280 AI weird groups??

[Texis]

Gentleman,
My other hunting rifles, 708 & 308 both with Shilen barrels will consistently print 1/2 MOA, I've printed tighter. I have attached a 400 yd target I shot with my 708 for your approval that I can shoot adequately. It measures .375.
As for tune… we are WAY past that . After 250 rounds of speed graphing for nodes, SD graphing and seating depth test and graphing and going on my 4th bullet and 3rd powder. If this were a tuning issue it would be over long ago.
"It's not a bench rest rifle"… must not have read the thread. .750-1.00 consistently is acceptable on this rifle.
I understand most are trying to be helpful, keep in mind if this was a simple issue, or I couldn't shoot I would not be posting on this forum.
Most inputs have been helpful and I appreciate them as they give me some interesting options I had not considered.

 

[Texis]

All your suggestions are getting me closer and closer. After bedding the recoil lug, checking all the tolerances, opening up some action landing areas, what I know so far.. it doesn't like 150 or 160 NABs, 160 Barnes LRX. It prefers H1000 over 4831SC and likes VLDs at .010 off jam. 60.5gr going 2756 with an SD of 16.
If I can just get it to stop throwing the first d### round… it will be a tack driver.
Fired 5 today. Overall .880". Making good progress. I have some 180 VLD coming, maybe they will finish this puzzle.

 

[Texis]

Also reduced neck tension by .002 BTW.

 

[Mike Matteson]

In reading back from the start of this. You have a 22" barrel which generally doesn't work as well with slower burning powders. I would suggest H 4350, and Fed 210M or Fed 210. You might step up to Fed 215 primers being a shorter barrel. You will have to work up your loads again. Being H4350 is a faster powder burn rate. I nornally don't use Fed 215 primers, but I use 26"+ barrel lengths.
I did see mention earlier about annealing the neck and part of the shoulder. That should be done after each firing. That set up better consistence tension with each case, If you haven't done that before, you'll need to read up on it. Bumping the shoulder back only .002 to .003. Check your case lenght too. A few .000th can create problems too. Finally I don't see where you using a mandrel to set you neck tension, nor straighten the neck out. Or are you cutting your necks for thickness with new cases unfired.
I may have missed it, but after cleaning your barrel are you using a fauling shot to start with. Then wait for the barrel to cool off completely. So you have a cold bore shot to start your group. It a must for me to be able to place a shot where it's aim on a cold bore shot.

 

[Texis]

Thanks for the productive inputs. I have wanted to add 4350 to the list. I did notice listed velocities are lower with 4350, so it was last on the list.. but the temp stability is the best. I'm going to try it, as it's fantastic powder.
I do use mandrels, Century 21is great, also use Whidden bushings for measurements. I reduced tension by .002 on the most recent test. The last test was set up at .001-.001.5 (depending on spring back).
I am not cutting the neck OD, have to draw the line somewhere lol. The AI case has yet to reach max SAAMI length, hasn't really grown so I haven't had to trim yet. I had heard this about AI cartridges / brass.
I love 26" barrels, my other rifles have them, free speed! I wanted the 22" on this one for convenience of carrying and storage while hunting. 22" + 4" Apollo brake and I'm still fighting gun cases on the 4 wheeler. 26" + 4" brake wasn't working for me in the field.
I did tightened up on the shoulder bump to .002 on the most recent loads.
As I increase round count on my best loads now, it's starting to look more like a cold bore issue, throwing the first round high and to the left by .500-.750. Currently researching this.

Thanks

 

[Texis]

Sorry I missed the question, yes I foul with 10-12 rounds after cleaning, before shooting for accuracy. Currently I'm cleaning between 110-130 rounds.

 

[Mike Matteson]

Sorry I missed the question, yes I foul with 10-12 rounds after cleaning, before shooting for accuracy. Currently I'm cleaning between 110-130 rounds.

You can work with the powder charge. I load several cartridges over the manual stated max load. I fully under stand the quest for velocity. I am very much the same way. I have Peterson brass in 280AI and found right out of the box they varied several thousand in length from case to case. i went through 30 to 40 pieces of brass and they inconsistence to say the lease. There been a lot of talk about when to trim cases. From what I have read that different case lenghts changes the release of the bullet. I can't prove that one way or the other, but I can see it causing problems.
Now I cut my necks for thickness from the get go. I start with making sure all my case are the same lenghts, then cut for thickness. I have a 6mm/280AI chambered rifle with a 30" heavy barrel, 7-1 twist rate. I had a reamer made for it. The reamer ended up cutting a little tighter in the neck area by .001. So I am having to cut my necks to .0012th. The tools I am using are automated. So I set up everything to be the same. So case length is very important to me. I don't want to cut into the start of the shoulder from the neck. That was one of the reason I went to a 280AI case was for more powder charge. I also having 25/280AI being built.
Being you are using an AI case, they suppost to not grow much. That probably why you are not seeing the cases growing much if any.
I put together a 34 page doc on general procedures and case prep. It's make up from other people and what they have stated over the years, and I reduced it to the form I have now. There is thing that I have found that work also and placed into the doc.
In thinking about your problem. Possible to set up with a neck sizing die and only size the neck partly, leaving about 1/4 of the neck unsized, so it chamber size for part of the neck. I stumble on to this a great many years ago with my 308NM rifle. The 308NM case is shorter to the shoulder than the 300WM case. The necks on the 300WM are shorter than the 308NM cases. So I tried a 300WM neck sizing die to resize my brass. It size the case about 2/3 the lenght of the neck. So I end up with a kind donut shape in the neck area. It did two things. It stop the case separation dead in it's tracks, and my accuratic improved just a bit. I would lose a case in 3 firing and after that I would lose case do to primer pocket would get to big to hold a primer any longer. That was after about 10 to 12 firing. No more case separations. My loads are about 5grs over the max shown in the manuals. That was using H4350 powder, and Fed 210 primers. I tried 215 primes but couldn't get the velocity out them and the accuratic decreased too. The H4350 is faster burning powder and help with the velocity.
I could got about 100fps with IMR powders, but the temp got me in only about 50 dr weather change. I blew a primer out of the case into the action. That load was also about 5gr over max. So I never use IMR powder in my rifle every again. There only 3 rifle I use other powder in. Is my 338WM 25/06 and 220 swift. I am have a 338 WM being built in a 28" barrel to see if I can acheive the same velocity as I get in my Ruger Mark 11 with a 24" barrel but using H 4350 or some other H powders. I'll never cross that bridge again with IMR powders.
The worst of it was I took down my reloading area. I planned on using my son exter area in the garage to relaod in. His wife figure she wanted it for an office. So I lost out. No biggy, but then I had to come with another spot, and building. I make it to be portable. We have trucks that can pick it up and move it to a different location if need be. I am finally just about to complete the reloading shack. I think I'll be back into the reload ammo again a few weeks.

 

[med358-boise]

Here's the weird. I shot 3 shot strings, cooling 10 minutes between strings. Could a poor heat treat on the barrel do this???
Shoot the first shot, the gets barrel is warm.
The next 2 shots touch, but they are 1/2-5/8" away from the first shot.
This pattern repeats non-stop. This is the most consistent rifle I've ever owned

Yes an improperly or poor heat treated barrel will do that.

 

[Rflshootr]

As for tune… we are WAY past that . After 250 rounds of speed graphing for nodes, SD graphing and seating depth test and graphing and going on my 4th bullet and 3rd powder. If this were a tuning issue it would be over long ago.
"It's not a bench rest rifle"… must not have read the thread. .750-1.00 consistently is acceptable on this rifle.

All your suggestions are getting me closer and closer. After bedding the recoil lug, checking all the tolerances, opening up some action landing areas, what I know so far.. it doesn't like 150 or 160 NABs, 160 Barnes LRX. It prefers H1000 over 4831SC and likes VLDs at .010 off jam. 60.5gr going 2756 with an SD of 16.
If I can just get it to stop throwing the first d### round… it will be a tack driver.
Fired 5 today. Overall .880". Making good progress. I have some 180 VLD coming, maybe they will finish this puzzle.

It's under an inch and within your specs.

 

[BillLarson]

Getting strange groups, 2 touching.. next shot 1/2"-1" away. Repeat the best load, .350" and then get a 1.5" group.

Background:
I built the rifle, Remage 700 with a 22" 1:8 twist Criterion barrel. HS stock, Trigger Tech, NF SHV 5.5x20. Scope mounts are tight. I've owned this NF for years, it has been rock solid.

To start, I love the round, smooth, no pressure signs pushing 160gr AB or LRX at 2900 with 58.7 gr 4831SC. COAL at SAAMI.

I'm an experienced hand loader, I've tried moving the COAL in .010 increments in both directions, shoots the best at SAAMI lenght. I've tried working the load in 1/10gr increments, 58.7gr works the best.

I use RCBS dies and Whidden bushings and mandrel, bump the shoulder back .004-005 (it's a hunting rifle) Redding scales. I have been seeing 9-15 SDs, all good there.

I keep round counts, currently at 143. My next move is give the barrel a deep cleaning then lead it with dozen rounds or so, and try again!! This is about the point I typically deep clean, but it hasn't degraded in accuracy.. it's shot like this since I started.
Any ideas are appreciated.

I have cured this problem more than once..... using an "O" ring up under forearm at the end of stock..... if successful put bedding there...

 

[Muddyboots]

Curious, have you tried shooting factory ammunition?

 

[Texis]

I have cured this problem more than once..... using an "O" ring up under forearm at the end of stock..... if successful put bedding there...

An "O" Ring!! Very clever.

 

[Mike Matteson]

Question: Why some many fowling shot. I generally only fire one round to fowl the barrel after cleaning the barrel. Maybe I missed something on using 12 rounds to fowl a barrel? With that it's bring another question? How does it shoots after cleaning and the first few rounds out the barrel. I wouldn't think you are just shooting just willy and nilly to do that. It would be a long time in cooling the barrel after 12 round being fired that many to cool the barrel.
Here what I would do. Clean the barrel, Go to the range and set up targets, Set up and fire the first round at the target to see where it hits. (clean barrel) Then follow up the a string of 4 additional shot at the same target and same loaction on the target. This will tell you how your clean bore places the shot, and the follow up will show how that works.
OR, Just fire one round to fowl the barrel on one day. Come back the next day to allow for the barrel to cool completely. Then shoot a group to see whats' a doing. Making note of where each shot places on the target. The first round down the tube is the importance one for a cool bore shot. That's what you have when hunting is a cold bore shot.
Some barrels love to be clean, and other don't care, but most like a fowling shot down the tube. You do need to take note of what's going on from first shot and after that. It appears you are doing that, but after putting a bunch of fowling rounds down the tube. In my estimation that to many round down the tube to start with.
I also feel you need a bore scope to look down the barrel too. They are not that expensive, and a good thing to have around. With the amount of ammo you are putting down range surely a bore scope isn't to much.
Trying to help not trying to give you greft about it. Sure got me a thinking, and that at times. won't get me to far.

 

[quandary]

I've tried both. Both seem to behave the same, inconsistent. Yes.. I am using them interchangeably, but never in the same set. I've tried monos one day, ABs the next, then try the monos again a few days later.
Could the differences in alloys be causing it?

I haven't read all 6 pages so if this is redundant, sorry. I had heard, Ron Spomer, on a podcast that monos lost their accuracy if shot in a barrel on top of traditional bullets. But not visa-versa. Ron stated he had no idea why this was but that he had experienced it as well as a number of others he knew.

I decided to test this observation. I was at a range testing my 160LRX 7PRC load at 500 yards. Was banging away on the target and the small steel plate. I then switched to 180VLDs. Same result hit target and steel no problem. Switched back to the 160s couldn't hit the steel to save my life. Cleaned the barrel to the metal, went back to the range the 160s are accurate again. Go figure.