HELP- Accuracy problems

[mrlnfshr1]

I have a CVA Optima that I have had for a year and shot probably about 300 shots through it. Always been happy with its accuracy, especially with the 300g Barnes Expanders and loose 777. Swabbing between shots with windex, I get all the expected deviation between different loads, sabots, bullets etc. The last 3 sessions at the range have bewildered me. After 10 shots or so, groups become erratic and bullets even begin tumbling, even the trusty Barnes, something that never happened before. If I hadn't been using a piece of posterboard to back my target, I wouldnt have even been able to find where they hit at 50 yds. The first time this happened was with my 1st can of BH209, and then only after 30 or so shots, and I just chalked it up to fouling of the BP or such. The next time out I used 777 and had similer problems after a dozen or so shots, but I cleaned it real good w/ Hoppes #9 and got 3 excellent 3 shot groups w 300 gr XTPs before it opened up dramatically and I quit. Cleaned the gun real good with windex, then followed up with another cleaning with Hoppes and another with TC foaming cleaner in case there was plastic residue. Back to the range w/ BH, double swabbing with Hoppes and had excellent accuracy with the XTPs, but only fair accuracy with the Barnes.
Even with this swabbing and an occasional brushing, after 15 shots or so the groups opened way up .I even pulled and cleaned the BP. Switched to 777 with same inconsistant results. Last shot with a XTP missed the poster board at 50 yds. What the hell is going on? The bore is mirror brite and the is no pitting or visible fouling.

 

[flint head]

Sounds like you may have close to 400 shots on your breech plug, which in some instances can be it's life span. I would buy a brand new plug and try that if you are sure your scope is not the problem.

 

[mrlnfshr1]

Was wondering about the life span of the Breech Plug. Doesnt appear to have any wear, but I am more familiar with sidelocks than inlines. Anything I should look for, although i will order a new one in the AM just to eliminate that variable.

 

[Lee 9]

I would check the mounting bolts to the stock and the scope mounts I they are all tight and holding well then I would try a different scope or iron sights. Lee

 

[frontier gander]

ditch the t7, get some pyrodex r s or select and swab every 3 shots. 100gr RS should be good to go.

 

[Doohan]

Given your experience....

I would give the bore a darn good scrubbing with US Bore paste. This will remove the plastic fouling and bring your bore back to near new condition. This will require some elbow grease 8) but is well worth the time spent.

I have had this happen with nearly all my sabot shooting guns. Smokeless or otherwise.. When accuracy goes it is time to scrub the bore.


I would also replace the breech plug as part of this regiment. A slightly larger flash channel can kill your groups.


Lastly, double check your scope and mounting system... It doesnt take long and is piece of mind.


IMHO T7 is fine and no less accurate than many other powders. If it has worked for you in the past, no reason to change.

There you go-

Barrel
Plug
Sights

Happy Hunting!

 

[choc-dog]

You might have plastic residue from the "Sabots" built up in the bore. You cannot always see the build-up. Use choke tube cleaner or carburator cleaner and a wire bore brush to remove it.

Chocdog

 

[Doohan]

Choc-Dog

I have never removed it like that... do you let the cleaner "soak" in? Some use acetone as well.

 

[mrlnfshr1]

Was kind of figguring there was some sabot residue. Had checked at the local Bass Pro and the only cleaner I saw that mentioned plastic removal was the foaming TC cleaner. Have used carb cleaner in my new Lyman sidelocks to remove the factory grease with no ill affects. Will also look into the US bore paste.

 

[choc-dog]

I let it soak for a few mnutes ans then scrub it out. I also remove the cleaner with a degreaser after I am done.

Most ML rifles are "Button rifled" and they are by nature rough on the inside. Since most of us only shoot sabots in them the inside of the barrels are not exposed to any HARD bullet jacket to smooth them out.

A few boxes of the newer Hornday hollow base bullet would suffice to remove any tool marks that the sabot body will scrape on as the sabot is forced down the barrel.

Chocdog

 

[WA. Smoke]

Is the nipple considererd part of a breech plug??

The USA Muzzleloading team members throw away a nipple after ever 25 shots. At least that's what I've been told. Accuracy seems to drop off I guess..

 

[Chasam60]

I had a similar problem with my Rem 700ML. I used Hoppe's Benchrest copper and plastic solvent. Had to scrub the bore several times to bring it back. I use it now about every 4 or 5 cleanings to keep the problem from coming back.

Charlie

 

[JohnDeere]

Before doing anything, check this "bore salvage" article out from Brownell's and pay close attention to the remarks about sabot fouling. Notice the author claims to have removed the plastic fouling in about six passes of the bore swab.

http://www.brownells.com/aspx/NS/GunTec ... &t=1&i=544

 

[JohnDeere]

Before doing anything, check this "bore salvage" article out from Brownell's and pay close attention to the remarks about sabot fouling.

http://www.brownells.com/aspx/NS/GunTec ... &t=1&i=544

 

[mrlnfshr1]

Well, found some Brownell's Sabot Solvent locally and scrubbed the bore really well with both patches and a brass brush. Damn that stuff stinks. Seems to have helped but still having problems getting the Barnes to shoot as well as before, but for now, the gun really likes the 300gr XTPs. Got a new shipment of bullets and sabots in today. Oh well another excuse to go to the range.