To all the great varmint shooters I come to you for wisdom.

I am shooting a Browning 243 with a standard sporter bbl. with handloads that are getting around 3/4 or abouts in groups for the first three or four shots,then on my last one or two shots it starts to open up to 1 1/2 .

I tend to think it's the bbl. heating up, I let 5 minutes go by between shots.

I have had the stock full length bedded and it has made the groups shrink.

I was wondering if I put moly on my bullets and bbl. if it would keep the bbl. cooler and help the groups shrink even more, or is there something
else I could do.

The load it seems to like the best is 52.5gr. H414
Noslet 55gr. BT, seated deep.

Any advise of the master varminters would be appreciated.

hunter966

I'm not a "Master" but will try to answer a couple of your questions. Having used moly for over 5 years now in all my rifles I can honestly say it will help keep the barrel cooler due to less friction. Wether or not it will shrink your groups you will only find out when you use it, on average the groups remain close to the same or shrink slightly. I have only seen one rifle that didn't like it and the groups opened up to a little over 1 3/4" from 1".
If you are waiting a full 5 minutes between each shot and the gun isn't sitting in the direct sunlight during this time [negating the cooling] you may have something else going on to cause your groups to open up. You didn't say wether you started out with a squeeky clean bore or how often you clean.

Thanks for the reply.

It is shot from a clean bbl. I try to shoot the same bullet and powder combo before I try another so it will give better results.

I tried different primers CCI BR to Federal 210M and that made a little difference.

hunter966

Never have had any luck with full length bedding of any barrel. It seems you are still subject to the changes of the stock: temp and humidity. Since your gun is full length bedded you may be retaining heat selectively on the underside of the barrel causing uneven expansion. You are only looking for about .003 change in the barrel to increase the group by 1 inch at 100 yds.

My biggest concern about bedding the barrel is that you may improve the precision of the groups but the accuracy decreases. Think of precision as the ability to put several bullets close together (where ever that group may be). Accuracy is the ability to tell where the group will be day after day. Letting a barrel flop around in free air makes it come back to the same point every time but tends to open up the group. Putting the barrel under bedding pressure seems to tighten the group but never lets you know exactly where that group will be because of the stock influence.

IMHO, the best bedding I have found is to stop the barrel glassing around the end of the chamber; i.e., about 2 to 3 inches. Doing this on my 22-250 heavy barrel instantly cut the group size in half. Some folks recommend glassing just the action only.

Good shooting.
Ron

I have allot of rifles that will shoot well for 3 rounds and then need cooling time for the 4th and 5th rounds.

Not so with my Lothar Walthar barrel [light varmint taper]. It is a premium barrel with serious stress releiving. Probably Hart, Lija, Pac Nor, Shilen stainless, etc would do the same.

My most accurate rifles shoot moly, but that does not have much to do with the barrel heat warping.
Thick, short, heat stress relieved barrels are what gives immunity to that.

But then, I have a Ruger #1 223 with original barrel [cheapee] that does not wander when hot. I guess I just got lucky.