V-max overpressure

[CMV]

Why would I get signs of overpressure with 55 gr V-max that I do not get with 55 gr Hornady FMJBT?

I've run LC brass trimmed to 1.751-1.752, CCI #41, H335, OAL 2.220 & Hornady 55 gr FMJBT up to 26.3gr with no issues. Out of a 20" 1:9 AR they go right around 3300-3310fps @ 26.3 gr

Today with the same brass, primer, powder, 2.250 OAL, & 55 gr Vmax & same rifle, out of 45 rounds, I had 1 FTE, 6 blown primers, and about 8 with very pronounced ejector marks on the case head. I've never seen either of my ARs leave an ejector (not extractor) mark before but admittedly I never looked twice at brass before I started reloading. Going back through my 2x fired stuff there are no ejector marks.

At 25.3 gr I was at 3486 fps. I should have just stopped right there. Either Chrony wasn't telling the truth or something was up. But they functioned fine & first 3 cases looked good, so I kept going.

Next was 25.7 gr & got 3500 fps but the Chrony only read 2 all day at that charge so that average is only 2 data points.

Last was 26.1 gr & got 3540 fps.

I was firing in groups of 3. 3 shots at one charge, then 3 at the next, then 3 at the next. For the first set, all rounds functioned fine and all brass looked good upon inspection. It wasn't until later on I started seeing issues.

I took these larger steps between charge weights because I figured I already know the slightly heavier (2/10) 55gr FMJBT is fine in this rifle up to 26.3 gr - probably beyond that - just never tried. Since I was staying under that, no big deal right? Bad assumption.

So when I got home I inspected the cases with the blown primers. I figured maybe these were some I cut the crimp out with a chamfer tool before I got the super swage. Sadly, that wasn't the case & these all went thru the SS - no cutting around the primer pocket. That's when I noticed the ejector marks.

All I can figure is I have the bullets set too deep which is spiking the pressure. I'm seating .030 longer, but the Vmax is .078 longer than the FMJBT. That put the base of the bullet almost .050 deeper in the case. Would that alone account for the large rise in speed and pressure?

BTW, 25.3 gr wasn't my start with the Vmax - that's just where I left off & started back today. Lower loads in the work up showed no signs of anything out of the ordinary but i didn't run them over the chrony. That would have probably alerted me a lot sooner that something was wrong. I'm not crimping these either - the FMJ I do, but none of the Vmax have seen the FCD. All charges were trickled on a beam scale.

Anyway, I'll start over and go with the 2.260 mag length and expect to stop a lot shorter in charge weight than I can with FMJBT due to the increased length. One thing about the Vmax - it really seemed to like the speed. Most groups were under an inch, several were at/under .8"

Below - from left to right - two 26.3 gr w/FMJBT, four with blown primers and pronounced ejector and extractor marks, two at highest charge with no pressure signs. Excuse the sharpie - that's how I tell what was what afterward. Blue=25.3 gr, green=25.7 gr, black=26.1 gr.



Same order, standing up.

 

[PCCUSNRET]

According to Hodgdon's web site reloading data the max load for a 55 gr. bullet using H-335 is 25.3 grs. Regardless, there are definite signs of excessive pressure with these loads. This is normally caused by bullets jammed into the lands, bullet seated too deep or too much powder. Too many choices to guess, but first thing I would do is go back to under 25.3 grs of powder. How did you determine the C.O.A.L. for the Hornady V-Max bullets? Any chance the bullets are being jammed into the lands?

 

[CMV]

Yeah, I'm at/over max in 2/3 references I have but Lyman #49 goes up to 27.0. 5.56 chambers in both rifles too - both of which have had thousands of XM193, Q3131, SA battlepack, etc that's all hotter than the 25.3 max for .223

I determined COAL by the very scientific approach of "2.260 will fit in the mag so -.010 will give me a little room to make loading easier". I never measured how far I have to go to hit the lands since I'm not loading any long, heavy match bullets. If it can fit in the magazine, it's not going to be close to hitting the lands in a 5.56 or Wylde chamber - but i might be way out in left field on that one.

I can go check real quick for this rifle though.

 

[rcmodel]

Why would I get signs of overpressure with 55 gr V-max that I do not get with 55 gr Hornady FMJBT?

Because the V-Max is a true Secant Ogive shape, and the FMJ-BT is a true Spitzer shape.

If you set the two bullets side by side and look at them?
The bore dia bearing surface of the V-Max is about half again longer then the FMJ-BT.

So, bore friction is higher, and pressure is higher.

rc

 

[T Bran]

It is likely that the V Max bullets have a longer bearing surface than your FMJ. I would be backing down the charge as well as miking the OD of the bullets. More contact area means more resistance going down the bore. Just a thought. You are in the danger zone.

 

[rsrocket1]

It looks like those cases are toast. I think I see imminent case head separation on those cases too (the pronounced ring) on the case body above the head. I would start over and work up from about 24 or 24.5g h335 and tripple check the loads. Also try chambering several rounds from the magazine and remeasure the COL to see if the bullets are getting jammed into the case.

 

[rg1]

Your chronograph readings to me indicate even your 55 fmj Hornady load is too hot. Also the primer firing pin mark on your 55fmj's shows pressure with the primer extruding into the firing pin hole. Don't think that handloads for a 20" AR with H335 and Horn. 55 fmj's should go above 3200fps at maximum pressures. I agree that 25.3-25.5 should be max with Horn. 55fmj's and with the 55 Vmax I'd say that less than 25.3 would be maximum. And you're firing them in cooler temps. My experience is that with AR-15's pressure signs are hard to see until they get a lot over safe pressures. At 2.250" your 55 Vmax isn't close to the lands. I just think from my experience with both bullets in 1/9 and 1/7 twist 20" AR's that your velocity readings indicate 100-300 fps more than normal and it shows your pressure is very very high. Again, AR's typically don't show pressure signs until pressure is sky high.

 

[Walkalong]

Regardless of what OAL you choose next, back off on the charge. You are over thinking the OAL. You simply used too much powder, and ignored signs to stop sooner.

How heavy is the brass? It can be quite different from lot to lot and year to year.

 

[CMV]

Both mike at .224 but I see what you mean about the V Max having a lot more area that is .224 diameter vs just a spot on the FMJBT.

rg1 - the primers that are still there look bad to you? They look pretty typical even for my 24.2 gr plinking load. Here is the one from the far left and the far right gently decapped. I understand the Vmax I tested today is way overpressure. But the 26.3gr w/ the FMJBT - while hot - aren't nuts or anything. For a .223 they probably are, but in a 5.56 chamber? They're still a little on the tame side compared to most M193 spec ammo.

 

[rcmodel]

Primer signs are right up there with Crystal balls, Tea leaves, Palm reading, and Ouija boards when it comes to reading pressure signs.

Your cases with ejector pin hole marks and bolt face markings indicate you are up around 75,000+ PSI.

Whatever it is you are doing, stop doing it until figure out what is wrong!

Have you tested your scales for accuracy with check weights for instance?

rc

 

[NCsmitty]

With your ejector extrusions on the case base showing quite prominently, my guess is that you are exceeding 70,000 PSI at the very least, and probably closer to 75,000PSI. The ejector extrusions are a dead giveaway of your overpressure.
It's time to rethink your reloading workup procedure, and hope that you haven't damaged your rifle.


NCsmitty

 

[rg1]

Not a ballistic expert but just what I've read is that it takes about 60-62 k pressure psi to "start" seeing brass flow into the ejector groove and that is what Nato rounds are supposed to be loaded to. Most commercial rounds are 50-55 K psi. Just looks like to me your rounds show higher than Nato pressures and the velocity you get is higher than normal. Like I said, not an expert here. My experience with Horn. 55 fmj and H335 in my rifles start showing pressure if my charges and velocity exceed 3200 fps. Your pics also look like the rims are bent from the ejection. The rounded edges of the firing pin mark sometimes indicate pressure with the primer flowing into the firing pin hole but not always.

 

[CMV]

Yes - too much powder for sure. The extra .050 seating depth isn't the issue then - its the long bearing surface?

The only sign I ignored was the high chrony reading which is somewhat typical at our range due to the amount of fluorescent lights - some of which I can't turn off because they're on the same circuit as the floodlights over the chrony station. It has told me my 4.8 gr W231 - 230 gr Hornady HAP .45ACP were going 1250 fps before. It's constant trial & error getting that thing set up and reading correctly if I'm shooting inside.

But i shot 3 at 25.3 gr, stopped & checked them & they were fine. Then 3 at 25.7 gr, stopped & checked, then 3 at 26.1 and those 3 were fine. After that I wasn't looking at spent cases and the first sign I got was a FTE and that one had a blown primer. That should have been it & next time I'll know. Just figured it was loose from poor crimp removal technique and first one I ever had (not first FTE, first blown primer).

I did miss the ejector marks though. I can blame that on having most of the range lights off to cut down on chrony interference, but it was negligent. I should have taken them outside or flipped the lights back on.

I've shot about 850 .223 reloads so far and about 450 in pistol calibers with no issues. Kind of got complacent since everything had been going along just fine. I never really understood why everyone here keeps posting "start low and work back up" even for minor changes. Now I know & get it. I assumed changing from one 55 gr jacket bullet to another would be a pretty quick work up (minor change) and really all I had to do was find what charge gave the best groups. It didn't even occur to me to be as cautious with the bullet change as if it were an entirely different weight or powder or caliber even. Now I know...

 

[clone]

Maybe this will help.

My Hornady 8th edition manual says,

Bullet #22271 V-MAX, COL 2.250
Powder H 335,
20.8gr 2800fps (start)
21.6gr 2900fps
22.4gr 3000fps
23.2gr 3100fps (max)


You should double check this data as I could have miss typed/read. Always double check.

 

[rcmodel]

Congratulations.

Now you know, and are smart enugh to realize it!

Reloading, as with parachute packing, scuba diving, and extramarital sex?

It's the little details you neglect or fail to notice that will really get you by the short hairs sooner or later.

rc

 

[CMV]

Your cases with ejector pin hole marks and bolt face markings indicate you are up around 75,000+ PSI.

Whatever it is you are doing, stop doing it until figure out what is wrong!

Have you tested your scales for accuracy with check weights for instance?

Yikes!

Stop doing it - yeah that's for sure! I started this one at 24.2 gr & will stay under 24.9. I might just stop with Vmax altogether. I was looking for accuracy & these were inexpensive on sale so I tried them in hopes of having something very accurate that I could have ready to go when the 55 gr Zmax are available since they are priced really nice. But I'm not out there hunting prairie dogs or coyotes with an AR so I really don't need that round. I do need to replenish projectiles so might just go with the Hornady 55 gr soft points next as that should be a good compromise between cost accuracy compared the the FMJBT I'm using now.

I'm using an Ohaus 505 and it's pretty much spot on. The only issue it has is at the 0-10 setting (where the big weight is at 0). It doesn't sit firmly in that position and has some play so I have to check it frequently for pistol cartridges. But it only varies to + 2/10 so when it's off it's reading heavy. I use a Hornady auto dispenser scale and calibrate it after warming up. The 505 & the Hornady digital are always within 1/10 of each other. But I've never taken the Hornady's scale calibration weights, converted them to grains, & then tested the 505 with them. I did run various loads on the Lee scale the 505 replaced and they measured the same on both so I figured the 505 was good to go.

Why do you ask about the scale? Is what I'm seeing atypical of that load for others? Or if you (or anyone) loaded around 26 gr of H335 under a 55gr Vmax would you get the same bad results?

 

[CMV]

Clone - I have that book too. It's max is around the starting of others for H335. I only use the Hornady book for something I can't find anywhere else because its just too conservative. Or if I'm looking to load something light it's a good place to start to find a safe min.

That sounds like I'm trying to wring every fps possible out of every load. Combined with the above it probably looks that way!

I went to 26.3 gr for the FMJBT very slowly and cautiously trying to duplicate M193 to replace some of my stash that I'd been dipping in to. I wanted something I could use interchangeably with XM193, IMI M193, or Q3131A. It's not my everyday plinking round which is 24.2 gr & well under everyone's (except Hornady's) published max. I'm barely at starting load with .45 ACP because I didn't have to go any higher - my 1911's both loved 4.8 gr of W231 with 230 gr Hornady HAP so I didn't see any sense in going higher. My 9mm is a little shy of factory loads as well - CCI Blazer is hotter.

But in this case, I thought I might find the best performance going through the full range of what I considered "safe". Lyman #49 says I'm 9/10 under max and I'm under what I'm safely using for other 55 gr jacketed projectiles.

Live & learn....

 

[gamestalker]

I load the V-max, and even though I shoot BA's, when I work up I reach my comparative velocity at a lower powder charge, because of this. Different bullet, different load criteria.

 

[Walkalong]

I never really understood why everyone here keeps posting "start low and work back up" even for minor changes. Now I know & get it.

Excellent!

Blown primers are getting close to blown case heads, and that is seriously bad juju.

 

[helotaxi]

I think I see imminent case head separation on those cases too (the pronounced ring) on the case body above the head.

That's from the size die and is totally normal. .223 cases usually break near the middle of the case body.

 

[MEHavey]

I've run LC brass trimmed to 1.751-1.752, CCI #41, H335, OAL 2.220 & Hornady 55 gr FMJBT up to 26.3gr with no issues. Out of a 20" 1:9 AR they go right around 3300-3310fps @ 26.3 g

QL says 61,700psi 3,264fps (post script: that's hot.)

Today...same brass, primer, powder, 2.250 OAL, & 55 gr Vmax...

QL says 65,000psi, 3,300fps
QL also tells me that V-Max bullet is seated 30% deeper in the case compared to the FMJ, even w/ the longer OAL.

In both cases you are hot, and need to back off a full grain+
postscript: That's with nominal case volumes. Using LC volumes only 3% less, add 8,000psi to each of the above loads.

 

[CMV]

I thought LC volumes were higher for .223 & only lower for larger calibers?

 

[MEHavey]

I went down a weighed a few Win & LC case water weights. They actually came out about the same -- which would tend to mitigate against adverse pressure build as you note.

(Unfortunately your rifle/load combo doesn't seem to care either way about theory. As a previous poster noted, your pressure/ejector markings show mid- 70's pressure by empirical means.)

 

[Clark]

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The High Road, nor the staff of THR assume any liability for any damage or injury resulting from use of this information.
Hodgdon website: 223 Rem, H335, 25.3 GR. 55 GR. SPR SP, 2.200", 24"
barrel, 3203 fps, 49,300 CUP

Test 8-19-2003: Ruger #1, CCI 400 small rifle primers, LC brass once fired
processed from Scharch and prepped by me, 55 gr Vmax moly, H335

pic left to right: unfired 27 gr, 28, 29, 30, and 31 gr.
27 gr, unfired, extractor groove .329"
28 gr, extractor groove .329", 11% overload 69 kpsi QL estimate
29 gr, extractor groove .329", 15% overload 80kpsi QL estimate
30 gr, extractor groove .3295", 19% overload 92kpsi QL estimate
31 gr, extractor groove .3320", 23% overload 106kpsi QL estimate

The case heads fail at 86,000 psi.

__________________

 

[NCsmitty]

Wow, big difference in a bank vault action.

Thanks for the pics Clark.


NCsmitty