6.5 sst (sherman short tactical) arrived

[elkaholic]

Looking forward to seeing the results since I don't have mine yet!! I may have one in a couple weeks so I hope to add to the data before the end of June...........Rich

 

[tbeckstead11]

I got the ladder test done. I got to 3200fps with re26 at 58.5 grains and 3100 fps with H4350 at 53.5 grains before I saw pressure signs. This is a super efficient case. There weren't too many big flat spots. But from 56.5-56.9 there was only 8fps gain, and it's right where I want to be at 3060fps so I'm going with that. I'll load at 56.7 and see where I'm at with SD and Extreme spread. I'd be really happy if that works out. There isn't any reason for it not to work.

I'm bringing my chassis in this week to get bedded so I won't have any more results for a while.

 

[tbeckstead11]

I hope that picture works.

 

[elkaholic]

Good job Thane! I can't wait to see what you do on some steel in a couple weeks. With a coal shorter than your Lapua, this may be just what the doc ordered for MANY applications.
I sent my rifle off to Rhian yesterday with a new 3b, 8 twist Bartlein to replace my current 3b, 8 twist Bartlein which shoots .o's with my SS" WHAT!!" I thought that would be cheaper than building another rifle!
I plan on testing some more powders, but with those numbers, RL26 will likely be difficult to beat. I do think that N560 will be a good one as well as H1000. I may play with H4831 too.
If there are PRS shooters in other states that might want to try the SST, I may be interested in helping you out. ..................Rich

 

[elkaholic]

I spoke with Thane after he got some data on the case capacity and it falls right in the range we thought. Average capacity H20 with Norma brass is 69.7 grains. This should make a sweet competition rifle loaded in the mid 3000's since it maxes at 3200'. Barrel life should be very good for that kind of performance...........Rich

 

[tbeckstead11]

I finally got the XLR Evolution chassis all bedded up. It's ready to go. After my velocity test, I decided on 56.7 grains of Re36. This should have given me 3060fps, right where I want to be.

So, loaded up some depth tests and I was all over the place. Started doing some checking and my rail had come loose. So, loaded up some more, and this time it felt like there was too much recoil. My magnetospeed confirmed that the barrel has sped up about 60fps.

Back to the reloading bench for another velocity test. This time 55.5 grains of Re26 put me at 3060. 1.1 grains less powder for the same velocity. That's what happens when barrels break in sometimes.

I've now loaded up another set of depth tests at 55.3 grains. I'm hoping I don't work another 65 hour week so I can get out and shoot them.

Something very interesting about this round. Velocity tests are not showing flat spots at all. The velocity increase is extremely consistent. This only happens with VERY efficient cartridges.

I'm loving this super efficient cartridge!

I'll try to get some pictures up tomorrow.

 

[Greyfox]

Tagging on

 

[tbeckstead11]

I settled in on my powder charge and did some seating depth tests. I'm not very good and stacking bullets, so my groups are never great but I think .060 jump is pretty good. That's what I'm going with.

For comparison, on the left is a 7 Sherman Shot mag, then the 6.5 Sherman Short Tactical (this rifle), then 6.5x47, 6.5 Creedmoor, and .243.

Plus an obligatory picture of the finished rifle.

 

[Bullet bumper]

It's a nice rig but don't be surprised to eventually find out that the stock design is loosing you some accuracy due to flexing at certain points.
Butt pad positioning is bad and too far below the cheek rest . Ok for a heads up shooting position on a bench but not that good prone , well I could not use that stock prone anyway . Groups look ok for a new barrel but i think some small verticle will persist with that stock design.

 

[elkaholic]

.030, 060 and 070" all look pretty good. That is one gnarly looking weapon!!. It should be a ***** cat with that brake!. With a .060" jump, you must be around a 2.730", give or take, coal?....Rich

 

[tbeckstead11]

It's a nice rig but don't be surprised to eventually find out that the stock design is loosing you some accuracy due to flexing at certain points.
Butt pad positioning is bad and too far below the cheek rest . Ok for a heads up shooting position on a bench but not that good prone , well I could not use that stock prone anyway . Groups look ok for a new barrel but i think some small verticle will persist with that stock design.

That stock is 100% adjustable. And it's absolutely solid. The weak link in this is definitely not the chassis. XLR makes good stuff.

The groups issue is the shooter. I never practice shooting tiny groups.

 

[Bullet bumper]

That stock is 100% adjustable. And it's absolutely solid. The weak link in this is definitely not the chassis. XLR makes good stuff.

The groups issue is the shooter. I never practice shooting tiny groups.

I can't see butt plate adjustment up and down but it is hard to see in a distant photo.
You may think that's a solid as chassis but it's a lightweight chassis in reality .
Not saying it's bad at all just saying that it will lack some rigidity compared to other heavier designs . I get that it needs to fulfill a role and weight is always an issue for many people .
Light weight chassis can give away some small amount of accuracy even to a heavy laminated stock because they do flex a bit more than you think .
Chassis makers know that most shooters are so weight conscious that they make them as light as possible and light equals , thin and thin equals flex . You have to experiment making chassis designs to see it . It is not practical to go all the way to a super rigid chassis because the market wants light as possible so some accuracy will be lost but good accuracy is still attainable . I still say that there will be a small amount of persistent vertical that you will blame on yourself but in fact will be the chassis design limitations . It may well stay within a very good group and be hard to pick and overall the accuracy is seen as good by most shooters .

 

[tbeckstead11]

.030, 060 and 070" all look pretty good. That is one gnarly looking weapon!!. It should be a ***** cat with that brake!. With a .060" jump, you must be around a 2.730", give or take, coal?....Rich

2.71" OAL. It fits in any magazine with room to spare.

The brake is good. I don't notice much difference between my 6.5x47. Helps that the rifle is heavier too.

 

[tbeckstead11]

I shot my first match with the new SST yesterday. I still I'd some things to work out with the rifle but I wanted to see how it was going to preform.

I didn't have the rifle zeroed and I didn't have a velocity with the new seating depth yet so I got there early to take care of that. 3030fps at the .060 jump using 55.3 grains of Reloader 26. I'm pretty happy with that.

I only had one AICS magazine ready to go. With a 2 round extension from AxisWorks, I can get nine in there but the first one won't feed. I think I can fix that but I haven't tried yet. So essentially I had one eight round magazine. This ended up really hurting me in this match. I timed out on every stage trying the dig two more bullets out of my pocket. Last thing that isn't quite ready is My shoulders aren't bumped (Whidden is rushing the dies but they aren't quite here yet). As soon as the dust started kicking up, I was fighting stiff bolt and extration issues. That'll go away with the dies and I'll probably go with a 2 piece rail just so the brass has more room to eject.

So, now that my excuses are out of the way, the rifle shot light out! The wind was switchy and ate people up on several stages. I just aimed center target. When the wind settled to something resembling constant, I just went left of center. If I could get solid, I hit the target. This little caliber is awesome for PRS! I was a little worried about recoil coming in because spotting shots and adjusting is so important but I never had issue spotting shots. It worked out great!

I ended up 18th out of 65 shooters. I lost at least 5-7 makable points because of the magazine issues that will be worked out. This was by far my best match of the year. It's just a lot easier when you don't have to factor in the wind.