I need some advice from the guys that have been doing this much longer than I have. I am loading 90gr Swift Scirocco II bullets, using S365 powder (South African equivalent to IMR4350 I believe) and CCI250 primers in Federal cases. I've seated the bullets .020" from the lands and shooting them out of a brand new Weatherby Vanguard. My problem is that when I run them through a chronograph, the muzzle velocity is roughly 400fps faster than what is stated in the manuals. I started at 40.7gr powder and was working up from there. When I got to 42.5gr, which is roughly in the middle of the spectrum, it blew a primer out of the case. What should I look at to figure out why I am getting these high pressures?

Your powder seems to be equivalent to H4350 which is the Aussie made AR2209 and the loading range ADI who make the AR2209 powder give in their loading manual for the 243 Win and 90gr bullet is 42.0 - 44.5grs. You seem to be loading okay within that range.

Check your scales, weigh a 90 grain bullet, it should weigh very close to 90grs maybe not spot on as bullet weights do vary slightly.

Are the cartridges easy to chamber? Perhaps you have a tight chamber neck area and the Scirocco is expanding the neck when seated in the case to leave no room for neck expansion in the chamber. Similarly check your case length, again you should feel resistance to chambering a round if the case throat was crimping when chambered.

Don't know that you need to use magnum primers in such a small case, maybe they are raising pressures.

I haven't heard that the Vanguards had any barrel problems, an undersized barrel could raise pressures as you are seeing.
Being brand new I guess you have not fired any other ammo, factory or reloads in it, try a factory round if you can get one.

Each rifle is answer onto its self.

that rifle with that lot of powder needs less of it.

Thanks for the feedback eagle27. I calibrated my scale and checked it for accuracy before I started. Only about 4 rounds out of 40 were a bit stiff when closing the bolt and I opted not to shoot those. I didn't check the case length. The cases I used were from factory ammo that were once fired. The factory ammo weren't grouping near what I want, but in hindsight I should have run them through the chronograph too. I did test some loads with 100gr Hornady Interlock bullets. Different cases, but all else the same. Looking over the figures now I see they were running about 250fps faster than the published figures.

Thanks p dog shooter. So you reckon I should just load less powder until I get to the speed I want?

It seems I have located the problem. The data in my older manual (2009 print) is not the same as the data in the newer edition. In my 2009 edition of Somchem's manual the load spread is on average 2gr higher than in the newer manual. The starting load in my manual is the maximum load in the new one, which would account for the high pressures I've been experiencing.

So, for anybody using Somchem's Ballistic Data Manual, double check the data if it is an older print. They have up to date data on their website (www.somchemreload.com)

Uh, whenever that happens, the solution is, use less powder. Each rifle is different.

quote:

Originally posted by dpcd:
Uh, whenever that happens, the solution is, use less powder. Each rifle is different.

and try another primer, as that CCI 250 may be a bit "warm" for a 243 case.

Back off on the powder charge - this not rocket science. Always approach from well below maximum charges, until you get the velocity you want and still be within safe operating pressure.

Thanks for all the feedback, guys. I appreciate it.

quote:

Originally posted by Ackley Improved User:
Back off on the powder charge - this not rocket science. Always approach from well below maximum charges, until you get the velocity you want and still be within safe operating pressure.

He was doing just that using the published range for the powder but it seems Somchem have changed their powder or their recommended loading range. If using a powder burn rate comparison/equivalent chart as I was doing then MH was loading below the minimum for H4350/AR2209 and only just got to the minimum before he experienced the high pressures with his S365 powder.

Like Terry Blau posted, I too believe and posted, that the magnum primer is having an unwanted influence in the small case.

I've loaded for quite a range of cartridges over the years and never run into any issues starting at the minimum recommended loads even when using equivalents for powders where loading data is scarce. Popping a primer as MH did in once fired cases is showing pressure is way up there.

I'm not sure if the data Somchem published originally was wrong or if they changed the powder. Be that as it may, I have the latest reloading tables from them and also got some CCI200 primers today. I'll shoot some loads next week and post the outcome, but I'm sure the reduced loads and primers will do the trick. Thanks again for everybody's input.

quote:

Originally posted by Terry Blauwkamp:

quote:

Originally posted by dpcd:
Uh, whenever that happens, the solution is, use less powder. Each rifle is different.

and try another primer, as that CCI 250 may be a bit "warm" for a 243 case.

Terry, just as a matter of interest, in my copy of the Somchem Ballistics Manual, they published loads for the .243 using CCI250 primers. The loads were for a different powder though (S361, which is a ball powder as opposed the extruded S365). In the current tables they are now listing LR primers for all .243 loads. Just thought is was interesting, but I agree that the CCI250's are definitely not the right primer for what I'm loading.

Not familiar with SA powders - are they Ball powders like Win 748 & H380? Ball powders are said to work better with magnum primers.

When I used to load the 243 Win with 95gr Nosler Bal Tip, I used 44 gr of AR2209 for just over 3000 fps & good accuracy.

Flippie,

Back in the day Somchem used to recommend magnum primers for ball powders (S341, S261(?)) and so on. For the normal extruded powders they used to recommend standard primers (Apart from giant cases full of S385 and so on).

I never really noticed a great deal of difference between magnum and non-magnum primers on the extruded powders, but I was not pushing the loads very high at all.

With only one exception, I've found very little, if any, difference in velocities and pressures when comparing magnum and non-magnum primers - that is, keeping everything else equal.

The one exception was using large charges of Hodgdons H870, which liked magnum primers to achieve maximum velocity.

In my experience, the causes of blown primers or "stuck" cases (i.e., over pressure situations) are using too much powder for the bullet weight, especially relatively fast burning powders, or shooting hot loads at relatively high ambient tempertures.

Ackly,
My experience matches yours but; the people with the real equipment have shown standard to mag primer switch can take a load from 60K to over 70K or higher with some cases and powders. John Barness did some work there I think if someone wants to find it.
It makes sense; if one lights something that burns progressively with pressure, the faster you start the pressure curve, the higher it will top out.
Best regards,

Pressure in hand loads has always been a case for caution after my experience in the first year of reloading, 20 years ago.

I was loading for my Tikka LSA55 in 222 Rem. The load I got from the previous owner was using PMC brass & 52gr Sierra HP with AR 2207 (similar to 4198). I got safe accurate loads at top velocity with round primers, easy extraction and little case length creep. I still use that same load for 1.5" - 5 shot groups at 200 meters!

I then loaded up a 20 pack using Federal brass after firing the factory ammo. I presumed that such round primers etc. would be safe! Wrong! - I blew primers in 2 out of 3 shots! The remaining 17 bullets are still with me in my man cave!

Hi guys,
I am still struggling with this. I am using brand new Sako brass (FL sized and trimmed) with CCI200 primers, and with the minimum load of 38.5gr S365 they are still running 240fps over. Any ideas?

Hi Flippie

Have you thought of talking to the guys at the reloading association?

Mauritz Coetzee always was ready to lend a helping hand, but a nagging feeling says he's not around any more.

I would just bring my loads down fractionally until I was happy that they were round about the right velocity, check for pressure signs and call it a done deal.

quote:

I would just bring my loads down fractionally until I was happy that they were round about the right velocity, check for pressure signs and call it a done deal

+1

quote:

Originally posted by Bren7X64:
Hi Flippie

Have you thought of talking to the guys at the reloading association?

Mauritz Coetzee always was ready to lend a helping hand, but a nagging feeling says he's not around any more.

I would just bring my loads down fractionally until I was happy that they were round about the right velocity, check for pressure signs and call it a done deal.

Hi Bren7x64,

Unfortunately Mauritz Coetzee is no longer with us. I had the privilege of being interviewed by him for a TV program shortly before he passed away.

The problem is that bringing the load down fractionally is not going to bring me within the speed range I want to be in. To drop 240fps I would probably have to drop the load by about 2 or 3 grains (I'm guessing from experience). I have, however, found something in Somchem's tables that doesn't make sense to me. The starting load for 90gr bullets using S365 is HIGHER than for 75gr bullets. Maybe I'm missing something here but the way I understand it is the heavier the bullet, the lower the charge, right? And the jump from 90gr to 100gr bullets is a difference of 5.3gr of powder, according to the tables. Something doesn't seem right here...

At this point with these problems, I'm asking..

1. Is the powder you're using actually S365? Where did you get it? Can you trust the vendor? Has it deteriorated causing the burn rate to significantly change to a faster burning rate? Are there known marked variations in lot-to-lot burn rate for S365?

2. Can you trust your chronograph? Have you checked it against a second chronograph?

3. How good is the manual you're using? Is it an out-dated version based on powders that have changed in their formulations over time?

A couple of suggestions that might help you find the problem: Approach the problem as if it were an investigation:


1. Cut the powder charge as stated above is always a good idea. Your rifle may have a minimum chamber and get the same velocities with less powder, a very common problem..

2. Check the length of your cases, they may need trimming.

3. Measure your case heads with a mic. you don't want more then two thousands expansion

4. Federal and Rem usually get max velocity with about 2 grs. under book max or what WW cases would.

5. Use a standard CCI 200 primer as opposed to a 250 CCI std. primer and that just might solve the problem..Check your Aussie reloading reference book that has loads for that particular Aussie or African powder not US 4350, cross referencing powder is a practice in destruction, regardless of what your told. They may have the same buring rate but the pressures can be considerably different.

6. If one of the above won't solve the problem, give me a call or talk to your local gunsmith.

Describe your case inspection practice as that should tell your what the problem is..if you 400 FPS past max, that's very dangerous and you should have a stuck bolt, the bolt should have spewed some gas your way, and a crack as opposed to a regular boom, and primer should be smeared with the case head showing a shiny extractor indention...Without these your chronograph may be out of wack..Lots of things can be wrong and without being there its hard for us to determine the problem.

It seems I have found the problem. I phoned up Somchem today to query their tables for the .243 Win. The person I spoke to confirmed that the data in their manuals, as well as on their website is INCORRECT! According to him the starting load is 2 grains lower than what they have published (and 4 grains less than what is printed in my manual). His actual words when I told him what the published loads were was "Oh no! That's wrong. They must have made a mistake". They don't inspire much confidence. Needless to say I'll be looking at which other brands of powders are readily available here in South Africa.

Well, well. Somchem does it.


I think you're going to find that there are NO steady, reliable sources of nitro powders in SA. There certainly weren't when I was there, and talking to friends still there, there still aren't. Best of luck, however.

Just a general advice.

We never use magnum primers in cases as small as this.

There is no guarantee that any rifle will follow the loading manuals velocity and powder charge.

Hardly any manuals agree anyway.

Some rifles will take several grains more powder than shown in the manuals as maximum, and show no sign of excessive pressure.

Other rifles we have tried blew the primers with 10% less than minimum charge in the manual.

As stated above, each rifle id a law unto itself!

Go to standard primers regardless.