Good reloads gone bad! Strange...

[mistahmojoryan]

Years ago I found a great load for my Sako 75 in 300 Win Mag; 60gr IMR 4320/150gr Nosler Partition. Back in 98 I was getting .5" groups with this load. So yesterday I took it out to a range with the aforementioned load, plus, two new ones; one with 62gr IMR 4320 and one with 64gr IMR 4320.

Problem: The original load wasn't accurate at all. I was getting 2" groups with it. The faster 62gr load was better grouping at 1.5". The fastest with 64gr IMR 4320 was the best at .5"-.75" groups.

A little history. I haven't fired this rifle for four years but it has been cared for well and mostly in storage. The strangest thing is when I took this rifle out in the late 90's, slower loads worked best. Now the faster loads are shooting better.

Ok, so I have no clue what to make of this except that guns are finnicky little critters sometimes. Ever experienced anything like this with your guns? Comments?

(As an aside, I was having some ejector problems with the Sako. Sometimes it would eject the empty but most of the time it would not. It's very frustrating to have a $1000 rifle that was purchased based on consistency and reliability and I'm having issues with both. The old Remington 742 (30/06), ironically, was perfectly reliable and consistent with 1"-1.5" 3-shot groups. I think I'll be taking the 742 into the woods this year .)

[Howler]

I'd guess it the change accuracy has something to do with break in of the rifle. When a rifle goes from brand new upto a few hundred shots, things change. I recently read a magazine story about the .204 cal. The rifle was chrono'ed with factory ammo and the same load kept getting faster and faster as more shots were fired. A few months after the first bench sitting with the rifle, shooting the same factory ammo., the .204 was spitting bullets about 200 fps faster than when it was brand new.
Goes to show that there is a need to re-sight in every now and then!

4grains is alot, even for a heavier load >50gr. But I have seen it. My root cause was powder storage, I believe. Alliant is the powder I notice the biggest variations from lot to lot. But IMR has never gave me an issue. Temperature is another variant. I have a very hot accurate load for my 300RUM, when shot in 15degrees, where I tested the load. But 80F it was all over the place and over pressure. Rifles change, but you would have noticed this slowly over the years. Maybe a primer lot change. Interesting article in 1999 Precision Rifle, that shows big variations in primers compared from 1975 to 1995.

[Virginia7]

You do not note if the rifle has a synthetic or wood stock, but I'm guessing wood.
You had it stored for four years? I suspect you've had a little change in the bedding.
Check for barrel clearance. Sako rifles have free floated barrels. Make sure there is
no area of contact. I'd take the barreled action out of the stock, clean it all, including
field stripping/cleaning the bolt. Check the ejector too for any oily residue/buildup.
After a thorough take down/cleaning, put her back together, and try again.

Also, what about your reloads? I hope the ammo is not four year old too? Is the powder and primers four years old? How was it stored (ammo or components)?
And, if you're using a new can/different lot of the powder that can change things too.
Kind of like factory ammo, each lot of primers, powder, etc. is a little different.
Sometimes the changes are insignificant, sometimes not.

I wouldn't complain too much about inconsistency - things change over four years!

[mistahmojoryan]

Wow! A 200fps difference over time...that's an amazing difference.

It could be the barrel being broken in since I've put about 100 shots through it since I first tested this load. It can't be primers or powder because I used some leftovers from the very first batch I tested. The temp was about 20 degrees Celsius warmer (36"F) the first time I tested it so that could definitely be the major factor here. I didn't think that an accurate load would go sour in colder weather.

It seems that in warmer weather the slower loads group better and in colder weather the hotter loads are better. At any rate, I'm seriously considering selling/trading in the Sako for something more user friendly since I really don't need all the punch of such a big cartridge and can do without a throbbing shoulder after firing 10-30 rounds!

[mistahmojoryan]

Hey Virginia7, I just read your post. Yes, those reloads were 4 years old and they were stored in a gun cabinet; I thought with proper storage they would be fine over a few years? (Note- I don't do my own reloads; I have a very professional guy do them for me.)

The barrel is fine with plenty of clearance and I cleaned out the ejector yesterday. If anything, there seemed to be a little oil build up in there so it should be fine now.

(BTW, I'm not thinking of selling the Sako because it's a bad rifle; it's a GREAT rifle and EASY to find accurate loads for. It's just too much gun to take to the range on a consistent basis and I'm not planning on hunting anything bigger than whitetails anytime soon.)

Thanks for all the quick feedback!!!!

[iowabuckslayer]

i had this problem in my 7 mag. i load some 150 rounds 3 years ago. they shot very well when they were fresh but after a year or so they started shooting eratic groups with lots of fliers. then i read in a magazine that chemical reaction occurs between the brass case and the copper jacket. it said to remedy the problem by seating the bullet just deep enogh to break this bond but dont go over the min. oal.the reason my groups went wacky was because of the pressure being higher. which it sounds like yours is also doing if extraction is getting tough. good luck.

[mistahmojoryan]

Thanks again for the feedback. It seems I had a number of factors working "against" me; temperature, barrel break-in, chemical reaction.

I believe I'll hang on to the Sako and re-evaluate it's usefullness in the Spring (never know when I'll want the extra power). For the time being, I'm putting a new 3-9x40 scope on the 742 and I'll sight it in tomorrow. I should be able to tighten my groups a bit more with it than with the old Bushnell Banner 4x.

Cheers!

[DM]

I'm still shooting reloads i put together 8 years ago for my 8x57jrs, 338-06 imp, 240 Wby.. and several others. All of them are still shooting the same groups, and with the same accuracy they always did.

I have no problem shooting my "old" reloads no matter how long they were stored, as long as they were stored properly!!

Drilling Man