TSX vs TTSX seating depth

[Shootin4fun]

I have shot a fair amount of TSX and have a pretty accurate load. They have performed very well out of my 270win in bringing down game fast and hard. Now I'm trying TTSX because they're supposed to open up at a lower velocity, allowing for slightly longer shots, etc.

Anyway, the 130gr TTSX is .100" longer (!) than the TSX and the point on the ogive where it hits the comparator is .040" farther from the base of the bullet than on the TSX. (I am using a Hornady bullet comparator to measure ogive and I also measure COAL.) Now, if I load the TTSX at the same ogive length as the TSX so that the jump is close to the same, then it is about .040" deeper in the case and still .020" longer COAL. (If I leave the seating die the same as the TSX, the resulting TTSX round it .050" longer and doesn't even fit in the magazine.)

My question is, should I start with a a lower powder charge in order to avoid excessive pressure problems because the case capacity is being decreased? Will I get a higher velocity with a slightly lower charge because of that? Barnes says to seat them the same, what ever that means. Do I need to start from scratch??

 

[Shane Lindsey]

I had the same problem when I did development it was the old TSX. Found a sweet one and ten went and bought up all I could find, got home and found out Barnes had changed the ogive.

I just seated mine to the same jump to the lands on the ogive as a starting point vice the same COAL. It was slightly longer COAL but not enough to change everything. 270 win with 130 gr TSX COAL 3.18" with a jump of .04".

Re-barreled since and need to tweek it a bit.

I think the minor change should not effect your pressure as long as you are still jumping to the lands and are not way over max book charge weight. If you were seated in the lands on the original, then I would start over completely and find your new pressure limits.

Hope you find it.

 

[Shootin4fun]

Thanks Shane. Ha! Same thing happened to me when they changed the TSX and it was shortly before a hunt. I didn't have a comparator at the time & could only measure COAL so just made a few small sample batches & a few quick trips to the range.

This time around I made the ogive length the same on the TTSX as TSX and tomorrow I'll find out.

 

[feelinducky]

Same thing happened to me when they changed the ogive. I was getting ready to go to Wyoming for antelope and went and bought a box of 50 in .277 130g and noticed they changed the ogive. My thoughts are they reduced the ogive to better market the LRX 129g bullet. I'm still not happy about it.

 

[Shootin4fun]

Actually I think they changed the ogive to give more reliable robust expansion. I have read about experiences by some wherein the previous design (secant - longer and narrower) folded over rather than expanded in line with the body of the bullet. I think they should have changed the part number or something. The newer "stubbier" ones look unlikely to do that. Barnes did say they would sell me the previous design directly if I so desired before my hunt but I opted to move on.

Anyhow, I have no complaints about their (the new ones) performance on 2 wild pigs (one through the shoulder bone angling down through the neck exiting below the far shoulder pulverizing all bone & tissue around the wound in between). Deer are much thinner skinned animals so I thought TTSX might even work better on them.

 

[feelinducky]

I had zero problems with the old type. In my TIkka 270win it shot fantastic. Numerous pigs and antelope all one shot kills. When did Barnes tell you they would sell you the old design? When I spoke with them they did not mention a thing about selling the old design.

 

[Shootin4fun]

When I spoke with them they did not mention a thing about selling the old design.

About 14 months ago, shortly after I bought the first box of bullets that were different from all previous. They may have changed that policy by now. I can imagine how hard it would be in a manufacturing/inventory environment to maintain 2 different designs with the exact same name and part number.

 

[TBuckus]

They told me that same thing about using the same reload data.

My feeling is to start a little less powder and work it up just as with other loads. Their charted tsx data came pretty close to what the ttsx data I got.

 

[Shootin4fun]

Update after a few range visits...Using same powder charge which is below max (54.0 of H4350), I started by seating the TTSX .040 shorter (ogive) measurement than TSX because it is longer. NG. So I made it as long as the magazine would allow which is .010 ogive measurement shorter than the TSX ogive and that turned out to be a very accurate load configuration. I checked it in 10 - 25 mph swirling winds (target was moving and I tried to shoot between gusts) and still got .3" wide by .1" high groups @ 100 yards off of a bipod and undersized picnic bench that barely fit the rifle. 2900 fps average. I love this gun.

All is good, ready to go deer and hog hunting with TTSX.

Interestingly, I found that the SSTs like a 53.0 gr charge instead of the Barnes 54. They shoot .3" groups in the low 2800s. I'll opt for accuracy over speed.