Finally bought an STW

[riemer]

Picked up 700 SPS 26" STW w/o a brake. Put it in a hogue overmold stock with EGW 20 MOA rail and Viper LR 4-16. Put around 30 rounds through it so far with a couple groups showing some potential. The confusing part is I'm getting 200-250 FPS slower velocities compared to what the book and others are posting.

 

[Lefty7mmstw]

what is your load?? what brand of chrono??

 

[riemer]

CED M2 chrono

The loads have varied from Sierra 140, Berger 168, Sierra 175 & Berger 180. Powders were RL-25 & 7828. The book load for Sierra 140s was 3400fps, I got 3150 book load for 180 Berger 3050 I got 2778. I bumped the Berger 168 load up 1 grain over book max and the velocity stayed the same at 2846.

 

[MudRunner2005]

If you're not getting any pressure signs, keep working up in .5 grain incriments (load 3 rounds of each) to test for accuracy and untill you start getting a sticky bolt lift. Then back if off 1 grain, and work up in .1 grain incriments to find you're best load.

 

[Lefty7mmstw]

CED M2 chrono

The loads have varied from Sierra 140, Berger 168, Sierra 175 & Berger 180. Powders were RL-25 & 7828. The book load for Sierra 140s was 3400fps, I got 3150 book load for 180 Berger 3050 I got 2778. I bumped the Berger 168 load up 1 grain over book max and the velocity stayed the same at 2846.

specific load tops please... It's hard to compare what differences there are without specifics. Also, some barrels are simply different and you may have to try a few combinations to get accuracy, uniformity, and speed at the same time.

My current stw is a bit slow (3250 fps with a load that ought to do 3400) with 140's but it shoots so well I'll keep shooting the load and use heavier pills in my 7rum since the accuracy is better with that rifle (using 168-175 grain) and the speed seems to be there too.

 

[riemer]

Ok, here's what I've tried so far;

IMR 7828 79.0
Sierra PH 140
Fed 215M
3185FPS

IMR 7828 75.0
Berger 168 VLD
Fed 215M
2979FPS

IMR 7828 72.0
Berger 180 VLD
Fed 215M
2827FPS

IMR 7828 73.0
Berger 180 VLD
Fed 215M
2846 FPS

RL-25 73.0
Berger 180 VLD
Fed 215M
2753FPS

 

[Lefty7mmstw]

your 26" bbl'd rifle is shooting slower than my 24" bbl'd one is by around 100 fps. I'd switch to rl50 or h50bmg (getting to a slower powder burn speed range may help with speed while keeping pressures in check). 86 grains of either should do ~3,000 fps with a 175 in an stw. I'd go up a grain on the 168's and down a grain on the 180's.... work up of course.

What is your chono's make??? I don't trust some of the cheaper ones as far as I can throw them...

 

[riemer]

CED M2 chrono.

Anyone else try the powders that Lefty has suggested?

 

[MudRunner2005]

Have you tried having the barrel hand-lapped? That will smooth out the bore and SHOULD help increase speed.

 

[riemer]

I can do that with some JB bore paste right? If so I have some and will try it.

 

[Lefty7mmstw]

I have a ced m1 and it's not that great of a chrono... The oehler 35 my pops and I have is a heck of a lot better... error checking between the two screen sets is just the start... I wish I could get my hands on the oehler but it needs a bit of work and it's in his shop...

I've gotten away from the rl22/7828 speed powders a long time ago (2004) with the overbore 7mm's ( bigger than the 7rem/roy) and now start at rl25 or retumbo and go slower. I like 5010 but it's nearly unavailable of late. wc869, h50bmg, and rl50 are the easiest slow burners to get your hands on lately. Even mil-surp wc872 and 867 are hard to find.

My current 7stw load is 82.0 rl25, 140 nos ab, rp brass, 215.... 3.650" oal. The ced says it's heading out at 3250 fps (24" bbl.-- 10" twist) ... my pop's rifle was 100 fps slower over the ced as compared to the oehler with one of his loads though, so who knows. I haven't put a bullet through anything over 500 yards out with the rifle though, so I really can't compare expected drop to reality.

 

[MudRunner2005]

I run 71gr of 7828 SSC and it's pushing Berger 180 Hybrids at 3000 fps with a 26" barrel. And stacking 5 shots inside of a 1/2 MOA group. I don't understand why yours is so much slower.

 

[Lefty7mmstw]

I can do that with some JB bore paste right? If so I have some and will try it.

How does the bore look when you look down it?? Are there tight spots when you clean it?? Does it foul extremely badly?? If so you may need to lap the barrel. I wouldn't unless you need to though, as lapping removes metal and if you aren't extremely careful you may just make the situation worse by removing too much metal in the wrong places.

I've only lapped one barrel; a marlin 270 my wife got me that I was intent on making shoot rather than trading. Even as a horrible fouler it had normal speed though.

I wouldn't doubt your remmy is pulling the same crap that a rem '06 I had did. With certain combinations this rifle was 200+ fps down from where it should have been; other combinations and the rifle was normal. The velocities shown in reloading books are only valid for the rifle they were shot with... your results will likely vary...

 

[slewis12]

Lapping a barrel that has been fired will not help lapping only smooths out microscopic inclusions in the metal every time you fire the barrel you do that any ways friction and normal barrel wear just because it's soft doesn't mean it's not cleaning those areas up hence barrel break in McMillan will attest to this and many known gun smiths a few that are on here and a few that aren't and all a very reputable will say no way don't do that. Car makers don't lap production valves because its not needed only gear heads do because they try to squeeze every last bit out of a engine setup I would know I'm a gear head, a service engineer and LRH. Not bashing any one just if your gonna lap a barrel do it on a new factory barrel on a lower quality line gun not on descent quality factory rifle that has been started on barrel break in and even then I might not do it On the lesser quality one IMO