Increasing Pwdr Chrg Yields Lower Speed

[Prerylyon]

Ok guys-I made it out to the range today before leaving for WY-you knew I had to, right? [emoji38]

I am observing a speed plateau with this bullet, this powder loading, in my gun.

So, within the parameters already shared, I ran a chrono test earlier today; 3 rounds each using AA4350 and the 145 gr Speer BTSP:

53.4 gr: 2,687 2,693 2,690
Avg= 2,690 Std Dev= 2.45

53.7 gr: 2,649 2,681 2,710
Avg= 2,680 Std Dev= 24.91

Its a small sample size, but FWIW, the stats support the idea of a velocity plateau. The hotter charge averaged lower speed and has more spread.

I checked the chrono with my older lower performance load-3 shots before the aforementioned test-and it checked out ok.
I am left with this:

1. A velocity limit has been reached

2. My scale is messed up? (not exactly supported by the consistent performance of the 53.4 gr load)

3. Bad powder

4. I may had some chrono problems and copper fouling issues when 2,805 fps was measured a few weeks back at the 53.4 gr charge

I've run out of time for tweaking this anymore before hitting the plains. I will use 53.4 gr and adjust my holdovers accordingly. I have target data at 100, 200 yards that is rock solid with 53.4 gr. I am dissapointed I am not getting the speed I want, but can take solace in the high accuracy of the load.

Certainly keep the thread going if there's interest.

This isn't the end of the story - something to mess with when I get back. Now, off to finish packing! [emoji6]

Regards,

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

 

[Colorado Cowboy]

Which one had the best group?

 

[tim]

I am not an engineer. I employee people, I am stupid. With that said, has anyone tried calling the manufacturer of the powder and asking them?

I know, to simple not as much fun as asking on here, but maybe.

 

[Prerylyon]

'CC,

Both 53.4 and 53.7 grouped identically for all intents and purposes. I heard these bullets were forgiving in that respect and I think I am seeing that.

'Tim,

Good idea. May do that next week.

Regards,

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

 

[Bonecollector]

I wanted to revive this thread to provide the terminal results of my ammunition development.
Barnes 145gr LRX with a velocity of 3,200 f/s from my Browning LRH 26" barrel using RL26.

The bullets opened upon penetration producing a hole the size of bullet & front petals or 1.5x the size of the bullet. It passed-through 1 elk, 2 mule deer, & 1 antelope respectively. The exit wounds were about the size of a golf ball and the animal's internals were destroyed.

MY OPINION BASED ON MY EXPERIENCE:
I've used a variety of bullets, but none performed as well as the LRX. I've used Remington Core-lokt (average bullet), Hornady SST (very accurate but explosive- messy), and Hornady Interlock (good bullet) in the past. All killed game, but I like the performance best from the LRX due to accuracy and the best performance on game.

 

[Prerylyon]

'BC,

4 animals shot provides a nice test sample to evaluate the bullet's terminal performance. Sounds like a winner to me! [emoji6]

My load worked great; although it was slower than I hoped; if everyone remembers where I had to leave things with the load work-up and testing, with my hunt date bearing down fast on me. Accuracy was excellent; on my antelope, it was a one shot deal, double lung, 263 yrds, DRT. Antelope are known to be pretty soft targets, but the old school 145 gr 7mm Speer BTSP killed quickly; with little to no loss of meat. I was unable to recover the bullet, but it must have expanded rapidly as the heart and lungs were destroyed. I had a little bloodshot meat in 1 front quarter from bone fragments, but no evidence of lead or copper. Super impressed with the accuracy. Holdover was dead on. I need to kill a few more critters before I can fully sing that bullet's praises, but I have no complaints so far and suspect it would be fine for antelope and deer.

Regards,

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

 

[Prerylyon]

At the risk of making this into a zombie thread , I wanted to share that for all intents and purposes, I have figured out what caused this velocity drop-off in my setup last year. I made 3 changes (seating depth, primer, powder)-yes, I know the pitfalls of changing too many parameters at a time-but one of these changes was huge and is making the biggest difference.

I've posted a bit lately about CBTO and rifle seating depth/jam depth right?

Well, using reloading book and SAAMI max COLs somewhat blindly as my measurement for seating depth, and being stupid, I discovered I have been seating some of my bullets upwards of 60 thous into the lands. Not good. Or safe.

The original load in this thread, where I left things last yr, was actually jammed 55 thous into the lands! This came about due to an error I made in measuring max COAL for my rifle and putting too much emphasis on the SAAMI max COAL for .280 Rem, that seemingly supported my incorrect measurement.

Using comparators and gauges here recently, I found the correct jam depth; and basically started over, using Speer's load data and some guidance from the Quickload program. I also used the correct primer in the recipe-Fed 210-instead of the CCI mags I was using. Why did I use the mags? I had a stock of them from the Obama era when stuff was hard to buy; they were all I could get and was told they were close enough. I have found several reports, with measured pressure data that show how a hotter primer can increase pressure or even cause unusual pressure profiles that can affect your loads performance.

Velocities are in line now and consistent.

The correct starting seating depth gave the most corrective action; using the correct primer also helped. For powder, I used RL-16, but after how messed up my seating depth was, RL-19 and AA4350 are worth trying again when I have time.

These are the velocities I chrono'd yesterday with the aforementioned changes-shooting a 9 shot charge ladder test:

51.4 2709
51.7 2730
52.0 2764
52.3 2773
52.6 2786
52.9 2792
53.2 2797
53.5 2838
53.8 2853

 

[mallardsx2]

Sounds like your doing some serious wildcatting. Be careful doing that with rifles.

 

[Prerylyon]

No wildcatting at all here-I was unintentionally using incorrect seating depths jamming bullets way too deep into the rifling-COL too long to be safe-due to incorrect interpretation of load data, specs, and techniques-where I am now is all in line for this caliber, load, and rifle-well within safe limits-no pressure signs seen. There is a nice node just under and approaching 2,800 fps. I will prob pick one of those loads and adjust seating depth a little bit to see which is most accuarate-in 5 thous steps up to 30 deeper (away from the lands).

 

[mallardsx2]

Gotcha. I'm no expert but I use a permanent marker and a case that is fired.

Dent the mouth of the unloaded case with your fingernail a little so the bullet fits in the mouth of the case without sliding out (it drags the marker off the bullet).

Then ya can stick the unloaded case and bullet in the gun and close the action. Then ya can pull it out measure it and walk it in with your die to get the best distance to "Jump" the bullet to your lands. I use the Bullet caliper attachment. Without this I would be lost and I record all measurements.

I'm sure you have read how to do this but this is the way I do it.

Like I said I am no expert. I did however stay at a holiday in express on my return trip from Colorado this season.. lol

 

[Prerylyon]

Gotcha. I'm no expert but I use a permanent marker and a case that is fired.

Dent the mouth of the unloaded case with your fingernail a little so the bullet fits in the mouth of the case without sliding out (it drags the marker off the bullet).

Then ya can stick the unloaded case and bullet in the gun and close the action. Then ya can pull it out measure it and walk it in with your die to get the best distance to "Jump" the bullet to your lands. I use the Bullet caliper attachment. Without this I would be lost and I record all measurements.

I'm sure you have read how to do this but this is the way I do it.

Like I said I am no expert. I did however stay at a holiday in express on my return trip from Colorado this season.. lol

More or less similar; before recently, I did not own the comparator attachment and OAL measuring gauge; I got the Sinclair set and it agreed with the sharpie marker method and smoked bullet way I posted about in some recent threads. I'm just glad I caught my mistakes before something serious happened; and that my performance is finally making good sense.

 

[Prerylyon]

Its super nerdy-but I am an engineer after all-here's a graph I made to show the improvement resulting from using the correct jam depth for my rifle with these bullets:

 

[buckbull]

I'm an engineer too (software) with 20 years experience at Boeing. Don't no crap about reloading but dig your graph.

 

[Sawfish]

I ran into this some years back. It is simply the gun telling you that is the maximum load for that powder, gun and bullet combination. You can verify that by CHE measurements. I will generally back off two loads before the decreased load, or in your example 52.8 grains. There is not an animal on this earth that can tell the difference in the sacrifice of the 50 +/- fps. Easier on you, easier on your gun and usually more accurate.

 

[mallardsx2]

Looks like something Ross Perot would have put together! lol