7mm ultra mag performance

dthunter

dthunter

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Hi guys, what kind of velocities are you getting with a 168 grain Berger VLD?
What kind of powders you using?

I am getting above max listed velocities with minimum/starting loads.
I tried 95.0gr. Of H870. Seated the bullet 0.070" from the rifling.
Pressures were definitely on the higher side, but extraction was perfect.
I have yet to measure the case head dia. And compare it too an unfired case.
I have to see if the primer pockets are loose as well.

This rifle has had problems from the start with sticky cases (only after reloading a second or third time). I built it in 2000.
I put a 27.284" barrel on it.

Recoil is not bad.

Any ideas guys?

I havent shot this rifle since 2002, and would like to stretch it to 1000+.
i just want to get my velocities/pressures down to normal.

My friend and I built this rifle
Before the 7mm Ultra Mag was introduced.

We had Clymer grind us a reamer.
No dimension changes from a 300 ultra, except for neck dia.

I will take some measurements soon an post them here.

Straight shootin and keep it fun!
 
You will have to take into consideration the length of the barrel used to get the starting velocity (most likely in the 20-24" range), having a longer barrel will give you more velocity (25-50fps/inch)

So if test barrel was say 22" and you have a 27" barrel it would be expected that you would be 125-250fps faster than barrel used for book values.

Not sure how you worked your load up, but if you have no pressure signs and are going off velocity alone, it soiunds like you are well within where you should be.

If you get sticky bolt lift, flattened primers, extractor marks on case heads or any combination of these signs, then I would lower the load by a couple of grains and work up again.
 
Hi guys!

Took the 7mm Ultra out last night.
168 Berger VLD'S

90 grains of H870, Ave Vel: 3292fps, E.S. 22.36fps, S.D. 11.70fps. Group size: 0.679" (4shots).

90grains of H869, Ave Vel: 3279fps, E.S. 8.00fps, S.D. 3.60fps, Groups size: 0.426" (4 shots).

90 grains of H50BMG. Ave Vel: 3335fps, E.S. 73.11fps, S.D. 32.54fps, Group size: 0.936" (4 shots).

I am very pleased with the performance! Some serious velocity for the 168's!
They should hit HARD!

I look forward to trying these loads out to 1000+ yards!
I dont plan to shoot this rifle much, but it will be nice to have it calibrated out that far.

I may try the 180Gr. Berger VLD as well. hopefully it will shoot as well.

Hope you guys enjoyed the test results.

Take care,straight shootin, and keep it fun!
 
I havent had too much trouble with the VLD's, but would like to try the hybrids.

Due to the short barrel life tendancy of this caliber, I want to shoot hunting bullets exclusively. When the best loads are found, BINGO!
 
You will have to take into consideration the length of the barrel used to get the starting velocity (most likely in the 20-24" range), having a longer barrel will give you more velocity (25-50fps/inch)

So if test barrel was say 22" and you have a 27" barrel it would be expected that you would be 125-250fps faster than barrel used for book values.
Click to expand...

Every source of data that I have seen published for the 7mmRUM listed a 26" barrel.
 
If your barrel meauers 27 from the lug then it is actually about 28 inches. That is why you are getting the velocities.Also some barrels are just really fast. I have a 280 which is as fast as an ackley( but it is a gain twist RKS).
I am getting 3575 fps with ease in my 7mm ultra mag with 168 bergers but I have a 32 inch barrel.
 
Canuk525:

My barrel is exactly 27.284" from breech end to muzzle. What
Powders are you using?
I have got 3450fps from A starting grain charge of H870.

How many rounds have you shot from your barrel?
Have you been tracking your throat erosion?

Thanks for the replies gunnutz!
 
I am using RL25 and retumbo. I have less than 200 rounds though it.I have not kept track of the errosion.
I know guys getting over 3400 fps with their factory senderos with 26 inch barrels but they are hot loads.
 
Canuck 525:

Have you ever tried the H869?
It seems to be super consistant.

I used a single bullet to measure my overall length (with the stoney point/hornady overall lenthg guage). I marked "that bullet" with the measurement I got. Periodically, I will take that bullet and remeasure the overall length. It gives me a bullets perspective on the throat erosion.

It sure seems weird how all the loading manuals quote such slow potential perfirmance from the 7mm Ultra Mag!

By the way, I know the exact length of my barrel because I built the barrel myself years ago with the help from a gunsmith friend of mine.
An awsome opportunity it was!

What are you shooting your rifle for? Target? Hunting?

What kind of groups are you getting so far?

My goal is around 3250 ish with the 168 VLD. Good enough for my purposes.

Have you tried the Berger 180 VLD yet?
 
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I am able to measure throat errosion I simply am not bothing with it. The combination is extremely accurate so no need to play further. I was shooting 162 Amax but was losing some( burning up). My best group to date at 109 yards was a 5 shot group which measured 0.137 .I have never really come close to repeating that( usually 0.25 - 0.3 and sometimes bigger if I screw up) and I don't want to burn the barrel trying. I usually only shoot 3 shot groups with it. My best 3 shot group at 1000 yards was 3.4 inches but usually is more like 6-7 inches( again only 3 shots). I imagine if I was shooting 5 shot groups the size would open up considerably. I have also shot some really bad groups but it was the nut behind the wheel.
It is built on a Barnard PT action,Robertson composites stock, 32" trueflight barrel ( 1.25 straight tube)with Vais muzzle brake.It's topped with a Sightron SIII 8-32 MD.
 
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