7mm STW and Reloder 25

[just_jon]

I shot Satterlee tests this morning with my Weatherby Vanguard 7mm STW with 140 Berger VLDs and 140 Accubonds and came up way short of advertised speeds. The Berger manual max of 81.2 grains is advertised as 3,262 fps from a 24" barrel. I achieved only 3,092 fps from the same length barrel. That is 34 fps slower than the starting load of 77.0 grains. Nosler website shows max of 81.0 grains at 3,432 from a 26" inch barrel. My 24" barrel should be in in the range of 3,350, but shot only 3,108 (84 fps slower than their starting load of 77 grains).

I'm not complaining as the last 5 shots (79.2, 79.7, 80.2, 80.7 and 81.2 grains) with the Berger fell just under .4 MOA, but I am curious if others have had similar experiences.

 

[Dnk9444]

I tried 145LRX and with 82.0gr of RL25 and I got 3451 with light extractor marks from a 26in barrel. 81.0 got me 3307 with a 160ab. Those loads ran in the 3/4in range. 175 ELD-X with 79.0 gr of Retumbo gets 3196fps and most of the time the bullets are touching.

 

[jd5521]

How many rounds on your rifle are there?

 

[just_jon]

I'd guess somewhere around 100-125.

 

[jd5521]

I'd guess somewhere around 100-125.

You may just have a barrel that is a little slower.

 

[just_jon]

I think I confirmed that this morning with three different powders (IMR 7828, IMR 4831 and IMR 8133) using 140 BTs and two chronographs. Nosler published max loads shot over 100 fps slower than their starting load. Time for a new barrel.

 

[jd5521]

But you're still getting good accuracy right?

 

[ButterBean]

Just keep pushing and watch for pressure, You'll Prolly end up around 82.5 - 83 with RL25, What Primer are you using ? and what is you COAL ?

 

[eshorebwhntr]

What chronograph? If your drops line up with your chronograph its probably true.

Also, I agree with possibility of a slow barrel.

 

[just_jon]

But you're still getting good accuracy right?

Accuracy has been great. Almost every combination I've tried has shot sub-3/4 moa. Hate to give up on it, but I didn't rechamber from 7 RM to get 7 RM performance,

Just keep pushing and watch for pressure, You'll Prolly end up around 82.5 - 83 with RL25, What Primer are you using ? and what is you COAL ?

I'm shooting Fed 215M In Winchester brass. COAL is 3.682". No signs of pressure, so I think I'll keep moving up.

What chronograph? If your drops line up with your chronograph its probably true.

Also, I agree with possibility of a slow barrel.

I've shot it through a Beta Shooting Chrony and a Competition Electronics DLX. Shot my 6.5 creedmoor this morning and speeds were spot on with both units set at 10 feet. I'm planning on trying my buddy's LabRadar tomorrow.

 

[ButterBean]

Accuracy has been great. Almost every combination I've tried has shot sub-3/4 moa. Hate to give up on it, but I didn't rechamber from 7 RM to get 7 RM performance,



I'm shooting Fed 215M In Winchester brass. COAL is 3.682". No signs of pressure, so I think I'll keep moving up.



I've shot it through a Beta Shooting Chrony and a Competition Electronics DLX. Shot my 6.5 creedmoor this morning and speeds were spot on with both units set at 10 feet. I'm planning on trying my buddy's LabRadar tomorrow.

Your on track, It will come around

 

[just_jon]

Your on track, It will come around

My friend's LabRadar confirmed this is indeed a slow barrel. Also ran it through QuickLoad which the mailman just dropped off. It shows 81.2 of RL 25 should yield 3196 fps which is only 104 fps below what I'm getting. I can live with that since it is a very accurate rifle. QL max safe load is 82.82 grains which I will work up to cautiously. Also plan on trying Reloder 26 to see if I can wring out a bit more speed.

Is it possible that the speeds I'm seeing are the result of a misaligned chamber? I see no uneven wear on the lands in front of the throat which I would expect if it was off center. Perhaps that would not show up this early.

A little history. Rifle started out as a 7 RM in 1993. Didn't own a crony then so I have no clue whether it was a slow barrel in that chambering. I had the rifle rechambered by a well regarded local smith in 1996 in preparation for a 1997 Idaho elk hunt. I ended up not using it on that hunt after discovering a month before the hunt that the magazine was too short. Despite providing a dummy round, the smith never mentioned that other modifications may be needed with the rechambering, He had the reamer on hand which tells me this is not the first 7 STW he's done, but I take responsibility for not being an educated consumer. I had another smith correct the issue, but the rifle ended up spending the next 20 years as a safe queen.

I was discussing this issue with a buddy last evening and he asked which smith did the chamber job. I said I thought it was a one man operation, but was told that the smith's son had taken over the business around that time and ran it out of business within a year by doing shoddy work. I will do a chamber cast when I get the necessary supplies.

 

[ButterBean]

My friend's LabRadar confirmed this is indeed a slow barrel. Also ran it through QuickLoad which the mailman just dropped off. It shows 81.2 of RL 25 should yield 3196 fps which is only 104 fps below what I'm getting. I can live with that since it is a very accurate rifle. QL max safe load is 82.82 grains which I will work up to cautiously. Also plan on trying Reloder 26 to see if I can wring out a bit more speed.

Is it possible that the speeds I'm seeing are the result of a misaligned chamber? I see no uneven wear on the lands in front of the throat which I would expect if it was off center. Perhaps that would not show up this early.

A little history. Rifle started out as a 7 RM in 1993. Didn't own a crony then so I have no clue whether it was a slow barrel in that chambering. I had the rifle rechambered by a well regarded local smith in 1996 in preparation for a 1997 Idaho elk hunt. I ended up not using it on that hunt after discovering a month before the hunt that the magazine was too short. Despite providing a dummy round, the smith never mentioned that other modifications may be needed with the rechambering, He had the reamer on hand which tells me this is not the first 7 STW he's done, but I take responsibility for not being an educated consumer. I had another smith correct the issue, but the rifle ended up spending the next 20 years as a safe queen.

I was discussing this issue with a buddy last evening and he asked which smith did the chamber job. I said I thought it was a one man operation, but was told that the smith's son had taken over the business around that time and ran it out of business within a year by doing shoddy work. I will do a chamber cast when I get the necessary supplies.

What the round count on the tube?

 

[jshepherd61]

What chronograph? If your drops line up with your chronograph its probably true.

Also, I agree with possibility of a slow barrel.

Sounds right! I have two 7mm STW's and rebarrled both two months ago. One with a Proof carbon the other with a Bartlein, both 28" same round 168 ABLR over Retumbo. The difference is surprising, the Bartlien is over 100 fps faster with four different loads from 150 gr to the 195 gr EOL each one was approx 100 fps slower in the Proof compared to the Bartlien!