early pressure with tsx's

[splattermatic]

early pressure with tsx\'s

started some loads with my new 300 rum and am noticing somwthing.
i loaded 99.0 grains of reloader 25 behind the 168 gr tsx's and they looked fine, set at mag length.
then i tried another 5 at .20 off the lands, and had signs of high pressure.
accuracy was about the same, so i am thinking the free bore jump let's pressure spike and maintain low during the jump.
velocity was mid/high 3300's for the mag length, but over 3400 for the .20's.....
now fast forward to the other day.
i tried some 180 gr nab's, and started off at 98 gr's of reloader 25, and no pressure signs, fired the next 5 with 98.5 grains, and think this is all it can handle.
accuracy was good, all rounds at mag length, velocity was mid to high 3200 with 3 of the 98.5 loads just over 3300.

why can i load a 180 grainer to within a half grain of a 168 grainer ?
shouldn't the 168's be able to handle more powder than the 180's ??

i may be able to go a bit more with the 168's, but all this was shot at cool/cold tempts. summer heat may be another story.

do barnes develpoe high pressure sooner, than normal lead/copper bullets ?

what should i expect for a top velocity from the nab 180's with what powder ??

thanks all

fixed

 

[davewilson]

Re: early pressure with tsx\'s

shouldn't the 180 be able to handle more powder than the 168 ??

generally speaking no.the heavier bullet usually has less powder.you're also comparing a groove style solid bullet against a conventional lead jacketed. 2 very different animals.it's all about the bullet to bore fit and how it affects peak pressure which occurs getting the bullet fully engraved into the rifling.

 

[Michael Eichele]

Re: early pressure with tsx\'s

Dave is right. You are running the 168 Barnes against the 180 AB. The barnes solid copper bullets WILL generate more pressure than a conventional bullet of the same weight. This is why you are using similar powder charges for very differant weight of bullets with similar pressures.

[ QUOTE ]
what should i expect for a top velocity from the nab 180's with what powder ??


[/ QUOTE ]

Depending on the rifle, on average you should see about 3300 with a 180 class bullet in the 300 RUM. That is dependant on barrel length, barrel twist and style of chamber. Some powders that are safely capable of this velocity would include RL-25, Retumbo, and US869. My advice is to stay with the RL-25.

 

[splattermatic]

Re: early pressure with tsx\'s

oops, put the 168 and the 180 in the wrong spot.
should have read the 168 take more powder than the 180..
also it's a 26 inch tube..
so i am right at peak velocity with 98.5 grains of rldr 25, running right about 3300 fps..

recoils pretty stout too !

 

[travelr47]

Re: early pressure with tsx\'s

splattermatic,
I've been reloading Barnes TSX bullets since they were introduced, and before that, the X-bullet since the late
1980s.
According to the Barnes Reloading Manual #3, and the guide sheet Barnes encloses in every box of TSX bullets, a maximum load for the 168-gr TSX, using Reloader 25 would be 96.0 grains! That they worked fine in your rifle, at maximum COAL
tells me your rifle has some leade in the chamber, or just one of those quirks from rifle to rifle. When you set the bullet .20 off the lands, you automatically bumped the pressure curve to over maximum! Barnes recommends .50" off the rifling. Your load would be .5 gr over maximum if you were using the Barnes XLC bullet. I'm "assuming" your barrel is 26" or shorter. That's for starters.

If you're loading nab's, I'd recommend you use Nosler's Reloading Manual, NOT Barnes'. You need to compare apples to apples, and nab's are NOT TSXs! Or if you prefer, TSXs are not nab's. While still not the same, possibly the Barnes' MRX would be closer to the nab than the TSX. But I digress.

Being guilty of comparing powder charges to bullet weight, even though the two bullets are of different mfr, I appreciate your dilemma. However, when I do this, I prefer to find two reloading manuals (bullet mfrs) who come close
with their data. Such as Speer and Barnes. Since Barnes won't "officially" have reloading data published until their new 2007 manual is published, we've all been winging it. Following the "up to two grains over maximum load data for the X-bullet". Carefully working up to two grains!

"why can i load a 180 grainer to within a half grain of a 168 grainer?"

Simple enough. Not all bullets are created equal. Different bullets have different ogives, bearing surface, composition,
and perform differently under pressure and with different powders.

"do barnes develpoe high pressure sooner, than normal lead/copper bullets?"
I don't think so, but I've honestly NEVER compared this aspect of the two different types of bullets. I use Barnes bullets, et al(variants of Barnes), because they don't disintegrate under high velocity at short ranges, and their terminal ballistics are awesome regardless of the range. That they are extremely accurate is a plus. NO, they aren't as accurate as a SMK. But their terminal performance on game is so beyond anything any SMK could hope to attain, I don't think this is an issue. If it is, I'd opt for a Berger VLD bullet, which also outperforms the SMK, but is just as accurate, maybe more so.

Just a thought, but I'd suggest focusing on your goal. Hunting or targets, the performance required to make clean kills, or one-ragged hole, and go from there. There are plenty of bullets capable of filling each requirement, but few, if any, of accomplishing both.
I realize what I'm about to say is heresy amongst the "magnum velocity" crowd, but velocity is only one criteria in the overall scheme of things. Yes, higher velocity equals flatter trajectory. But consider, the U.S. military sniper round launches a 175-gr bullet around 2600 fps MV, and will reach out and drop their target dead out to 1,000 yds! BTW, that's a SMK, 175-gr bullet. But a Berger would work just as well, maybe better.

Unlike most of you on this list, those I've witness using nab's, have a difficult time hitting the bullseye. In fact, one such fellow was so disappointed, he asked me if he wasted his money purchasing them. Compared to the accuracy he was getting from his 300 WM from his M70, using Remington
Ultra CoreLoks, I said, yep! He was getting MOA with the CoreLoks, and minute of milk jug with the nab's. And we weren't concerned about velocity. Even though I chronographed both the nabs and CoreLoks (the CoreLoks produced a higher velocity than the nabs, were extremely accurate in his 300 Win Mag).

BTW, Nosler puts out a lot of excellent load data with regards to reloading and their bullets. If you're reloading their bullets and not reading their manual, you're short-
changing yourself.

 

[splattermatic]

Re: early pressure with tsx\'s

i do look at the manuals and on-line information for starting data, but like so many do, push the envelope to the point of pressure signs, then back down a bit.
i have been reloading since the mid 80's, and know a lot, and have no clue about a lot more.
it seemed to be that all these years i used barnes bullets, and didn't look at others.
now i am, and am noticing, that maybe i'm just not wringing all the performance i can from a given cartridge, because of the barnes's. i just got my chrono about 2 years ago.
so now, i am loading for accuracy and velocity. if accuracy suffers due to trying to reach max., then the valocity will suffer, because if you can't hit what your shooting at, the power isn't going to matter.

it just seemed odd to me that i can get within a half grain of a powder charge for different bullets.