Perplexing problem with .30-30

[336A]

Good morning folks was hoping that maybe some of you might be able to offer some insight here. I took a trip to the range yesterday in hopes of finalizing my rifles zero with my hand loads. My hand load was as follows
Cases: once fired Hornady Frontier all trimmed to minimum length
Primers: Win large rifle
Powder: 29.7gr H322 all powder charges were individualy weighed to ensure they were exactly 29.7gr
Bullet: Sierra 150gr FP
Crimped with Lee FCD

My first 3 round group at 100yd formed nice ragged hole hole in the target dead center and right where I wanted it 2" high I've never had this hapen ever, I almost packed up to call it a day right then and there. I was conversating with fellow range members for quite some time so the barrel had time to cool down. The next 3 shot group wasn't as good but again centerd and 1.5". After every 3 round group I would talk with these other fellas or help spot thier rounds with my spotting scope so as to allow my barrel to cool before the next group.

This is where it gets perplexing. The remaining three 3 shot groups moved 1" to the right hmmmm says I. The last 3 shot group acted as if I didn't let the barrel cool at all as the group was again 1" to the right and had severe vertical stringing. The barrel was completely cleaned and I ran a dry patch down the bore to remove the CLP that I put in my bores after cleaning when the rifle goes back in the gun safe.You fellas have any idea what may cause this to happen? I've been racking my brain trying to figure why things would go from outstanding to horrid and I can't think of anything.

[bgmkithaca]

You did'nt say that you have a scope so I am guessing that you do. It sounds like a scope related problem. First thing to check is the mounting-rings and bases for tightness. If that does not take care of it try a different scope.

[Hobie]

Yep, sounds like the mount was shooting loose. Doesn't have to be much loose either!

[336A]

Thanks guy's. Yes the rifle is scoped with a Bushnell Elite 3200 2-7X32. The scope being loose is the first thing that I thought of as well and I checked it. The scope is nice and solid so that eliminates that as the problem.

[Hobie]

Well something changed in the midst of your shooting session. Not the scope, not the rifle (check all the screws particularly those associated with the stock and forearm), then it had to be you... I still think it is the scope, if not the mount or rings then internally.

[Nath]

What gun is this please?

This is exactly the problem I had with my last Win 94 trapper a new one, drove me nuts!

I tried everything including removing the scope and putting the peep back on and it made no difference. I got rid of it in the end after all sorts of mods, powders, primers and bullets.

I was convinced in the end but have no proof that the bore was to eccentric or the chamber cut eccentric, the brass cartridge throut would clearly show more contact on one side more than the other. Also recovered in-tact bullets would show more contact with the rifling on one side than the other!

Nath.

[336A]

Hi Nath, the rifle is a 2002 vintage Marlin 336A. What makes this even more perplexing is I don't have this problem what so ever with factory ammo. My next range trip will include Hornady and Speer bullets. I'm not asking for much from this rifle just consistent repeatable groups nothing less nothing more. So far my load work up with this rifle has been a long and tedius road.

[J Miller]

336A,

If the rifle does not have this trouble with factory ammo, then it's not the rifle, it's something to do with your load.
Amongst other things give this load a try. Use Win WLP primers, 34.5 grs of 748 and your Speer bullets. I've found that load to work very well with every 30-30 I've shot it through.

Joe