Shot Card (Veggie Wad) vs. MMP Sub Bridge
 

Returned to Popes farm this morning to run a quick test.

I wanted to compare the velocities I would get with the Lehigh 50x325 shooting the bullet with a card and/or with a Sub-Base. The picture below shows the Circle Fly Shot Cards (Veggie Wads) that I use and a few of the MMP Ballistic Sub-Bases or Sub Bridge.



Today I set up the chrono and decided to shoot only T7-2f with a #11 Mag cap comparing the two velocities. The same projectile was used Lehigh/Bloodline .50x 325:

t7-2f ----------- t7-2f ---------------t7-2f ------------ t7-2f
110 grain ------ 110 grain----------120 grain-------120 grain
Sub-Base------- Shot Card----------Sub Base-------Shot Card

1. 1762----------1. 1790------------1. 1884---------1. 1879
2. 1765----------2. 1780------------2. 1883---------2. 1856
3. 1760----------3. 1775------------3. 1884---------3. 1878

Really can not say that I proved anything at all other putting a few bullets down range - which is always fun...

That's interesting. With the lighter load the sub base showed less velocity but vice versa with the 120 gr charge. Seems that the sub base needs more pressure to start becoming effective.
Maybe a larger difference in the charge would reveal that to be the case. Like maybe 80 gr. vs. 120 gr.

Even though the samples are too small for drawing any conclusions, it is a thought provoking exercise.

Bronko's suggestion to add an 80 grain load to the mix makes sense to me.

I like velocity data because it's fun stuff to know. But in the long run I'm interested mostly in accuracy. I know it can be a pain in the butt to shoot for long range group accuracy when working with a chronograph. By any chance were you able to gather groups size data also?

The last two shoots, both across the chrono were only 50 yard targets so the groups while clover leafed really doesn't anything. And again today the shots were in two different groups. 110 grain group was directly under the POA and the 120 grain loads were at POA height but just left of the POA.

Never thought about an 80 grain load as it would never be a load that I would use.

I also am quite interested in the groups, not only the size and location but the type of dispersion often indicates what is going on.

Had to recover it out of the recycle bin but here is the target.

This target was actually shot by 3 different people, myself and two other. During the shoot a couple of guys drove up to see what was going on. I offered to let them shoot if they wanted to because really all I was after was velocities. Dan and John both shot two shots into the paper. I claim the rest...



The last three shots I shot were 3 reduced loads. 2 shots were taken with 60 and 70 grains of T7 and a shot card. You can see that the reduced loads did not stabilize the bullet out of the barrel and a tumble resulted.

The 60 gr. velocities were 1376 and 1344. The 70 grain load was 1436

Next trip I plan to add a small knurl and repeat these low velocity loads.

One of these days i need to try the CF Nitro cards. They are twice as thick as the CF .060 veggie wads. Im not going to buy 1000 though to find out. I still have a lot of .462x.060 veggie wads.

Yes but even so - it would definitely show that the sub base needs a heavier charge to creat a better seal.