Hi , My 788 Rem 223 is giving me fits ,, It is producing 2 different groups from the same magazine load ?? One will always be higher , sometimes by 2" and one will be spot on .....@ 100 yrds .. What causes this ??????

Thanks ..gumboot ..

Gumboot, You might want to post this on the gunsmithing forum on this site.

Sounds like barrel heating, but the distinctly-separate groups is unusual.

Either that or the bullets from one side of the magazine or the other are getting exposed lead tips "bashed" when fed from the magazine.

I had a similar problem with an autoloading 30-06 and the problem was permanantly corrected by switching from the 165gr Nosler solid base I had been using to the NEW (at the time) Nosler ballistic tips

AD

Check to be sure your scope isn't the problem.
Check the mounts also.

Could also be a bedding problem.

muck

Make this as little work as possible and attack it in order.
1)make sure everything that should be tight is
2)if you are not letting the barrel cool, give it a try
3)if you think it's your mag, as suggested, try single feeding rounds.
4)mount a different scope
5)bed and float

If you shoot it and allow 5 minutes between shots, and the vertical dispersion goes away, it is probably the barrel. I have one that is like this, it was explained to me that the barrel was straightened, not properly stress relieved, and that when it gets hot it tends to go back the way it was originally. I have seen this happen with trap shotguns that had the barrels bent to change POI, but don't know if it is the proper explanation or not. I do know that some of them will shoot tiny groups if you let them cool, but will shoot high or low when hot. I have a Sako 7Mag that will do just that it will shoot two inches higher when hot. You have to be careful sighting it in, as the next shot from a cold barrel will be low. I just take my time sighting it in, it has no effect on hunting accuracy and it will shoot under 1MOA forever if you don't let it get hot. If you warm it up and keep shooting it, it will group, just a different POI than when cold

Hi everyone , sorry I,m so late getting back here .... The rifle is a 788 Rem in 223 rem , as it is clip fed and I have only shot FMJ bullets in it , it can,t be tip deforming due to battering ... The barrel really doesn,t get much chance to heat up , my last range session was @ 2 below 0 degrees F. and I moly tumbled the bullets ..... , Everything is tight but it may be the foreend .. As the stock is wood that may be it .... I have been debating between a laminated thumb hole stock and working on this stock .... Does anyone think it could be the muzzle .. This gun was a Tlingit,s skiff gun for seals and deer in Southeast Alaska ......I thot about bucking 1 inch off the muzzle and recrowning it . It has a 24 " barrel now ... The scope is a Burris Posi Lok .and the lock is screwed in ..???

Gummie,

788's are known for their good, "stiff" barrels and the two I owned would shoot excellently. I did though, play with the barrel channel inletting and free floated both; a .243 Win. & 308 Win.

I've got a Buddy's 300 Win. Mag. 202 Sauer in the Basement that I brought back from our load-testing session on Saturday as we've got the exact same issue; "Two-Group Syndrome". 5 shot groups that contiually depict 2/3 rounds in two distinct groups. It's gonna get a complete review, rings, mounts (screws), stock (especially the two piece forearm and the screw pressure attaching it), muzzle crown, action screws, etc.

I personally, think it's his unstable rest, bench technique combined with recoil overload but my shooting schedule didn't allow me the time to shoot it.

The last Two Group Syndrome I had on a .30/06 Sprg. was ulitmately determined to be a techincal failure, as the recticle in the scope (Kahles) finally broke. The last 50 or so (head-scratching) shots outa the rifle eventually leading to "catastrophic" failure.

As for the difference between technique and techical I'd suggest with a .223 Rem. it's technical and as you've already suggested I don't think I'd spend much time trying to analyse the ammo issue but rather go straight to the rifle and it's ancilliary bits & pieces, mounts, rings, scope, stock, action screws, especially the middle floorplate Wood Screw & the trigger? 788's aren't knowm for their superlative triggers, either?
Waht about the focus ring on the Burris scope - have you got this eactly where you can see best or are you potentially seeing "two " different views due to inadequate focus?

gumboot458

FMJs? What FMJs? Are your two groups a shift from point of impact during the same shooting session? Or does the point of impact shift on different days?

Many of the 24" barreled M788s have a 14" twist. The reason that the M16 barrel was changed from a 14" twist to a 12" twist was because the M193 FMJ bullet would not stabilize in cold weather. Guess what kind of weather "my last range session was @ 2 below 0 degrees F" is? The 24" barrel is giving just enough velocity increase that stability is marginal at best.

If you've one of the 12" twist barrels and stability is not the issue then and you are shooting on different days is there a major (20-30 degrees) change in temperature?

Second is the Moly. Are you cleaning the barrel after shooting? It manytimes takes several rounds to "condition" a clean bore with Moly again. A shift in point of impact is many times the result. Also, what is the rest of your load including primers. Some primers do not give consistent ignition to some powders (some ball powders in particular) and vertical dispersion with cold weather changes is the result.

Inspect the crown. Is it dinged or damaged? Is there obvious signs of rust or damage just inside the bore? Before recrowning I'd get some quality 55 gr bullets like Hornady SXs or Speer 52 gr HPs and see how they shoot.

Right now you don't know whether the problem is ammo related or rifle/scope related. You need to sort out which before proceeding.

Larry Gibson

..... Oh Boy ,, I hadn,t taken the focus into consideration ....I,m so used to large caliber rifles that are usually as accurate as this little rifle ..........The bedding is probably the problem ... I have been debating on weather to get a different stock ........... The focus I thot was good , but I can,t see 22 cal bullet holes so maybe its not good enough .......Thanks for the info ....