I have been working with my CZ 550 American, chambered in .375 H&H, to improve its group size, and would appreciate any advice as to my next move. Out of the box, best five-shot groups with handloads were in the 2-2 1/2" range at 100 yards. The stock (wood) was rather poorly fitted to the barreled action, so I free floated the barrel (that is, the part of the barrel extending beyond the barrel recoil lug). The bolt handle, when the bolt was closed, was pressing hard against the cut-out area for the handle, so I relieved that area so that the bolt handle does not touch the stock. I also glass bedded the receiver at the main recoil lug and at the tang, glass bedded the first two inches of the barrel, and I glass bedded that 2" long metal piece that fits into the barrel channel (the thing that the barrel recoil lug bears against).

I have tried a few powders (H4350, IMR 4350, IMR 4831, RL 19) and a couple types of bullets (300 grain Sierras and Hornadies, and 270-grain Hornadies). Best 100-yard groups after stock work and bedding are about 1.6". Should I be able to do better? (I am able to get 0.8" groups off the bench with my .300 Win Mag, so I don't think it is entirely my shooting .) I intend to try some other loads (including Barnes 270-grain TSX bullets); but are there any other things I could do to the rifle itself that are likely to improve accuracy, short of rebarreling it?

BigBras,

HCR made my CZ shoot Half MOA

HCR, the do a good job for a reasonable price, ask for Matt Bettersworth.
Tree rifles have been done for me, excellent job, realistic time frame and honest people.

http://www.hillcountryrifles.com

tel: 830.609.3139
fax: 830.625.4020

Hill Country Rifle Company
5726 Morningside Dr.
New Braunfels, Texas - 78132

Success,
Roland

Thanks, Roland. What did HCR do to your rifle that accounted for the enhanced accuracy?

To all: This is the only rifle I have that has an extra recoil lug on the barrel itself. That extra recoil lug on the barrel bears against a metal piece that fits inside the barrel channel, and there is a screw in the forend that goes into that barrel recoil lug and holds it down so that it bears properly on that metal piece. I keep wondering about the effect of this arrangement on the rifle's accuracy. It seems as if that screw, when tightened, would pull the barrel downward slightly -- maybe even introducing a slight downward bend in the barrel. Surely that can't enhance accuracy. Would it help to glass bed the entire length of the barrel up to that barrel recoil lug (rather than just the first two inches), in such a way as to make sure that when that forend screw is tightened into the barrel recoil lug, the barrel can't be pulled or deflected downward? Alternatively, is is feasible to eliminate that barrel recoil lug altogether on a .375, so that the entire barrel can be floated?

Dear Bigbrass

I have a Browning 375 H+H that shot 2"+ groups with federal ammo. I fully glass bedded the barrel and action as there seemed little point in free loating 1-2" infront of the barrel lug(very scary thing to do). With homeload ammo using R19 and 300gn woodliegh I get 1" groups.
Lets remember homever this is a hunting rifle not a heavy barrel target-rifle and its the consistency of the first shot that counts so try a group of cold barrel shots only.
When my 458 Lott arrives in 8 weeks time I know I wont be shooting sub minute groups whatever.

MarkH: Thanks for your comment. I understand from your post that you glass bedded the entire length of the barrel, on both sides of that barrel recoil lug. I am not sure whether your Browning has a screw in the forend that goes into the barrel recoil lug, as my CZ 550 does. I assume that that if I did that on my CZ, the barrel would have to be supported by the bedding in such a way that when that forend screw going into the barrel recoil lug is tightened, the glass bedding prevents the barrel from being pulled down, deflected or bent. Is that how the barrel bedding functions on your Browning?

BigBrass - FWIW - I full-length bedded my 602 in .375 - before i ever shot it - so I don't know that it helped or hurt, but i bedded everything from one end to the other.

Just use some clay around the recoil lug "nut" that fits into the dovetail on the barrel recoil lug and lots of release agent. The clay will keep the acraglass from entering int the dovetail and locking the barrel to the stock.

Center-to-center, mine shoots clover-leafs at 50 and about 1" at 100 with a 4x scope.

I think that's probably better than the average production gun that's had only minimal work done to it.

I say if you can get 1.5" at 100 that's more than sufficient - unless you just want to keep putting money into it to get smaller groups.

BigBrass,

Click the link http://www.hillcountryrifles.com and click on accurizing.

Success,
Roland

BB

You may simply have just not hit the right combo of bullet, powder and seating depth.

Mark

Bigbrass

Yes, my barrel recoil lug is attatched to the foreend with a screw. Once the rifle was glass bedded I locked the screw in with glue. The idea is to minimise any movement of the barrel in the stock between shots. Once this platform stabilises it is up to bullet testing to relocate the correct harmonic of the barrel as Mark H Young posted. One thing to remember is that a fully bedded barrel cannot lose heat very quickly so test load development very slowly using the ladder test etc. I had the best accuracy on my 375 on a freezing windy day as the barrel cooled really quickly

quote:

Originally posted by BigBrass:
I have been working with my CZ 550 American, chambered in .375 H&H, to improve its group size, and would appreciate any advice as to my next move. Out of the box, best five-shot groups with handloads were in the 2-2 1/2" range at 100 yards. The stock (wood) was rather poorly fitted to the barreled action, so.....

I'm of the opinion that the CZ550Mag barrel generally shoots well provided it has a good crown. As long as your barreled receiver sits flat and solid in the bedding w/out binding, it should shoot to the potential of the barrel.

I've handled a few "American" versions that were poorly inletted; there-by, binding the barreled action when torqued down. Several of these had very poor crowns as well.

My personal rifles were bedded in multiple steps. Pillars were installed to give square/even platforms for the tang and recoil lug. The barrel recoil lug was bedded to be square and even w/ the pillars. This makes a solid platform/locator for the tang, recoil lug and barrel lug. Then it was bedded from the rear tang forward to just beyond the forward lug. On a 375 w/ a good stock, you could get by w/ eliminating the barrel lug and just bedding normally. On wood stocks, I also add crossbolts and relieve the rear tang. As long as the action screws do not contact the pillars; w/ proper bedding and crossbolts, you should never have problems w/ your wood stock as long as it is sealed well.

Mine have all shot well and were not picky on loads. They've proven consistent hot or cold, wet or dry and stay tight in the bedding.

Gary

A gunsmith helped me to bed my CZ 550 in 375H&H. We decided to lose the recoil lug and I've never had any problems with the rifle afterwards.

Thanks very much for your help, guys. In the end what I decided to do, as a start, was to add glass bedding so that the barrel is now bedded from the main recoil lug up to the barrel recoil lug, skipping over the barrel recoil lug itself, and then the barrel is bedded out to about an inch from the forend tip. (I couldn't bed the barrel recoil lug itself, because the strange shape of it would make it difficult to bed without creating a mechanical lock with the bedding material.) If that doesn't work, then maybe I'll start over with some of the other suggestions made in this thread.