Home Forums Hunting & Shooting Hunting Rifles Horizontal stringing...

So I'm working up loads for a M788 .243 Win. It's got the original factory stock, cut down for younger kids, and bedded well. I also have a Boyd's laminate stock that I bought for it that was for the shorter action. So my winter project was converting it to long action. I did the first shooting with the gun with the original stock. Several different loads with little tiny groups, sub-MOA at 100 yds. I put the converted stock on and went to the range today with different loads. I did use one set from the first trip that shot well to check with this stock. Not quite as good a group, MOA, nice and round. Then I tried some 85 gr. TSX groups with I4350, I4831, and H4350. They only had about 1/2" variation at most in vertical spread, but around 2" on horizontal spread - aka stringing. I haven't checked the same loads with the original factory stock, but that is the next step. I did some looking for binding in the bedding and only found one thing. The stock bolt holes were pretty tight compared to the factory stock. So I relieved them with a slightly oversized drill bit to give them some space. Any other suggestions? I'm going to take two sets of the same loads out and compare impact and group size from stock to stock. I suspicious that the action may be binding in the converted stock, but it seems to fit well and fit snug in the bedding.

Is the barrel freefloating in both stocks?

Yes, plenty of free-float in both stocks, first inch or so of the barrel is bedded. I have a feeling that relieving the stock bolt holes will do the trick, but won't get to the range again until at least Friday.

Don't forget the scope mounts. I had a rifle stringing horizontally that was driving me crazy until I found a loose scope base. I finally checked the bases on the advice of a good friend after I had tried everything else.

Picatinny rail, torqued and Loctited. But I'll check it.

wind flags ?

TSX and TTSX bullets are very sensitive to seating depth. Somewhere around .050" - .070" off the lands will produce the best accuracy. What twist is the barrel? Some slower twists won't shoot the Barnes bullets as well. The 85 grain TSX should do okay in 1:10" twist, but may require 1:9".

From your description you seem to have two things going on: The stock isn't bedded to the liking of the rifle, and the TSX isn't doing well in the rifle with the loads you are using. Get the stock to work first, use the ammo that worked to test it. Then experiment with the TSX.

Remington 788 bedding works best for me with the barrel fully free floated, and the action bedded with stress free techniques. Be sure there is nothing touching the barrel forward of the recoil lug, and that the front, sides and bottom of the recoil lug has clearance from the bedding. The action should tighten against the stock inlet (glass bedding) with nothing else bearing. If the recoil lug is touching the bottom or sides of the mortise that can throw things off. I use strips of 20 mil pipe wrap tape to establish the clearances on the recoil lug, then peel it off and install the barreled action.

Well, I switched into the bedded factory stock that is known to be stress free and produced great groups with other bullet and powder combinations. The good news is also the bad news. The laminate stock that is bedded/converted is most likely okay because the same powder combos with the 85 gr. TSX and same seating depth in the same brass produced the exact same results - horizontal strings with less than 1" variation vertically but 2" horizontally. Bullets are seated .050" off the lands. Loads were 45 gr. of I4350, 45 gr. H4350, and 45 gr. I4831. So...do I keep trying with the TSX or take the sub 1/2 MOA groups that I get with 42 gr. of H380 and the Sierra 85 gr. BTHP? The rifle should be a 1-9" twist, so stabilization should not be an issue. At least I'm content that the stocks are okay...

I'd go with what it likes.

i'd fool with the seating depth.

Ed

Which direction would you fool with seating depth? One group .010" closer and one group .010" farther?