tikka t3x powder residue on case, pressure signs, etc

[Tac-O]

Hello All,

In my last round of hand loads, I noticed a few cases had powder residue down onto the shoulder of the case, which isn't normal for my gun. The residue always covers the whole neck down to the shoulder/neck junction, pretty uniformly. I've done some research on what various people say can cause this and it doesn't quite all add up for my gun and loads. And, I'd like to figure out what my best options are for remedying it. Here's the details:

I've been shooting a tikka t3x in 30 06 since last year and have been working on developing my hand loading skills. When I first bought the gun, I shot some factory ammo out of it and noticed that the powder residue would cover the whole neck down to the junction. It's always been consistent, so no big deal. Also, after firing these factory rounds, there was a clear case stretching line just above the case head. This was the case with both 168 and 180gr factory loads. This, to me, sounds like the chamber is on the long end of saami specs. With my handloads, it's the same. Residue on the whole neck, uniformly. On my last round of shooting, I decide to test some loads on the higher end of Lee's loading manual for my bullet weight and powder. On the two highest loads (one max) I had a few cases that showed residue on the shoulders.

Here's some chamber measurements particular to my gun:

I *think the headspace length is about 2.042 or 2.043. I use the hornady comparator to measure fired unsized cases. My base to lands lendth is about 2.733 using the hornady comparator.

With my hand loads, here's what I've mainly been shooting that's only been showing residue on the necks:

win brass - FL sizing die adjusted to bump shoulder back, doesn't smooth out the webbing stretch line, I've reloaded cases up to 4 times and haven't seen any case head separation cracks starting
sierra prohunter 150gr
cci200 (just started testing out federal gm210)
h4350 57.2gr
3.288 COAL (should be about 0.015 off lands)

Here's what showed residue on the shoulders:

win brass, fired twice - FL sizing die adjusted to bump shoulder back
sierra prohunter 150gr
federal gm210
h4350 61.4gr AND 62.0gr
3.288 COAL
No signs of high pressure. Did not seem to be accurate loads, but I may try them again.

So, in the researching I did it seems that most people say it can be one of these, and I also put my thoughts on why each of these do or don't make sense for my gun and loads:

1. the headspace is excessive or is on the long end of saami specs (doesn't build pressure and seal quickly enough). I think this is the most likely scenario, but if I had a long chamber, then I would think my max COAL for this gun would be longer than what I measured it to be.

2. the powder for the bullet weight being used is on the slow side for burn rate (doesn't build pressure and seal quickly enough). h4350... I haven't seen many other powder that are faster except for RL16.

3. the powder charge is too low (doesn't build enough pressure to seal). This happened with charges that were at max level according to Lee's manual. Oddly, in looking at a few bullet manufactureer's load data as well as hodgdon's, it seems they list the max load for this bullet weight and powder at ~60.7, not 62.0 like Lee's. So it would seem that I SHOULD be seeing some high pressure signs on my cases for the two max loads I did, but I saw none at all.

4. necks are too hard and need to be annealed (too hard to seal well/quickly enough) - Only the 3rd firing on these cases.

5. The chamber near the neck could be dirty. This shouldn't be the problem because I typically use a large patch and a bit of solvent to give the chamber a quick cleaning after cleaning the bore.


I'd like to remedy this, because it sounds like the loads won't be as accurate if you're getting a bit of gas leakage before it seals, especially if it's not a consistent amount. So, my thoughts for what I could do is:

1. try a faster powder ( I have RL16 and have used it in place of 4350 - different charges of course) - still had residue on necks, but never saw it on the shoulders, despite trying a couple max loads per Alliant's load data. Should I try an even faster powder?

2. Try using MORE powder - not sure if I want to do this one since the max charge is where I saw residue on a few case shoulders... this indicates to me that something was wrong. But, if the headspace is on the long end, shouldn't I be able to use higher charges compared to typical manual data with seeing high pressure signs? Not that I really want to test this out to its limit, but I'm just trying to think through the whole scenario.

3. Should I get a No Go gauge? I wouldn't think Tikka would send out a rifle with out of spec headspace...

 

[cohunt]

To know what your chamber is for sure, do a chamber cast

 

[Mikecr]

None of your notions are correct. Excess chamber end and neck clearances are the contributors to gas blow-back.
I notice you didn't consider & include chamber end clearance. That is actual chamber end distance minus case OAL.
Basically, your chamber neck may be too long and big, and/or you're over trimming.

 

[Tac-O]

None of your notions are correct. Excess chamber end and neck clearances are the contributors to gas blow-back.
I notice you didn't consider & include chamber end clearance. That is actual chamber end distance minus case OAL.
Basically, your chamber neck may be too long and big, and/or you're over trimming.

Just my notions on the chamber size? Or all others as well?
I see I had confused headspace the headspace measurement with chamber end clearance. I just use Lee's hand trimmer with the case length gauge screwed all the way down. I believe my cases are trimmed to 2.487 or 2.488. The chamber end clearance is the cause, I wonder why I haven't experienced residue on the shoulders at any other time, factory or handloads?

 

[Canhunter35]

Are ur primers pushed out slightly after firing?

 

[Tac-O]

If they were, it wasn't enough to be obvious. I haven't put calipers on these cases yet. In the past, with my 57.2gr charge, I've noticed that they'd protrude by around 0.005 or so.

With these two max charges, the primers weren't very flattened at all. Didn't look much different from the 57.2gr.

 

[Canhunter35]

It could be excessive headspace then

 

[Mikecr]

Head spacing has zero affect on neck sealing. If the necks were sealing correctly there would be no sooting back at the shoulders.

 

[bigedp51]

Lay a straight edge on your fired primers and see if they are flush with the base of the case. If the primer is protruding it is a sign of low pressure.

Note, my fired 30-30 primers always protrude at 38,000 cup or 43,000 psi and I have soot on the necks.

Below both these .303 British cases were fired in the same No.4 Enfield. The HXP case on the right has a smaller base diameter and expanded more to contact the chamber walls when fired. And the smaller the diameter of the base of the case the more pronounced it will be.

Below you can see where the base of the case contacted the chamber walls and normally a case head separation is higher up the case.

The SAAMI establishes chamber pressure for the oldest and weakest action it will be fired in. This is why the max chamber pressure on the 30-06 is 5,000 psi lower than a .270 Winchester. I bring this up because with a new bolt action rifle the 30-06 could be loaded warmer. Your brass will last longer with your 30-06 at the lower pressure and I'm not telling you to load over the manual. But many firearm manufactures are making rifles with longer throats so the cartridge and company lawyer will fit in the chamber.

Bottom line my 30-06 Remington 700 does the same thing as your rifle until it is loaded closer to max. So again check for primer protrusion, even the slightest protrusion is an indicator of lower pressure.

 

[86alaskan]

load up a ladder test for pressure at .3gr increments starting where you are now up past book max. watch for signs along the way- flat primers, ejector marks etc...

when you size the cases, it isn't altogether totally necessary to push the shoulders back to spec. load for the chamber you have instead of what a book says. start with the die a couple turns out and work it down until it just barely touches the shoulder. after that size, check for ease of chambering. if it chambers ok, stop there. if you're setting the shoulder back too far on a case that's already stretching, you could be exaggerating a problem that can be worked with.

I find it hard to believe that you're anywhere near maxed out, I load more h4350 with a heavier bullet for the same rifle.

 

[Tac-O]

Lay a straight edge on your fired primers and see if they are flush with the base of the case. If the primer is protruding it is a sign of low pressure.

Note, my fired 30-30 primers always protrude at 38,000 cup or 43,000 psi and I have soot on the necks.

Below both these .303 British cases were fired in the same No.4 Enfield. The HXP case on the right has a smaller base diameter and expanded more to contact the chamber walls when fired. And the smaller the diameter of the base of the case the more pronounced it will be.

Below you can see where the base of the case contacted the chamber walls and normally a case head separation is higher up the case.

The SAAMI establishes chamber pressure for the oldest and weakest action it will be fired in. This is why the max chamber pressure on the 30-06 is 5,000 psi lower than a .270 Winchester. I bring this up because with a new bolt action rifle the 30-06 could be loaded warmer. Your brass will last longer with your 30-06 at the lower pressure and I'm not telling you to load over the manual. But many firearm manufactures are making rifles with longer throats so the cartridge and company lawyer will fit in the chamber.

Bottom line my 30-06 Remington 700 does the same thing as your rifle until it is loaded closer to max. So again check for primer protrusion, even the slightest protrusion is an indicator of lower pressure.

Thanks for the info!! Yes, I checked a couple of my cases last night when decapping and sizing them.

The max loads I did at 62gr did have the primber protruding ever so slightly to where it wouldn't sit flat on the edge of my calipers with the primer still in the case.

load up a ladder test for pressure at .3gr increments starting where you are now up past book max. watch for signs along the way- flat primers, ejector marks etc...

when you size the cases, it isn't altogether totally necessary to push the shoulders back to spec. load for the chamber you have instead of what a book says. start with the die a couple turns out and work it down until it just barely touches the shoulder. after that size, check for ease of chambering. if it chambers ok, stop there. if you're setting the shoulder back too far on a case that's already stretching, you could be exaggerating a problem that can be worked with.

I find it hard to believe that you're anywhere near maxed out, I load more h4350 with a heavier bullet for the same rifle.

Here's an interesting bit that I didn't mention about my sizing. I *attempt* to size to where I'm just pushing the shoulder back, or where there is the tiniest bit of resistence on the last 1/2 of closing the bolt. This usually will leave a slightly larger band at the bottom of the neck that wasn't sized down (using a Lee FL sizing die). BUT.... after decapping my fired cases I'll measure base to ogive with my comparator and get around 2.040 or 2.041. Then after I size them, they'll measure 0.002 longer. So my loaded and ready to go cases measure ~2.042 with my comparator. I know that If you have new cases that have only been fired once with a lower pressure load, then when you size it can increase the base to ogive measurement. I can't adjust my die out any further to NOT make the length increase when sizing because then I'll end up moving that uncompressed portion of the neck further and further up the neck until it gets too close to where the bullet is seated. So, that's how my sizing works... strangely.

I'm interested to see how it will change my fired case measurements and sizing measurements if I bump my charge up higher.