M39 Bore Condition

[firebat]

Hi all, I bought my first M39 a few days ago and it's an interesting rifle. It has an almost brand new post war stock but it looks like the rifle itself has seen a lot of use during its life. Bluing is almost gone and the bore is far from perfect. I spend a couple of evenings and hundreds of patches removing all the crud from it and it seems that I could finally get to the actual bore surface. Question is, how bad is it? All my other rifles have shiny, almost like new bores and I don't have too much experience with not so good ones. I can see that the rifling is quite worn out but it goes all the way to the crown, so it's not damaged by an issued cleaning rod. There's quite a bit of pitting but there are no big defects that I can see with my naked eyes, even this pitting that is visible on the pictures was picked by my phone camera only, it's not really visible when I look down the pipe. Please let me know what you think.

[Junk Yard Dog]

Welcome to the board. A military rifle that saw war and decades of use after it, the bore is normal. It's the high shine bores that are the exception, or would be in other countries surplus rifles from the corrosive primers era. The Finnish army training leaned heavily toward the creation of individual marksman, and rife maintenance is part of that. However sometimes it is not possible to clean a rifle right away because of being in constant contact with the enemy, or because one is dead, and the rifle lying in the snow next to the body for a few weeks. As pitting goes that is minor, I have seen far worse, craters of the moon worse. That's a nice rifle, ignore the little dusting in the grooves.

[Junk Yard Dog]

Oh yea, and the other thing. These rifles have been here a little over 30 years, most being imported in the late 1980's, and sold up into the first decade of the 21st century before the dealers ran out of imported stock. It's possible some US collector didn't clean the weapon properly, I have seen or heard of an amazing amount of ignorance about what corrosive primers are and how to clean up after them. More than one nice milsurp has been ruined by Bubba back when these rifles sold for well under a hundred bucks. One of the good things about these now going for $600 and up is that buyers are more likely to look after their investments, and take care of them.

[Longcolt44]

JYD has covered the important items but the real test is how they shoot. I have seen and own several rifles that upon first look would swear the bullet would come out sideways but turn out to be great shooters.

[firebat]

Thanks, I'm going to take her to the range soon and see how she shoots pretty soon, hopefully this weekend. I have D166 bullets and N140 powder to handload a period correct ammunition. This is one of the two Finnish rifles that I bought, the other one is a M27 with a bright shiny new bore, I didn't even have to spend a lot of time to see clean patches coming out. I hope this M39 can shoot because I really like this battle worn look

[Junk Yard Dog]

I have at least two that are the same, or a bit darker than yours, they are tack drivers like all the rest. I have one with an odd patch just around the barrel crown, like it was stuck in the mud and not cleaned, fortunately only the outside is pitted, not the rifling. Shoots as well as the best of them, all 2-3 moa at 100 yards with my shitty eyesight.

[firebat]

I have at least two that are the same, or a bit darker than yours, they are tack drivers like all the rest. I have one with an odd patch just around the barrel crown, like it was stuck in the mud and not cleaned, fortunately only the outside is pitted, not the rifling. Shoots as well as the best of them, all 2-3 moa at 100 yards with my shitty eyesight.

I'll be totally happy with 2-3 moa at 100 yds I'll post the results here after the range trip.

[Junk Yard Dog]

I have at least two that are the same, or a bit darker than yours, they are tack drivers like all the rest. I have one with an odd patch just around the barrel crown, like it was stuck in the mud and not cleaned, fortunately only the outside is pitted, not the rifling. Shoots as well as the best of them, all 2-3 moa at 100 yards with my shitty eyesight.

I'll be totally happy with 2-3 moa at 100 yds I'll post the results here after the range trip.

I was also a lot younger then.

[steelbuttplate]

I have at least two that are the same, or a bit darker than yours, they are tack drivers like all the rest. I have one with an odd patch just around the barrel crown, like it was stuck in the mud and not cleaned, fortunately only the outside is pitted, not the rifling. Shoots as well as the best of them, all 2-3 moa at 100 yards with my shitty eyesight.

I'll be totally happy with 2-3 moa at 100 yds I'll post the results here after the range trip.

I had one of those with rounded lands, much rougher than yours, real pitting, it would still shoot 2-3 @ 100 , back when I could see. In your 3rd and fourth pics you can see the crown has an almost slight square shape to it, it's tight .

[Rongo]

Welcome to the Forum!

That bore looks pretty good actually. I have plenty of very accurate rifles with bores like that.

[firebat]

Thank you everyone for your replies So I went to the range, shot some handloads and I think this rifle defintely has potential. It was pretty hot (30c/86f) and I think my handloads were on the hotter side too, so I feel like some load development will definitely produce good results. I like the fact that the horizontal spread is pretty small, may be 2 1/4 inches, so playing with powder load will likely shrink the vertical dispersion. This group was shot at 100 meters, not yards, because I'm in Canada It is a 9-shot group, I thought it was a 10-shot group but apparently I can't count.

[Kemo357]

I would say that you can’t complain about that group!

[Flatlander]

A few questions:

So I went to the range, shot some handloads and I think this rifle defintely has potential.
Agree. What bullets and brass were you using?

I feel like some load development will definitely produce good results.
In agreement as well. Knowing what you're current loading is at this time will maybe get you some suggestions from the handloaders out there.

I like the fact that the horizontal spread is pretty small, may be 2 1/4 inches,
That's good news from the aspect of the rifle's condition. An exclusively vertical spread is usually shooter issue.

It is a 9-shot group.
Next time you take the rifle out, instead of shooting all of your shots into one group, load three rounds at a time into the rifle. Then fire a three shot group on one point of aim (target), reload three more rounds and fire them at another target. load your last three rounds and again, another target. Then measure the greatest distance between the apex of the two furthest shots from each three shot group. The average will give you a more accurate picture of the rifle's potential.

My guess is that with a little work and some good home brewed ammo, you may have a sub 2-MOA rifle.

[Flatlander]

.... another concern.

All of the M-39's I've owned had metal shims at the front and rear of the receiver. I once picked up an M39 that just didn't perform. After lifting the action off the stock I found that a previous owner had removed the shims. All that was left were pressed in shadows of where the shims once were; those shims are there for a reason. I recreated replacements from feeler gauges; that did improve the issue somewhat.

If you haven't done so already, you might want to check it out.

[firebat]

A few questions:

So I went to the range, shot some handloads and I think this rifle defintely has potential.
Agree. What bullets and brass were you using?

I feel like some load development will definitely produce good results.
In agreement as well. Knowing what you're current loading is at this time will maybe get you some suggestions from the handloaders out there.

I like the fact that the horizontal spread is pretty small, may be 2 1/4 inches,
That's good news from the aspect of the rifle's condition. An exclusively vertical spread is usually shooter issue.

It is a 9-shot group.
Next time you take the rifle out, instead of shooting all of your shots into one group, load three rounds at a time into the rifle. Then fire a three shot group on one point of aim (target), reload three more rounds and fire them at another target. load your last three rounds and again, another target. Then measure the greatest distance between the apex of the two furthest shots from each three shot group. The average will give you a more accurate picture of the rifle's potential.

My guess is that with a little work and some good home brewed ammo, you may have a sub 2-MOA rifle.

Thanks, Flatlander, some very good advice that I'll try next time. I never thought about 3x3 shots technique.

My load was: full sized PPU brass, F210M primers, D166 Lapua bullet, 43gr of N140, OAL 3.000", lightly crimped in the cannelure. This rifle has a very long throat, I used a Hornady gauge to measure it and D166 practically goes all the way out of the case before it touches the rifling.

That load was inspired by IV8888 youtube video. He shot a 42.8gr of N140 in Lapua brass in his M39 with great success, I decided to go up to 43.0gr of N140 in PPU brass, because PPU case has more capacity. I also had good success shooting 43.1gr of N140 with all other components being the same and shorter OAL in one of my M91/30 rifles and it chronographed ~2400 fps in a 29" barrel. So my reasoning was that in a 27" m39 barrel and at a max cartridge OAL of 3.000" it should produce somewhat close to 2350 fps, so that it's close to Finnish specs.

[firebat]

.... another concern.

All of the M-39's I've owned had metal shims at the front and rear of the receiver. I once picked up an M39 that just didn't perform. After lifting the action off the stock I found that a previous owner had removed the shims. All that was left were pressed in shadows of where the shims once were; those shims are there for a reason. I recreated replacements from feeler gauges; that did improve the issue somewhat.

If you haven't done so already, you might want to check it out.

I didn't find any shims when I took the rifle apart for cleaning and I didn't notice any imprints of the previous shims at that time but I wasn't really looking for them either, so I'll take another look and inspect those areas more carefully

[firebat]

Shot some more groups today. My hypothesis that 43gr was too hot seems to be correct. The lightest load of today shows the best result. I think it's worth trying going down another grain and see what happens.. It already looks decent at this point, but I wonder if I can shrink it a bit more..

[steelbuttplate]

3 inches is about what they do at 100. 1.5 inches out of a vice was the standard test for Finns.

[Flatlander]

Shot some more groups today. My hypothesis that 43gr was too hot seems to be correct. The lightest load of today shows the best result. I think it's worth trying going down another grain and see what happens.. It already looks decent at this point, but I wonder if I can shrink it a bit more..

Don't know your age, but this analogy goes back generations. If you go back to the day when kids had those wooded tops as toys, the tops had a groove in the top end of the toy where a kid would wrap a string around the groove and at the other end of the string would be a loop. The kid would wrap the string around the top's groove and put his middle finger into the string's loop. The top is now held like a hand grenade. The kid would sling the top across a flat surface causing the top to hit the deck spinning.

The idea of the game is to get the top to spin true for as long as possible
Most kids new to the game would sling the top with maximum effort (velocity), causing the top to hit the deck wobbling the moment it touched ground. The top may or may not correct itself, but it will soon expend its energy trying to correct itself and will topple out of control.

A skilled seven year old knows to use just enough energy to have the top spin true the moment it touches down and and then spins true for the longest time. This is kind of a poor analogy, but the idea is to develop a load that brings the bullet spinning true for a maximum period.

Your bore has been around the block a time or two, reducing loads is sometime the answer.

[Mangrove]

I didn't find any shims when I took the rifle apart for cleaning and I didn't notice any imprints of the previous shims at that time but I wasn't really looking for them either, so I'll take another look and inspect those areas more carefully

The correct Finnish barrel bedding style from the mid-1920s onwards was three-point contact: at the front and the rear action screws and at the front barrel band ("lukonkehyksen etumaisen ja takimaisen kiinnitysruuvin sekä vläsiderenkaan kohdalta"). There should be a space for a sheet of writing paper to move freely between the barrel and the stock, but make light contact at the front barrel band. The action itself should have 0.5 to 1.5 mm space between the back of the action and the inset on the stock.

According to 1959 and 1978 Finnish Defence Forces standing orders, the barrel should be in contact with the stock only at the front band and the receiver. "Minor" gaps between the receiver and the side of the stock are allowed. There should be a 1-2 mm gap between the back of the receiver and the corresponding cutaway on the stock. The two standing orders forbids loosening and/or overtightening any of the screws on the stock as this will cause cracks on the stock and lower the accuracy. If the rear band spring is not providing enough tension, the stock should be modified by adding a metal bar to the rear band.

According to another post-war Finnish Defence Forces permanent order, recoil lug must be in full contact with the stock. The contact area must be wide enough to counteract any force caused by tightening of the nut. There are both horizontal and vertical cracks. Horizontal cracks occur mainly near the "neck" of the stock and near the receiver. These are caused by rough handling, e.g hitting the butt to the ground. Vertical cracks near the receiver are cause by shooting with loose receiver screws.

The correct front band loosening/tightening procedure, according to Finnish Ministry of Defence manual "Kivääri 91", is as follows:
1) Tighten the screw so that the band does not move at all.
2) Loosen the screw 1/2 turns or more until the band can move a little bit.
3) Tighten the screw 1/4 turns.

Two tests mentioned in the Civil Guard and Finnish Defence Forces literature and the permanent orders are the sheet of paper test described earlier and an angle test. The angle test can be performed after the sheet of paper test. If the rifle is lifted to a 45 degree angle (from the floor or a table?), the barrel should noticeably lift up from the stock and return to the original position when the rifle is turned to rest on its butt (i.e. 90 degree angle).

3 inches is about what they do at 100. 1.5 inches out of a vice was the standard test for Finns.

Unfortunately figures like these seems to be part of the internet folklore. The first Civil Guard precision requirements for m/39 rifles, drafted in July 1940, were circa 1.2 (best 9 shots out of 20) and 2.3 MOA (best 18 shots out of 20) at 300 meters:

c) Precision test.
The same rifle barrels used in the high pressure test fire, shall also be used for precision test firing from a distance of 300 meters (20 cartridges). Either hand or machine loaded Civil Guard cartridges shall be used in the test firing.

To be accepted, each barrel must achieve the following result when fired from a machine rest or by a good shooter from a rest:
- The radius of the best 18 shots = 100 mm
- The radius of the best 9 shots = 50 mm

The circles formed by the radii have the same centre.

According to SAKO factory acceptance tests I have seen, the average result for a 1943 m/39 (n=128) with D-166 ammunition was 2 MOA at 300 metres (8 best hits out of 10) or 0.9 MOA at 300 metres (the best 4 hits). Thus a new m/39 using D-166 should be a sub-MOA rifle at 300 metres around 40 % of the time. The factory used a machine rest. The post-war tests with S-283/4 ammunition resulted in a bit better accuracy over the D-166.

Here's a summary of 1937 Civil Guard acceptance trials for SAKO D 108A ammunition using a m/28-30 barrel on a machine rest. They used 2.75 ± 0.04 grams (c. 42.44 ± 0.06 grains) of Finnish VPT powder (batch 144/36) and Sinoxid primer. Bullet weight was 12.0 - 0.1 grams. Average measured muzzle velocity (temperature adjusted) was 736.7 m/s (c. 2417 fps). Average measured chamber pressure was 2846.7 kg/cm² (c. 40489.6 PSI).

The average result for this D 108A batch was 1.0 MOA at 300 metres (9 best hits out of 10) or 0.6 MOA at 300 metres (the best 5 hits). The acceptance limits for the batch were 2.8 MOA (9/10 hits) and 1.4 MOA (5/10 hits) at 300 metres.