Pressure Signs and New Brass

[sithlord6512]

Getting frustrated with my .300 WSM load development. Tested IMR4831 with 180 grain TTSXs with phenomenal results (3 holes touching on one loading) - unfortunately the two chronies were not picking up the speeds AND upon examining my brass, I started getting clear ejector marks on the brass with loads at 5% below max (and even a very faint ejector mark at 8% below a max=63.0g). The thing is, not all all brass within each 3-shot load load had the marks.

A similar phenomena happened when I was testing loads using H4350 - ejector marks at 5%-to max loads(using 64g as my max). Also, all loads I have ever tested have cratered primers (including those 10%) below max. Any theories?

I am wondering if the cratering and the sooner than expected (and wanted) ejector marks on my brass are related (i.e., problem with my Rem700 firing pin?). Alternately, could this be happening because the I am using new WW brass.

 

[rick smith]

How far off the lands are you seating the bullets? How much powder compression? Have you loaded a few and leave them sit for a few days and measure their length?Rick.

 

[sithlord6512]

I am loading them .050 of the lands. I don't know about compression. However, I have I used 63 grains as my max. I find that load data for the Swift Scirocco is generally identical and sometimes slightly higher than the TSX data - 62 grains is the min and 66.3 COMPRESSED is the max for the Scirrocco. In other words I assume my 63 max is not compressed load.

I never taught to recheck my OAL - I will do this next time. However, because even the loads at 8% and 6% below max showed faint ejector marks, I suspect compression is not the culprit (i.e., OAL length increasing due to pressure from compressed powder). I've just made H4350 loads. I will check their OAL in couple of days to see what happens.

 

[Desert Fox]

I have this same problem when using 180 grain Scirroco. This from my friends 300 Weatherby. I haven't measured it but I suspect the bullet shank is a bet long, therefore creating more friction. Threat the Scirroco like the old Barnes X bullet when loading.

 

[sithlord6512]

Thanks Desert Fox,

However, I am actually using the Barnes TTSX. I only mentioned the Swift Scirocco because the Hodgdon online data for 180 g bullets of this flavor are pretty much idential to the Barnes #4 data for the 180 TSX/MRX data (and supposedly, TTSXs). Where there is a difference, the max load data for a 180 g TSX is higher than the SCI. This led me to assume that using Max Load Data for Scirrocco could be used as a "Conservative" and safe estimate of TSX data - i.e., if not equal to TSX max load data, the SCI max load would be lower = safer).

I did check the max load data for IMR4831 (69.0) and H4350 (65.0) in the Barnes #3 manual for the Original 180 g X-bullet (not the XLC or moly coated version). In both cases, these max loads are much higher than the Max loads I used (IMR4831=63; H4350=64).

I used a different lot of new Win brass with my IMR4831 loads because I thought the lot of new Win Brass I used with the H4350 may have been a "soft" lot. In other words, it seems unlikely the brass is the cause for eariler ejector marks (unless all WW brass is prone to showing premature ejector marks).

 

[rick smith]

I recently finished working-up loads for two different 300WSMs and a 7mmWSM. The three rifles were a Rem 700, Kimber and a Browning A-bolt. All used Win brass and none showed any pressure signs. Can you measure the case headspace on your rounds? Untouched new brass, a fired piece that showed pressure signs and a resized piece.Rick.

 

[DrMike]

In more recent days, I'm allowing for more jump to the lands (0.100 inch or more) with monolithic bullets. The signs of pressure you describe may be due to pressure, or an artifact of the case. In a number of rifles chambered in the Short Magnums, I have observed ejector marks and deeper than normal cratering. The deeper than normal cratering is not that unusual in Remington firearms that I have shot. I don't ignore the phenomenon, but I look for other signs that either verify that it is due to pressure before I draw a final conclusion. Whilst I don't use a strain gauge to measure pressure, I don't believe they are always related to excessive pressure. Especially when it was new, my previous 300 WSM showed such marks. I was getting up to ten firings from the cases without evidence of separation at the web or enlarged primer pockets. As is true with the deep cratering, the ejector marks are not that uncommon in some rifles with the short magnums. Ultimately, you must make the call. However, the fact that your observations are evident even at ten percent and five percent below pressure tested maximum charges would indicate that the marks are an artifact of the load. You will need to be alert to other pressure signs for a definitive warning sign of pressure. You could always mic the web to see if you are observing excessive expansion on a second firing.

 

[Divernhunter]

According to the Bares #4 manual they do not show a load with IMR4831 and the 18gr TSX. They told me use the TSX data for the TTSX bullets. They do show IMR4350 57.5 to 65.5 grains. RL19 was their powder of choice.

If this matters.

 

[1Shot]

How hot was the weather when you were doing your shooting? Was the ammo left in a hot auto for a while? Hot temperature can raise your pressure quite a bit with some powders.

 

[sithlord6512]

I recently finished working-up loads for two different 300WSMs and a 7mmWSM. The three rifles were a Rem 700, Kimber and a Browning A-bolt. All used Win brass and none showed any pressure signs. Can you measure the case headspace on your rounds? Untouched new brass, a fired piece that showed pressure signs and a resized piece.Rick.

Hi Rick - interesting findings - fired factory brass tonight (Federal 180 PSPs - 2 rounds)

I measured the headspaces. The results are as follows:

2 Factory Federals rounds
Round 1
Before = 1.725 (same as twice fired brass that I used to determine the headspace of my chamber as recommended by RCBS)
After = 1.7245 (estimate at the .0001 decimal place)
Resized = 1.722

I noted that resistance was met when trying to close the bolt on bullet 1 - this, to me, is consistent with the fact that Bullet 1's headspace was the same as the what I have been using as the headspace of my rifle (i.e., 1.725)
- No excessive bolt lift, primers cratered, AND Very Clear Ejector Marks (more than any of the IMR 4831 loads that will be referred to below and more pronounced than the Round 2 ejector mark).

Round 2
Before=1.722
After = 1.7232(estimated at .0001 decimal place)
Resized = 1.722

Easy bolt life, cratered primer, and ejector mark (Recall: not as clear/shiny as round 1)

IMR4831 Handloads (sample of 5 round at 5 different loads that had ejector marks)
All 5 pieces of virgin brass = 1.720 (I resized my new brass to "bump" .003 below my measured headspace using Lee die with expander removed - expanded necks with Redding Expander Die with expander mandrel)

After
4% below max = 1.7218
3% below max = 1.7225
2% below max=1.7219
1% below max=1.7224
Max (63.0g) = 1.7219

Not Resized = My die is set to "bump" the shoulder back .003" (i.e., 1.722)

Easy bolt lift, cratered primers, and all five, as desired had ejector marks. Ejector marks barely noticably, but as would be expected, increasing in "noticability" as Max load approached. However, even at the max IMR 4831, the ejector mark was not nearly as noticable as the ejector marks on either of the 2 Factory Federal rounds.

I use the RCBS precision MIC - based on the instructions, my chamber appears to be below the minimum SAAMI spec by .001" (i.e., 1.7260-1.7369 is the SAAMI specs). Could this explain ejector marks?

 

[sithlord6512]

According to the Bares #4 manual they do not show a load with IMR4831 and the 18gr TSX. They told me use the TSX data for the TTSX bullets. They do show IMR4350 57.5 to 65.5 grains. RL19 was their powder of choice.

If this matters.

Thanks Divernhunter. However, the Barnes #3 manual has data for both H4350 and IMR4831 for 180 grain pills - the max's listed for these powders in this manual all higher than the loads I used (should be lower, as the Barnes#3 manual is for the "stickier", and since discontinued X-bullet). I used H4350 and IMR4831 Max loads generated by Quickload for the Barnes 180 g TSX/TTSX (thanks again Dr. Mike and POP) - this was the most conservative load data I came across - all the load data for these powders and 180g pills available on the loaddata.com site had higher Maximum loads than the Quickload data - i.e., my Max loads should be more than safe.

 

[sithlord6512]

How hot was the weather when you were doing your shooting? Was the ammo left in a hot auto for a while? Hot temperature can raise your pressure quite a bit with some powders.

with the H4350 loads, the temperture was in the 10-15 celsuis range - July temperatures in Iqaluit, Nunavut - i.e., the Canadian Arctic

with the IMR4831 loads, the outside temperatures were approx in the 20-30 celsius range - Hot August temps in Ontario, Canada. However, my test loads where keep in an Air conditioned vehicle, as was my rifle after each firing. I also wrapped a wet cloth around my barrel between shots. I fired 15 rounds, round-robin still as per the OCW method, with a 2-3 minute break between each round (shot 1 - 2-3 min. wait - shot 2 - 2-3 min wait....etc.).

 

[sithlord6512]

Ultimately, you must make the call.

I suspect, but am not certian, that my loads are safe given that Factory Federal Loads I have tested would appear to be even more dangerous than the IMR4831 (and H4350) loads I have tested (i.e., have the same craterering but EVEN MORE PRONOUNCED EJECTOR MARKS THAN MY HANDLOADS). However, as my gun is still under warranty, I am now investigating whether I can send my gun to be evaluated by a Remington authorized gunsmith (located in Montreal, Quebec, Canada). I am hoping that they can "repair/address" whatever is causing what I now think are premature ejector marks (and the ever present primer cratering which are present on all the loads and factory ammo I have tested).

If they can't address the issue, I fear that my handloading journey will have come to a halt as I will have lost two important indicators of excessive pressure (unless heavy bolt lift and/or chronographed velocities alone, can be depended on as guides).

 

[DrMike]

I do believe it would be a good move to send the rifle to the factory for an evaluation. FWIW, within the past year I have twice had factory loads from a major manufacturer of ammunition that were so hot they locked the bolt up on two separate WSMs. The ammunition was just plain "hot." The giveaway was the velocity was excessively high.

 

[sithlord6512]

With help, I may have found the culprit for my seemingly "premature" ejector marks - A small burr/ridge around the ejector hole caused when the hole was initially drilled. Apparently, it is known problem on some Remington M700 rifles. In any case, I am now working on sending my rifle to Remington for evaluation.