Load Workup Order

[Riggerjon]

Where do you usually start with a gun new to you when figuring out the most accurate load combination? I usually start with a fairly loose patch ball combination and a light powder charge. I increase the powder charge to find the best group and then vary the patch size to see if I can improve things any. Acceptable accuracy will vary depending on if it is strictly for target shooting or used for hunting.

 

[Rifleman1776]

If it works for you stick with it. This is a do yer own thang game.

 

[wiscoaster]

Sounds to me like a workable method.

 

[Grenadier1758]

Do some measurements for land to land bore diameter and the depth of the grooves. I use a starting ball of 0.010" less than the land-to-land diameter. The patch thickness should be compressed to the groove depth plus 0.005". The lubricant can be one that has been good on the past or if one is starting out, then the mix of 1 part Ballistol to 6 or 7 parts of water to dampen the patch before loading. Starting loads will depend on bore diameter. For a bore of 45 or larger, I start with a volumetric charge of the bore diameter in grains for a 5 shot group. No sight adjustment is done until the group size is satisfactory. If the patches are being cut by sharp lands or crowns, then the bore must be eased a bit before load development begins. Be prepared to record the results of each ball, patch, lubricant and powder charge.

 

[JDBraddy]

Do some measurements for land to land bore diameter and the depth of the grooves. I use a starting ball of 0.010" less than the land-to-land diameter. The patch thickness should be compressed to the groove depth plus 0.005".

How do you measure? I have a micrometer and a digital caliper, do not have pin guages. Don't always get consistently repeatable number. Have especially hard time when barrel has odd number of lands.

 

[Riggerjon]

How do you measure? I have a micrometer and a digital caliper, do not have pin guages. Don't always get consistently repeatable number. Have especially hard time when barrel has odd number of lands.

The easiest way is to measure the outside diameter of your barrel and then the thickness at a groove and and a land and calculate using those measurements.

 

[snakebit]

I've learned the best way to develop a load is good field notes. Rome wasn't built in a day, I use the same powder, patch, and ball combo. Varying powder charges. If I think I can do better, next trip I will use different patch/ball combo, with a squeaky clean rifle, again taking good notes. I also got into the habit of shooting a 5 shot string verses a 3 shot string like I used to do.

 

[Grenadier1758]

How do you measure? I have a micrometer and a digital caliper, do not have pin guages. Don't always get consistently repeatable number. Have especially hard time when barrel has odd number of lands.

A micrometer is best for outside dimensions, such as ball diameter and patch thickness. Most modern barrels have an even number of lands which works out well for inside measuring with a digital caliper. Sometimes one must measure a lead slug or cerrrosafe slug. I do the slug by dropping a 6" or longer brass rod down the barrel. Then I drive an oversized ball in. The brass rod can be shaken in the barrel to drive the ball out. I have also drilled a # 8 clearance hole through an oversized ball and inserted a long 8-32 bolt. Drive the ball in the barrel leaving enough of the threads of the bolt to pull the ball out. Then all the measurements can be taken.

Just how inconsistent are the measurements? If only a few thousandths, then average them out and the result will be close enough to the bore diameter. This measurement isn't a scientific result, and the measurements can give acceptable results with an approximation.

Bore measurements are easier with the 3 land military rifles. Do as @Riggerjon suggests and measure from the land to the outside of the barrel and measure from the bottom of the groove to the outside of the barrel. Measure the diameter of the barrel. The ball diameter will the barrel diameter minus twice the measurement for the land to the outside of the barrel. Easy for a round military barrel.

 

[longcruise]

I don't usually measure anything. I start with two ball sizes and more than a few patch materials.

I shoot max loads with both ball sizes and the different patch materials. Then I examine the fired patches for condition. If they all look good I'll settle on the ball/patch combo that was tightest but still manageable in the field or at the bench.

Then I shoot some groups with charges that are suitable to the end use of the rifle. At least five shots per group and maybe ten shots with the one that looks best.

If any of the patches were sliced and diced it's over for the day and time to do some serious muzzle and bore conditioning.

 

[JDBraddy]

Do some measurements for land to land bore diameter and the depth of the grooves. I use a starting ball of 0.010" less than the land-to-land diameter. The patch thickness should be compressed to the groove depth plus 0.005". The lubricant can be one that has been good on the past or if one is starting out, then the mix of 1 part Ballistol to 6 or 7 parts of water to dampen the patch before loading. Starting loads will depend on bore diameter. For a bore of 45 or larger, I start with a volumetric charge of the bore diameter in grains for a 5 shot group. No sight adjustment is done until the group size is satisfactory. If the patches are being cut by sharp lands or crowns, then the bore must be eased a bit before load development begins. Be prepared to record the results of each ball, patch, lubricant and powder charge.

So, my new .36cal Rice barrel, as best I can measure land to land is .360" and groove to groove is .384" gives a difference of .024" divided by 2 would makes the lands .012" each.

.360" - .010" = .350" so starting with a .350" ball, patch should be compressed to the groove depth of .384" + .005" = .389" so .350" plus .017" X2 = .384" so .017" drill cloth would be too loose, .024" Denim would = .398" and be too tight, .020" twill would = .390" and be about right, because groove depth of .384" + .005" = .389"

 

[Grenadier1758]

@JDBraddy, I beg to question your calculations. The groove diameter (0.384") measured will include the windage of 0.005" (x2 for there is windage on both sides of the ball). There is no need to add that 0.005" windage. You are starting off with the difference of 0.384-0.350= 0.034" (divided by 2) that the patch must fill up all around the ball. The 0.017" to 0.018" cotton drill will fill the groove and compress the cloth and the lead into 0.005" windage between the ball and the lands. The patch will wrinkle slightly to add more patch material into the grooves and with the lubricant in the patch will fairly effectively seal the grooves in the barrel. Nothing at all wrong about trying the 0,020" twill. With a smooth crowned muzzle, that will be a tight load but may still cut patches on the lands. With a new rifle one must look for the spent patches to see if the lands or crown may be cutting patches.

 

[JDBraddy]

@JDBraddy, I beg to question your calculations. The groove diameter (0.384") measured will include the windage of 0.005" (x2 for there is windage on both sides of the ball). There is no need to add that 0.005" windage. You are starting off with the difference of 0.384-0.350= 0.034" (divided by 2) that the patch must fill up all around the ball. The 0.017" to 0.018" cotton drill will fill the groove and compress the cloth and the lead into 0.005" windage between the ball and the lands. The patch will wrinkle slightly to add more patch material into the grooves and with the lubricant in the patch will fairly effectively seal the grooves in the barrel. Nothing at all wrong about trying the 0,020" twill. With a smooth crowned muzzle, that will be a tight load but may still cut patches on the lands. With a new rifle one must look for the spent patches to see if the lands or crown may be cutting patches.

Ok, good, because I wasn't sure of my calculations either, I was just trying to reason through your system, that's why I posted the calculations. I was thinking you had added the .005" to add a certain amount of compression on the patch cloth and lead, not just to equal the difference between the ball diameter and bore size. But guess the area occupied by the lands more than takes care of that!

 

[GriscomRun]

Where do you usually start with a gun new to you when figuring out the most accurate load combination? I usually start with a fairly loose patch ball combination and a light powder charge. I increase the powder charge to find the best group and then vary the patch size to see if I can improve things any. Acceptable accuracy will vary depending on if it is strictly for target shooting or used for hunting.

Well, first -- sage advice -- take your time , use the search function to see what others did for the caliber they use. What cal DO you use ?
Mostly I shoot for fun, but still want a good group. And I don't think using a mallet to pound that ball into the barrel is much fun.
So I shoot .490 round balls.
Tried .012 red pillow ticking patching. Sorta ok but .....
Then tried #40 Drill Cloth from Joann's fabrics. Was way better.
I shoot .50 so I started with 50 gr. of 3F. That was ok. Then tried 60 gr. 3F. That was better.
Do shoot at least 5 round for groups. 7 would be even better. 3 round groups won't tell you the truth when starting.