Optima Update (very long).

[JimG]

I'm starting a new thread concerning my Optima problems because I'm now not sure that it is the gun but is likely some other unknown factor. For those who have not followed my other thread here's a brief summary- The gun is a nickle finish/Mossy Oak stocked .50 Optima that was purchased brand new. The bore and breech plug was cleaned before firing. The first range session showed that 223 gr. Aerotip Powerbelts and some hard cast .44 lead bullets in Knight Sabots (not sure of exact weight but they are in the 225-250gr range) shot to exactly the same point of impact with very good to excellent accuracy. The problem was that the POI was extremely low. Upwards of 8" low at a measured 50 yards. The bore was swabbed dry of any oil before firing. I called BPI and requested a different set of sights (taller rear or shorter front sight). They promptly sent a new set out. Since the sights are for a Winchester branded rifle they don't fit quite right (a screw length issue) however I can remedy this. I shot the gun again at the range and had mixed results. I thought long and hard about this and came to the conclusion that there are too many variables in my range sessions. So I went back to the range and carefully recorded all the data. I've found that I think the rifle is very load sensitive AND ramrod pressure is extremely critical. I've also found something extremely odd concerning velocity. The manual included has some conflicting info regarding loose powder charges. The max load for loose is either 100gr or 110gr. I don't think that it's completely a safety issue after consulting two Lyman BP loading manuals and checking on proposed pressures for various loads of 100gr loose, 110gr loose, 2 pellets or 3 pellets. Anyhoo here's what gives-

Shooting only 223gr. Powerbelts and Pyrodex Select RS or Goex BP FFG to keep variables down.

100gr. Pyrodex gives 1529 avg. fps
100gr. Goex gives 1546 avg. fps
110gr. Pyrodex however gives 1728 avg. fps!

How can 10 grains by volume generate that much extra fps!? According to Lyman and everything I've ever been taught about BP shooting, this is impossible. I also found that by varying the ramrod pressure that the velocity can vary by as much as 83 fps! Also a dirty bore in this gun produces less velocity than a clean bore. I would of thought that it would be the opposite due to higher pressure in a dirty bore.

At any rate the new sights look like they may be the solution after some very careful shooting. I'll have to locate some proper screws to properly mount them to the barrel. The new sights actually seem to be far better quality than the ones that came with the gun.

Any thoughts on the velocity and ramrod pressure data?

[Mac11700]

Ram rod pressure will effect accuracy & velocity...This I know for a fact in my brief time using one...Think ofthe reloading of a center firte cartridge..If you have more pressure compacting the powder then the O.A.L. will be different...and  as the crimping stage of loading a center fire cartridge...The higher the crimp pressure...the higher the pressure is for any given cartridge

There is a loading tool that I was going to buy & try It gives you a poundage scale for seating the bullet...It is called the Pack Jack...and is made by this company...http://www.ultimatefirearms.com/bulletsetc.php..

..I never got around to buying one..since my first outing with my 50 cal. Elite produced excellent results with the Barnes TMZ bullets...

I was using a scope and found if I was inconsistent when seating the sabot on top of the powder exactly..my groups would open up...a-lot...I still might get one before deer season and try it just to see how much it helps...The folks at Ultimate can tell you more about them...since they build some of the best long range B.P.  rifles around...

Mac

[quickdtoo]

Jim, how far from the muzzle do you have the chrono set up? If it's too close, it can register gas and unburned powder which are moving much faster than the bullet giving a false reading.

Tim

[oldrookie]

JmG not sure about the ram rod pressure for I simply try and duplicate the same every time. I have the same rifle as yours. When really getting finite with the loading process most of the debate goes in the direction of measuring by weight and not volume. With that said, I haven't messed with that either.

What I can pass along after 300 loads is how my Optima reacts. First shot out of clean barrel will fly high right. Learned quickly from others to foul the barrel. Once I did, I started grouping right from the first shot.

My pet load is 90g of 777 2F pushing a 300g hornady xtp hp. I use harvester crush ribbed sabots and winchester 777 primers. I only spit patch and dry patch in between loads. I am only interested in a 100 yard max shot so I really do not need a real hot load. I am guessing that load to be a little over 1500 fps. I have tried up to 110g 777 2F and it was a waiste of powder for me at 100 yards.

I don't know why but my Optima does not like lighter weight bullets. I have tried the 240g and 250g hornadys, 250g speer and my Optima will spray them. It will shoot the 250g sst but not as well as the 300g xtp.

With the above pet load, off of sand bags my Optima will do 1.5" 3 shot group, if I do my part.

[JimG]

The chrony is set 8' foot from the muzzle.

[quickdtoo]

That's a bit close, I'd move it to 15' or so and see what kind of readings you get.

Tim

[JimG]

I'll give it a try in a few days. I need to purchase more projectiles. Those Powerbelts are a little pricey!

[quickdtoo]

The .50 cal 245gr and 295gr copper clad powerbelts are available in value packs of 50 if you're inclined to shoot those.

Tim

http://www.powerbeltbullets.com/copper.html

http://www.basspro.com/webapp/wcs/stores/servlet/Product_10151_-1_10001_95328_400003003_400000000_400003000_400-3-3

[300winman]

I had the same problem with my T/C 54 cal. Grouped good but about 6 in low at 75 yards(with sight set up very high).  I went to 100 gr of Triple 7 loose powder, and got it shooting way high(7-8 inches) at the same sight height.  Dialed it in with Powerbelts and not had a problem since.  So I would go with oldrookies advice and try some Triple 7, it worked for me.