Compressed Charge help needed!

[coloradokevin]

I'm in the process of developing some hunting loads for my 8mm Mauser (M48 surplus rifle), and have encountered a few questions regarding compressed loads. I don't normally dabble much in compressed loads, so this is fairly new territory to me!

Today I'm loading 180 grain Barnes TSX BT bullets, using H380 powder. This powder shows a starting load of 49.5 grains, and a maximum load of 54.5 grains. The Barnes data also shows a COAL of 2.980", which I have to admit is a good chunk shorter than what I've been developing with some Sierra bullets! I should also note that, due to availability, I am using new Winchester brass (rather than the Remington that was listed in the data). This brass has been full-length sized and fully prepped.

(LINK TO PUBLISHED DATA: http://www.barnesbullets.com/images/8x57mmMauserWeb.pdf )



Anyway, I noticed that my very first loads (at 49.5 grains) seem to be compressed, even well before I've seated the bullet to the listed COAL. Although I have seated these bullets to the published COAL, I still can't help but wonder how this load will possibly fit in the case with another 5 grains of powder? Because of the fact that I'm building this ammo for hunting, I'd like to get the most power out of these loads that I can... But, having not dealt with compressed loads much in the past, I'm wondering if I'm heading down a dangerous road if the STARTING loads are already compressed?

For sake of clarification, I'm obviously planning to work my way up to maximum loads... I just wonder if it is even worth trying to load any heavier charges, given that the "light" loads are already compressed?

Any help that you guys could provide would be greatly appreciated!

 

[coloradokevin]

Well, I'm hoping someone knows something on this subject!

In the mean time, I'll provide a quick update, which only serves to further confuse me:

After typing my initial post, I loaded a round at the 2nd charge weight I had chosen (50.9 grains of H-380), then did some more reading on compressed charges. I then decided to follow Lyman's advice for determining whether a load is overly compressed or not, which involves comparing a charged cartridge to an empty one with a bullet seated in the same manner.

Anyway, I loaded an empty casing with a bullet seated to the same depth as the others. This bullet showed a COAL of 2.993". My first 2 cases that were charged at 49.5 grains showed matching COALs of 3.000", and my one round at 50.9 grains of powder showed a COAL of 3.005", and felt hard to seat when I put the bullet on top of the casing to begin with!

So, my assumption is to say that this load is definitely overly compressed. Now the question is WHY?


Here's what I have so far:

1) I'm using published data from the bullet manufacturer who made these bullets.
2) I'm using powder that is recommended for this bullet, and the MAX loads are listed as being compressed.
3) I'm currently only in the range of "starting loads", but I'm already overly compressed.
4) The one outside variable is that I had to use Winchester brass rather than Remington, but I wouldn't be inclined to think that they'd be so different that I couldn't even use starting loads in the Winchester cases!


To me this doesn't add up, and is leaving me a bit confused! As I mentioned in my first post, the Barnes data shows a recommended seating depth that is deeper than what I was using with the Sierra bullets I tested last week. I've seen some anecdotal evidence to suggest that Barnes bullets often perform better when seated deeply, so I was attempting to follow the company's data for seating depth, rather than going to the longer length I used on the other bullets!

I seated last week's Sierra bullets at 3.150", which is the longest length that my gun's magazine seems to be able to accommodate (SAAMI max for this cartridge is listed at 3.25"). On the max load with those 175 grain Sierra bullets I was noticing that it was a bit compressed, but not to the degree that I reached with just the starting loads today with Barnes bullets (again, I'm clearly seating to a different depth, but not to a depth that is deeper than what the manufacturer suggests).



A couple of possibilities:

Should I just extend the seated length for the Barnes bullets out a bit to reduce compression?

Should I choose another powder (I don't want to, as I am currently using H380 elsewhere)?

Also, without checking the gun's chamber, is it always safe to go to the SAAMI maximum COAL, or can you only go as far as the individual bullet lists (I've actually always wondered on this... every load manual I've seen lists the SAAMI max COAL on the cartridge diagram, along with a different COAL for each bullet)?

Am I completely missing the point here, or should I do something else?



(Thanks again for the help everyone! My end results always seem to turn out nicely, but I sure wouldn't have become successful in any of my reloading ventures if it wasn't for the advice I've been able to get around here!)

 

[steve4102]

First, the seating depth in a Manual doesn't mean squat for your rifle. You can seat the bullet to whatever you wish as long as you don't pig jam it into the lands. This will increase pressures. This is what Accurate Powder says about COAL.


SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”
It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must
be seen as a guideline only.
The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.
This parameter is determined by various dimensions such as 1) magazine length (space), 2) freebore-lead dimensions of
the barrel, 3) ogive or profile of the projectile and 4) position of cannelure or crimp groove.


Second, I do not think you are "overly" compressed. Measuring bullet tips is not an accurate way to measure COAL. It should be measured off the ogive of the bullet. Also, when compressing a load it you may need to adjust the seating die deeper to take up some of the slack in the press.


Third, I do not load for the 8mm Mauser so I cannot check to see how much 380 fills the case, but have you checked, double checked and triple checked your scale? Are you sure your charge is correct?


Fourth, Compressing powder in itself does not increase pressure. If the load is tested and published, compressing it will not cause a catastrophic failure. I like compressed loads and use them all the time. In some cases I have to let the rounds sit over night and reseat them the next day to push them back into the case. However, 380 is a ball powder and ball powders are a little harder to heavily compress.

Lyman 48 says that 43gr of 380 is compressed, so use it, load it, work it up, it's normal.

 

[BADUNAME37]

One variation that you may be experiencing is that of the longer bullet length of Barnes solid copper bullets.

That is why, on their web site, they recommend dropping down to the next LIGHTEST bullet than you would normally use. Their reasoning behind this is that the X Bullet causes such internal and massive damage (after hitting your quarry), that you don't need to use the regular weight bullet that you normally would.

I am assuming you are using the Barnes X bullet that is solid copper.
If the bullet weight (with a conventional lead-core bullet) is 105 grains, then you may want to use the Barnes X bullet that is down one lighter than that which (for reasons of illustration only) may be a 95 grain X-Bullet!

In doing so, you are not only using the bullet that Barnes RECOMMENDS, but you are also using a bullet that is a bit shorter. That difference in the shorter bullet length might be just enough so you are not compressing the powder so much that the cases begin to bulge.

I have compressed powder loads for some of my cartridges. One in particular has 4350 cylindrical powder almost at the top of the bottleneck case, and upon seating the bullet, the powder is "crunched" down to about the bottom of the case neck.

DO NOT USE BARNES' DATA FOR ANY BULLETS OTHER THAN BARNES BULLETS!

Also, I believe Barnes states you should seat their X bullets .005" off the rifling lands. Double check that measurement at the Barnes' Web Site!

 

[243winxb]

Poor choice of powder IMO. H380 should go the way of H450 "discontinued" Even Hodgdon load data webside does not list H380 for the 8MM. This alone should tell you something.

 

[fireman 9731]

First off, powders can vary lot to lot volume wise, that may be a possibility for your problems.

Secondly, Barnes is horrible for only listing a few powders to use for each cartridge. One simple solution would be to just look in another manual and find a similar bullet weight. But I'm sure you've probably already done that and realized that Speer lists a dozen different powders but with bullet weights at 170grs and 200grs, instead of 180grs, you are in a tight spot.

Also, the Barnes manual has a disclaimer saying that they tested their loads to 51,000 PSI while the SAAMI max is 35,000 PSI. As long as you have a modern rifle in good condition you should be OK though.

Just keep in mind that you are treading in potentially dangerous territory.

My solution would be to switch powders, either one that Barnes lists (which aren't many) or maybe try Reloader 15 which Alliant lists for use in bullets weights all the way from 150 to 200grs.

 

[coloradokevin]

Thanks for the follow-ups so far guys! To provide a few more pieces of information, and some clarification from my previous posts:

1) Barnes only lists three powders for their bullets in this diameter (H-380, AA 2700, and H414). Moreover, H-380 is the ONLY powder listed for both the 180gr and 200gr bullets, both of which I have. So, if I use Barnes data -- which I feel like I should for these rather unique bullets, it looks like I'm stuck with H-380, at least as far as I can tell!

2) I have also read the advice from Barnes to use the next lighter bullet. Unfortunately the lightest bullet they even make in this diameter is 180 grains. .323" bullets are a bit hard to come by.

3) I know that Barnes goes above SAAMI pressures, but I've also read from multiple reliable sources (load manuals, etc) that the 8mm Mauser has been unecessarily handicapped due to the fact that American ammo is made at reduced power levels because of the variance in barrel diameters between the 8x57J at .318", and the 8x57JS at .323". The Europeans apparently do understand that these are two different cartridges, but Americans apparently do not... As such, American ammo is reportedly much more anemic than European ammo (historically the 8mm Mauser's power has been able to match or slightly exceed that of the .30-06. If you look at typical American loads you get little more than a .30-30). For these reasons I wasn't too concerned about the hotter loadings shown by Barnes, despite my normal apprehension towards loading on the hot side. Again, I am making hunting ammo, so I want the most out of it. But, with the higher pressure factor coupled with the weird charging I was dealing with, I became a bit concerned!

4) I know that bullet seating depth can vary from rifle-to-rifle, and that SAAMI is only providing a guide. But, it was also my understanding that the Max COAL reported by SAAMI should work in all rifles of that caliber (essentially a universal length, even if it isn't optimum). Anyway, I tried using the published length that Barnes was using, only because I've heard anecdotal reports that seem to suggest that most rifles like Barnes bullets seated deep. Either way, I'm just surprised that the PUBLISHED length would appear to be heavily compressed on the starting loads.

5) While I realize that tip-to-tip length isn't an entirely reliable way to measure bullets, I currently due not have the capability of measuring from the ogive. Despite this fact, I've noticed that the typical bullet length variations I'm experiencing with quality bullets are usually in the +/- .001-.003 range. As I listed earlier, the length variations I was seeing with these loaded cartridges are more like .005-.007". And, each more heavily loaded case was longer than the last, with the heaviest load at 50.9 grains of H-380 feeling compressed as I seated the bullet. That's what is leading me to believe that I have excessive compression.

6) I don't have a reason to doubt the scale at this point. I'm using an RCBS Chargemaster Combo, which was calibrated right before these charges were weighed. I re-weighed every single charge before placing it in the cartridge, and all weights were repeatable. In the past few days I have compared the Chargemaster's weights to that of my Lee Safety Scale, and the measurements matched.

 

[rcmodel]

You might try making a powder drop tube out of a 18" - 24" length of copper or plastic tubing.

Allowing the powder to fall a ways into the case somehow makes more of it fit in less space.

rc

 

[243winxb]

From Barnes website

3. Where do I seat the Triple-Shock, Tipped TSX and MRX bullets?

Answer. We recommend seating these bullets .050″ off the lands {rifling} of your rifle. This length can be determined by using a “Stoney Point Gauge” or other methods. You do not have to seat the bullet at, or on one of the annular rings.

The reason this is done, it reduces pressure before the bullet takes the riflilng. My books have maximum powder charges for H380 listed for 170 bullets (not barnes) at 54.0-53.0-49.0grs.

 

[coloradokevin]

The reason this is done, it reduces pressure before the bullet takes the riflilng.

While I understand that seating the bullet slightly *off* of the rifling reduces pressure, part of the reason that I haven't tried to seat these bullets nearly to the rifling is because I don't have a stoney point type of gauge. As such, I was just trying to go with what I've understood to be the "one size fits all" SAAMI spec data. Unfortunately that's when I run into my compression problem.

Given that these bullets are a good bit longer than the Sierras that I previously loaded, I can imagine that I might end up with trouble even if I extend the seating depth out a bit (Again, going beyond 3.150" exceeds the length of my magazine, but still doesn't appear to quite reach the lands... though I don't know by how much).

 

[243winxb]

measure out 5 grs of H380, you will see its not a whole lot of powder. RC comment on the powder drop tube is a good one. Try it.

 

[243winxb]

Your missing the point on OAL. Barnes wants you to keep the bullet away from the rifling to reduce pressure. This is why they say ".050″ off the lands" If you know about the free bore in Weatherby rifle, this is the same thing. Years ago the first copper bullets made way to much pressure when using normal load data for normal bullets. Caused many problems. Barnes cut the grooves in the bullet to reduce bearing surface that lowered pressure and reduce fouling. Barnes bullets are longer in the body compared to normal lead filled bullets of the same weight. This causes a seating depth problem also.

 

[243winxb]

Finding the Maximum OAL the Old Way.

I don't have a stoney point type of gauge.

You dont need one. Take a fired case from your rifle. Pinch the neck closed with plyers just enought to hold the bullet that it wont fall out. Put in chamber by hand, unless your action is controled feed, then feed from magazing. Close the bolt on dummy round. Extract it making sure it does not rub against the receiver if possible. Measure its OAL. Do this enought times till you get the same readings a few time. This is your maximum OAL. Seat bullet .050" deeper. This is what Barnes wants. Does it fit the magazine? If not seat bullet deeper till the dummy round does fit the magazine. Some old well used barrels on military rifes have the throat shot out. You many end up not touching the rifling at all and still keep the bullet in the case mouth.

 

[fjlee]

Kevin, I sent you a PM........

Lee in Denver

 

[mrcooper]

With compressed loads is if they set very long your OCL grows and will effect acc.

 

[Shoney]

coloradokevin wrote
For sake of clarification, I'm obviously planning to work my way up to maximum loads...

All the speed in the world is useless if you cant hit something. Your goal should be the fastest accurate load, achieved by working up several powder/bullet combimations.

The sum of all the above posts give you great information. If you go to Hodgdons site, they list 180 GR. BAR TSX with many powders. They do not list H380. Another powder should be selected.

As far as compressed loads RC mentioned an 18" drop tube. I use old aluminum ski poles (48") where the tip is cut and filed so it will fit into the case. I made 3, one for 0.223 to 6mm, one for 6.5mm to 0.264, and one for 0.308 and up. I also made a vibrating case holder using a high speed 6 volt motor with an unballanced flywheel. The commbination of long drops and vibrating the cae will pack the powder, if it is truely necessary.

 

[sonier]

drop tube will help a lot, helps fit more powder in. reminds me of a interesting shotgun barrel i hear about where it compresses the shot then allows it too expand then compress again 3 times threw barrel, by the time it leaves the choke its very compacted. id have some expirements by making a 2 foot copper tube drop and trying that little technique. regardless try the drop tube it should help.

 

[243winxb]

Drop tubes work best with powder like IMR stick types. Not so much with Spherical or Ball Powder. But will help some.