Another seat length, load development question.

[Iamero]

I have a 300 win mag, an old school one built by HSP on the R700 before they did their own action.

I took it out with a variety of loads, just to see how it shot. This is a brief summary:

Factory FGMM 190 SMK = 1.5” crap
Old hunting 180 SMK loads = 1.25” crap
180 Nosler loaded to factory length = crap
Random 180gr Winchester PSP = .75” group

I was a little curious at this point and figured it might be the stock touching the barrel up front so I sanded it open a bit and shot the FGMM again. Still crap.

Now I decide to do some hand loads with H4350 and 208 Amax. I did OCW at the lands and found pretty consistent POI around 64.5-65.0gr and no pressure signs, so I loaded up 65.0gr at .01” jump, lands, and .005” jam.

Jump was absolute crap. Lands was hardly better, and jam finally tightened it up; but nowhere near satisfacation for a custom rifle.

I decided to shoot some PPU 180gr SP and again it grouped 5 shots under 1”.

So my questions are:
- why would these cheap 180gr PSP loads shoot well with a big ol jump?
- is my handloadig with 208 amaxes proving anything about the barrel? Is it shot out? Is it just picky?
- could it be a bedding issue?
- do I say screw it and put a new barrel on there?

I know there’s a lot of missing info and I’ll try to answer it to the best of my ability as it is asked.

Pics below are the .01” jump and.005” jam results from tonight.

 

[XLR308]

How many rounds have you put on the barrel ?

 

[Iamero]

That’s the issue. Bought it used. By what I’ve been told and what I Shot it shouldn’t be more than 400-500.

But it is starting to remind me a lot of my 7mm mag back in the day that I shot out around 1,100. That gun would do 2-3 in a small clover, and then 2 fliers.

With the exception of a bore scope, is there any good way to know how worn the throat is?

 

[supercorndogs]

Have you run any patches to see if there is a tight spot in the bore that might need cleaned out?

 

[Iamero]

Not since I cleaned it. I soaked it in bore foam, ran a copper brush through several times, then ran hoppes 9 with a brush a couple times, and then patches until it was clean. Did all that right before starting to play with the groups so it shouldn’t be a dirty bore.

 

[supercorndogs]

What makes you think it might be a bedding issue? Did you change stocks? Is it a chassis? Have you checked the scope base to make sure it doesn't need bedded? I have had a chassis and a hump backed remnigton action run me in circles for a couple barrels.

 

[Iamero]

Yea I guess bedding was farfetched because normally that puts it in two smaller groups and not just all over randomly like my loads are showing.

Am I correct in assuming that even if there was some throat erosion that chasing the lands would aliviate that?

 

[supercorndogs]

Depends on how heat cracked the throat could be. My factory remington shot the 208 a max very well with a mile of jump. All the way up until it didn't anymore. I could barley touch the lands and keep the bulls in the case. Has it ever shot well for you?

 

[Iamero]

Only with the soft point hunting ammo really. My buddy had similar results while he owned it.

That’s why I was debating how much I screw around with load development trying to get other stuff to shoot. Problem is, once I invest in a new barrel and the labor, I’ll lose big time if I ever sell it; and I’m bad at keeping guns around for long haha.

I was thinking about trying some 220 SMKs or 178 amax since those were the two other types of 30 cal bullets on my bench.

 

[mdmp5]

I bought a R700 Police in 300 WM back in 2002. Even after bedding the action years later, truing the action and putting on a new trigger, the thing was an absolute turd. We are talking 3-4 MOA with factory ammo, and maybe 2-3 MOA with reloads. Turns out the barrel was an absolute piece of shit. Replaced the barrel and I had a ¼ MOA gun with loads, but factory never shot much better than 1 MOA. Moral to the story is that your barrel won't shoot anything good if it is a turd

 

[Iamero]

Yea I guess I wanted to expect more from the HSP barrel; or KP, whatever they used back in the day. I have a.224 blank I might just have to try and trade for a 7mm or 30 cal blank.

 

[supercorndogs]

If its never shot well, you might find something in the bedding. Do you have anything slower than 4350? Mine really likes 4831SC both the factory barrel and the Criterion.

 

[Iamero]

Yea I have 4831 I can try. No bedding work done on this rifle ever.

 

[supercorndogs]

I had extremely accurate pretty light load at 68.5 with the 208 a max. Is it in an HS stock with the bedding block? Have loosened the rear action screw and seen if the tang raised away from the stock?

I have an action now that shot like crap for two barrels. I assumed the factory 223 tube was crappy. I put a different bolt and a BHW 1 in 7 22-250 barrel on it. Shot it out shooing bad. Then I learned about warped remington actions and chassis. I ordered a pillar bedded stock, bedded the rifle and all was better. I had to re-bed the base also because the first time I did it with the action pulled down into the V block.