Same weight bullet, different powder charge

[rcairflr]

I would like opinions from some of you very experienced reloaders on this.

Attached is reload data from Sierra and from Hornady. If you look at page 6 of the Sierra load data, they give a max powder charge of 27.5 grains of H335 for their 55 grain bullets and Hornady give a max charge of 23.2 grains of H335 for their 55 grain bullets.

I find it very hard to believe that there can be such a difference in the makeup of the Hornady vs Sierra bullets that it warrants a difference in powder of 4.2 grains. Especially when the Sierra and Hornady powder charges cover a wide range of bullets for each manufacturer.

It seems to me like Hornady is just being extremely conservative on their published load data.

[JLA]

I find hornady is a bit on the conservative side..

But also they are using completely different components including the test vehicle. Changing components does have an impact on the pressures generated by certain powder charges.

[The Duke]

You right, JLA...I find the Lyman book gives the best loads if your interested in loading the upper end stuff......

[woolleyworm]

Also note that the Sierra data is listed for Bolt Action rifle and testing set-up was probably much different from Hornady's testing.
Even a few thousandths can make a difference in bullet design, so it's best to work up the load properly and find what works in your set-up. It's always a good idea to cross reference and when you see differences in data like what you've shown; that's just another good reminder that little things can make a big difference and how important it is to NEVER assume and follow good practices.

[rcairflr]

I have worked up 2 very accurate loads for my Xbolt .223 using H335 powder and 55 grain Vmax bullets.

The first is 23.3 grains of H335 and the second is 25.2 grains. I have cronographed only the 25.2 grain load. It was 3150 fps average.

Neither one has shown any obvious signs of overpressure and if I put the spent casings side by side, I can't tell any obvious difference.

According to Hornady, even the 23.3 grain load of H335 is beyond their maximum.

Attached is a picture with (2) 3 shot groups with the 25.2 grain load shot at 100 yards, each group was shot by a different person. I would hate to give up this load since it does give very good groups everytime.

[JLA]

If they arent producing loose primer pockets or sticky bolt lift then i wouldnt give them up. Keep in mine data manuals list data based on a specific test set up, its your job to choose the data to work with that best matches your setup. This doesnt mean everything has to match perfectly, it just means if one data source used an AR15 to develop loads in .223 and another used a remington 700 bolt action, and youre using a Browning Xbolt, then obviously the data developed with the rem 700 is going to best fit your requirements. Thats part of cross referencing. Learning to recognize pressure signs is key too, and shooting over a chrony is a good idea as well, as you will usually see a major velocity spike a round or 2 before sticky extraction shows up.

Reloading manuals are merely guides. They provide guidelines for reloading safely, and each one is a little different, and thats why you need several..

[rcairflr]

None of my loads have produced a sticky bolt lift, but my understanding is that from rifle to rifle or load to load there could be a difference in what overpressure signs are produced.

When you say loose primer sockets, how loose do they get from overpressure. I would guess the more you reload a case, the primer pocket will loosen up some anyway.

[steve4102]

Originally Posted by rcairflr

When you say loose primer sockets, how loose do they get from overpressure. I would guess the more you reload a case, the primer pocket will loosen up some anyway.

Not really, If you are loading to safe operating pressures your primer pockets should not loosen up. The case will eventually were out and fail at the web or the neck before your primer pockets loosen up from were and tear.

[steve4102]

Originally Posted by rcairflr

Attached is reload data from Sierra and from Hornady. If you look at page 6 of the Sierra load data, they give a max powder charge of 27.5 grains of H335 for their 55 grain bullets and Hornady give a max charge of 23.2 grains of H335 for their 55 grain bullets.



.

I always check several manuals and the powder manufacturers web site. In this case Hodgdon.
http://data.hodgdon.com/cartridge_load.asp
Note they used a Speer SP with a Max charge of 25.3gr H-335. Right in the middle of the other two. I would tread lightly when exceeding the powder manufacturer's data.

Here is some interesting QL generated data.
25.3gr of H-335(Hodgdon Max) with a Sierra 55gr BK

 +00.0   95    25.30   3239    1281   51761psi   7018     97.9    1.006  ! Near Maximum !

Here is the same load with 55gr Hornady V-Max.

 +00.0   98    25.30   3291    1323   55869psi   6939     98.3    0.975  !DANGEROUS LOAD-DO NOT USE!

[steve4102]

Originally Posted by JLA

I find hornady is a bit on the conservative side..

But also they are using completely different components including the test vehicle. Changing components does have an impact on the pressures generated by certain powder charges.

Good point, which brings up another question.

How do bullet manufacturers that test with actual firearms like the AR-15 or Rem 700 instead of a Pressure Barrel measure pressure? Notice neither Hornady or Sierra list actual pressures.

[rcairflr]

Originally Posted by steve4102

I always check several manuals and the powder manufacturers web site. In this case Hodgdon.
http://data.hodgdon.com/cartridge_load.asp
Note they used a Speer SP with a Max charge of 25.3gr H-335. Right in the middle of the other two. I would tread lightly when exceeding the powder manufacturer's data.

Here is some interesting QL generated data.
25.3gr of H-335(Hodgdon Max) with a Sierra 55gr BK

 +00.0   95    25.30   3239    1281   51761psi   7018     97.9    1.006  ! Near Maximum !

Here is the same load with 55gr Hornady V-Max.

 +00.0   98    25.30   3291    1323   55869psi   6939     98.3    0.975  !DANGEROUS LOAD-DO NOT USE!

Interesting data, how did you get this?

[rcairflr]

I found a interesting article on reloads and there is a section that talks about over pressure signs. Also there are some pictures of overpressure signs (see picture #1 below)

http://riflemansjournal.blogspot.com...ng-safety.html

I have also included a picture of some of my brass from shooting 3 days ago (picture #2). The rounds were loaded at the upper end of the range for 50 grain Vmax and Benchmark powder (25.6-26) grains (according to Hornady load data). I don't see any obvious signs of overpressure to include, no signs of ejector marks. I couldn't cronograph the loads since I was in a indoor range.

The third picture shows the target that was used for these loads. Based on the target, I am going to use the 25.7 grain load and reload a batch and see if they repeat. The 25.5-25.8 grain rounds basically landed in the same location (+/- my lousy aiming). At the 25.9 & 26 grain load, the rounds went to the right.

[Caneman]

i did some research on pressure signs a while ago and it seems that these are not all that consistent in telling you what is going on... from what i could tell the only reliable way to know what is going on with pressure is to use a chrony...

in the fwiw department, it seems that the Speer manual gives loads that are always much higher than any other published loads and they scare the pee out of me!!!

[steve4102]

Originally Posted by rcairflr

Interesting data, how did you get this?

Quickload.

[JLA]

In my experience primer pockets will eventually loosen up as the brass wears from normal reloading use. They usually wont drop primers unless the case has been over stressed by extremely high pressure.

I did a test for a very mis-informed friend of mine. He was under the assumption that you could load any case with IMR trailboss and not worry about ever overloading it. I proved to him, with a slightly compressed charge in a PMC .30-06 case and topped with a 110 gr sierra HP bullet that evgen though the load felt light that it was indeed a very dangerous load. That load destryed the primer pocket and bolt lift had to be performed with a rubber mallet. I then reloaded that case with a normal charge of IMR 4350 topped with a 168 gr AMAX along with another to shoot before it. The stressed trailboss case dropped the primer in the magazine under recoil from the round on top of it. He now believes me when i say you shouldnt use data you find on the net unless its from a reputable source. Using joe blows favorite load can destroy your firearm.

Any time you fire a round and the extracted brass has powder residue around the edge of the primer, that pocket has been destroyed by high pressure. Usually the primer pockets are the first part of the case to show stress. another is brass extrusion into bolt face crevices (like the ejector marks on the cases in the pics above) Takes alot of pressure to make a casehead flow like that.

Flattened pirmers can be an early warning, but only if factory fired rounds arent flattened. Some high powered rifle loads flatten primers normally.

[rcairflr]

Originally Posted by JLA

In my experience primer pockets will eventually loosen up as the brass wears from normal reloading use. They usually wont drop primers unless the case has been over stressed by extremely high pressure.


Flattened pirmers can be an early warning, but only if factory fired rounds arent flattened. Some high powered rifle loads flatten primers normally.

On my next trip to the rifle range, I was planning on taking some production Hornady 55 grain Vmax to the range and compare the used primers to my reloads. On the ones that I have checked, it seems like all of my primers are flattened, regardless of the load.

Also based on what you mentioned above, I'll pay close attention to see if there is residue around the primer edges.

[rcairflr]

Originally Posted by steve4102

Quickload.

Very cool, I just looked it up, not cheap at $152. It's amazing how much money you can spend in the reloading hobby. Kind of like my other hobby (RC airplanes).

[JLA]

I done accepted a long time ago that everything I do is gonna cost me money. Double for stuff i enjoy doing. So when it comes to expense, i usually dont spare any and get my boots on and go to work everyday.

Things will change for me one day in the future, someday ill not be able to work anymore. By then i hope to be a rich man, but prolly wont be, so Ill have to figure somethin out..

[reynolds357]

Originally Posted by Caneman

i did some research on pressure signs a while ago and it seems that these are not all that consistent in telling you what is going on... from what i could tell the only reliable way to know what is going on with pressure is to use a chrony...

in the fwiw department, it seems that the Speer manual gives loads that are always much higher than any other published loads and they scare the pee out of me!!!

How is a Chronograph going to tell you that? I have used a Chronograph for over 20 years and have yet to see anything that would clue me in on the fact I am about to separate a case.

[reynolds357]

Originally Posted by Caneman

i did some research on pressure signs a while ago and it seems that these are not all that consistent in telling you what is going on... from what i could tell the only reliable way to know what is going on with pressure is to use a chrony...

in the fwiw department, it seems that the Speer manual gives loads that are always much higher than any other published loads and they scare the pee out of me!!!

I have never had any problem with any Speer loads. Go dig out some real old loading manuals; they are 6 to 7% hotter than anything published today.

[JLA]

Originally Posted by reynolds357

How is a Chronograph going to tell you that? I have used a Chronograph for over 20 years and have yet to see anything that would clue me in on the fact I am about to separate a case.

You mean a sudden 250 fps velocity spike isnt a clue? Guess not if every round in your box is already dangerously overloaded..

[Caneman]

Originally Posted by reynolds357

How is a Chronograph going to tell you that? I have used a Chronograph for over 20 years and have yet to see anything that would clue me in on the fact I am about to separate a case.

velocity is related to pressure... when working up a load you should know ahead of time what velocity you are trying to achieve, if you chrony an unknown load and it significantly and unexpectedly exceeds the target velocity it is probably a sign of over pressure...

[JLA]

Been reading muzzle velocities off a chrony for 20 years and never thought to correlate the velocities with the pressures??

[reynolds357]

Originally Posted by JLA

You mean a sudden 250 fps velocity spike isnt a clue? Guess not if every round in your box is already dangerously overloaded..

I have never seen those sudden spikes. I have gone from safe pressure to pre belt separation and seen no disproportionate increase in velocity. Of course with a case belt separation you will usually see a decrease in velocity. I do not load hot for everything, Just my .264 Win Mags. I wish I could find a 250 fps spike on it.

[reynolds357]

Originally Posted by JLA

Been reading muzzle velocities off a chrony for 20 years and never thought to correlate the velocities with the pressures??

Yes sir, more pressure equals more velocity. I have never seen disproportionate spikes. On everything other than my .264 I stop when I see pressure signs that would most likely cause me to stop before I get in that range. Having said that, I have pushed the .264 to case belt separation and did not see a DISPROPORTIONATE increase in velocity.