Load development for accuracy

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muley posted this 25 December 2025

I look at the match results in the Fouling Shot that have a similar cartridge and rifle and then use their powder. I start about one grain below their load and then work up in 1/2 grn increments. I shoot three shots at each load.( I know to some shooters that is not enough shots), but it gives me a start point. When the group tightens and then starts to open up I will work around that load. Each rifle is different, like each of us.

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MarkinEllensburg posted this 25 December 2025

I shoot a series of 5 shot groups at 100 yards. 5 or more. Each range session, over several range sessions. If the initial powder charge is not showing what I desire I increase and try again. If the trend is not in the right direction, groups getting larger with more powder I back off and try again. Earlier this year I did that. I thought I needed more velocity, testing proved otherwise. I do chronograph but don't dwell on the finer data of SD and ES. I'm more interested in average velocity and group size.

I have found some loads that shoot great at 100 yards but perform poorly at 200. Since most of my match shooting these days is at Spokane where we only shoot 100 yards. I have not been too concerned with 200 yard groups. (At least until this spring. Spokane will have an either-or match 100 or 200 60 rounds score and group. Due to space and range design 200 yard participants will have to demonstrate 200 yard sight in at 100 yards first.)

As usual, once you have the load you think is the "right" one you'll decide to change something. Primer, maybe due to availability, or lube or alloy. Any change and I start over. Five 5 shot groups will show if the change did much.

Like Muley, I will choose my initial components based on data gleaned from match data as posted in TFS or in the match results of our site.

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Duke_M posted this 25 December 2025

Similar to stated above I use 5 rounds per load to narrow it down to a few loads. FS is a good place for reference loads. Then I run 5-5 round groups to verify consistency. If not, keep trying. Primer change seems to make little difference but lube type and qty can really change things. Our 200 yd match this spring could be interesting as I have yet to test at that distance. Mike

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John Alexander posted this 26 December 2025

I use at least two five shots for each variation but only for the very first cut. After that, when the differences in group sizes aren't huge, I do something similar to Mark. Anything less and you are kidding yourself that you know which is the best load.

Put another way, If you want to know which of four powder charges is best and two of the average of two 5 shot groups are three times as big as the best average of the four loads, it isn't unreasonable to assume the loads with the larger groups can be ruled out. But if one of if the other two loads produced group averages of only 50% bigger than the smallest average group average, it is going to take four or five groups (or two or three ten shot group s) for each load to have a reasonable estimate of which load is best. And even that isn't certain.

The numbers above are not exact, but just to do a "for instance".

John

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Bud Hyett posted this 27 December 2025

I've submitted an article to Glenn for the Fouling Shot not on laod development, but load confirmation. and the rationale. This involves the technique and the rationale. This is two separate topics

Farm boy from Illinois, living in the magical Pacific Northwest

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shootcast posted this 28 December 2025

I enjoy shooting everything I own. Often just plinking at the club. Using whatever powder I have on hand. If there is data for your firearm from say Lyman, it’s your starting point. Load and shoot just a few rounds each starting low and increase. Somewhere between minimum and maximum you will hopefully notice what works best for you. There maybe a window that shows promise. Work in this area. Try adjusting overall length. Sometimes a jump isn’t as bad as some folks think. Or maybe you will need more of a jam. After you do this try sizing diameters and even alloy changes. After all this and you think it shoots ok or the best you can get it. Try try again. The combination that repeats most often at your range sessions being most consistent is your best load.For most people Lino will provide the best accuracy. I use a blend of w/wts. Because that’s what I have. I normally don’t do as well as others. Consistency seems harder to find. Why I don’t know. Softer alloys may shoot well but at lower pressure/ velocity. If it works in one firearm it probably won’t in another. You will always be looking.

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Wm Cook posted this 28 December 2025

“ …..I have a cartridge, bullet, and powder selected. …..”

Any chance you could share what you’re working with?

This may sound funny, but I’d start with getting a baseline on velocity, and to a lesser degree standard deviation. Once I see where incremental powder increments stops showing incremental velocity gains I conclude I’m topping out on the functional capability of the powder, bullet, cartridge combination.

Then I pick a range of charges that’ll give me, say about, 40 or 50 fps stepped increases in velocity. Faster rifle powders may have steps of .3 to .4 grain. Slower rifle powders will take more.

With that done I stake out a velocity spread that makes sense based on the powder/bullet/cartridge combination, (example 1650 to 1750fps) then shoot 4 to 6 five shot groups through that range to see how, in general, that particular powder/bullet/cartridge combination performs.

Assuming that the first round of testing shows promise, the next step is to narrow it down with smaller incremental adjustments to the powder charge, focused in the velocity range where it showed the most promise. Preferably doing that with 10 shot groups. Just some thoughts. Bill C.

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Idahocaster posted this 28 December 2025

Bill, I am working on a rifle and load to shoot in hunter class next year. I am using a rifle and bullet I already have to minimize expense for this initial try. My rifle is a Savage 111 in .270 Winchester. I bought it about 15 years ago. It shot reliable 1 to 1 1/4 inch groups with jacketed hand loads last time I played with it, and I know I have improved as a shooter since then. I will be shooting postal matches as the nearest club to me that does CBA matches is in Spokane Washington, 6 hours from here on a good day.

The bullet I am using is a Lyman 287346 135gr 7mm bullet that I am sizing down to .278. In my rifle the gas check is right at the base of the cartridge neck when the bullet is just short of the rifling. I will be using IMR 4227 powder. My starting load is 17gr, which should give me about 1500fps. Unfortunately I do not have a chronograph, so I will not be able to measure velocities.

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Wm Cook posted this 28 December 2025

There’s not much data that combine the 270, 4227 and the 287346. It shows up with the 7x57 Mauser but the case capacity of the Mauser is 15% less than the 270. It’s close…..but?? Lyman #4 showed 17 grain and 1582fps with the Mauser, 4227, 287346.

If 4227 were the only choice and if I had a chronograph I would try a couple groups at 16.0, 16.5 grains. Save some steps and just shoot at 50 yards. You just want to see how the 4227, 287346 & the 270 velocity behaves with the .5 grain increase in charge. And who knows, you might be able to incrementally gain velocity with further .5 grain charge increases and it may work for you. You aren’t tuning a load here, you’re just looking for powder, cartridge, bullet compatibility. But without a chronograph you’ll be working in the dark and that’s dangerous.

With no load data, (that I could find) using 4227 & the .270 one might draw the conclusion that it’s not popular enough to try. I didn’t coin that phrase, LG did.

I’d be inclined to find a powder that has some cast references to 135 grain bullets, start at the low end, shoot two 5 shot groups at 50 yards. Maybe Unique in .5g increments starting at 11grain. Or you might have something on the shelf that might work?

I have no problem straying into unique conditions, but a chronograph is needed to see if the velocity is steeping up politely with incremental increase in charge, plus looking for/measuring case heads expansion.

Once you have a powder that behaves in the velocity range you want to shoot, load development can start in earnest.

Out of habit, with the ogival nose that the 287346 appears to have, I’d start with the lands engraving the nose (assuming the front lube groove is in the case or the lubsizer is adjusted not to lube the top groove. But seating into the lands increases pressure and you fall back to needing a chronograph and watching for pressure signs .

The 270 looks to have a decent .384 neck to work with so stretching the COAL would be easy as you’ve described it.

I wish I was 900 miles closer. It sounds like a fun project. Bill C.

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Idahocaster posted this 28 December 2025

Bill, you are right about the miniscule amount of cast bullet data for 135gr bullets in the .270, or any weight cast bullet for that matter! I did choose my starting charge based on the 7mm Mauser, just like you found. I have data for IMR 4227 in the 25-06 and the 30-06 (same basic case as the .270, but lower SAAMI pressure). The 30-06 goes up to 29gr with a 200gr bullet, so I am not too worried about over pressure in my .270. Based on match results in the Fouling Shot of looks like best results are achieved between 1500 and 1800fps, so I don't intend to load hot loads anyway.

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Lucky1 posted this 28 December 2025

You mentioned not having a chrono and I would heartily recommend getting one. The new Garmin or Athlon ones are super nice but even the older style cheap Caldwell you set up in front will still help you a lot. Plus it may avert some major problems.
Right now I'm working on loads for 2 rifles, one new to me and one I'm not happy with my previous match load. I'm using a Shooters World powder and the SDs are under 10 most if the time so I'm feeling like it is a bullet test and not a powder one. Before the chrono (BC?) I was always wondering which was culprit on some bad groups. I realize the 270 is somewhat limiting on choices but I would recommend opening some communication with Glenn since he kind of stomped some people at Nationals earlier. Hope this helps a little.

Scott Ingle

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Glenn R. Latham posted this 29 December 2025

Tyler, I've been shooting a Savage in 270 Win for a couple years. I bought it used in the '90s for my daughter to hunt with. The best bullet I've found is the NOE 279-126-FN. It looks like it is still available. I tried sizing down the Lee 7mm and they shot OK but not great. The new Lee 270 bullet has a long undersize nose and does not shoot well. The old Lee RN bullet shot well (the one that looked like the current 7mm bullet).

The NOE bullet's dimensions looked good cast of WWs, but it didn't shoot great until I cast them from linotype. I guess it just needed a little more size. I've mostly used RL-7 and Accurate LT-30. I've settled on 19.0 grs. of LT-30 for 1700 fps. I managed one 10-shot group of .810", but they usually are closer to 1-1/4 to 1-1/2. At the 2024 CBA National Tournament my 100 yard aggs. were 1.134" for 5-shot groups, and 1.592" for 10-shot groups.

Glenn

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