pressure signs - rookie reloader for 7-30 w

[bob helget]

I am a new reloader for a new TC 7-30 super 14. the first load I started with was the first on GB's list of selected 7-30 loads.  30-30 reformed, Sierra 130 SSP, 35 Grains of AA-2520 and a Winchester primer.  I started at 31 grains and have a incredibly accurate load for my gun.  After a few rounds, at 100 yds, I shot a 5 shot group I could cover with a quarter.  My concern is, with 31 grains, all primers are quite flat.  I am weighting the powder on ever load and measuring ever case dimension, everything is in spec.  I have had two experience reloaders review my cases and primers and both have told me while my loads are showing pressure signs, I can continue to shoot this load.  I am looking for additional opinions.  What is the best pressure signs to read and when do you know when you are ok and when you need to reduce the load.  Are there other factors that may be causing the flat primers?

[New Hampshire]

This is always a big debate among reloaders.  But the simple fact is that primer flattening apperance alone is not a good pressure indicator.  YES, it tells you pressure is there.  But it should be taken in with other indicators.  Is the case hard to extract?  Is there pimer cratering or piercing?  Is there brass flow on the case head?  These are all additional indicators to high pressure.  My handload of 296 under a 158 gr XTP in .357 Mag really flattens the primers good.  But the cases extract fine and there is no other bad signs.
Brian M.

[Dave in WV]

One thing I watch is "soot" or carbon deposits on the sides of the case neck near the mouth. There almost always is with factory ammo. When I start working towards max loads I pay attention to this. If I get a load that doesn't leave carbon on the case neck I back down.

[Bullseye]

Of the many pressure signs, flattened primers is the most unreliable in my opinion.  I get flattened primers in my 44 mag Contender barrel with the minimum loads in the Hornady book.  If the load seems reasonable by checking a couple of sources and there are no other pressure signs, I would not worry about it.

[papajohn428]

I'd make up a few rounds at 33 and 35 grains, and see if the cratering persists.  My hunch is that it will be reduced, or it's just a fluke.  What kind of primers are you using?  I screwed up once and used pistol primers in 357 Max loads, I was freaked out until I figured out the problem!  :eek:

PJ

[Graybeard]

Soot on the neck is generally a sign of one of these things.

1. Pressure is rather low and isn't allowing the case to blow out and fill the chamber.

2. The pressure is happening too late and blow by occurs before the case fully blows out to seal the chamber.

3. Excessive headspace allowing case to be pushed back before pressure on case seals chamber.

4. Overly large chamber or undersize case.

Trying to duplicate it is bad business regardless.

In the case of the 7-30 it is most often used these days in the TC Contender. I assume that's what you are using. There are many things other than excessive pressure that cause flat primers and the TC is subject to most of them. Flattened primers from excessive pressure should NEVER EVER occur in the Contender. IF it does you are likely 50% too high on pressure at the time and it is possible you've already ruined your frame. Even softer primers usually won't flatten from pressure alone until way beyond the safe pressure limit on the frame with .30-30 head size cartridges.

BUT very often in the Contender you have excessive headspace or the gap between the barrel and frame is such that it allow the cartridge to set back prior to the pressure reaching a level to temporarily seal the case to the chamber. When this happens flattened and often braded primers will result. The primer will try to back out of the case and then the case slams into the frame and brads or flattens it.

Taken alone as has been said primer condition is an extremely poor way to gauge pressure.

But AA2520 is a ball powder. Generally speaking with all ball powders reducing loads below what the loading manuals recommend is bad business and can also result in excess pressures just as can too much of it. That load of mine has proven fine in many barrels for many people but remember I consider it a MAX load in my barrel and it may or may not be in yours. I don't generally drop below 33 grains of it.

Just my thoughs on the subject.

GB

[Dave in WV]

GB, every centerfire firearm I've owned has left a ring of carbon about 3/32"-1/8" down from the mouth of the case. The only loads I've shot that didn't do it were max loads. The carbon deposit was very thin and I refered to it as soot even though it won't wipe off like soot will. I guess soot is a bad term to use. Dave

[bob helget]

Thanks for all the responses, I will try and fill in some of the gaps that I left out on my original note.  I am using these loads in a New G2 with a super 14 7-30.  I am using a winchester WLR primer. The primers are flat but no cratering or piercing, and there is no evidence of the primer backing out of the case. the case comes out of the barrel as easy as it when.  I am not seeing any other signs of pressures that I have read about in the reloading manuals that I am using.

As I understand a couple of responses, I should load a few rounds at  33 grains and compare those cases to the cases at 31 grains?

[Leftoverdj]

Me. I'd stop right there. You have all the accuracy anyone can ask for, you're new at this, you have the advice of an expert that you can ruin your gun before sticky ejection occurs.

Nothing much to gain and a lot to lose.  Stop.

[The Shrink]

Ditto - stop here.  You have little to gain and a lot to loose.  That's the definition of a bad decision.  

Wayne

[bob helget]

I did load three at 33 grains.  The primers are showing a little more flattening.  Another thing I have determined is that at 33 grains the cases are stretching more than I would think is normal.  My cases are starting at the trim to length of 2.030 and after one firing, one had grown by .005, the others stretched 0.002.  One thing I read from the Lyman manual suggests, as did GB is a headspace issue.  If this is something that is common with contenders do I just live with it or can it be corrected.  The Lyman manual also suggests purchasing a gauge to assist in setting the die.  Could die adjustment effect head space for a rimmed cartridge?

[KYODE]

die adjustment can definately affect headspace for a rimmed cartridge. i suspect that, just as GB mentioned, you possibly have too little headspace.
die adjustment is pretty critical for me from my observations. you do not want to bump the case shoulder back too far with the sizing die. you do not want to bottom the die out on the shellholder. only slightly bump the shoulder back, and do use lube inside the necks to prevent pulling the shoulder back out when raising the press handle, or pulling the expander ball back thru the neck.

first....a chronograph would help in reading velocities, and definately aid in percieving your max load. if you're getting over loadbook stated velocities, it's quite possible you're over max.

second......you can use a feeler gauge, or plasti-gage(from auto parts store) to see what actual barrel to frame gap is. do this by closing the action on the plasti-gage, or feeler gauge. then you only want to bump the case shoulder back a couple thousandths more than that measurement. for example.....if you measure .008" barrel to frame gap, then adjust your full length sizer down until you get approximately .005-.006" of case protruding from a removed barrel.

you can eyeball with a feeler gauge, or get a headspace indicator(easier) to see how much a resized case protrudes from the REMOVED barrel. then relube, and keep adjusting the die down in small increments to get near perfect headspace.
since i've started using these methods, i have not seen a flat primer with max loads. i believe correct headspace will also help accuracy.

also note that if you resize down too far, and push the shoulder back excessively on a rimless case, you may have a case below flush with the chamber end of the barrel. misfires could be very possible in that situation.

as another note :lol:  if loading for an encore, as well as G2 contender, if you do not bump the shoulder back enough, you will have too much case protruding from the chamber, and it will prevent the hammer from cocking.
headspace....as i see it, is very critical. :wink:  

[hogship]

I am using a winchester WLR primer. The primers are flat but no cratering or piercing, and there is no evidence of the primer backing out of the case. the case comes out of the barrel as easy as it when.  I am not seeing any other signs of pressures that I have read about in the reloading manuals that I am using.

I've found that the Winchester brass colored primers flatten more easily than the Federals or CCI's.

You may want to get another brand of primer and to a test with the exact same load, except for the primer change.

I like Winchester primers, and use them quite a bit. They are consistant performers......but, as with others here, I've learned to trust other indicators of pressure sign for them.

CCI's and Federals are a different story. It takes more pressure to flatten them, so apply the pressure logic accordingly.

hog

[bob helget]

Thanks for the additional suggestions.  I obviously have a lot more to learn about my new gun and reloading.  Looks like I need to try the other brand primers and well as purchase the headspace gauge.  I also plan to buy some factory loads to compare then to my reloads.  This may not tell me a whole lot but will give me another perspective.

[jrcanoe]

The factory Ammo will tell you alot. After firing the factory loads measure their expansion and stop your reloads when they give you the same amount of expansion. If you are shooting The 7x30 in only one gun I would neck size only and orient the shell in the chamber the same way each time.