Fellas,

Finally got a day that I can play with loads on a closed range ( ... my side yard)

We have a bit of a slope issue and can't really set up a permanent bench at 50. So ... I took a very large photographic tripod (one for a 4x5 monorail view camera) and made an 8 x 10" wood plaform for the top. This allows me to rest my gloved left hand on the leveled platform while standing up to shoot for groups. Actually handles recoil well and is very pleasant as compared with a bench rest. (Caution! This really is a mother of a tripod!)

First load was a 540 gr Ballsti-Cast projectile with 36 gr of XMR 5744 and a Fed 215. Very mild load, but one that regulates in a Heym owned by an acquaintance.

(Kinda neat to blow smoke out of the bore from the open beech after firing a round.)

To my amazement, left bbl is shooting a 1" group an inch low , but dead center.

Right bbl is shooting groups with holes an inch higher, but 4" to the right.

Data for another bullet: 500 gr Ballisti-cast FPGC on 36.0 gr XMR 5744. Right bbl is 1 1/2" to the right 1 1/2" grp. Left bbl is same group 1" lower. Is some crossing here.

OK ... where to from here? Raise the charge (how much?) and see what happens?

How does one go about this regulation thing?

Thanks!

[ 06-23-2003, 21:48: Message edited by: mstarling ]

It is all guess work.

Just go up 1 grain at a time and see what happens.

Mickey1 is correct, go up 1 grain at a time, watching for pressure signs. If shots do not come closer together go back to your original loads and go down 1 grain.
Shooting with a "standing" rest is the best way to test loads in a double, amd probably any big bore as well.
After you get a good load at your test range of 50 yards, shoot at 25 and 100 yards. After you have shot and tested several loads in your double you will see trends start to develop.

Some people who have done a lot of shooting with accurate rifles off of the bench are dissapointed with the groups their double rifle shoots. I recommend to them that they take their "accurate rifle" and shoot it from the same position they are testing their double from. When they do this they usually say "This double is shooting better than I thought"

What velocity do you think you are getting?

450 NE No2,

I think the velocity of the 500's is about 1350 or so based on the chrono data from a Heym. Will try to get my chrono functioning today or tomorrow.

I had some additional loads built with 50 gr of XMR 5744 and the 500's. Left bbl was about 2" low with about a 1 1/2 group. Right bbl was a pattern about 5" surrounding the impact point of the left bbl. Not good. May just be my old eyes and these iron sights though. I suspect there are in the 1800-1900 fps range.

Ideally, I'd like to have a regulated load at about 1500-1600 fps to use for smaller game like deer. Have the perfect place to shoot them with it. Ranges tend to be from 40 to 60 yards.

Sometimes it can be very hard to get cast bullets to shoot good. Each bbl is a law into itself, you might find one of your bbls is more finicky with cast bullets than the other.
You might also try some "Nitro for Black" type loads with IMR4198 and poly filler with those cast bullets.
In my 450 No2 a @400gr Lyman [457193 I think] cast of Linotype with 50gr of IMR4188 and 15 grains of poly filler chrono'd 1822fps. This load shot good and hit with the sights.
That should be a safe starting load with 500gr bullets in your Searcy 470.

Keep us posted on your results.
Are you thinking about scoping your Searcy?

Actually regulating has nothing to do with what your doing, your simply trying to find a load that will shoot to the same POI that the gun was regulated for by the builder, that should be stated on the water table as x number of grains of cordite like 60 cordite or something simular, but only if it is a cordite gun, or cordite proofed black powder gun...

A rule of thumb for you is IF the barrels are shooting apart then up the load 1 gr. at a time until they shoot across each other (within reason)then go back to the load that shot them closest before they crossed over....Always good to have a chronograph working when setting up a double rifle or at least know its limits for whatever powder your using.

The opposite is true if the barrels (groups) are shooting across each other, in which case you would cut back 1 gr. at a time.

Your double will shoot only as good as the 6 shot group shot by the worst barrel, so that is what you can expect to end up with when all is said and done...therefore the first thing to do is see how each barrel shoots individualy.

Unfortunatly these directions are not written in stone, Fortunatly it does apply 98% of the time.

Remember to shoot the gun right, left, right left and so on...as that is the way they are regulated by the builder, again 98% of the time.

The formula for loading IMR-4831 is 1.33x the cordite load....For RL-15 its 1.19x the cordite load..This is with jacketed Woodleigh SN and Solid bullets....I have no clue as to cast bullets, its just going to be hit and miss I fear.

The actual sighting in is done by moving the sights up and down and laterally once you get both barrels shooting together, not changing the load....

Other grimlins well surface from time to time, buyt take that on a one to one basis and cross that bridge when you come to it, give me a call or one of the other guys on this board, there is a lot of doubly rifle savy on this forum...

Both of my British doubles shoot good with either one of those powders. Those formulas should put you within a grain or two of proper full power loads for your big bore doubles.

Ray,

Thank you for noting my abuse of the language ... should have realized what I was doing, but am not yet familiar with the correct terminology.

Also, thanks for the heuristics (rules of thumb) on how to proceed with loading for the rifle as it has been regulated by the builder. (Did I get it right this time?)