Blowing out primer at below recommended start load 300WM

[windfall]

Looking for advice on why loads are too hot even though I'm BELOW the recommended start load on my 300WM.

I'm using Berger's manual for 210 gr VLD target (page 767). I'm using:
-RE-22
-New Norma Brass
-210 Berger VLD Target
-Standard blue box Federal primers

Book says start load is 67.5 with a max load of 71.1. I'm at 66 gr and blew out 3 of the 26 rounds I shot today. ALL of them show signs of high pressure with a dent from the extractor.

I started getting this problem when I switch from Berger 210 BTLR to 210 VLDs. Naturally, I re-measured the ogive off the lands and reset the bullet seating die appropriately. What am I doing wrong?

thanks in advance

[243winxb]

http://www.thehighroad.org/showthread.php?t=730901 What i posted at link.

[windfall]

thanks

[reynolds357]

Rl 22, 25, Norma MRP, Ramshot Magnum, and several other slow powders are notorious for causing high pressure spikes when underloaded. I have experienced it several times over the years with Rl22. I blew a belt on a 7mag with Rl22 under starting load. Final work up was actually heavily compressed load way north of max that showed no pressure signs.
Where did data come from? Berger data is pretty unique. Usually, due to the shape of the Berger, you can push it higher than other bullets of similar weight. My Berger book is at my shop, so I cant look at it right now.

[jepp2]

ALL of them show signs of high pressure with a dent from the extractor.

Why would you ever fire 26 rounds showing excessive pressure? Do you not like your rifle? Work your way up and STOP at the first sign of excessive pressure. Extractor marks on the case head are a sure sign of excessive pressure. Blown primers are a sign of even higher pressure.

[steve4102]

Naturally, I re-measured the ogive off the lands and reset the bullet seating die appropriately. What am I doing wrong?

What does this mean?

How far off the lands are you in real numbers?

[kdemers58]

is it a 300 win mag or weatherby mag the weatherby needs mag rifle primes only and the correct powder low will increase pressure and cause blowen primers ,thats the reason for the hot primers allows the powder a faster burn rate.

[windfall]

So, I spent a couple hours in my garage and remeasured everything. I took out my Hornady OAL measuring rod and measured the two different bullets in my rifle: Berger 210 VLD and 210 BTLR.

This high pressure problem started when I began using the VLDs.

Looking at the two bullets, I can see that the VLD is "pointier" so it seemed obvious to me that the VLD would set farther into the barrel. Not the case. In fact, the opposite is true.

The VLD is slightly longer at 1.468 while the BTLR is 1.463.

The OAL for the VLD for my custom barrel "on the lands" is 3.406 while the OAL for the BTLR is 3.492. This results in an Ogive for the VLD at 2.729 and the Ogive for the BTLR at 2.800. And based on what 243winxb suggestion, I believe the bearing surface of the VLD is longer than the BTLR which I suspect means more friction in the barrell and so the charge is relatively hot.

My thinking is that when combining the fact that the VLD bullet is farther down in the case and that the bearing surface is longer, these may both equate to higher chamber pressure.

I've built a new batch of BTLRs at the minimum recommended Berger charge of 67.5 and will test them tomorrow. I'll let you guys know the outcome. Thanks again for the ideas. (BTW, I have a custom 29" Hart barrel. So, your rifle will likely have different numbers.)

[dahermit]

Starting at square one (in case I missed it), what does a case from a factory round look like with fired from that gun?

Edit: I missed it...it was a change of bullet when the trouble started. sorry.

[F. Guffey]

Berger 210 VLD and 210 BTLR.

If both bullets weigh 210 grain consideration must be given to the difference in design, something like hardness, both bullets are Berger, call Berger. Some bullets are load specific.

I could not help but notice you have covered the reloading forums like the wind.

F. Guffey

[steve4102]

Originally Posted by windfall

The OAL for the VLD for my custom barrel "on the lands" is 3.406 while the OAL for the BTLR is 3.492. This results in an Ogive for the VLD at 2.729 a

I'm trying to make heads or tail of your numbers here, so bear with me on this.

You set up your Hornady gauge and found the lands with the VLD at 2.729, correct?

I do not see any numbers for your finished round and how it relates to the 2.729? Basicall I'm asking what is your VDL OAL and how far off the Lands are you?

Originally Posted by windfall

My thinking is that when combining the fact that the VLD bullet is farther down in the case and that the bearing surface is longer, these may both equate to higher chamber pressure.

Half right, A longer bearing surface can increase pressures. Seating deeper into the case in a bottle necked rifle round does NOT increase pressures, especially in a Win Mag case with a 30 cal bullet. Not enough % of case volume used up to make any measurable difference in pressure.

[old roper]

Have you chronograph any of the any of those loads and how compressed is your loads?

I shoot the 30 cal 185gr VLD and half the length of the bullet is from the ogive forward and it should be about the same with the 210gr VLD.

If you look at figure 4 on this site
http://www.bergerbullets.com/effects...e-cbto-part-2/
You will see the same length from the base of the case to the ogive so according to how you measure your seating the VLD deeper?

No mention of what kind of chamber or throating rifle has and I'd be calling gunsmith first thing. You must of talked to him or gave him some idea on bullets you wanted to shoot and barrel being 29" isn't typical length.

[windfall]

I shot 6 rounds today with the BTLRs at 67.5 and 3 of the rounds popped the primers.

BTW, I'm reading everybody's responses. The thing is, I didn't have a problem with pressure with the BTLRs before. However, I have since changed R-22 lot numbers. So, I'm now thinking that the powder lot may be hot as someone suggested. I'll see if I can call them tomorrow.

I also bought a box of Federal 180s (at $70!!!) as a sanity check. I'll have to test them next weekend. I noticed that the ogive of these is 2.805 which is pretty close to the ogive of my BTLRs at 2.815.

I'll also try the another batch with a different powder lot next weekend.

[steve4102]

Can you answer the question I asked in post #11 or no?

[243winxb]

Call the gunsmith before you fire that factory ammo. Tell them your problems.

[precision_shooter]

Are you full length sizing and headspacing on the belt or neck sizing and headspacing on the shoulder? Are both cartridges sized the same so they are headspacing the same and not allowing one to have a longer seating depth by headspacing on the belt?

[windfall]

Sorry Steve. The 2.729 is the ogive of the VLD measured on the lands. The OAL is 3.407.

Thank you for the help.

[windfall]

Yes, I will definitely contact my gunsmith and try to call Alliant about the powder batch to see if there is a known problem with it.

Thank you

[windfall]

thanks. Good questions. In fact, since these are new brass from Norma, I'm not full length sizing the cases at all. All I'm doing to the cases is using the Redding competition bushing die to make the case mouths consistent. What are your thoughts about that? Thanks

[steve4102]

Sorry Steve. The 2.729 is the ogive of the VLD measured on the lands. The OAL is 3.407.

You are listing two different measuring techniques here.

If the Ogive to the lands is 2.729, what is the base to Ogive of your loaded rounds? In other words how far off the lands is your loaded round?



Listing two different measuring techniques will not tell us how far off the lands you are. That number is very important when trying to figure out why you are have high pressure issues.

[windfall]

It's a fair question. I was thinking that it wouldn't cause damage to my rifle. Am I wrong? I'm using the Berger Manual with Berger bullets and trying different charges, even going below the normal powder charge range. I've had some people respond that I should do increase the charge to over 74.

The community message board is a way to get ideas while working through a process of elimination.

[windfall]

I'm on the lands....touching. What is the relationship between distance from the lands and pressure? I don't know this. Thanks

[Jimro]

On the lands increases pressure. When there is a "jump" to the lands the bullet has some momentum to push it into the rifling, this increases the effective chamber pressure. When there is no jump pressure has to spike to overcome the additional resistance of the lands.

Backing off the lands at least 0.010" will help ease pressure.

Peak pressure will continue to decrease as you increase the distance to the lands, until the point when the bullet starts significantly impacting case capacity in which case pressure will start rising again. Unclenick has a good graphic showing this relationship.

Berger's with the secant ogive can be tough to shoot because they generally don't tolerate much jump into the lands, which is why Berger came out with their hybrid ogive, which is a tangent ogive near the bearing surface and secant for the rest.

Secondly, I would try IMR 7828 SSC instead instead of RL-22. I consider RL-22 to be a tad on the fast side for heavy bullets in the 300 magnum cases, but that is purely a personal opinion. I've had very good luck with both IMR 7828 and 7828 SSC in both 7mm Rem Mag and 300 Win Mag.

Jimro

[steve4102]

As Jim just pointed out, being on the lands is where your load will have the highest amount of pressure.

You are having high pressure issues with below max loads, this is directly related to your OAL and you bullets into the lands.

If you want to load into the lands, go for it, just back the charge down until your pressure signs go away. If you want to keep your current powder charge or go even higher then you MUST back that bullet out of the lands. The farther you back it out the LESS the pressure will be.

[F. Guffey]

I want my bullet to have a running start, I do not want my bullet setting at and shoved into the lands, I want my bullet to hit the lands a=running, I do not want my bullet to hesitate.

I am the fan of 'the jump start', I know, it sounds cool "I seat my bullets to the lands" and I ask 'why?' and the answer is cause.

And now we have another new reloader hitting the road to reloading from a dead stop to a dead run.

F. Guffey