Odd Vel with 7MM STW

[Teknys]

I loaded RL-22 @ 71gn up to 74gns.
71gn = 3000 fps
72gn = 3050 fps
73 & 74 = No gain in velocity.
Gun is a Rem 700 Sendero 26" 7MM STW
No pressure signs on any the loads.
I haven't had a gun "stall" the velocity like that before. I've had small gains that were not worth the extra powder but not just stop gaining speed.
Any ideas?
Oh, what could I hope to get for fps from a STW?

 

[Antelope_Sniper]

How many rounds were you chronographing at each interval?

 

[JD338]

Teknys

What bullet? 160 gr?

What are you using for a chronograph and how far from the muzzle?

JD338

 

[FOTIS]

JD is correct! What bullet? I am guessing 140???????

Either way when you reach a point of no improvement that is usually indicative of "you have reached max efficiency" ie nothing else to gain. Like I said usually!

My load from my sendero SS/Fluted was 80 gr of 7828 for 3500 fps and 1 1/8" at 300 yards groups.

 

[rick smith]

Time to stop adding powder you are just adding pressure. Or your chronograph is faulty.Rick.

 

[R Flowers]

Well, join the club. I have seen this happen before, mostly with IMR 7828.
Sometimes you just reach a point where more powder simply does nothing more than the last charge.

When using fairly light bullets for the case involved you just reach a point where more powder does no good. The first time I saw this was when IMR 7828 first came out. With heavy bullets in the 25-06 it did good, but with 100 grain bullets it topped out on velocity several grains before we ever saw any pressure signs.

I have seen this any number of times, where more powder just does no good at all.

 

[30-338]

I've had that happen it's been in my longer barrel rifles 26" to 28".

I take another rifle along with some known loads and the first time I think my reading may be off even if I've only fired 2/3 shots I'll shoot that rifle over the chronograph.

Alot of things will effect a chronograph might want to retest your load again.

 

[Teknys]

The bullet was a 160 ACCU
3 shots per set through the chrono.
It's a ProChrono from Cabelas I bought a while back.
It was late morning and sunny. After the 3 rd gun, it just started giving HUGE numbers 4000fps+ so I put it aside. I blamed the sun over head, at least that what I thought it was.

 

[Antelope_Sniper]

Sun overhead or a weak battery can give you odd readings.
I've had instanced wtih the STW and 7 RUM in the past where it would stall out for a few grains, then start gaining again. Sometimes a hotter primer will solve this. I do suggest FED 215, or FED 215M with the 7STW.

 

[DrMike]

What you describe is a indication that you have reached max efficiency. POP and Rick are absolutely correct--you are adding pressure w/o gaining velocity. There can be a variety of reasons why this happens. As has already been suggested, you can readily verify the accuracy of the chronograph. Assuming that it reads correctly, the answer is to consider 72 grains of RL22 as max. That is somewhat slow for a 7mm STW, but there are other powders to try. That is what makes hand loading so interesting.

 

[ElkHunter]

I too have had similar results with my 7STW, stalled velocities with RL22.

I shot 3 groups, 3 shots in each group, 139gr Interbonds. The velocities barely changed as I increased the powder charge. 73gr-avg vel 3125fps, 75gr-avg vel 3131fps, 77gr-avg vel 3188.

So, I switched powders. imr4831 seems to do just fine for me.

 

[Teknys]

I'm going to change batteries and make a sun shade.
I'll try again.
I shot my 300WSM - RL22@67gn - Accu200gns, it shot very well but no readings.

 

[Ridge_Runner]

I couldn't get my STW up to speed with RE-22 either
H-1000 with the 140's and WC872 with the 160's work well.

My 160 AccuBond load clocks 3340 fps with 94 gr of WC-872.
RR

 

[tx7mm]

Howdy Yall! My STW was partial to 80gr. of 7828 and a 140 Ballistic tip. Went thru the gates at 3495 fps. Nearly took the chronograph down tripod and all! LOL! Had a custom 28" barrel + muzzel brake that would fit an Abrams tank!LOL!

 

[Antelope_Sniper]

Ridgerunner, that 872 load looks like a winner! :grin:

 

[JD338]

My 160 AccuBond load clocks 3340 fps with 94 gr of WC-872.
RR

Ridge_Runner

That would make for one flat shooter! Dials would be the way to go but a 300 yd zero would look like this-

100 2.7
150 3.5
200 3.3
250 2.2
300 0.0
350 -3.3
400 -7.9
450 -13.7
500 -20.9

JD338

 

[Ridge_Runner]

yeah JD have taken more than a few holding a foot over the back at 500 yards, I have target turrets on the loopy 6.5x20 vari-x III but only dialed a few times, took a buck at 626 years ago.
I prefer the 160 AccuBond at 3575 fps from my 7mm AM and a loopy mark 4 on top of it for my long range stuff.
RR

 

[CZ]

I loaded RL-22 @ 71gn up to 74gns.
71gn = 3000 fps
72gn = 3050 fps
73 & 74 = No gain in velocity.
Gun is a Rem 700 Sendero 26" 7MM STW
No pressure signs on any the loads.
I haven't had a gun "stall" the velocity like that before. I've had small gains that were not worth the extra powder but not just stop gaining speed.
Any ideas?
Oh, what could I hope to get for fps from a STW?

Using Nosler Ballistic Tip in a 28" Shilen-Weatherby Custom.-

84gr-h1000- 3326fps @ 8ft chrono
83gr-RX22-3590fps@8ft chrono smokeing, safe in my rifle, in the limits.
R/P Cases-Fed215M

 

[CZ]

I loaded RL-22 @ 71gn up to 74gns.
71gn = 3000 fps
72gn = 3050 fps
73 & 74 = No gain in velocity.
Gun is a Rem 700 Sendero 26" 7MM STW
No pressure signs on any the loads.
I haven't had a gun "stall" the velocity like that before. I've had small gains that were not worth the extra powder but not just stop gaining speed.
Any ideas?
Oh, what could I hope to get for fps from a STW?

Using Nosler Ballistic Tip in a 28" Shilen-Weatherby Custom.-

84gr-h1000- 3326fps @ 8ft chrono
83gr-RX22-3590fps@8ft chrono smokeing, safe in my rifle, in the limits.
R/P Cases-Fed215M

NOSLER BALLISTIC TIP 140GR

 

[tx7mm]

The BEST part of SHOOTING a STW is watching the tall grass FLATTEN out for the 1st 100yds down range! LOL! :twisted: Then while lost in recoil hearing the UNMISTAKABLE "WHOP!" of a Ballistic tip hitting home!