Building a benchrest rifle

[Lee Martin]

Mar 18, 2021 18:13:49 GMT -5 flyingzebra said:

If it was easy, everyone would be doing it

So true. Case in point - the 6.5 Creedmoor crowd whose rifles routinely print 1's or better. They never seem to make an appearance at benchrest matches. Then again, if you peruse IBS or NBRSA short range, 600 yard, and 1000 yard match results, you rarely ever see a 6.5 Creedmoor.

-Lee
www.singleactions.com
"Chasing perfection five shots at a time"

[bradshaw]

Lee.... that Wayne France and you both drifted left at the same time (?) tells me the same Ghost Wind bit your bullets. I’ve watched this very JUKE happen in handgun silhouette, adjacent or close revolver shooters firing at the same time, with the same POI drift. Good shooters. It could never be seen on chickens (50 Meters), and would be hard to discern on pigs (100m), but the visuals is graphic when you pick it up in the spotting scope on turkeys (150m), and rams (200 meters).

The flags in silhouette, and there aren’t always flags, generally stand much taller than ground the bullets pass over. And ground slows wind, unless its a drop-wind, or scour across a treeless flat. Just as I believe targets, I believe the bullet. Which, like a dog not telling you where it’s been, the bullet may carry atmospheric secrets to its grave.

I’ve never seen a wind howl so steady as a hot summer wind ripping West to East across the plains, the same wind which blew up the buffalo's touch hole as it mowed grass and spread manure, marching toward the Mississippi; then blew into its nostrils as the beast did an about face, heading west to mow the next crop. Bend a bullet the plains’ wind will, but it doesn’t wrinkle the bullet the way a dancing wind grabs it.
David Bradshaw

[Lee Martin]

Matches #114 & #115
Black Creek Gun Club – Mechanicsville, VA
Fairfax Rod & Gun Club – Manassas, VA
IBS 100 yard VFS
________________________________________________________

Shooting matches the past two weekends, I was reminded why it pays to trust your rifle. At Black Creek, the gun was drilling X’s on the warm up frame. Then the wind stiffened a bit on record #1. And in spite of the sighters telling me to shoot straight through it, I held off the dot. Basically at 4:00 on the dominant right-to-left. Played it safe and thought I still caught the edge of the X on the three questionable bulls. Then the targets came back and I began scoring them. When I got to mine, on all three that weren’t X wipeouts, the bullet went exactly where I held at 4:00. Each time I missed the X by a few hundredths. That 50-2X put me in a hole. The rest of the match I waited for mild wind and held dead on the dot. It paid dividends and I took second place (losing to Cyril on the tiebreaker).



Fast forward to last Saturday at Fairfax. Conditions were mild, but there was enough movement to keep you honest. The first two shots through a cold bore went in the same hole:



I said to myself, “TRUST THE GUN”. Sitting to my right was a good shooter by the name of Mike Nance. We joked about not doubling on each other. Doubling is when you and a competitor to your right or left touch the trigger at the exact same moment. It’s rare, but when it does happen the blast from your gun moves their bullet and vice versa. On the first target, bull #1, I broke the sear and heard a big boom. Either the gun blew up or I didn’t want to look through the scope. The gun was fine, my bullet hole was not. Mike was seated to my right. His shot pushed mine left, just off the dot. I looked over at him and he shook his head. My shot moved his bullet off the dot to the right. It happens, but here’s the kicker. I took every X from that point on, earning another screamer. That’s the 5th time I’ve shot a 24X at 100 yards. And every time, the dropped X happens on target #1. One of these days I hope to shoot a perfect 25X. It has only happened a few dozen times since 1970. The upside is, I took home the win.





My gun on the left. Mike Nance’s on the right. For a few milliseconds, there was simultaneous muzzle blast between the two.



-Lee
www.singleactions.com
"Chasing perfection five shots at a time"

[bradshaw]

Brilliant shooting. Once again, Lee articulates a phenomenon noticeable only at the top level of sharpshooting. In silhouette we had no name for it when adjacent shooters touched off simultaneous. It is not a desirable state of affairs. I attributed any deflection to concussion alone. Bench resters call it doubling, with----at this level of precision----a consequence on exterior ballistics. I doubt a pair of revolver maestros could measure any effect on the bullet’s path. Here, in bench rest, a pair of shooters do exactly that.
David Bradshaw

[flyingzebra]

Excellent

[Lee Martin]

New 6 PPC barrel
______________________________________________

I got a week off from shooting matches and broke in a new barrel on my light varmint 6 PPC. This one is a Kreiger 13.5 twist cut to 21.5”.

The break-in process has nothing to do with the lands and grooves. These barrels come hand lapped. Break-in entails wearing off reamer marks left in the chamber lead. I bored scoped the barrel after chambering and it cut well. Be that as it may, there’s no way around radial machine marks which form perpendicular to the bore axis. These tend to strip copper until fire lapped out. With Kreigers, the blue usually disappears from the cleaning patches after 15 – 20 shots. My process for breaking in is as follows:

• Fire one round, then clean:
• Push 1 patch of Kroil down the barrel
• Bronze brush with Butch’s. 5 strokes per shot. Let this sit for 5 mins
• Push 2 patches soaked in Butch’s.
• Push 2 dry patches
• Repeat the one shot/clean process for 5 rounds
• Shoot 3 shots and clean. Repeat 3 more times.
• Shoot 5 shots and clean. If there’s no blue coloring on the wet patches that come out after bronze brushing, I’m done

The rifle - BAT 3L action, Scoville carbon fiber stock, March 48X scope:



Next I fouled the barrel with 3 shots and went to test groups. Many test without the tuner installed, but I prefer to have it on (backed off the shoulder 1 turn). With my 67 gr Martin bullet, I’ve had very good luck with LT-32 powder. The prior five PPC barrels showed nodes between 27.7 gr. and 28.6 grs. My initial trials are all done the same way with LT-32:

• Start at hard jam for seating depth
• Begin with moderate tension. I use a 0.260” bushing for 0.0025” neck tension. With LT-32, my second tension would be lighter. Unlike N133, LT-32 wants mild pull.
• Load 9 rounds for each charge and shoot three 3-shot groups.
• I loaded 28.0, 28.3, and 28.6 grs

There was moderate wind last Saturday. Nothing horrible, just a steady 6 – 8 mph blow. It’s better to test loads in wind. You want a tune that’ll shoot tight in conditions above dead calm. All of these were done over flags. Here are the group sizes for each three 3-shot group by powder weight:

• 28.0 = 0.156”, 0.114”, and 0.167”. Average = 0.145”
• 28.3 = 0.232”, 0.218”, and 0.194”. Average = 0.214”
• 28.6 = 0.071”, 0.082”, and 0.042”. Average = 0.065”

The 28.6 gr groups - I moved POI closer to the mothball after each. For reference, the inner circle is 0.500”:







28.0 and 28.6 appear to be solid nodes for 55 degrees and 60% humidity. Next time I’ll go down on seating depth to see if that changes anything. I’ll also begin moving the tuner to find the ends of each node. While this is encouraging, 6mm PPCs are finicky. LT-32 is pretty forgiving, but you still have to stay on top of it. LT nodes are wide and can buck temperature changes pretty well. It’s when humidity rises that LT tends to jump tune. I hope to try this barrel in wet weather soon.

-Lee
www.singleactions.com
"Chasing perfection five shots at a time"

[flyingzebra]

Nice

[Lee Martin]

Match #117 – IBS Virginia State Championship
Fairfax Rod & Gun Club – Manassas, VA
IBS 100-200 yard VFS
___________________________________________________________

The VA State Championship was held early this year and fit into one day. We shot 200 yards first, followed by 100. There was an intense storm the night before, and while the rain stopped by Saturday morning, the wind did not. Gusts hit 30 miles per hour throughout the day. When those let up, we still faced swirling 10 – 15 mph sustained blow. These were some of the roughest conditions I’ve seen at Fairfax.

I began the 200 yard leg with my backup .30 Stingray. It was already sighted for that distance and has done well. Going into the final target, I was in fourth place. Unfortunately, I couldn’t hold that position. I shot a ton of sighters and in spite of the wind, landed those in the 10-ring with very aggressive holds. But I couldn’t get that to carry-over to the record bulls. The wind was changing faster than I could get back to the rings that mattered. I dropped 3 points and fell to 12th out of 22.

For the 100 yard segment, I switched to my Martin action in .30 Stingray. Its Krieger barrel has shown a propensity to get through wind. And boy did I need that edge. By the afternoon, the conditions worsened. At times, the flag tails were flipping straight up in the air. Nothing stayed constant enough to trust your sighters. One second, there would be 20 mph right to left, then a shift, and then bi-directional movement across the very short 100 yard span. The gun did not disappoint however. Out of 22 very accomplished shooters, only 5 managed to stay clean (meaning no dropped points). I was one of the five and took fourth place with a 250-14X. Never was I so happy to nab a “250 Club Decal”. Overall, I took 9th in the agg.

View from the firing line:



Looking back at the benches from 200 yards:



-Lee
www.singleactions.com
"Chasing perfection five shots at a time"

[leftysixgun]

Good job Lee!!

[bradshaw]

Lee.... congratulations.
Talked with David Clements this evening. Mentioned wind bends a bullet. Mentioned the job Lee Martin sets himself in benchrest; how I wouldn’t trade offhand on silhouettes with a revolver for the way you stalk a pinhead with a bagged rifle.
david Bradshaw

[Lee Martin]

Match #118 – The Maine Firecracker
Orrington Rod & Gun Club
Orrington, ME & Lincoln County Rifle Club
Damariscotta, ME
IBS 100-200-300 yard VFS
__________________________________________________________________

The Maine Firecracker is the biggest IBS Score match north of the Mason-Dixon line. I hoped to shoot it last year, but COVID threw a wrench in that plan. This year my good friend Wayne France and I made the 1,650 mile round trip and had a blast (pun intended). The Firecracker is unique because the weekend spans two ranges. The 100 yard is held in Orrington on Saturday followed by the 200 on Sunday. Immediately after that match, we pack up and drive south to Damariscotta to set flags for Monday’s 300 yard leg. 36 guns showed-up this year for the event.

I’ve heard about Maine wind, particularly at Damariscotta (which is only a mile or two off the coast). Orrington gave us some tough conditions both days. I finished 2nd place at 100 yards and almost had the win. On the last bull, I needed an X to tie Greg Palman. Had I nailed it, I would’ve gotten him on a 22 X tiebreaker. Unfortunately, that shot strayed from the dot by a hair. I was pleased with 2nd however. Sunday’s wind was even stronger. I hung around only dropping two points, finishing 5th at 200 yards. Wayne put on a clinic and took the 200.

Wayne France and I after setting flags at Orrington:



My gun at 100 yards Saturday:



The firing line at Orrington:



Orrington flags:



Wayne closing out the 200 yard match for the win:



Monday was unusually calm for Damariscotta. Nevertheless, I leaked a few shots into the 9-ring and finished 16th at 300. The most memorable moment of the ’21 Firecracker came on the last target. Wayne and I shared a bench so I witnessed him handling 300 yards first hand. Going into the fifth frame, he needed 2 X’s to tie Robert Brooks. Unlike 100 yards, and even 200, X’s are hard to come by at 300. I watched through the spotting scope as he laid down some sighters. Then the wind picked up. This wasn’t going to be easy. On bull #1 he center punched the X. Moving fast, he wiped out the second X 20 seconds later. He missed the 3rd by a hair, shot a couple more sighters, then proceeded to blow out the last two X’s. A 50-4X target at that yardage is downright stellar. The dot we're trying to hit at 300 yards is only 0.250"....and wind moves bullets a ton over that distance. Wayne won the 300 and took the overall event, shooting a clean 750. Up until this year, no one had ever shot a 750 at the Firecracker (a 750 is a 250 clean target at all three distances). But Wayne was not alone. Randy Jarvais also achieved a 750 and came in 2nd. And even though my 300 yard wasn’t that strong, I finished 7th in the grand agg.

Damariscotta 300 yards:



The benches are fully enclosed at Damariscotta. You actually shoot through flip up windows:







-Lee
www.singleactions.com
"Chasing perfection five shots at a time"

[Lee Martin]

Match #122
Fairfax Rod & Gun Club, Manassas, Virginia
IBS 200 yard VFS
_____________________________________________________________________

I shot my way out of a little slump by winning the 200 yard match at Fairfax.



The slump - after doing well in Maine, I competed in four consecutive 100 yard matches and wasn’t happy with the results:

• June Black Creek – I host this match and it was the first time a 100-100 yard IBS aggregate was done. The Score committee recently passed a rule allowing ranges limited to 100 yards to offer agg events. I finished with a 250-18X in the first match and 250-19X in the second. That was good enough for 3rd overall, but I felt I should’ve done better. Conditions were calm. The gun is quite capable of 20+ Xs in mild air if steered correctly.

• June Fairfax, 100 yard – no explanation on this one except I sucked. The wind was almost none existent, yet I could only get a 250-15X. Oddly, the gun printed extremely tight in the sighter box. But coming around the target, I was missing X’s by a slither. Nothing hung on the edge of the 10-ring. All ten missed X’s were splitting the 10-ring line, mostly at 3 and 9 o’clock.

• July Black Creek – here’s where I figured out what I was doing wrong. On the first three targets, my X count wasn’t great. Mostly 3’s. Sensing my frustration, a friend told me I was letting the gun free recoil too much. I was prone to that mistake early in my shooting career and thought I fixed it. Old habits die hard and often creep back. On target #4 and #5, I put my shoulder closer to the stock. Enough to where my shirt was just touching it. The rest of the day were solid 4 and 5 X’s. I took 6th place with a 250-18X.

Last Saturday at Fairfax, I focused on situating my shoulder in the exact same place. These rifles are sensitive, especially how I set mine up. Using dryer sheets on top of the front and rear bag eliminates drag. But it also causes the gun to slide back fast. How much you allow it to slide can impact precision. That sounds weird because rearward recoil happens after the bullet it gone. I can’t fully explain it, but suspect that as the sear breaks and the firing pin falls, vibrations set up that become the first wave of gun movement, albeit small. Ultimately, the science doesn’t matter. My shooting improved with consistent bench manners. The other thing I did at Fairfax was focus more on the flags out to 100 yards. That doesn’t mean the ones from 100 to 200 don’t matter. They do. But wind closer in has more time to bend on the bullet. This is nothing new. I’ve known it for years. I believe I've been weighing the full range of flags equally. The proof? At 200 yards, the closer in reads worked well. There were times where the 150 yard flag was moving and the three between the bench and 100 weren't. In that condition, the bullet held POI relative to POA. Meaning the 150 yard flag didn't influence it much.



-Lee
www.singleactions.com
"Chasing perfection five shots at a time"

[kings6]

Okay Lee. I know NOTHING about benchrest shooting so here comes some dumb questions. When you say the gun was enjoying too much free recoil until you got close enough for your shirt to touch, does this mean that in essence, the only place you humanly touch the gun is the trigger? If so, how much of a running start does he stock get before you arrest its rearward motion by letting it impact your shoulder? I assume on these calibers and weight of guns, the recoil impact is something that is not objectionable. IF it were, I would think your body would be subconsciously reacting to the coming impact by the time you shoot all the rounds.

[Lee Martin]

You're correct Robb. In free recoil, the only thing touching the gun is your trigger finger. Depending on the class, short range BR rifles weigh 10.5 - 13.5 lbs. They're heavy. And the cartridges we use don't generate a lot of recoil. For instance, my .30 Stingray shoots a 114 gr bullet at 3,020 fps. 6 PPC's are 60 - 70 gr bullets at 3,200 - 3,400 fps. Basically light bullets sent fast (we do run a lot of case pressure).

The key to free recoil is let the gun do the same thing every time. You don't want it to come back too far or it'll get disrupted in the bags. I think I was allowing an inch plus between the butt and my shoulder. That was sloppy and it showed on paper. I went back to near touch and saw improvement. Two keys to all this:

1) Don't influence the rifle, but stop it quickly as it recoils. 1/2" or less movement before contacting you is good.
2) Keep your head down throughout. As you noted, anticipating recoil is bad.

-Lee
www.singleactions.com
"Chasing perfection five shots at a time"

[Lee Martin]

Match #123
Black Creek Gun Club, Mechanicsville, VA
IBS 100 yard VFS
______________________________________________________________

The forecast called for heavy rain all morning through mid-afternoon. And that forecast was spot on. The minute we arrived at 7 AM, the skies opened up and poured solid until we finished at 1:00. It made for a very wet and muddy match. The targets were so soaked the paper tore when I scored each bull. But we made a fun day of it in spite of the conditions. The wind was calm early on, but then picked up during the second half. At one point the rain was blowing in under the roof. No surprise the competitor count was down.

My .30 Stingray shot extremely tight. Target #1 was almost a 5X. I missed the last dot by a couple of hundredths. I thought it may reticle in, but no dice. The next three frames were 5X scores with a lot of wipe outs. Going into the last target, I thought I had a good chance at shooting another screamer (which is a 24 out of 25 X’s). Unfortunately, the wind really picked up and bullets went everywhere. I wasn’t the only one that struggled. I only took 2X’s, but it was enough to get the win.







Video of the rain. This was as mild as it got for the duration of the match. Big nod to the target crew.



The ride home wasn’t much better.



-Lee
www.singleactions.com
"Chasing perfection five shots at a time"