Anyone getting very erratic speeds with TSX?

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Northman999

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Fellows,

I'm trying to develop a top end load for my 375 RUM with 300gr TSX's, but I've had a couple of hiccups - twice now I've had a bullet jump out of the muzzle 200 fps -or more- faster than expected, and faster than the others with the same load. ( i.e - 90gr 4831 gives me 2625 one time, then 2836 next time and then 2628 the next). Normal variation with my loads is about +/-10 fps. Only with my 375 RUM, and only with the TSX's, have I seen two rounds basically off the scale in terms of velocity. One had powder loaded from an RCBS powder thrower and the other was very carefully weighed on my scale, with me literally adding or subtracing one granule at a time at the end.

Has anyone else come across this? I also measure all my rounds for a consistant COL. I'd like to get my rifle shooting these TSX's, but I've already had one round completely lock up my rifle as it put out a 300gr TSX at a crazy 3080 fps, so I'm understandably hesitant to even approach a max load again, in case I end up picking brass out of my face.
 
I shoot TSX's in a 6.5X55, 7mm SAUM and .338WM. Never had that issue, all shoot well and velocities a consistent.

I just re-read your post and saw that you had a bolt lockup too, wow. Could your cartridge overall lenght be an issue?
 
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Have you weighed a 100 gr bullet to verify that your scales are correct?

First thing I would do is neck size cases after they are decapped with the decapping pin removed. This will greatly increase neck tension and get more pressure inc ase before releasing the buillet. This can help.

Is your bullet close to the rifling? If so, try 20 thou more jump.

Are the primers OK. Don't have some pistol primers mixed in?

Try differnt primers. Mag instead of stnd, or vice versa?

Is your Chrony working well?

When I get some bad results I shoot a 22 through it to make sure the numbers make sense.
 
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GANDERITE said:
Have you weighed a 100 gr bullet to verify that your scales are correct?

First thing I would do is neck size cases after they are decapped with the decapping pin removed. This will greatly increase neck tension and get more pressure inc ase before releasing the buillet. This can help.

Is your bullet close to the rifling? If so, try 20 thou more jump.

Are the primers OK. Don't have some pistol primers mixed in?

Try differnt primers. Mag instead of stnd, or vice versa?

Is your Chrony working well?

When I get some bad results I shoot a 22 through it to make sure the numbers make sense.
Click to expand...

I'll have to try the neck sizing as you described, as well as adding more jump if needed. Things that I have confirmed are right (and usually double checked) are: correct primers/powder/bullets, primers seated correctly, scale tested several times, cases measured for length, COL measured on each completed round, no rounds are harder than any other to chamber, chrony seems fine (all results are as expected, and the only rounds that it reads high are with these 300gr TSX's and the ones that read high also tell me in the shoulder that they're high).

One thing that I did notice while reloading is that sometimes a TSX is noticeably harder to seat than others, with little bits of copper shavings coming up - I had chalked this up to the copper flanges sometimes catching on the case neck, but maybe there's more to it than that.
Hopefully the "double sizing" of the neck will address this.

Thanks for the responses so far fellows!
 
I have found with the TSX bullets the inside of the case mouth requires a fairly heavy chamfer to avoid shaving. A VLD type of cutter is the best.


The velocity fluctuations are probably caused by bullet tensions issues. The grooved design of the TSX removes a lot of bearing surface on the bullet shank and I have found that the larger calibre bullets are affected more. A good solid crimp has solved the problem for me.
 
Try a different brand of primer. I had some WLRM that gave inconsistent readings in my .338WM with 225gr TSX, switched back to 215M and they levelled out...
 
I had been using CCI #250 magnum primers. If I still have problems after eliminating neck sizing/tension then I'll move on to a different primer. I have been using them for years in .338 win mag and .375 H&H, but if something as simple as a primer change could sort this out, that would be great.
 
I put a Lee valley taper reamer in my electric drill and stick the drill in my vice, then process all the brass. The 11 degree taper means much less risk of shaving a bullet.

The reamer here is one I got in the USA. The Canadian taper reamer is small and nicer. They sell the same reamer for two applications: drilling holes for wooden dowls and in trees for doing grafts.

DSCN0398.jpg
 
Northman99: CCI 250 primers are not particularly hot. Fed 215's , WLR's and WLRM's are hotter and you are trying to get a pretty big pay load ignited. REDUCE your loads to starting levels with the new primer and try again working up in increments as per proper procedure. Also, which of the 4831's are you using and are you using data correct for that make? Have to assume you may not know the difference but in all likelihood you are quite familiar with them. Given the problem you have been having I would abandon the component mix you are using with no further shooting of them. Tera them down. One bolt lockup should be warning enough.
 
Ganderite - that reamer idea looks great, Ilkk have to try it.

stocker - I tried IMR 4831 as it is one of Barnes reccomended powders for thier 300gr TSX. I had already tried RL22 (often reccomended in many manuals and by other shooters) with my 300gr Gamekings, but I wasn't really impressed with the velocity I was getting. I was hoping that a faster powder might do the trick, as my XCR has a 24" tube and many manuals list loads for 26" barrels - I was getting about 150 fps less from my rifle than reloading manuals (and internet loads) were suggesting. I'm thinking I may try IMR 4064 or IMR 4350. I'd really be experimenting with these powders however, as Barnes only lists two powders for their 300 gr TSX, IMR 4831 and Hunter (which I don't have).
 
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Get a Barnes #4 manual...

Or from Barnes #3, try IMR4350 start at 87gr and work up, or H4350 starting at 89 gr.
 
There have been all sorts of issues with Barnes bullets, and especially with their manuals.

check their Web site and you will find all sorts of "amendments" to the loads they have posted in their manuals.

Compare the loads they post for their blue bullets to those for the same bullets without the coating; in some cases the STARTING load they give for the blue bullet is higher than the MAXIMUM load for the same bullet without the coating. No matter how good the lubricity of the polymer, there will not be that large a difference in chamber pressure.
 
oldbadger said:
There have been all sorts of issues with Barnes bullets, and especially with their manuals.

check their Web site and you will find all sorts of "amendments" to the loads they have posted in their manuals.

Compare the loads they post for their blue bullets to those for the same bullets without the coating; in some cases the STARTING load they give for the blue bullet is higher than the MAXIMUM load for the same bullet without the coating. No matter how good the lubricity of the polymer, there will not be that large a difference in chamber pressure.
Click to expand...

Yeah, they don't make those bullets anymore. And they have a new manual now too.
 
Northman: Visit the Barnes website (loading data). Notice that Barnes developed their loads using Federal GM215M primers. With IMR4831 and 300grain TSX bullet they show starting load at 89 grains and 97 max.

I think you are getting wild pressure spikes due to delayed ignition of the powder caused by an inadequate primer. Sort of a fizzle, boom effect. By the time it is really ignited the bullet has already advanced a bit into the barrel. This has the effect of creating extra burning space, much like a reduced load with some powders and is skating into the Secondary Explosion Effect (SEE) area which has been reported as destroying some rifles.

As well send Barnes an e-mail and explain what is happening with the exact components you are using and seek their advice.
 
Thanks fellows for all the advice. I've pulled all my 375 RUM loads, I'm re-sizing, re-trimming, re-reaming (??) and re-tumbling the brass, buying Federal GM215M primers, changing powders, and crimping my loads. I won't be able to get to the range for a while, but I'll report back when I do.

I had actually emailed Barnes about this (with exact details of my load), but all they told me was to start at the bottom load and work up, and that their reloading info could only be considered guidelines as they could not account for differences in individual rifle chambers and powder lots etc. So that wasn't helpful at all. You guys are lots more useful actually. Thanks!
 
I'm loading the 300 gr TSX in my Ultra and this thing shoots like a varmint rifle. Without casting dispersions to your equipment, I wonder if you are having repeatability issues with your powder scale.

The powder I have been using the last few years has been H-4350, but now I am switching to Hybrid 100V, which is similar to Re-19 but has a higher loading density due to the small granule size. As a result I have gained 50 fps across the board with 260, 270, 300, and 380 gr bullets. H-4831 bulks out before I reach my velocity, and I intensely dislike compressed powder charges

I full length resize after each firing, anneal the cases every other firing, and crimp my bullets at the top groove. I use Remington 91/2M primers, not because they are any better but because I have lots of them. Federal 215 primers are probably the correct choice.
 
Northman: I've just read a short internet reply by a firearms writer whose word is about as good as you can get. He says CCI250 primers are actually slightly hotter than standard Fed 215's. I stand corrected on that. Possibly the Fed GM215 M takes it another notch higher yet. I still think inconsistent ignition is what your problem was but it is a little harder to blame the CCI's directly since reading that.

A bit of testing with the primer Barnes recommended would seem to be in order.
 
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