FX M3 Javelin 40gr can't find tune

[jskd82]

Looking for some help or starting tune to shoot the Javelin 40 grain slugs out of my M3 700mm Sniper with Slug power kit installed, Superior heavy liner and barrel tensioning kit. I had it tuned that it was shooting sub MOA for 50 and 100 yards but I changed some settings and now can't find that sweet spot again. I should have taken note of the tune settings I had but I thought I sort of knew it and would be able to find it again because it didn't take me long, I guess I just got lucky the first time, because I cannot find it to save my life! I think the reg pressure was around 160 on the second reg and I thought the FPS was at around 912 or the low 900's. I don't quite remember what the hammer was set to. I have gone through seven tubes of slugs so far and just can't find it, this is getting very expensive and frustrating. The groups are horrendous and shooting all over the place, I would give up and say it isn't possible to get good groups with these slugs if I didn't find it previously, so I know what it can do.

I'm starting from 25 yards like I did the first time I found the tune. I have tried 150 to 170 in 5 bar increments. I start with the valve unscrewed around the imaginary 6 mark, macro at 16, micro at max almost till the gun won't cock. I lower the macro until there is a drop in velocity and then do the same with micro. I am getting keyholes at higher velocity, I would say 930+ I get clean holes around 920 FPS and lower but the grouping is wild. One thing is I can't remember what valve spring I had in the gun when I found the tune. I am adjusting the valve in until velocity drops as the final step. Any ideas?

 

[weevil]

Keyholes mean that the slugs are not getting sufficient spin. Lower speed requires less spin to stabilize. However, first question is: when did you last clean the liner?

 

[Long_Gun_Dallas]

Clean your bore

 

[jskd82]

Keyholes mean that the slugs are not getting sufficient spin. Lower speed requires less spin to stabilize. However, first question is: when did you last clean the liner?

Forgot to add that I did dry run a snake thru, without the brass brushes of course. Thanks.

 

[jskd82]

Ok so I just ran some patches thru with Ballistol and it seems to have stopped the keyholing. I did some tuning and I got a few holes pretty tight but would then get some thrown in a complete different area. Would switching to a lighter grain slug be easier to tune?

 

[MEC17670]

What caliber are you shooting?

 

[weevil]

Second question I would ask is: Was it hotter when it was shooting better? Warmer air is less dense and demands less spin. More broadly, it’s certainly worth trying something lighter and easier to spin stabilize.

(And heavy slugs can mandate cleaning in as little as every 100 shots)

 

[jskd82]

What caliber are you shooting?

.22

 

[jskd82]

Second question I would ask is: Was it hotter when it was shooting better? Warmer air is less dense and demands less spin. More broadly, it’s certainly worth trying something lighter and easier to spin stabilize.

No it was around the same temps. Maybe that's why the 34gr Javelin is sold out lol I might try to find some and give those a try. Sucks cause I know I had it shooting good.

 

[Long_Gun_Dallas]

Very possibly could shoot better with lighter slugs. At heaviest I shot griffin 36gr 218 slugs out of my 700mm crown mk1. 65fpe. Shot around 1/2 moa as long as I kept it clean. It is worth trying 217 slugs to see if they will work. Would definitely foul less. My gun did not like moderators no matter what I tried. I believe due to the barrel being so long. Also polished the bore and used gunzilla to keep it from fouling so fast. Old slug a liner

 

[jskd82]

Thanks I'll try some lighter ones as well. The 40gr Javelins I am using are the .217, I thought about trying .218 but maybe not a good idea?

 

[Long_Gun_Dallas]

Personally, I'd try the 218s as well if you haven't. Especially if the 217s aren't working out.

 

[weevil]

My heavy liners always favored the Jav 218s, but now I only shoot Altaros, which I think are 2175.

 

[jskd82]

Looks like cleaning the barrel was a major part of it, another thing is I put the harmonic dampener back on and it started shooting a nice group at 50 yards. I tightened it up by slightly closing the valve and got a nice 10 shot group with me screwing up on the last shot, these were at 895fps. I then moved to 100 yards and the grouping spread out a little more. I tried some H&N .217 36gr slugs at 100 yards using the same tune and it was shooting a tighter group going at around 965fps. How often do you guys clean the barrel?

 

[weevil]

The longer the slug, the quicker it fouls but every liner is different and you’ll need to track how yours behaves with your slugs. Some folks clean every 50 shots. In my experience, if they start keyholing when dirty, it suggest that the diameter is too small.

 

[Vetmx]

Once you are content that this is the best you and your gun can do, it’s time to see if it will do it tomorrow. If it does and you’re still happy, then it’s time to clean the gun and see how it tracks from shot #zero to when it goes bad. My slug guns with real barrels or FX barrels with a bunch of parts all operate at their best from shot 15-175. Your lube will determine some things and you will have to determine just what it takes to get your barrel back to performing for another X amount of shots. You can try to use my info or Billy-Bobs info but if you aren’t using the same slug, same lube, same velocity, and same barrel prep as another guy, things might be a little different for you. Some brands of slugs because of their recipe, shoot cleaner. I was going to reply to your topic earlier but something weird was going on with my connection to AGN so I couldn’t. I wanted to tell you that shooting slugs out of an airgun is not like pellets or a powder burner. A slug shooting airgun is more like a muzzleloader. You just can’t keep shooting and shooting. You have to clean it, and clean it right. If your gun requires a brush, use one. I believe you fouled your gun horribly when you went on a frustrated tuning rampage. Get it clean and keep it cleaner by not waiting so long.

 

[jskd82]

The longer the slug, the quicker it fouls but every liner is different and you’ll need to track how yours behaves with your slugs. Some folks clean every 50 shots. In my experience, if they start keyholing when dirty, it suggest that the diameter is too small.

Thanks for the advice, I will definitely keep an eye on it now that I know how much a fouled barrel is impacted.

 

[jskd82]

Once you are content that this is the best you and your gun can do, it’s time to see if it will do it tomorrow. If it does and you’re still happy, then it’s time to clean the gun and see how it tracks from shot #zero to when it goes bad. My slug guns with real barrels or FX barrels with a bunch of parts all operate at their best from shot 15-175. Your lube will determine some things and you will have to determine just what it takes to get your barrel back to performing for another X amount of shots. You can try to use my info or Billy-Bobs info but if you aren’t using the same slug, same lube, same velocity, and same barrel prep as another guy, things might be a little different for you. Some brands of slugs because of their recipe, shoot cleaner. I was going to reply to your topic earlier but something weird was going on with my connection to AGN so I couldn’t. I wanted to tell you that shooting slugs out of an airgun is not like pellets or a powder burner. A slug shooting airgun is more like a muzzleloader. You just can’t keep shooting and shooting. You have to clean it, and clean it right. If your gun requires a brush, use one. I believe you fouled your gun horribly when you went on a frustrated tuning rampage. Get it clean and keep it cleaner by not waiting so long.

I think you are spot on with me going on a tuning rampage and all it needed was to be cleaned. I'm fairly new to the game and never thought of it having that much significance on accuracy. Another thing I am noticing is how sensitive it is to the way the gun is held. It seems like loosely gripping and tightly gripping will give a different POI, or it's just me. Thanks for the help!

 

[Vetmx]

Yes, a good accurate tune is a good accurate tune no matter how you hold the gun. Just like a scattergun tune will always be a scattergun no matter how perfect you hold the gun. But I do believe when you are looking for that last couple percent on paper, you have to test different holds. The question is are we doing it for accuracy or consistency? But on the other side of the coin is if you have to have everything just right for your gun to be accurate, you better not hunt with it. All airguns are hold sensitive to a point because of the hammer system and how long it takes for the projectile to leave the barrel after we squeeze the trigger.