204Ruger

I just put together a Thompson Contender (old style) with a new, Thompson Arms 204 Ruger , 23" SS barrel with the standard 1:12 twist. Beautiful custom stock set from Highplains Gunstocks and Vortex Viper HS 4-16x44 scope. It is one of the best looking rifles in my arsenal. Now the problem. Taking it to an indoor, 100 yard range, I sighted in the scope in 3 shots, using factory, Hornady 40 gr. V-Max rounds. When I sent the target out to 100 yards, something is off. Groups are 4" at best. Right, then left then low, high, etc. brought the target to 50 yds. and could shoot 1" groups.

The next day I returned to the range with some hand loads, IMR8208XBR, using the recommended loads from the Hodgeon website. Loaded 3 different loads, 3 bullets of each. Same result, wide pattern at 100 yards. I checked scope mounts were tight, gun closes tight and true. Comments from shooting friends are it either the barrel, scope or the 40gr. bullets are too heavy. That being said, why does it shot good at 50 yards?

By the way, I built another Contender exactly like this one for a buddy first and it shoots perfect. Same caliber, same barrel, same factory ammo. Suggestions?

Holes should be touching @ 100 & 50 yds. The rate of twist my not be fast enough to stabilize the 40gr prjectile. Does your buddy have the 1:12 twist? Try a 32gr and see what happens....

Grendel, as I said, my buddy's gun is exactly the same, 1:12 twist, 23". Only difference in our guns is mine is fancier looking.

Wierd how that fancier stuff throws off the grouping......

With both guns together, accurately measure the actual rate of twist in each. You may be surprised to learn that there's a slight difference in actual twist rate, and that difference if present, could make shooting the problamatic 40gr V-Max not stabilize properly.

As you're probably aware, the majority of 12-twist 204's do not shoot the 40gr V-Max well, but may shoot the 39gr SBK into bugholes....three of my 12-twist 204's do.

204 Ruger in 23" SS contender w/custom furniture
She likes 32 gr. pills

gemihur wrote: ↑Mon Jun 28, 2021 3:46 am204 Ruger in 23" SS contender w/custom furniture
She likes 32 gr. pills

Nice Contender, but you do realize that this post is 8 years old, right?

Resurrecting old posts is called "Zombie Posts".......

gemihur, nice rifle Start a new thread.

Thanks, skipper, I've dressed her up and she shoots like a laser!

zombie life!

That TC looks very nice and should be shooting well.

However with what the original poster asked about his, after the years gone by, I wonder if Surfcitydude found his twist was wrong for the 40 gn bullet and corrected his problem ?

It is my most accurate setup!
I can literally hit a dime at 100 yds.
I need to shoot at a variety of ranges that I can get a feel of it's trajectory
I look forward to that learning curve
Jimmy

I'm sure you already know this, but write down how many clicks you have to dial in when changing distances so you create a come-up chart.

The method I've used for years is below. Zero range is always 100 yards.

Use your ballistics program for your chosen load and make up a 'come-up' chart for the scope's ocular lens cap. I use Sierra Infinity program.
Get your actual velocity via your chronograph at 100 yards.
Then input all environmental conditions where you intend to shoot.
Enter the velocity into the program and make note of the velocity at 50 or 100 yard increments. This will give you the drop in MOA at all ranges.
Use all this data to make up the chart using your printer and affix it to the ocular lens cap for quick and easy field reference.
Simple and effective assuming your scope (I use Leupold exclusively) turrets are marked in 1/4" increments. This translates very well to MOA +/-.

For more exact results, some use 50 or even 25 yard increments for their chart, but for varmint shooting in the field, I've not found this to be necessary, and also results in a cluttered chart and a bit more difficult to use quickly when the varmint might not be sitting still for the shooter to figure out what reference to use. When marked in 100 yard increments, simple extrapolation is used for intermediate distances, say 260 yards vs 200 to 300.

An example is my chart for my Cooper 20VT. The chart is made up for shooting at 4,500' elevation at 68*F, which is average for where most of my rat shooting takes place.



Another one on one of my 204's using two bullet weights (32gr & 39gr) SBK's:



The use of Leupold's most excellent military MK4 elevation turret makes all this a virtual snap. Their "Target" elevation turret can also be used for this application, but I've found the minimal cost of adding their MK4 turret is money well spent for field use, and I've had them installed on all my rat rifles, some of my Cooper rat rifles, all with the M1 elevation turrets installed are shown. The bottom rifle, Cooper Montana Varminter in 204R has both M1 turrets for elevation and windage, but the windage turret is only used for longer range than normal, as 'Kentucky Windage' hold-off is usually adequate for ranges under 500 yards here:



In actual field use, the protocol is; sight varmint, laser range, consult chart for elevation adjustment, dial into elevation turret, allow for wind holdoff if applicable, hold dead-on and press trigger. It works as described as countless prairie dogs, ground squirrels, badgers and rock chucks will attest.

Some may disagree with my method, but since about 1990, I've used this system with excellent results in the rat patch. No matter the range to target, the sound of 'boom whop!' is a constant occurrence. Not many misses, lots of hits 'way out there'.

Thanks for the sage advice, both of you guys.
I'm still learning.