Developing a new load for a new rifle

[bugabob]

Have a few general questions about the process for developing a new load:

Do you shoot several groups with each powder/weight/bullet combination and choose the one with the smallest average group size? If yes, do you shoot a minimum # of groups? At what distances?

Any other suggestions on how to find the magic load?

Is MOA accuracy good enough for HP silhouette? I'm using Win and Rem brass, CCI primers, prefer Sierra bullets and IMR8208 and H-380 powders.

FYI, I have a Rem 700 in 7-08, Hart barrel in a McMillan stock - put together by Evelio. Weaver T-24 scope w/ 1/2 min dot. Have never shot in a HP match and will use this rifle for hunter and standard class. Thanks.

Bob

[kevinbear]

Use Varget, 120s or 130s for cpt, 162s or 168s for rams.If you don't have a chronograph buy one and let it tell you what best load is, Kb.

[Jim Beckley]

Depends on how deep your pockets are. If they are deep and you want to buy all kinds of junk that you think will make you shoot better, then by all means do so. If you struggle to get your well worn fingernails inside your pockets (like me) put together a load that has acceptable accuracy and then make sure it has enough umph to knock over all the animals especially rams and then go about your shooting business and don't worry about any numbers.

[Bob Mc Alice]

I will add my nickles worth of advice, too.

First off you have a top notch rifle build put together by a legend builder. It will shoot fine if fed the right mix of components assembled properly. Your scope is also perfect for the game. Like Kevin said, Sierra MK's and Varget are a match made in heaven for the 7-08. More on that in a bit.

I don't spend too much time on the bench developing loads. I have recipes that will work predictably well in most any decent 7-08 rifle. Three to five shots will tell me all I want to know if a load is any good. I do not group test at short range instead going right to 300 meters for all CPT testing. You might as well prove a load at the range you will be using it at. 500 meter load testing too is done at 500 meters for the same reason. Waiting for good testing conditions will all but eliminate the worry of wind messing up your groups. Very good bench rest shooting technique is mandatory.

MOA is acceptable accuracy for the game, but I want better, a lot better. Your rifle should do much better. Some suggestions to achieve sub MOA accuracy would include using good quality loading tools, match grade bullets, and keep loaded bullet concentricity (run out) to less than .003 TIR. Seat your bullets so they are .010 to .012 from touching the lands. Your choice of brass is good, keep them trimmed all the same length and neck size only. CCI 200 primers are all I use and never had one fail to do its job. There is a host of other tricks to improve accuracy, I will let others add to the list.

I have never had good accuracy in the 7-08 with H-380, maybe you will. I have not tried I8208 and most likely wont. The powders that have given me the best accuracy results have been I4895- I4064 -I4831- Reloder 15 and Varget. I don't want to experiment with the large variety of propellants to find something better. I burn up a lot of Varget. It is the 7-08 powder for me. I have a dozen 7-08 rifles and they all shoot sub MOA with 37.0 grs. and a 130 gr. MK for CPT. My Douglas barrels clover leaf this load at 200m in good conditions. It is also a mild, easy on the shoulder load. I use 39.0grs. with a 168 MK. on the rams. Also, 38.0 grs. with a 150 MK will do a good job on all of the targets. A few in our group have equally good results with it in their 7-08's.

If your rifle wont shoot tight groups with 37 to 38grs. of Varget and 130 gr. Sierra MK's.....well send it back to the builder with a bitch letter.

Just kidding, Evelio.

[Trent]

McAlice, I just saved that post to my computer for safe keeping. One of the best "advice/knowledge" posts I've read. Should be a sticky for us 7-08 shooters.

Got any advice for me on a 6.5 Creedmoor? I'm only getting 0.2 MOA out of it.

[bugabob]

Appreciate the responses, guys.

Bob - regarding your comment about keeping loaded bullet concentricity to less than .003 TIR - I have no idea what this is! Can you explain or point me to a reference?

Also not sure how to seat bullets .01 to .012 from the lands. I did chamber an unloaded case and bullet and measured the OAL. It was 2.825 with a 130gr SMK and 2.815 with a 120gr Sierra Hunter. When I loaded up some rounds the 120's made the bolt hard to close. No problem with the 130's.

I'm only neck sizing brass at this point.

Bob

[kevinbear]

Hornady's reloading manual has a good introduction to the basic concepts for beginners with pictures, pick one up and read it.
Kb

[Evelio Mc Donald]

Bob
The Hart barrel in bugabobs rifle was installed by another Smith over 25 years ago. It was a heavy contour, and would not make weight as is, so I send it out to be fluted, I did look at it with a borescope, and everything, looked good, I did lap the bolt for full contact, and then it was bedded in the stock. I shot 3 rounds thru it to make sure everything worked, but I never tested it for accuracy.
And you are correct, that rifle should shoot under 1 min. all the time with the right loads, otherwise I will want to get it back, and do some serious accuracy testing, and do whatever is needed to get it to shoot to its potential at no cost.
If the customer is not happy, I am not happy !
Evelio.

[Bob Mc Alice]

At the risk of pissing off my old pal JB again, here is a photo of a tool I made to measure bullet run out and other parameters of cartridge measurement. Concentricity is simply the center line axis measurement of two or more cylinders to each other. The bullet is one and the case is the other. You are measuring how straight they are to each other. Straight cartridges are generally more accurate. Standard seating dies will rarely seat a bullet with out run out. Load one and roll it across a smooth hard surface and watch for wobble at the bullet tip. Using an in line bullet seater die such as the excellent Redding Competition Seater Die assures very minimal or no bullet run out.

The measurement is taken with one cylinder (the case) stationary and supported, the other cylinder (the bullet) free to be touched with the gage probe. Put the probe close to the tip of the bullet to obtain worst condition wobble. Now rotate the case a full turn and watch the gage needle movement. This is TIR....total indicator reading. Ideally you want to keep this needle movement to.003 or less for match grade ammo. You can use thumb pressure to straighten any that exceed .003. My Redding die does such a good job it almost makes the gage not needed. There are a few commercial gages available from several sources for reasonable cost.




A simple and cheap way to measure and set your COAL is to take a fired case and full length size it. Take a small flat file or Dremel cutter wheel and cut a slot on both sides of the center neck, 180 degrees apart, down below the shoulder. The resulting "collet" will spring inwards with enough force to tightly hold a bullet. Seat a bullet in by hand about an eigth of an inch. Chamber this "tool" and close the bolt. The leade on the lands will push the bullet into the case. Carefully open the bolt and with draw the tool. With calipers measure and write down the overall length. Repeat this several times to get a repeatable number. This is the COAL when actually touching the leade of the rifling. Adjust your seating die to to seat a bullet .010-.012 less that the recorded number at touch. There are also a few commercial tools available that accomplish the same thing.




Come on people. This is a good topic to discuss in detail. Add your thoughts to this thread.

[Trent]

I have two thoughts for now and I'll say more when I get home to a real computer.

My first thought is that it probably took McAlice more time to type that post than it did for him to engineer and fabricate that BEAUTIFUL work of art. Bob, if you ever want to sell that guage I will pay a handsome fee. I would place it in a glass case and never use it. That isn't a tool, it's modern art.

Second thought, I have tried several different ways of "finding the lands" including the commercial tools and I find the way that McAlice described it to be the easiest AND very accurate.

[kevinbear]

Bob, that runout gauge makes my rcbs casemaster look downright primitive! When loading for br it is the general accepted practice to push the bullets into lands far enough to get square scuff marks on the bullets there by insuring perfect bullet alignment with the bore. This of course is difficult to achieve if the necks are not concentric and fitted to the chamber besides the runout issue.

[bugabob]

Sorry, Evelio, I should've made it clear about what you did and didn't do. For the record, I also own an Evelio-built 1712 (bought it from the original owner) and can't be happier! Will try to post pics of my 7-08 soon.

I've learned a lot from this thread and hope there are more suggestions. Thanks to everyone.

Bob

[Jason]

I hadn't thought of just cutting a strip out of a case before to do the measurements with. That's a lot cheaper and easier than what I already have and what I was planning on buying.

[Bob259]

I have two thoughts for now and I'll say more when I get home to a real computer.

My first thought is that it probably took McAlice more time to type that post than it did for him to engineer and fabricate that BEAUTIFUL work of art. Bob, if you ever want to sell that guage I will pay a handsome fee. I would place it in a glass case and never use it. That isn't a tool, it's modern art.

Second thought, I have tried several different ways of "finding the lands" including the commercial tools and I find the way that McAlice described it to be the easiest AND very accurate.

I ditto what Trent said..... Well done Bob

[Evelio Mc Donald]

How about that, I did not realize about two Bob's in the same thread. Bugabob, my first posting was in reference to Bob Mc Alice posting, not to you in particular, but my statement is still good, no matter who all worked on your rifle, if after trying more different loads, you can't get it to shoot under 1 min. I will be glad to go thru it completely, to find the problem and fix it.
Bob Mc Alice, grate postings, and pictures, they should be very informative to new reloaders. I really like the idea about the split neck in the case to check seating depth. The only thing I disagree with, is jumping the bullet, all the benchrest shooters that I know like to seat the bullets into the lands, anywhere from .003 to a hard jamed. I get my best accuracy in my benchrest rifles with anywhere from .005 to .010 into the lands, even in rimfire benchrest rifles, you want the bullet to be engraved to at least the first ring in the bullet.
Evelio