Interpreting load data

[SteveT-NV]

I'm trying some Ramshot X-terminator in my AR and have a question regarding how to interpret load data from different sources.

First the back story -

From the Ramshot Load Data Sheet - http://www.ramshot.com/wp-content/uploads/2010/09/ramshot_handgun_rifle.pdf - they list an upper load of 23.5 g of X-Term for the 55 g VMax. The rifle in their data is a 24 in barrel with a 1-12 Twist.

Yesterday's results (only giving the upper end load that I loaded):

• From a 18 in JP Rifle
  
• OAL - 2.25
  
• Once fired Federal Brass
  
• Federal Primers
  
• Hornady VMax - 55 g
  
• Powder - X-term at 23.3 g
  
• Avg Muzzle Velocity was only - 2817
  

I was a little disappointed in this result, since I'm hoping to get a good load that will give me a higher muzzle velocity. Currently using W748 with good results, but concerned about the reported temperature sensitivity of this powder. Have not experienced this myself though.

Checking out the Sierra Load Data- http://accurateshooter.net/Downloads/sierra223ar.pdf - Colt AR15, 20 in Barrel, 1-7 Twist. They list an upper limit of 25.1 g of X-Terminator for all 55 grain bullets.

My questions are:

• Is it safe to assume that I can use the Load Data from Sierra for a 55 g VMax?
  
• Is it usually safe to use the data for bullets of the same weight interchangeably?
  

Thanks for any help,

Steve

[Hi-Power Jack]

Steve, I'm responding ONLY because no one else has -

I don't reload rifle at all:(

Usually with pistols, it is safe to use same weight

bullets interchangeably if they're both similar (lead

or copper), with the exception that you might have to

change the OAL due to bullet shape - sounds like it

should be true for rifle also??

Until someone comes along with experience on YOUR

specific powder, I'd cautiously work up, slowly, to

the powder charge listed, looking for signs of over

pressure - but, if Sierra publishes it, I'd take

that as a good sign.

Usually manufacturers are a

little conservative in what they'll publish as safe

loads - can't imagine they'll get reckless with that

number.

I shoot 9mm major, and no manufacturer lists ANY

safe loads that I (or anyone else) shoots in 9mm major

But, to be safe, I'd wait for someone who's experienced

with loading .223 to come along with a more definitive answer

for you, or check with Sierra

Good luck,

Jack

[SteveT-NV]

Steve, I'm responding ONLY because no one else has -

I don't reload rifle at all:(

Usually with pistols, it is safe to use same weight

bullets interchangeably if they're both similar (lead

or copper), with the exception that you might have to

change the OAL due to bullet shape - sounds like it

should be true for rifle also??

Until someone comes along with experience on YOUR

specific powder, I'd cautiously work up, slowly, to

the powder charge listed, looking for signs of over

pressure - but, if Sierra publishes it, I'd take

that as a good sign.

Usually manufacturers are a

little conservative in what they'll publish as safe

loads - can't imagine they'll get reckless with that

number.

I shoot 9mm major, and no manufacturer lists ANY

safe loads that I (or anyone else) shoots in 9mm major

But, to be safe, I'd wait for someone who's experienced

with loading .223 to come along with a more definitive answer

for you, or check with Sierra

Good luck,

Jack

Thanks for the reply Jack. I will also email Ramshot to see if they have any data.

Steve

[Matt in TN]

It should be perfectly safe to use the Sierra data, but AS ALWAYS - work up slowly to that max and watch for pressure signs along the way. It is much more common to find the best accuracy below the max load, but you'll have to find our for yourself with your particular rifle and load.

Somewhat related - the shape of the rifle bullets can have a huge effect on pressure and velocity as well. Similar to a pistol bullet, if one 55gr bullet has a longer bearing length than another, then the friction against the bore will be increased. This will increase the pressure for the same charge of powder.

Sierra knows this and is conservative with their numbers to account for it, but it is also why you should always start low and work up your own load.

[VinceU1]

Both Matt and Jack are correct. The only thing you need to watch out for are the "solid" bullets like the Barnes "X" bullets and any other solid copper/brass/whatever bullet. Even though they might be listed as hollow points, they tend to act like a solid and they tend to be long for their weight. That longer length also increases the bearing length of the bullet increasing friction in the barrel, and also increasing pressure. So listen to Matt and Jack and start low and slowly work up to the maximum powder weight.

edited because I type faster than I think. Umm, make that think faster than I type. Sigh, did it again!

Edited March 12, 2012 by VinceU1

[Mbauer67]

There are a lot of a variables with different bullets from different mfg's, but for the most part if you can take data from one mfg to another if you use the bullets that are the same spec. For example a FMJBT from Hornady and Sierra are pretty close but they are slightly different. But the length and weight of the bullet are easy to check and make a big difference on your load.

The best piece of advice is to contact the bullet MFG and powder MFG to get starting point data from them and of course start out low and work up

I use a similar load to you, and emailed Ramshot to get an intial starting point, the tech there said to use the load data for FMJ VNE.

55 Hornady FMJBT

23.8gr Exterminator

2.225 OAL

just under 3000 FPS

CCI #40 Primers.

This load is no where near max for my rifle, but shoots nice.

[Cotys]

I ran QuickLoad with your sample Sierra load except using the 55 grain Vmax. It is showing your load to be over pressure at 25.1 grains. Even though both are 55 grain bullets, the VMAX is a little longer at .813" where the Sierra is .738".

QuickLoad estimates pressure and muzzle velocity with a ton of other variables. It is showing max pressure with the VMAX at 24.8 grains of X-Terminator.

I think starting lower and working up is good advice. Your max may be a tad lower than for the Sierra.

[SteveT-NV]

Thank you all for your comments. I will work up some more loads, especially keeping the 24.8 max number in mind, and let you know the results. It may be a few weeks until I get time again, though.

Thanks again!!!

Steve

[SteveT-NV]

In case any one is interested I thought I would follow up on my post. I was finally was able to get out and do some more testing today. Below are the results.

Rifle - JP - SCR-11 - 18 in

Bullet - Hornady VMax 55 g

Brass - Federal once fired

Primers - CCI

Powder - Ramshot X-Terminator

OAL - 2.250

Chrono results

24 g of X-Term

Low - 2807

High - 2950

Avg - 2859

24.6 g of X-Term

Low - 3040

High - 3157

Avg - 3091

No pressure signs seen. Sub MOA group with the 24.6 g load. These seems like a good powder and I plan on continuing to use it. I also like the VMax bullets. More accurate than FMJ, better MV than heavier bullets, seem to handle the wind pretty well. Activates targets at least to 400 yds.

I've attached my target from today, in case anyone would like to see the results.

loadtest41712.pdf

[Hi-Power Jack]

Steve, good looking targets

Again, I don't load rifle, but isn't

+/- 140 fps a little too much deviation

in velocity?

The accuracy is sure there, so, guess

it doesn't matter?

[SteveT-NV]

Steve, good looking targets

Again, I don't load rifle, but isn't

+/- 140 fps a little too much deviation

in velocity?

The accuracy is sure there, so, guess

it doesn't matter?

I've only been reloading a few months, but I agree that it seems high as well. It's higher than I've gotten in the past as well. Not sure if it's user error or the powder. Since the accuracy was there I shrugged it off yesterday, but I should probably try and figure out what the problem is.

Steve

[Cotys]

Steve, good looking targets

Again, I don't load rifle, but isn't

+/- 140 fps a little too much deviation

in velocity?

The accuracy is sure there, so, guess

it doesn't matter?

I've only been reloading a few months, but I agree that it seems high as well. It's higher than I've gotten in the past as well. Not sure if it's user error or the powder. Since the accuracy was there I shrugged it off yesterday, but I should probably try and figure out what the problem is.

Steve

I recently loaded some .308 and 5.56 and saw a deviation of 20 - 25 fps from each string. I loaded them on my 650, but I weighed each charge to a tenth of grain. I need to do the same with my large batches on the 650 and see what deviation I get. I expect the deviation to be higher, but not sure how much.

It looks like you found an accurate load for your rifle. Depending on the distance you plan to shoot, you may not want to worry about the deviation. Its doing its job on those targets!

[Graham Smith]

The thing about loading rifle that can be a bit tricky is that different bullet types can have different profiles, so two bullets of the same weight but with the same OAL may not perform the same because the case volume is being changed by one bullet being seated deeper than the other. This in turn changes the pressure and may mean that the same volume of powder may be fine with one bullet but overpressure for another. Clear as mud?

Generally speaking, you can use the upper and lower limits for two bullets of the same weight as a guide. ALWAYS pick a starting volume below the max and work your load up from there.

As to velocity, shorter barrels will generally give you a lower velocity. That may or may not be much of an issue. How well a load groups out of your rifle at different distances is ultimately much more important. And that's something you can't get from a book.

[Doc Hunter]

Primers matter - sometimes a lot. Many times large SDs can be reduced by changing the primer. However, changing rifle primers can drastically change pressure in the same load. Ball powders generally work better with a hot primer.

[SteveT-NV]

I guess this thread has gotten a little off topic from my original question. But I did more testing today to see if I could improve on the high variation in MV. I used a different Chronograph and compared two different primers. I took my time and was more careful in positioning the chronograph and tried to make each shot from as close as possible to the same position. Not sure if that's why I got better results though.

Here are the results.

Rifle - JP SCR11

Powder - Ramshot X-Terminator 24.6 g

OAL - 2.250

Once fired Federal Brass

Bullet - Hornaday 55g VMax

Temp - 69 F

BP 30.05 in

5 Shot Strings

Primer - CCI 400

Low - 2937

High - 2997

Avg - 2952

Es - 60.38

Sd - 25.63

Primer - CCI BR4

Low - 2950

High - 2982

Avg - 2966

Es - 31.98

Sd - 14.96

I also shot some groups at 100 and at 300 yds. I got better groups with the CCI 400 than the CCI BR4 though I attribute that more to my shooting than the primer. I was "in the zone " for the first 4 shots at 100 yds (0.516 in group) but lost it on the 5th shot and was unable to get back into it after that. It would seem that even though the BR4 primers showed better results as far as variation in MV goes, they are probably not worth the additional cost for the targets/distances shot in Multigun.

Attached is the 100 yrd target. I will attach the 300 yrd targets to additional posts.

Steve

loadtest100yds.pdf

[SteveT-NV]

300 yrd target with the CCI 400 Primers. All other date above is the same.

3 Shot group - 1.53 in

300ydsCCI400.pdf

[SteveT-NV]

300 yrd target with the CCI BR4 Primers. All other date above is the same.

3 Shot group - 2.50 in

300ydsCCIBR4.pdf

[Doc Hunter]

Three shots mean nothing. Shoot at least 10.

[Steve RA]

Depends on whether or not you hit what you are shooting at on the first shot.