MP 6.35 Airgun Bullet mold and dechoked GM .25 barrel

[mackeral5]

Yesterday I received a couple of molds from Miha.  One was his 6.35 airgun bullet mold.  It's an aluminum 8 cavity.  After a quick spray with brake clean and a few heat cycles on a hotplate I cast up 120 or so slugs.  They are dropping right at 48-48.5gr.

I will say this mold is easier to cast than the 5.52 mold.  I think the reason is I have a difficult time managing the pour rate with my bottom pour mold and on small projectiles this results in overflowing into the adjacent cavity.  With larger projectiles it is not a challenge.  Something for me to work on.... 

I tested with one of my contraptions that I built.  it is a single shot B-rod based on a Gen 1 Marauder.  Normally it is in .357, but I also have a .25 barrel/bolt for it.  Since this is a Gen 1, with transfer port sealing modified to seal from valve too breech, caliber swaps are as simple as removing the scope to access the barrel screws, then swap barrel's/bolts.  Then a slight HST adjustment and you are ready to go with the caliber of choice.  The barrel is a Marauder Green Mountain .25 with approximately 1 inch trimmed at the muzzle, removing the choke.  These are great barrels, but the rate of twist is relatively fast.  Not the best match for 34gr pellets running in the 900's, but a great slug barrel, albeit a little short.  It measures about 18" from muzzle to barrel port.



The gun is unregulated, using a modified Cothran valve that results in a pretty flat shot string across a 1000psi or so range of pressure.  Call it 3000psi down to 2000psi. 

Shooting these slugs yields a shot string of 20 shots averaging 825fps.  It can be tuned higher, up to 900fps, but shot count is cut in half.  20 shots of 72fpe isn't bad for an 18" barreled gun.

Here are the slugs. These are not weighed/sorted, they have been rattled around in this pellet tin with a little 10wt shock oil.  They were shot unsized, as-cast.



And the shooting position



And the target.  20 shots, unregulated.



The lone flier occurred around shot 3, I'm pretty sure I inserted the bullet backwards.  That is fairly easy to do with these if one isn't paying close attention. 

This target is typical of this particular gun's 50 yard accuracy, regardless of tune, regardless of caliber.  it is not a surgical instrument, long range precision was not in scope for the build.... 

Early results indicate this bullet is a good match for a de-choked GM barrel. 

[mackeral5]

I think I found my heavy pellet replacement. 

After 4 or 5 attempts the wind cooperated and I just clicked off this 5 shot group at 100 yards.  Not the best group, but considering what it was shot with, it is a very good group for me.  This gun is very difficult for me to shoot precisely.... 







This mold is proving to be very forgiving, easy to cast.  No sizing/weighing/sorting was done, these were shot as-cast.

[Firewalker]

I think I found my heavy pellet replacement. 

After 4 or 5 attempts the wind cooperated and I just clicked off this 5 shot group at 100 yards.  Not the best group, but considering what it was shot with, it is a very good group for me.  This gun is very difficult for me to shoot precisely.... 

This mold is proving to be very forgiving, easy to cast.  No sizing/weighing/sorting was done, these were shot as-cast.

Mine is on the way! Thank you for the "push"!!   

[Nvreloader]

Mike
Thank you for the test results, sounds like that bullet might work the the Sentry/Dar Gauntlet etc.

Were these pure soft lead or an alloy? Do you plan on sizing for the best accuracy?

When you do the 22 cal, I'll be following along............

Thanks,
Don

[mackeral5]

Mike
Thank you for the test results, sounds like that bullet might work the the Sentry/Dar Gauntlet etc.

Were these pure soft lead or an alloy? Do you plan on sizing for the best accuracy?

When you do the 22 cal, I'll be following along............

Thanks,
Don

Don--Bullets were an unknown alloy.   A mix recovered from my trap.  JSB, NSA, DCB, GT.  It is a bit on the hard side.  At some point I'll try for better accuracy, but with the test gun the results were "good enough".  it is really an inside of 70 yards gun.  I don't have another gun that is good fit for this bullet, at least not assembled.  IMO, the Gauntlet is not a good fit due to the tiny plenum and (again, IMO) the Gauntlet isn't suitable for >70 fpe repeatable long range accuracy.  I may catch some flack on that, but again that is just my opinion--my primary reason---breech flex in the mag slot. 

Mike

[Nvreloader]

Thanks Mike
I was not aware of that info on the Gauntlet............

I have my Sentry and Dar for a back up........I think? 
IMHO, I would think/believe that either of these should work with bullets............?

I shoot nothing, but pure lead for pellets, as soon as the molds get here, I'll find out...........

Don

[mackeral5]

Thanks Mike
I was not aware of that info on the Gauntlet............

I have my Sentry and Dar for a back up........I think? 
IMHO, I would think/believe that either of these should work with bullets............?

I shoot nothing, but pure lead for pellets, as soon as the molds get here, I'll find out...........

Don

Bear in mind that is just my opinion on the Gauntlet, your mileage may vary.  Many have cranked up the Gauntlet's power much further, so in theory it can be done.  That is just a bit too far outside of the gun's sweet spot, IMO it would be better to pick a more suitable platform. 

With a 23-24 " barrel these bullets should produce around 95-100fpe, which is well outside of the operating window I would run a Gauntlet.....

[Firewalker]

Thanks Mike
I was not aware of that info on the Gauntlet............

I have my Sentry and Dar for a back up........I think? 
IMHO, I would think/believe that either of these should work with bullets............?

I shoot nothing, but pure lead for pellets, as soon as the molds get here, I'll find out...........

Don

The DAR looks to be working just fine with the MP slug. Ill grab the Chrony tomorrow and see what the fps is but so far, the DAR seems to have enough gas in the tank for a magazine of those 46gr beauties! I have my daily shooter (.25) sighted in at 50y and took an offhand shot at a starling with a head shot but it didnt slow the slug down a bit.

Ill have to be careful to only make flat shots with these as the overtravel may be several hundred yards.