've been loading. And running through the bullet seating and crimp dies there is a clear increase in resistance vs the hornady bullets.

I finally had the thought to measure these new Zeros with my calipers. I got the same results measuring across and along the bearing surface.  Out of 20, they are 0.454 but a couple slightly smaller 0.4535.  I pulled the bullets from two Roze-loaded 185gr JHP cartridges from 2019 and those both measure 0.453. I measured 20 Hornady 185gr XTP and 20 Hornady HAP bullets and all are 0.452.  I measured a few Zero 185gr SWCs and those were 0.454 like these Zero JHPs.

I've fired 500 or so of these 2019 Roze-loaded JHPs through my Pardini GT45 that my sample of 2 measured 0.453 and they have shot well.  It's been shooting well with the Hornadys measuring 0.452.

SAAMI says 0.452-0.003 for jacketed.  The Hornadys all meet this spec.  Why don't the Zeros? Zero part #187 is supposed to be .451 bullet. 

I'd love to go shoot these in the morning like I had planned.  But because the bullets don't fit in the case nearly as well after expansion and the increased feedback in the ram handle when seating the bullets I don't think this is just a matter of the bearing surface being irregular and playing with the calipers.  And because each Hornady sampled measured 0.452 and the new Zeros measure 0.0015-0.002 larger in diameter, even if my calipers weren't accurate the Zeros are still repeating a relative increase of about 0.002" diameter over the Hornadys.

Has anyone measured the Zeros with these diameters?  Are your new Zeros larger than expected? Or is measuring the bearing surface here going down the wrong rabbit hole?

I was very excited to receive the bullets but now I'm apprehensive - not sure if they are safe for my pistol that I've invested so much time in.

Any input appreciated.  Thanks

To get an idea of accuracy of this trusty old dial caliper I just measured 20 Nosler 10mm bullets that Nosler calls 0.400. They were all 0.400-0.4005 on this caliper. So I believe the measure is acceptably accurate.

The bullets arrived in four boxes of 500. Unfortunately there are no lot numbers, just 45 185 JHP QTY: 500 #187. I opened another box, measured 5, all 0.454" across the bearing surface

I think I’d try sizing them down. I’ve never done it with jacketed bullets but don’t know why it wouldn’t work. Lee makes push through sizers in .451&.452.
On the other hand, it might be a good idea to give Zero a call to see what they have to say about it.
JKR

I would shoot them and see how they do.

David

Thanks JKR & David

I unfortunately don't have a means to bump them down to spec

I'm conflicted. They're out of spec. Will being too large increase chamber pressure from rifling resistance? Or maybe it's left the case before rifling engagement ... with COL 1.2 and fast-burnimg VV N310 powder I want to be careful with pressure. I'm in the bullets maybe $400 but have a lot more invested emotionally & financially in the gun. I still have about 1300 Hornady 185s I could load to complete the season in case they go back.

Does anyone else have very new and/or old Zero JHP 185gr they could measure? Any more thoughts as well?

SingleActionAndrew wrote:Thanks JKR & David

I unfortunately don't have a means to bump them down to spec

I'm conflicted. They're out of spec. Will being too large increase chamber pressure from rifling resistance? Or maybe it's left the case before rifling engagement ... with COL 1.2 and fast-burnimg VV N310 powder I want to be careful with pressure.  I'm in the bullets maybe $400 but have a lot more invested emotionally & financially in the gun.  I still have about 1300 Hornady 185s I could load to complete the season in case they go back.

Does anyone else have very new and/or old Zero JHP 185gr they could measure? Any more thoughts as well?

Yes, Give me a few moments.

Lots number 61904111, 71011111, and 72505115 are all pretty much at 0.4517 +/-.

What's your location?

I have a new box and an old box. The old one is from a year ago and the new box just arrived last week. I measured several samples from both. The old box came in at .4515 +/- .0005. The new box came in at .4520 +.0005, -.0000

I would recommend calling Zero

Hope this helps,

Jason

Do you know what lot number you have?

Thank you gentlemen

I see no indication of lot # anywhere on my 4 boxes of 500. All the sticker says: "45 185 JHP QTY: 500 #187" there are no other details on or inside the boxes. I am located outside Chicago

I ordered these direct from Roze

Well you made me open my boxes (delivered about a month ago) and they are consistent around .453". Weird stuff indeed, and I'll be interested to see what Zero says.

Just to add data, from a small sample, my boxes from a couple years ago measure mostly 0.453, with a couple close to 0.4529 and one at 0.4525.  I do not have any lot numbers, either.

Ed Hall wrote:Just to add data, from a small sample, my boxes from a couple years ago measure mostly 0.453, with a couple close to 0.4529 and one at 0.4525.  I do not have any lot numbers, either.

How did they shoot?  I am assuming they were fine.

One comment about attempting to resize jacketed billets.  Very often doing so will destroy the accuracy of the bullet.  Jacketed bullets are swaged to size by expanding them in the die. This is done to keep the lead core in intimate contact with the jacket.  Squeezing them down will likely cause separation of the lead core and the jacket.

Most 32acp conversions I’ve handled or have communicated with guns owners had 0.308 barrels and have shot xtp 0.314 bullets quite well. They are probably fine.
Jon

Thank you very muxh Vinkemulder, Ed & Firebird for taking the time to make measurements and report back.

I have not slugged the barrel but wish I had that data. Based on your feedback Jon & S148 I will give them a shot.

I asked a local friend to measure his, he has zeros a few years old and says they all measure 0.4515. Seeing here our members are measuring from there up through 453 but not consistent commonality in regard to when the bullets were shipped. I will call Roze this week and report back, along with how they shoot

Vinkemulder wrote:

Ed Hall wrote:Just to add data, from a small sample, my boxes from a couple years ago measure mostly 0.453, with a couple close to 0.4529 and one at 0.4525.  I do not have any lot numbers, either.

How did they shoot?  I am assuming they were fine.

I did not do any direct testing. Score-wise many things contribute, so I can't really say.

I shot them. 3.9gr N310 no surprise had a couple ejection issues no surprise. 4.0 and 4.1 functioned without issue and grouped similar to the Hornadys.

Would the larger diameter bullet potentially accelerate barrel wear or any other considerations before I continue shooting them? Thanks again

I pulled apart some old ammo I have and my 185's from a couple years ago measured .452. Loaded 100 of the new bullets (.453) and tested them this afternoon; excellent accuracy and no issues with function. They all plunked in my Shockbottle Case Gauge. I won't be contacting Zero, I am very happy with their performance.

71firebird400 did you get a chance to check your brass for any hints of overpressure?

For me, 3.9gr of VV N310 didnt reliably function. 4.0 was reliable and accurate at 25 yards. With 4.1gr some of the primers were starting to flatten, which I am interpreting as over pressure (fed match large pistol). Not sure if this is expected for COL 1.200 or if large bullets play a part. Powder here metered and measured by a RCBS chargemaster.

SingleActionAndrew wrote:71firebird400 did you get a chance to check your brass for any hints of overpressure?

For me, 3.9gr of VV N310 didnt reliably function. 4.0 was reliable and accurate at 25 yards. With 4.1gr some of the primers were starting to flatten, which I am interpreting as over pressure (fed match large pistol).  Not sure if this is expected for COL 1.200 or if large bullets play a part.  Powder here metered and measured by a RCBS chargemaster.

Federal primers are known to have the softest cups.  If you switched to CCI the flattening would likely disappear.

Wobbley wrote:

SingleActionAndrew wrote:71firebird400 did you get a chance to check your brass for any hints of overpressure?

For me, 3.9gr of VV N310 didnt reliably function. 4.0 was reliable and accurate at 25 yards. With 4.1gr some of the primers were starting to flatten, which I am interpreting as over pressure (fed match large pistol).  Not sure if this is expected for COL 1.200 or if large bullets play a part.  Powder here metered and measured by a RCBS chargemaster.

Federal primers are known to have the softest cups.  If you switched to CCI the flattening would likely disappear.

The primers look fine when shooting 4.3 & 4.4 gr of N310 with the Hornady XTP at COL 1.230. Not sure how much of the pressure headroom comes from the 0.030 extra length or if these .454 bullets are increasing pressure.

Primer flattening is also from low m dium pressure loads where the case had enough pressure to stick in the chamber and the primer pushed out the rear, expanded and then reseated itself as the case slid backwards. While I don't load 310, I would venture that 4.1 of 310 is not a high pressure load since much much higher weights of Bullseye are permitted.

There’s a LOT of headroom due to seating depth.  A Quickload run of 9mm showed safe SAAMI pressures with a 124 XTP and 5.2 Unique with an OAL of 1.12 but well into +P with a OAL of 1.10.

And N310 is faster than Bullseye.